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# WELCOME TO SQUID 4.13 # ---------------------------- # # This is the documentation for the Squid configuration file. # This documentation can also be found online at: # http://www.squid-cache.org/Doc/config/ # # You may wish to look at the Squid home page and wiki for the # FAQ and other documentation: # http://www.squid-cache.org/ # http://wiki.squid-cache.org/SquidFaq # http://wiki.squid-cache.org/ConfigExamples # # This documentation shows what the defaults for various directives # happen to be. If you don't need to change the default, you should # leave the line out of your squid.conf in most cases. # # In some cases "none" refers to no default setting at all, # while in other cases it refers to the value of the option # - the comments for that keyword indicate if this is the case. # # Configuration options can be included using the "include" directive. # Include takes a list of files to include. Quoting and wildcards are # supported. # # For example, # # include /path/to/included/file/squid.acl.config # # Includes can be nested up to a hard-coded depth of 16 levels. # This arbitrary restriction is to prevent recursive include references # from causing Squid entering an infinite loop whilst trying to load # configuration files. # # Values with byte units # # Squid accepts size units on some size related directives. All # such directives are documented with a default value displaying # a unit. # # Units accepted by Squid are: # bytes - byte # KB - Kilobyte (1024 bytes) # MB - Megabyte # GB - Gigabyte # # Values with spaces, quotes, and other special characters # # Squid supports directive parameters with spaces, quotes, and other # special characters. Surround such parameters with "double quotes". Use # the configuration_includes_quoted_values directive to enable or # disable that support. # # Squid supports reading configuration option parameters from external # files using the syntax: # parameters("/path/filename") # For example: # acl whitelist dstdomain parameters("/etc/squid/whitelist.txt") # # Conditional configuration # # If-statements can be used to make configuration directives # depend on conditions: # # if <CONDITION> # ... regular configuration directives ... # [else # ... regular configuration directives ...] # endif # # The else part is optional. The keywords "if", "else", and "endif" # must be typed on their own lines, as if they were regular # configuration directives. # # NOTE: An else-if condition is not supported. # # These individual conditions types are supported: # # true # Always evaluates to true. # false # Always evaluates to false. # <integer> = <integer> # Equality comparison of two integer numbers. # # # SMP-Related Macros # # The following SMP-related preprocessor macros can be used. # # ${process_name} expands to the current Squid process "name" # (e.g., squid1, squid2, or cache1). # # ${process_number} expands to the current Squid process # identifier, which is an integer number (e.g., 1, 2, 3) unique # across all Squid processes of the current service instance. # # ${service_name} expands into the current Squid service instance # name identifier which is provided by -n on the command line. # # Logformat Macros # # Logformat macros can be used in many places outside of the logformat # directive. In theory, all of the logformat codes can be used as %macros, # where they are supported. In practice, a %macro expands as a dash (-) when # the transaction does not yet have enough information and a value is needed. # # There is no definitive list of what tokens are available at the various # stages of the transaction. # # And some information may already be available to Squid but not yet # committed where the macro expansion code can access it (report # such instances!). The macro will be expanded into a single dash # ('-') in such cases. Not all macros have been tested. # # TAG: broken_vary_encoding # This option is not yet supported by Squid-3. #Default: # none # TAG: cache_vary # This option is not yet supported by Squid-3. #Default: # none # TAG: error_map # This option is not yet supported by Squid-3. #Default: # none # TAG: external_refresh_check # This option is not yet supported by Squid-3. #Default: # none # TAG: location_rewrite_program # This option is not yet supported by Squid-3. #Default: # none # TAG: refresh_stale_hit # This option is not yet supported by Squid-3. #Default: # none # TAG: cache_peer_domain # Replace with dstdomain ACLs and cache_peer_access. #Default: # none # TAG: ie_refresh # Remove this line. The behaviour enabled by this is no longer needed. #Default: # none # TAG: sslproxy_cafile # Remove this line. Use tls_outgoing_options cafile= instead. #Default: # none # TAG: sslproxy_capath # Remove this line. Use tls_outgoing_options capath= instead. #Default: # none # TAG: sslproxy_cipher # Remove this line. Use tls_outgoing_options cipher= instead. #Default: # none # TAG: sslproxy_client_certificate # Remove this line. Use tls_outgoing_options cert= instead. #Default: # none # TAG: sslproxy_client_key # Remove this line. Use tls_outgoing_options key= instead. #Default: # none # TAG: sslproxy_flags # Remove this line. Use tls_outgoing_options flags= instead. #Default: # none # TAG: sslproxy_options # Remove this line. Use tls_outgoing_options options= instead. #Default: # none # TAG: sslproxy_version # Remove this line. Use tls_outgoing_options options= instead. #Default: # none # TAG: hierarchy_stoplist # Remove this line. Use always_direct or cache_peer_access ACLs instead if you need to prevent cache_peer use. #Default: # none # TAG: log_access # Remove this line. Use acls with access_log directives to control access logging #Default: # none # TAG: log_icap # Remove this line. Use acls with icap_log directives to control icap logging #Default: # none # TAG: ignore_ims_on_miss # Remove this line. The HTTP/1.1 feature is now configured by 'cache_miss_revalidate'. #Default: # none # TAG: balance_on_multiple_ip # Remove this line. Squid performs a 'Happy Eyeballs' algorithm, this multiple-IP algorithm is not longer relevant. #Default: # none # TAG: chunked_request_body_max_size # Remove this line. Squid is now HTTP/1.1 compliant. #Default: # none # TAG: dns_v4_fallback # Remove this line. Squid performs a 'Happy Eyeballs' algorithm, the 'fallback' algorithm is no longer relevant. #Default: # none # TAG: emulate_httpd_log # Replace this with an access_log directive using the format 'common' or 'combined'. #Default: # none # TAG: forward_log # Use a regular access.log with ACL limiting it to MISS events. #Default: # none # TAG: ftp_list_width # Remove this line. Configure FTP page display using the CSS controls in errorpages.css instead. #Default: # none # TAG: ignore_expect_100 # Remove this line. The HTTP/1.1 feature is now fully supported by default. #Default: # none # TAG: log_fqdn # Remove this option from your config. To log FQDN use %>A in the log format. #Default: # none # TAG: log_ip_on_direct # Remove this option from your config. To log server or peer names use %<A in the log format. #Default: # none # TAG: maximum_single_addr_tries # Replaced by connect_retries. The behaviour has changed, please read the documentation before altering. #Default: # none # TAG: referer_log # Replace this with an access_log directive using the format 'referrer'. #Default: # none # TAG: update_headers # Remove this line. The feature is supported by default in storage types where update is implemented. #Default: # none # TAG: url_rewrite_concurrency # Remove this line. Set the 'concurrency=' option of url_rewrite_children instead. #Default: # none # TAG: useragent_log # Replace this with an access_log directive using the format 'useragent'. #Default: # none # TAG: dns_testnames # Remove this line. DNS is no longer tested on startup. #Default: # none # TAG: extension_methods # Remove this line. All valid methods for HTTP are accepted by default. #Default: # none # TAG: zero_buffers #Default: # none # TAG: incoming_rate #Default: # none # TAG: server_http11 # Remove this line. HTTP/1.1 is supported by default. #Default: # none # TAG: upgrade_http0.9 # Remove this line. ICY/1.0 streaming protocol is supported by default. #Default: # none # TAG: zph_local # Alter these entries. Use the qos_flows directive instead. #Default: # none # TAG: header_access # Since squid-3.0 replace with request_header_access or reply_header_access # depending on whether you wish to match client requests or server replies. #Default: # none # TAG: httpd_accel_no_pmtu_disc # Since squid-3.0 use the 'disable-pmtu-discovery' flag on http_port instead. #Default: # none # TAG: wais_relay_host # Replace this line with 'cache_peer' configuration. #Default: # none # TAG: wais_relay_port # Replace this line with 'cache_peer' configuration. #Default: # none # OPTIONS FOR SMP # ----------------------------------------------------------------------------- # TAG: workers # Number of main Squid processes or "workers" to fork and maintain. # 0: "no daemon" mode, like running "squid -N ..." # 1: "no SMP" mode, start one main Squid process daemon (default) # N: start N main Squid process daemons (i.e., SMP mode) # # In SMP mode, each worker does nearly all what a single Squid daemon # does (e.g., listen on http_port and forward HTTP requests). #Default: # SMP support disabled. # TAG: cpu_affinity_map # Usage: cpu_affinity_map process_numbers=P1,P2,... cores=C1,C2,... # # Sets 1:1 mapping between Squid processes and CPU cores. For example, # # cpu_affinity_map process_numbers=1,2,3,4 cores=1,3,5,7 # # affects processes 1 through 4 only and places them on the first # four even cores, starting with core #1. # # CPU cores are numbered starting from 1. Requires support for # sched_getaffinity(2) and sched_setaffinity(2) system calls. # # Multiple cpu_affinity_map options are merged. # # See also: workers #Default: # Let operating system decide. # TAG: shared_memory_locking on|off # Whether to ensure that all required shared memory is available by # "locking" that shared memory into RAM when Squid starts. The # alternative is faster startup time followed by slightly slower # performance and, if not enough RAM is actually available during # runtime, mysterious crashes. # # SMP Squid uses many shared memory segments. These segments are # brought into Squid memory space using an mmap(2) system call. During # Squid startup, the mmap() call often succeeds regardless of whether # the system has enough RAM. In general, Squid cannot tell whether the # kernel applies this "optimistic" memory allocation policy (but # popular modern kernels usually use it). # # Later, if Squid attempts to actually access the mapped memory # regions beyond what the kernel is willing to allocate, the # "optimistic" kernel simply kills Squid kid with a SIGBUS signal. # Some of the memory limits enforced by the kernel are currently # poorly understood: We do not know how to detect and check them. This # option ensures that the mapped memory will be available. # # This option may have a positive performance side-effect: Locking # memory at start avoids runtime paging I/O. Paging slows Squid down. # # Locking memory may require a large enough RLIMIT_MEMLOCK OS limit, # CAP_IPC_LOCK capability, or equivalent. #Default: # shared_memory_locking off # TAG: hopeless_kid_revival_delay time-units # Normally, when a kid process dies, Squid immediately restarts the # kid. A kid experiencing frequent deaths is marked as "hopeless" for # the duration specified by this directive. Hopeless kids are not # automatically restarted. # # Currently, zero values are not supported because they result in # misconfigured SMP Squid instances running forever, endlessly # restarting each dying kid. To effectively disable hopeless kids # revival, set the delay to a huge value (e.g., 1 year). # # Reconfiguration also clears all hopeless kids designations, allowing # for manual revival of hopeless kids. #Default: # hopeless_kid_revival_delay 1 hour # OPTIONS FOR AUTHENTICATION # ----------------------------------------------------------------------------- # TAG: auth_param # This is used to define parameters for the various authentication # schemes supported by Squid. # # format: auth_param scheme parameter [setting] # # The order in which authentication schemes are presented to the client is # dependent on the order the scheme first appears in config file. IE # has a bug (it's not RFC 2617 compliant) in that it will use the basic # scheme if basic is the first entry presented, even if more secure # schemes are presented. For now use the order in the recommended # settings section below. If other browsers have difficulties (don't # recognize the schemes offered even if you are using basic) either # put basic first, or disable the other schemes (by commenting out their # program entry). # # Once an authentication scheme is fully configured, it can only be # shutdown by shutting squid down and restarting. Changes can be made on # the fly and activated with a reconfigure. I.E. You can change to a # different helper, but not unconfigure the helper completely. # # Please note that while this directive defines how Squid processes # authentication it does not automatically activate authentication. # To use authentication you must in addition make use of ACLs based # on login name in http_access (proxy_auth, proxy_auth_regex or # external with %LOGIN used in the format tag). The browser will be # challenged for authentication on the first such acl encountered # in http_access processing and will also be re-challenged for new # login credentials if the request is being denied by a proxy_auth # type acl. # # WARNING: authentication can't be used in a transparently intercepting # proxy as the client then thinks it is talking to an origin server and # not the proxy. This is a limitation of bending the TCP/IP protocol to # transparently intercepting port 80, not a limitation in Squid. # Ports flagged 'transparent', 'intercept', or 'tproxy' have # authentication disabled. # # === Parameters common to all schemes. === # # "program" cmdline # Specifies the command for the external authenticator. # # By default, each authentication scheme is not used unless a # program is specified. # # See http://wiki.squid-cache.org/Features/AddonHelpers for # more details on helper operations and creating your own. # # "key_extras" format # Specifies a string to be append to request line format for # the authentication helper. "Quoted" format values may contain # spaces and logformat %macros. In theory, any logformat %macro # can be used. In practice, a %macro expands as a dash (-) if # the helper request is sent before the required macro # information is available to Squid. # # By default, Squid uses request formats provided in # scheme-specific examples below (search for %credentials). # # The expanded key_extras value is added to the Squid credentials # cache and, hence, will affect authentication. It can be used to # autenticate different users with identical user names (e.g., # when user authentication depends on http_port). # # Avoid adding frequently changing information to key_extras. For # example, if you add user source IP, and it changes frequently # in your environment, then max_user_ip ACL is going to treat # every user+IP combination as a unique "user", breaking the ACL # and wasting a lot of memory on those user records. It will also # force users to authenticate from scratch whenever their IP # changes. # # "realm" string # Specifies the protection scope (aka realm name) which is to be # reported to the client for the authentication scheme. It is # commonly part of the text the user will see when prompted for # their username and password. # # For Basic the default is "Squid proxy-caching web server". # For Digest there is no default, this parameter is mandatory. # For NTLM and Negotiate this parameter is ignored. # # "children" numberofchildren [startup=N] [idle=N] [concurrency=N] # [queue-size=N] [on-persistent-overload=action] # # The maximum number of authenticator processes to spawn. If # you start too few Squid will have to wait for them to process # a backlog of credential verifications, slowing it down. When # password verifications are done via a (slow) network you are # likely to need lots of authenticator processes. # # The startup= and idle= options permit some skew in the exact # amount run. A minimum of startup=N will begin during startup # and reconfigure. Squid will start more in groups of up to # idle=N in an attempt to meet traffic needs and to keep idle=N # free above those traffic needs up to the maximum. # # The concurrency= option sets the number of concurrent requests # the helper can process. The default of 0 is used for helpers # who only supports one request at a time. Setting this to a # number greater than 0 changes the protocol used to include a # channel ID field first on the request/response line, allowing # multiple requests to be sent to the same helper in parallel # without waiting for the response. # # Concurrency must not be set unless it's known the helper # supports the input format with channel-ID fields. # # The queue-size option sets the maximum number of queued # requests. A request is queued when no existing child can # accept it due to concurrency limit and no new child can be # started due to numberofchildren limit. The default maximum is # 2*numberofchildren. Squid is allowed to temporarily exceed the # configured maximum, marking the affected helper as # "overloaded". If the helper overload lasts more than 3 # minutes, the action prescribed by the on-persistent-overload # option applies. # # The on-persistent-overload=action option specifies Squid # reaction to a new helper request arriving when the helper # has been overloaded for more that 3 minutes already. The number # of queued requests determines whether the helper is overloaded # (see the queue-size option). # # Two actions are supported: # # die Squid worker quits. This is the default behavior. # # ERR Squid treats the helper request as if it was # immediately submitted, and the helper immediately # replied with an ERR response. This action has no effect # on the already queued and in-progress helper requests. # # NOTE: NTLM and Negotiate schemes do not support concurrency # in the Squid code module even though some helpers can. # # # # === Example Configuration === # # This configuration displays the recommended authentication scheme # order from most to least secure with recommended minimum configuration # settings for each scheme: # ##auth_param negotiate program <uncomment and complete this line to activate> ##auth_param negotiate children 20 startup=0 idle=1 ##auth_param negotiate keep_alive on ## ##auth_param digest program <uncomment and complete this line to activate> ##auth_param digest children 20 startup=0 idle=1 ##auth_param digest realm Squid proxy-caching web server ##auth_param digest nonce_garbage_interval 5 minutes ##auth_param digest nonce_max_duration 30 minutes ##auth_param digest nonce_max_count 50 ## ##auth_param ntlm program <uncomment and complete this line to activate> ##auth_param ntlm children 20 startup=0 idle=1 ##auth_param ntlm keep_alive on ## ##auth_param basic program <uncomment and complete this line> ##auth_param basic children 5 startup=5 idle=1 ##auth_param basic realm Squid proxy-caching web server ##auth_param basic credentialsttl 2 hours #Default: # none # TAG: authenticate_cache_garbage_interval # The time period between garbage collection across the username cache. # This is a trade-off between memory utilization (long intervals - say # 2 days) and CPU (short intervals - say 1 minute). Only change if you # have good reason to. #Default: # authenticate_cache_garbage_interval 1 hour # TAG: authenticate_ttl # The time a user & their credentials stay in the logged in # user cache since their last request. When the garbage # interval passes, all user credentials that have passed their # TTL are removed from memory. #Default: # authenticate_ttl 1 hour # TAG: authenticate_ip_ttl # If you use proxy authentication and the 'max_user_ip' ACL, # this directive controls how long Squid remembers the IP # addresses associated with each user. Use a small value # (e.g., 60 seconds) if your users might change addresses # quickly, as is the case with dialup. You might be safe # using a larger value (e.g., 2 hours) in a corporate LAN # environment with relatively static address assignments. #Default: # authenticate_ip_ttl 1 second # ACCESS CONTROLS # ----------------------------------------------------------------------------- # TAG: external_acl_type # This option defines external acl classes using a helper program # to look up the status # # external_acl_type name [options] FORMAT /path/to/helper [helper arguments] # # Options: # # ttl=n TTL in seconds for cached results (defaults to 3600 # for 1 hour) # # negative_ttl=n # TTL for cached negative lookups (default same # as ttl) # # grace=n Percentage remaining of TTL where a refresh of a # cached entry should be initiated without needing to # wait for a new reply. (default is for no grace period) # # cache=n The maximum number of entries in the result cache. The # default limit is 262144 entries. Each cache entry usually # consumes at least 256 bytes. Squid currently does not remove # expired cache entries until the limit is reached, so a proxy # will sooner or later reach the limit. The expanded FORMAT # value is used as the cache key, so if the details in FORMAT # are highly variable, a larger cache may be needed to produce # reduction in helper load. # # children-max=n # Maximum number of acl helper processes spawned to service # external acl lookups of this type. (default 5) # # children-startup=n # Minimum number of acl helper processes to spawn during # startup and reconfigure to service external acl lookups # of this type. (default 0) # # children-idle=n # Number of acl helper processes to keep ahead of traffic # loads. Squid will spawn this many at once whenever load # rises above the capabilities of existing processes. # Up to the value of children-max. (default 1) # # concurrency=n concurrency level per process. Only used with helpers # capable of processing more than one query at a time. # # queue-size=N The queue-size option sets the maximum number of # queued requests. A request is queued when no existing # helper can accept it due to concurrency limit and no # new helper can be started due to children-max limit. # If the queued requests exceed queue size, the acl is # ignored. The default value is set to 2*children-max. # # protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers. # # ipv4 / ipv6 IP protocol used to communicate with this helper. # The default is to auto-detect IPv6 and use it when available. # # # FORMAT is a series of %macro codes. See logformat directive for a full list # of the accepted codes. Although note that at the time of any external ACL # being tested data may not be available and thus some %macro expand to '-'. # # In addition to the logformat codes; when processing external ACLs these # additional macros are made available: # # %ACL The name of the ACL being tested. # # %DATA The ACL arguments specified in the referencing config # 'acl ... external' line, separated by spaces (an # "argument string"). see acl external. # # If there are no ACL arguments %DATA expands to '-'. # # If you do not specify a DATA macro inside FORMAT, # Squid automatically appends %DATA to your FORMAT. # Note that Squid-3.x may expand %DATA to whitespace # or nothing in this case. # # By default, Squid applies URL-encoding to each ACL # argument inside the argument string. If an explicit # encoding modifier is used (e.g., %#DATA), then Squid # encodes the whole argument string as a single token # (e.g., with %#DATA, spaces between arguments become # %20). # # If SSL is enabled, the following formating codes become available: # # %USER_CERT SSL User certificate in PEM format # %USER_CERTCHAIN SSL User certificate chain in PEM format # %USER_CERT_xx SSL User certificate subject attribute xx # %USER_CA_CERT_xx SSL User certificate issuer attribute xx # # # NOTE: all other format codes accepted by older Squid versions # are deprecated. # # # General request syntax: # # [channel-ID] FORMAT-values # # # FORMAT-values consists of transaction details expanded with # whitespace separation per the config file FORMAT specification # using the FORMAT macros listed above. # # Request values sent to the helper are URL escaped to protect # each value in requests against whitespaces. # # If using protocol=2.5 then the request sent to the helper is not # URL escaped to protect against whitespace. # # NOTE: protocol=3.0 is deprecated as no longer necessary. # # When using the concurrency= option the protocol is changed by # introducing a query channel tag in front of the request/response. # The query channel tag is a number between 0 and concurrency-1. # This value must be echoed back unchanged to Squid as the first part # of the response relating to its request. # # # The helper receives lines expanded per the above format specification # and for each input line returns 1 line starting with OK/ERR/BH result # code and optionally followed by additional keywords with more details. # # # General result syntax: # # [channel-ID] result keyword=value ... # # Result consists of one of the codes: # # OK # the ACL test produced a match. # # ERR # the ACL test does not produce a match. # # BH # An internal error occurred in the helper, preventing # a result being identified. # # The meaning of 'a match' is determined by your squid.conf # access control configuration. See the Squid wiki for details. # # Defined keywords: # # user= The users name (login) # # password= The users password (for login= cache_peer option) # # message= Message describing the reason for this response. # Available as %o in error pages. # Useful on (ERR and BH results). # # tag= Apply a tag to a request. Only sets a tag once, # does not alter existing tags. # # log= String to be logged in access.log. Available as # %ea in logformat specifications. # # clt_conn_tag= Associates a TAG with the client TCP connection. # Please see url_rewrite_program related documentation # for this kv-pair. # # Any keywords may be sent on any response whether OK, ERR or BH. # # All response keyword values need to be a single token with URL # escaping, or enclosed in double quotes (") and escaped using \ on # any double quotes or \ characters within the value. The wrapping # double quotes are removed before the value is interpreted by Squid. # \r and \n are also replace by CR and LF. # # Some example key values: # # user=John%20Smith # user="John Smith" # user="J. \"Bob\" Smith" #Default: # none # TAG: acl # Defining an Access List # # Every access list definition must begin with an aclname and acltype, # followed by either type-specific arguments or a quoted filename that # they are read from. # # acl aclname acltype argument ... # acl aclname acltype "file" ... # # When using "file", the file should contain one item per line. # # # ACL Options # # Some acl types supports options which changes their default behaviour: # # -i,+i By default, regular expressions are CASE-SENSITIVE. To make them # case-insensitive, use the -i option. To return case-sensitive # use the +i option between patterns, or make a new ACL line # without -i. # # -n Disable lookups and address type conversions. If lookup or # conversion is required because the parameter type (IP or # domain name) does not match the message address type (domain # name or IP), then the ACL would immediately declare a mismatch # without any warnings or lookups. # # -m[=delimiters] # Perform a list membership test, interpreting values as # comma-separated token lists and matching against individual # tokens instead of whole values. # The optional "delimiters" parameter specifies one or more # alternative non-alphanumeric delimiter characters. # non-alphanumeric delimiter characters. # # -- Used to stop processing all options, in the case the first acl # value has '-' character as first character (for example the '-' # is a valid domain name) # # Some acl types require suspending the current request in order # to access some external data source. # Those which do are marked with the tag [slow], those which # don't are marked as [fast]. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl # for further information # # ***** ACL TYPES AVAILABLE ***** # # acl aclname src ip-address/mask ... # clients IP address [fast] # acl aclname src addr1-addr2/mask ... # range of addresses [fast] # acl aclname dst [-n] ip-address/mask ... # URL host's IP address [slow] # acl aclname localip ip-address/mask ... # IP address the client connected to [fast] # #if USE_SQUID_EUI # acl aclname arp mac-address ... # acl aclname eui64 eui64-address ... # # [fast] # # MAC (EUI-48) and EUI-64 addresses use xx:xx:xx:xx:xx:xx notation. # # # # The 'arp' ACL code is not portable to all operating systems. # # It works on Linux, Solaris, Windows, FreeBSD, and some other # # BSD variants. # # # # The eui_lookup directive is required to be 'on' (the default) # # and Squid built with --enable-eui for MAC/EUI addresses to be # # available for this ACL. # # # # Squid can only determine the MAC/EUI address for IPv4 # # clients that are on the same subnet. If the client is on a # # different subnet, then Squid cannot find out its address. # # # # IPv6 protocol does not contain ARP. MAC/EUI is either # # encoded directly in the IPv6 address or not available. #endif # acl aclname clientside_mark mark[/mask] ... # # matches CONNMARK of an accepted connection [fast] # # # # mark and mask are unsigned integers (hex, octal, or decimal). # # If multiple marks are given, then the ACL matches if at least # # one mark matches. # # # # Uses netfilter-conntrack library. # # Requires building Squid with --enable-linux-netfilter. # # # # The client, various intermediaries, and Squid itself may set # # CONNMARK at various times. The last CONNMARK set wins. This ACL # # checks the mark present on an accepted connection or set by # # Squid afterwards, depending on the ACL check timing. This ACL # # effectively ignores any mark set by other agents after Squid has # # accepted the connection. # # acl aclname srcdomain .foo.com ... # # reverse lookup, from client IP [slow] # acl aclname dstdomain [-n] .foo.com ... # # Destination server from URL [fast] # acl aclname srcdom_regex [-i] \.foo\.com ... # # regex matching client name [slow] # acl aclname dstdom_regex [-n] [-i] \.foo\.com ... # # regex matching server [fast] # # # # For dstdomain and dstdom_regex a reverse lookup is tried if a IP # # based URL is used and no match is found. The name "none" is used # # if the reverse lookup fails. # # acl aclname src_as number ... # acl aclname dst_as number ... # # [fast] # # Except for access control, AS numbers can be used for # # routing of requests to specific caches. Here's an # # example for routing all requests for AS#1241 and only # # those to mycache.mydomain.net: # # acl asexample dst_as 1241 # # cache_peer_access mycache.mydomain.net allow asexample # # cache_peer_access mycache_mydomain.net deny all # # acl aclname peername myPeer ... # acl aclname peername_regex [-i] regex-pattern ... # # [fast] # # match against a named cache_peer entry # # set unique name= on cache_peer lines for reliable use. # # acl aclname time [day-abbrevs] [h1:m1-h2:m2] # # [fast] # # day-abbrevs: # # S - Sunday # # M - Monday # # T - Tuesday # # W - Wednesday # # H - Thursday # # F - Friday # # A - Saturday # # h1:m1 must be less than h2:m2 # # acl aclname url_regex [-i] ^http:// ... # # regex matching on whole URL [fast] # acl aclname urllogin [-i] [^a-zA-Z0-9] ... # # regex matching on URL login field # acl aclname urlpath_regex [-i] \.gif$ ... # # regex matching on URL path [fast] # # acl aclname port 80 70 21 0-1024... # destination TCP port [fast] # # ranges are alloed # acl aclname localport 3128 ... # TCP port the client connected to [fast] # # NP: for interception mode this is usually '80' # # acl aclname myportname 3128 ... # *_port name [fast] # # acl aclname proto HTTP FTP ... # request protocol [fast] # # acl aclname method GET POST ... # HTTP request method [fast] # # acl aclname http_status 200 301 500- 400-403 ... # # status code in reply [fast] # # acl aclname browser [-i] regexp ... # # pattern match on User-Agent header (see also req_header below) [fast] # # acl aclname referer_regex [-i] regexp ... # # pattern match on Referer header [fast] # # Referer is highly unreliable, so use with care # # acl aclname ident [-i] username ... # acl aclname ident_regex [-i] pattern ... # # string match on ident output [slow] # # use REQUIRED to accept any non-null ident. # # acl aclname proxy_auth [-i] username ... # acl aclname proxy_auth_regex [-i] pattern ... # # perform http authentication challenge to the client and match against # # supplied credentials [slow] # # # # takes a list of allowed usernames. # # use REQUIRED to accept any valid username. # # # # Will use proxy authentication in forward-proxy scenarios, and plain # # http authenticaiton in reverse-proxy scenarios # # # # NOTE: when a Proxy-Authentication header is sent but it is not # # needed during ACL checking the username is NOT logged # # in access.log. # # # # NOTE: proxy_auth requires a EXTERNAL authentication program # # to check username/password combinations (see # # auth_param directive). # # # # NOTE: proxy_auth can't be used in a transparent/intercepting proxy # # as the browser needs to be configured for using a proxy in order # # to respond to proxy authentication. # # acl aclname snmp_community string ... # # A community string to limit access to your SNMP Agent [fast] # # Example: # # # # acl snmppublic snmp_community public # # acl aclname maxconn number # # This will be matched when the client's IP address has # # more than <number> TCP connections established. [fast] # # NOTE: This only measures direct TCP links so X-Forwarded-For # # indirect clients are not counted. # # acl aclname max_user_ip [-s] number # # This will be matched when the user attempts to log in from more # # than <number> different ip addresses. The authenticate_ip_ttl # # parameter controls the timeout on the ip entries. [fast] # # If -s is specified the limit is strict, denying browsing # # from any further IP addresses until the ttl has expired. Without # # -s Squid will just annoy the user by "randomly" denying requests. # # (the counter is reset each time the limit is reached and a # # request is denied) # # NOTE: in acceleration mode or where there is mesh of child proxies, # # clients may appear to come from multiple addresses if they are # # going through proxy farms, so a limit of 1 may cause user problems. # # acl aclname random probability # # Pseudo-randomly match requests. Based on the probability given. # # Probability may be written as a decimal (0.333), fraction (1/3) # # or ratio of matches:non-matches (3:5). # # acl aclname req_mime_type [-i] mime-type ... # # regex match against the mime type of the request generated # # by the client. Can be used to detect file upload or some # # types HTTP tunneling requests [fast] # # NOTE: This does NOT match the reply. You cannot use this # # to match the returned file type. # # acl aclname req_header header-name [-i] any\.regex\.here # # regex match against any of the known request headers. May be # # thought of as a superset of "browser", "referer" and "mime-type" # # ACL [fast] # # acl aclname rep_mime_type [-i] mime-type ... # # regex match against the mime type of the reply received by # # squid. Can be used to detect file download or some # # types HTTP tunneling requests. [fast] # # NOTE: This has no effect in http_access rules. It only has # # effect in rules that affect the reply data stream such as # # http_reply_access. # # acl aclname rep_header header-name [-i] any\.regex\.here # # regex match against any of the known reply headers. May be # # thought of as a superset of "browser", "referer" and "mime-type" # # ACLs [fast] # # acl aclname external class_name [arguments...] # # external ACL lookup via a helper class defined by the # # external_acl_type directive [slow] # # acl aclname user_cert attribute values... # # match against attributes in a user SSL certificate # # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast] # # acl aclname ca_cert attribute values... # # match against attributes a users issuing CA SSL certificate # # attribute is one of DN/C/O/CN/L/ST or a numerical OID [fast] # # acl aclname ext_user [-i] username ... # acl aclname ext_user_regex [-i] pattern ... # # string match on username returned by external acl helper [slow] # # use REQUIRED to accept any non-null user name. # # acl aclname tag tagvalue ... # # string match on tag returned by external acl helper [fast] # # DEPRECATED. Only the first tag will match with this ACL. # # Use the 'note' ACL instead for handling multiple tag values. # # acl aclname hier_code codename ... # # string match against squid hierarchy code(s); [fast] # # e.g., DIRECT, PARENT_HIT, NONE, etc. # # # # NOTE: This has no effect in http_access rules. It only has # # effect in rules that affect the reply data stream such as # # http_reply_access. # # acl aclname note [-m[=delimiters]] name [value ...] # # match transaction annotation [fast] # # Without values, matches any annotation with a given name. # # With value(s), matches any annotation with a given name that # # also has one of the given values. # # If the -m flag is used, then the value of the named # # annotation is interpreted as a list of tokens, and the ACL # # matches individual name=token pairs rather than whole # # name=value pairs. See "ACL Options" above for more info. # # Annotation sources include note and adaptation_meta directives # # as well as helper and eCAP responses. # # acl aclname adaptation_service service ... # # Matches the name of any icap_service, ecap_service, # # adaptation_service_set, or adaptation_service_chain that Squid # # has used (or attempted to use) for the master transaction. # # This ACL must be defined after the corresponding adaptation # # service is named in squid.conf. This ACL is usable with # # adaptation_meta because it starts matching immediately after # # the service has been selected for adaptation. # # acl aclname transaction_initiator initiator ... # # Matches transaction's initiator [fast] # # # # Supported initiators are: # # esi: matches transactions fetching ESI resources # # certificate-fetching: matches transactions fetching # # a missing intermediate TLS certificate # # cache-digest: matches transactions fetching Cache Digests # # from a cache_peer # # htcp: matches HTCP requests from peers # # icp: matches ICP requests to peers # # icmp: matches ICMP RTT database (NetDB) requests to peers # # asn: matches asns db requests # # internal: matches any of the above # # client: matches transactions containing an HTTP or FTP # # client request received at a Squid *_port # # all: matches any transaction, including internal transactions # # without a configurable initiator and hopefully rare # # transactions without a known-to-Squid initiator # # # # Multiple initiators are ORed. # # acl aclname has component # # matches a transaction "component" [fast] # # # # Supported transaction components are: # # request: transaction has a request header (at least) # # response: transaction has a response header (at least) # # ALE: transaction has an internally-generated Access Log Entry # # structure; bugs notwithstanding, all transaction have it # # # # For example, the following configuration helps when dealing with HTTP # # clients that close connections without sending a request header: # # # # acl hasRequest has request # # acl logMe note important_transaction # # # avoid "logMe ACL is used in context without an HTTP request" warnings # # access_log ... logformat=detailed hasRequest logMe # # # log request-less transactions, instead of ignoring them # # access_log ... logformat=brief !hasRequest # # # # Multiple components are not supported for one "acl" rule, but # # can be specified (and are ORed) using multiple same-name rules: # # # # # OK, this strange logging daemon needs request or response, # # # but can work without either a request or a response: # # acl hasWhatMyLoggingDaemonNeeds has request # # acl hasWhatMyLoggingDaemonNeeds has response # # acl aclname any-of acl1 acl2 ... # # match any one of the acls [fast or slow] # # The first matching ACL stops further ACL evaluation. # # # # ACLs from multiple any-of lines with the same name are ORed. # # For example, A = (a1 or a2) or (a3 or a4) can be written as # # acl A any-of a1 a2 # # acl A any-of a3 a4 # # # # This group ACL is fast if all evaluated ACLs in the group are fast # # and slow otherwise. # # acl aclname all-of acl1 acl2 ... # # match all of the acls [fast or slow] # # The first mismatching ACL stops further ACL evaluation. # # # # ACLs from multiple all-of lines with the same name are ORed. # # For example, B = (b1 and b2) or (b3 and b4) can be written as # # acl B all-of b1 b2 # # acl B all-of b3 b4 # # # # This group ACL is fast if all evaluated ACLs in the group are fast # # and slow otherwise. # # Examples: # acl macaddress arp 09:00:2b:23:45:67 # acl myexample dst_as 1241 # acl password proxy_auth REQUIRED # acl fileupload req_mime_type -i ^multipart/form-data$ # acl javascript rep_mime_type -i ^application/x-javascript$ # #Default: # ACLs all, manager, localhost, and to_localhost are predefined. # # # Recommended minimum configuration: # # Example rule allowing access from your local networks. # Adapt to list your (internal) IP networks from where browsing # should be allowed acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN) acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN) acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN) acl localnet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN) acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN) acl localnet src fc00::/7 # RFC 4193 local private network range acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines acl SSL_ports port 443 acl Safe_ports port 80 # http acl Safe_ports port 21 # ftp acl Safe_ports port 443 # https acl Safe_ports port 70 # gopher acl Safe_ports port 210 # wais acl Safe_ports port 1025-65535 # unregistered ports acl Safe_ports port 280 # http-mgmt acl Safe_ports port 488 # gss-http acl Safe_ports port 591 # filemaker acl Safe_ports port 777 # multiling http acl CONNECT method CONNECT # TAG: proxy_protocol_access # Determine which client proxies can be trusted to provide correct # information regarding real client IP address using PROXY protocol. # # Requests may pass through a chain of several other proxies # before reaching us. The original source details may by sent in: # * HTTP message Forwarded header, or # * HTTP message X-Forwarded-For header, or # * PROXY protocol connection header. # # This directive is solely for validating new PROXY protocol # connections received from a port flagged with require-proxy-header. # It is checked only once after TCP connection setup. # # A deny match results in TCP connection closure. # # An allow match is required for Squid to permit the corresponding # TCP connection, before Squid even looks for HTTP request headers. # If there is an allow match, Squid starts using PROXY header information # to determine the source address of the connection for all future ACL # checks, logging, etc. # # SECURITY CONSIDERATIONS: # # Any host from which we accept client IP details can place # incorrect information in the relevant header, and Squid # will use the incorrect information as if it were the # source address of the request. This may enable remote # hosts to bypass any access control restrictions that are # based on the client's source addresses. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # all TCP connections to ports with require-proxy-header will be denied # TAG: follow_x_forwarded_for # Determine which client proxies can be trusted to provide correct # information regarding real client IP address. # # Requests may pass through a chain of several other proxies # before reaching us. The original source details may by sent in: # * HTTP message Forwarded header, or # * HTTP message X-Forwarded-For header, or # * PROXY protocol connection header. # # PROXY protocol connections are controlled by the proxy_protocol_access # directive which is checked before this. # # If a request reaches us from a source that is allowed by this # directive, then we trust the information it provides regarding # the IP of the client it received from (if any). # # For the purpose of ACLs used in this directive the src ACL type always # matches the address we are testing and srcdomain matches its rDNS. # # On each HTTP request Squid checks for X-Forwarded-For header fields. # If found the header values are iterated in reverse order and an allow # match is required for Squid to continue on to the next value. # The verification ends when a value receives a deny match, cannot be # tested, or there are no more values to test. # NOTE: Squid does not yet follow the Forwarded HTTP header. # # The end result of this process is an IP address that we will # refer to as the indirect client address. This address may # be treated as the client address for access control, ICAP, delay # pools and logging, depending on the acl_uses_indirect_client, # icap_uses_indirect_client, delay_pool_uses_indirect_client, # log_uses_indirect_client and tproxy_uses_indirect_client options. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # # SECURITY CONSIDERATIONS: # # Any host from which we accept client IP details can place # incorrect information in the relevant header, and Squid # will use the incorrect information as if it were the # source address of the request. This may enable remote # hosts to bypass any access control restrictions that are # based on the client's source addresses. # # For example: # # acl localhost src 127.0.0.1 # acl my_other_proxy srcdomain .proxy.example.com # follow_x_forwarded_for allow localhost # follow_x_forwarded_for allow my_other_proxy #Default: # X-Forwarded-For header will be ignored. # TAG: acl_uses_indirect_client on|off # Controls whether the indirect client address # (see follow_x_forwarded_for) is used instead of the # direct client address in acl matching. # # NOTE: maxconn ACL considers direct TCP links and indirect # clients will always have zero. So no match. #Default: # acl_uses_indirect_client on # TAG: delay_pool_uses_indirect_client on|off # Controls whether the indirect client address # (see follow_x_forwarded_for) is used instead of the # direct client address in delay pools. #Default: # delay_pool_uses_indirect_client on # TAG: log_uses_indirect_client on|off # Controls whether the indirect client address # (see follow_x_forwarded_for) is used instead of the # direct client address in the access log. #Default: # log_uses_indirect_client on # TAG: tproxy_uses_indirect_client on|off # Controls whether the indirect client address # (see follow_x_forwarded_for) is used instead of the # direct client address when spoofing the outgoing client. # # This has no effect on requests arriving in non-tproxy # mode ports. # # SECURITY WARNING: Usage of this option is dangerous # and should not be used trivially. Correct configuration # of follow_x_forwarded_for with a limited set of trusted # sources is required to prevent abuse of your proxy. #Default: # tproxy_uses_indirect_client off # TAG: spoof_client_ip # Control client IP address spoofing of TPROXY traffic based on # defined access lists. # # spoof_client_ip allow|deny [!]aclname ... # # If there are no "spoof_client_ip" lines present, the default # is to "allow" spoofing of any suitable request. # # Note that the cache_peer "no-tproxy" option overrides this ACL. # # This clause supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow spoofing on all TPROXY traffic. # TAG: http_access # Allowing or Denying access based on defined access lists # # To allow or deny a message received on an HTTP, HTTPS, or FTP port: # http_access allow|deny [!]aclname ... # # NOTE on default values: # # If there are no "access" lines present, the default is to deny # the request. # # If none of the "access" lines cause a match, the default is the # opposite of the last line in the list. If the last line was # deny, the default is allow. Conversely, if the last line # is allow, the default will be deny. For these reasons, it is a # good idea to have an "deny all" entry at the end of your access # lists to avoid potential confusion. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # #Default: # Deny, unless rules exist in squid.conf. # # # Recommended minimum Access Permission configuration: # # Deny requests to certain unsafe ports http_access deny !Safe_ports # Deny CONNECT to other than secure SSL ports http_access deny CONNECT !SSL_ports # Only allow cachemgr access from localhost http_access allow localhost manager http_access deny manager # We strongly recommend the following be uncommented to protect innocent # web applications running on the proxy server who think the only # one who can access services on "localhost" is a local user #http_access deny to_localhost # # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS # include /etc/squid/conf.d/* # Example rule allowing access from your local networks. # Adapt localnet in the ACL section to list your (internal) IP networks # from where browsing should be allowed #http_access allow localnet http_access allow localhost # And finally deny all other access to this proxy http_access deny all # TAG: adapted_http_access # Allowing or Denying access based on defined access lists # # Essentially identical to http_access, but runs after redirectors # and ICAP/eCAP adaptation. Allowing access control based on their # output. # # If not set then only http_access is used. #Default: # Allow, unless rules exist in squid.conf. # TAG: http_reply_access # Allow replies to client requests. This is complementary to http_access. # # http_reply_access allow|deny [!] aclname ... # # NOTE: if there are no access lines present, the default is to allow # all replies. # # If none of the access lines cause a match the opposite of the # last line will apply. Thus it is good practice to end the rules # with an "allow all" or "deny all" entry. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow, unless rules exist in squid.conf. # TAG: icp_access # Allowing or Denying access to the ICP port based on defined # access lists # # icp_access allow|deny [!]aclname ... # # NOTE: The default if no icp_access lines are present is to # deny all traffic. This default may cause problems with peers # using ICP. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # ## Allow ICP queries from local networks only ##icp_access allow localnet ##icp_access deny all #Default: # Deny, unless rules exist in squid.conf. # TAG: htcp_access # Allowing or Denying access to the HTCP port based on defined # access lists # # htcp_access allow|deny [!]aclname ... # # See also htcp_clr_access for details on access control for # cache purge (CLR) HTCP messages. # # NOTE: The default if no htcp_access lines are present is to # deny all traffic. This default may cause problems with peers # using the htcp option. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # ## Allow HTCP queries from local networks only ##htcp_access allow localnet ##htcp_access deny all #Default: # Deny, unless rules exist in squid.conf. # TAG: htcp_clr_access # Allowing or Denying access to purge content using HTCP based # on defined access lists. # See htcp_access for details on general HTCP access control. # # htcp_clr_access allow|deny [!]aclname ... # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # ## Allow HTCP CLR requests from trusted peers #acl htcp_clr_peer src 192.0.2.2 2001:DB8::2 #htcp_clr_access allow htcp_clr_peer #htcp_clr_access deny all #Default: # Deny, unless rules exist in squid.conf. # TAG: miss_access # Determines whether network access is permitted when satisfying a request. # # For example; # to force your neighbors to use you as a sibling instead of # a parent. # # acl localclients src 192.0.2.0/24 2001:DB8::a:0/64 # miss_access deny !localclients # miss_access allow all # # This means only your local clients are allowed to fetch relayed/MISS # replies from the network and all other clients can only fetch cached # objects (HITs). # # The default for this setting allows all clients who passed the # http_access rules to relay via this proxy. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow, unless rules exist in squid.conf. # TAG: ident_lookup_access # A list of ACL elements which, if matched, cause an ident # (RFC 931) lookup to be performed for this request. For # example, you might choose to always perform ident lookups # for your main multi-user Unix boxes, but not for your Macs # and PCs. By default, ident lookups are not performed for # any requests. # # To enable ident lookups for specific client addresses, you # can follow this example: # # acl ident_aware_hosts src 198.168.1.0/24 # ident_lookup_access allow ident_aware_hosts # ident_lookup_access deny all # # Only src type ACL checks are fully supported. A srcdomain # ACL might work at times, but it will not always provide # the correct result. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Unless rules exist in squid.conf, IDENT is not fetched. # TAG: reply_body_max_size size [acl acl...] # This option specifies the maximum size of a reply body. It can be # used to prevent users from downloading very large files, such as # MP3's and movies. When the reply headers are received, the # reply_body_max_size lines are processed, and the first line where # all (if any) listed ACLs are true is used as the maximum body size # for this reply. # # This size is checked twice. First when we get the reply headers, # we check the content-length value. If the content length value exists # and is larger than the allowed size, the request is denied and the # user receives an error message that says "the request or reply # is too large." If there is no content-length, and the reply # size exceeds this limit, the client's connection is just closed # and they will receive a partial reply. # # WARNING: downstream caches probably can not detect a partial reply # if there is no content-length header, so they will cache # partial responses and give them out as hits. You should NOT # use this option if you have downstream caches. # # WARNING: A maximum size smaller than the size of squid's error messages # will cause an infinite loop and crash squid. Ensure that the smallest # non-zero value you use is greater that the maximum header size plus # the size of your largest error page. # # If you set this parameter none (the default), there will be # no limit imposed. # # Configuration Format is: # reply_body_max_size SIZE UNITS [acl ...] # ie. # reply_body_max_size 10 MB # #Default: # No limit is applied. # TAG: on_unsupported_protocol # Determines Squid behavior when encountering strange requests at the # beginning of an accepted TCP connection or the beginning of a bumped # CONNECT tunnel. Controlling Squid reaction to unexpected traffic is # especially useful in interception environments where Squid is likely # to see connections for unsupported protocols that Squid should either # terminate or tunnel at TCP level. # # on_unsupported_protocol <action> [!]acl ... # # The first matching action wins. Only fast ACLs are supported. # # Supported actions are: # # tunnel: Establish a TCP connection with the intended server and # blindly shovel TCP packets between the client and server. # # respond: Respond with an error message, using the transfer protocol # for the Squid port that received the request (e.g., HTTP # for connections intercepted at the http_port). This is the # default. # # Squid expects the following traffic patterns: # # http_port: a plain HTTP request # https_port: SSL/TLS handshake followed by an [encrypted] HTTP request # ftp_port: a plain FTP command (no on_unsupported_protocol support yet!) # CONNECT tunnel on http_port: same as https_port # CONNECT tunnel on https_port: same as https_port # # Currently, this directive has effect on intercepted connections and # bumped tunnels only. Other cases are not supported because Squid # cannot know the intended destination of other traffic. # # For example: # # define what Squid errors indicate receiving non-HTTP traffic: # acl foreignProtocol squid_error ERR_PROTOCOL_UNKNOWN ERR_TOO_BIG # # define what Squid errors indicate receiving nothing: # acl serverTalksFirstProtocol squid_error ERR_REQUEST_START_TIMEOUT # # tunnel everything that does not look like HTTP: # on_unsupported_protocol tunnel foreignProtocol # # tunnel if we think the client waits for the server to talk first: # on_unsupported_protocol tunnel serverTalksFirstProtocol # # in all other error cases, just send an HTTP "error page" response: # on_unsupported_protocol respond all # # See also: squid_error ACL #Default: # Respond with an error message to unidentifiable traffic # NETWORK OPTIONS # ----------------------------------------------------------------------------- # TAG: http_port # Usage: port [mode] [options] # hostname:port [mode] [options] # 1.2.3.4:port [mode] [options] # # The socket addresses where Squid will listen for HTTP client # requests. You may specify multiple socket addresses. # There are three forms: port alone, hostname with port, and # IP address with port. If you specify a hostname or IP # address, Squid binds the socket to that specific # address. Most likely, you do not need to bind to a specific # address, so you can use the port number alone. # # If you are running Squid in accelerator mode, you # probably want to listen on port 80 also, or instead. # # The -a command line option may be used to specify additional # port(s) where Squid listens for proxy request. Such ports will # be plain proxy ports with no options. # # You may specify multiple socket addresses on multiple lines. # # Modes: # # intercept Support for IP-Layer NAT interception delivering # traffic to this Squid port. # NP: disables authentication on the port. # # tproxy Support Linux TPROXY (or BSD divert-to) with spoofing # of outgoing connections using the client IP address. # NP: disables authentication on the port. # # accel Accelerator / reverse proxy mode # # ssl-bump For each CONNECT request allowed by ssl_bump ACLs, # establish secure connection with the client and with # the server, decrypt HTTPS messages as they pass through # Squid, and treat them as unencrypted HTTP messages, # becoming the man-in-the-middle. # # The ssl_bump option is required to fully enable # bumping of CONNECT requests. # # Omitting the mode flag causes default forward proxy mode to be used. # # # Accelerator Mode Options: # # defaultsite=domainname # What to use for the Host: header if it is not present # in a request. Determines what site (not origin server) # accelerators should consider the default. # # no-vhost Disable using HTTP/1.1 Host header for virtual domain support. # # protocol= Protocol to reconstruct accelerated and intercepted # requests with. Defaults to HTTP/1.1 for http_port and # HTTPS/1.1 for https_port. # When an unsupported value is configured Squid will # produce a FATAL error. # Values: HTTP or HTTP/1.1, HTTPS or HTTPS/1.1 # # vport Virtual host port support. Using the http_port number # instead of the port passed on Host: headers. # # vport=NN Virtual host port support. Using the specified port # number instead of the port passed on Host: headers. # # act-as-origin # Act as if this Squid is the origin server. # This currently means generate new Date: and Expires: # headers on HIT instead of adding Age:. # # ignore-cc Ignore request Cache-Control headers. # # WARNING: This option violates HTTP specifications if # used in non-accelerator setups. # # allow-direct Allow direct forwarding in accelerator mode. Normally # accelerated requests are denied direct forwarding as if # never_direct was used. # # WARNING: this option opens accelerator mode to security # vulnerabilities usually only affecting in interception # mode. Make sure to protect forwarding with suitable # http_access rules when using this. # # # SSL Bump Mode Options: # In addition to these options ssl-bump requires TLS/SSL options. # # generate-host-certificates[=<on|off>] # Dynamically create SSL server certificates for the # destination hosts of bumped CONNECT requests.When # enabled, the cert and key options are used to sign # generated certificates. Otherwise generated # certificate will be selfsigned. # If there is a CA certificate lifetime of the generated # certificate equals lifetime of the CA certificate. If # generated certificate is selfsigned lifetime is three # years. # This option is enabled by default when ssl-bump is used. # See the ssl-bump option above for more information. # # dynamic_cert_mem_cache_size=SIZE # Approximate total RAM size spent on cached generated # certificates. If set to zero, caching is disabled. The # default value is 4MB. # # TLS / SSL Options: # # tls-cert= Path to file containing an X.509 certificate (PEM format) # to be used in the TLS handshake ServerHello. # # If this certificate is constrained by KeyUsage TLS # feature it must allow HTTP server usage, along with # any additional restrictions imposed by your choice # of options= settings. # # When OpenSSL is used this file may also contain a # chain of intermediate CA certificates to send in the # TLS handshake. # # When GnuTLS is used this option (and any paired # tls-key= option) may be repeated to load multiple # certificates for different domains. # # Also, when generate-host-certificates=on is configured # the first tls-cert= option must be a CA certificate # capable of signing the automatically generated # certificates. # # tls-key= Path to a file containing private key file (PEM format) # for the previous tls-cert= option. # # If tls-key= is not specified tls-cert= is assumed to # reference a PEM file containing both the certificate # and private key. # # cipher= Colon separated list of supported ciphers. # NOTE: some ciphers such as EDH ciphers depend on # additional settings. If those settings are # omitted the ciphers may be silently ignored # by the OpenSSL library. # # options= Various SSL implementation options. The most important # being: # # NO_SSLv3 Disallow the use of SSLv3 # # NO_TLSv1 Disallow the use of TLSv1.0 # # NO_TLSv1_1 Disallow the use of TLSv1.1 # # NO_TLSv1_2 Disallow the use of TLSv1.2 # # SINGLE_DH_USE # Always create a new key when using # temporary/ephemeral DH key exchanges # # SINGLE_ECDH_USE # Enable ephemeral ECDH key exchange. # The adopted curve should be specified # using the tls-dh option. # # NO_TICKET # Disable use of RFC5077 session tickets. # Some servers may have problems # understanding the TLS extension due # to ambiguous specification in RFC4507. # # ALL Enable various bug workarounds # suggested as "harmless" by OpenSSL # Be warned that this reduces SSL/TLS # strength to some attacks. # # See the OpenSSL SSL_CTX_set_options documentation for a # more complete list. # # clientca= File containing the list of CAs to use when # requesting a client certificate. # # tls-cafile= PEM file containing CA certificates to use when verifying # client certificates. If not configured clientca will be # used. May be repeated to load multiple files. # # capath= Directory containing additional CA certificates # and CRL lists to use when verifying client certificates. # Requires OpenSSL or LibreSSL. # # crlfile= File of additional CRL lists to use when verifying # the client certificate, in addition to CRLs stored in # the capath. Implies VERIFY_CRL flag below. # # tls-dh=[curve:]file # File containing DH parameters for temporary/ephemeral DH key # exchanges, optionally prefixed by a curve for ephemeral ECDH # key exchanges. # See OpenSSL documentation for details on how to create the # DH parameter file. Supported curves for ECDH can be listed # using the "openssl ecparam -list_curves" command. # WARNING: EDH and EECDH ciphers will be silently disabled if # this option is not set. # # sslflags= Various flags modifying the use of SSL: # DELAYED_AUTH # Don't request client certificates # immediately, but wait until acl processing # requires a certificate (not yet implemented). # NO_SESSION_REUSE # Don't allow for session reuse. Each connection # will result in a new SSL session. # VERIFY_CRL # Verify CRL lists when accepting client # certificates. # VERIFY_CRL_ALL # Verify CRL lists for all certificates in the # client certificate chain. # # tls-default-ca[=off] # Whether to use the system Trusted CAs. Default is OFF. # # tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1. # # sslcontext= SSL session ID context identifier. # # Other Options: # # connection-auth[=on|off] # use connection-auth=off to tell Squid to prevent # forwarding Microsoft connection oriented authentication # (NTLM, Negotiate and Kerberos) # # disable-pmtu-discovery= # Control Path-MTU discovery usage: # off lets OS decide on what to do (default). # transparent disable PMTU discovery when transparent # support is enabled. # always disable always PMTU discovery. # # In many setups of transparently intercepting proxies # Path-MTU discovery can not work on traffic towards the # clients. This is the case when the intercepting device # does not fully track connections and fails to forward # ICMP must fragment messages to the cache server. If you # have such setup and experience that certain clients # sporadically hang or never complete requests set # disable-pmtu-discovery option to 'transparent'. # # name= Specifies a internal name for the port. Defaults to # the port specification (port or addr:port) # # tcpkeepalive[=idle,interval,timeout] # Enable TCP keepalive probes of idle connections. # In seconds; idle is the initial time before TCP starts # probing the connection, interval how often to probe, and # timeout the time before giving up. # # require-proxy-header # Require PROXY protocol version 1 or 2 connections. # The proxy_protocol_access is required to whitelist # downstream proxies which can be trusted. # # If you run Squid on a dual-homed machine with an internal # and an external interface we recommend you to specify the # internal address:port in http_port. This way Squid will only be # visible on the internal address. # # # Squid normally listens to port 3128 http_port 3128 # TAG: https_port # Usage: [ip:]port [mode] tls-cert=certificate.pem [options] # # The socket address where Squid will listen for client requests made # over TLS or SSL connections. Commonly referred to as HTTPS. # # This is most useful for situations where you are running squid in # accelerator mode and you want to do the TLS work at the accelerator # level. # # You may specify multiple socket addresses on multiple lines, # each with their own certificate and/or options. # # The tls-cert= option is mandatory on HTTPS ports. # # See http_port for a list of modes and options. #Default: # none # TAG: ftp_port # Enables Native FTP proxy by specifying the socket address where Squid # listens for FTP client requests. See http_port directive for various # ways to specify the listening address and mode. # # Usage: ftp_port address [mode] [options] # # WARNING: This is a new, experimental, complex feature that has seen # limited production exposure. Some Squid modules (e.g., caching) do not # currently work with native FTP proxying, and many features have not # even been tested for compatibility. Test well before deploying! # # Native FTP proxying differs substantially from proxying HTTP requests # with ftp:// URIs because Squid works as an FTP server and receives # actual FTP commands (rather than HTTP requests with FTP URLs). # # Native FTP commands accepted at ftp_port are internally converted or # wrapped into HTTP-like messages. The same happens to Native FTP # responses received from FTP origin servers. Those HTTP-like messages # are shoveled through regular access control and adaptation layers # between the FTP client and the FTP origin server. This allows Squid to # examine, adapt, block, and log FTP exchanges. Squid reuses most HTTP # mechanisms when shoveling wrapped FTP messages. For example, # http_access and adaptation_access directives are used. # # Modes: # # intercept Same as http_port intercept. The FTP origin address is # determined based on the intended destination of the # intercepted connection. # # tproxy Support Linux TPROXY for spoofing outgoing # connections using the client IP address. # NP: disables authentication and maybe IPv6 on the port. # # By default (i.e., without an explicit mode option), Squid extracts the # FTP origin address from the login@origin parameter of the FTP USER # command. Many popular FTP clients support such native FTP proxying. # # Options: # # name=token Specifies an internal name for the port. Defaults to # the port address. Usable with myportname ACL. # # ftp-track-dirs # Enables tracking of FTP directories by injecting extra # PWD commands and adjusting Request-URI (in wrapping # HTTP requests) to reflect the current FTP server # directory. Tracking is disabled by default. # # protocol=FTP Protocol to reconstruct accelerated and intercepted # requests with. Defaults to FTP. No other accepted # values have been tested with. An unsupported value # results in a FATAL error. Accepted values are FTP, # HTTP (or HTTP/1.1), and HTTPS (or HTTPS/1.1). # # Other http_port modes and options that are not specific to HTTP and # HTTPS may also work. #Default: # none # TAG: tcp_outgoing_tos # Allows you to select a TOS/Diffserv value for packets outgoing # on the server side, based on an ACL. # # tcp_outgoing_tos ds-field [!]aclname ... # # Example where normal_service_net uses the TOS value 0x00 # and good_service_net uses 0x20 # # acl normal_service_net src 10.0.0.0/24 # acl good_service_net src 10.0.1.0/24 # tcp_outgoing_tos 0x00 normal_service_net # tcp_outgoing_tos 0x20 good_service_net # # TOS/DSCP values really only have local significance - so you should # know what you're specifying. For more information, see RFC2474, # RFC2475, and RFC3260. # # The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or # "default" to use whatever default your host has. # Note that only multiples of 4 are usable as the two rightmost bits have # been redefined for use by ECN (RFC 3168 section 23.1). # The squid parser will enforce this by masking away the ECN bits. # # Processing proceeds in the order specified, and stops at first fully # matching line. # # Only fast ACLs are supported. #Default: # none # TAG: clientside_tos # Allows you to select a TOS/DSCP value for packets being transmitted # on the client-side, based on an ACL. # # clientside_tos ds-field [!]aclname ... # # Example where normal_service_net uses the TOS value 0x00 # and good_service_net uses 0x20 # # acl normal_service_net src 10.0.0.0/24 # acl good_service_net src 10.0.1.0/24 # clientside_tos 0x00 normal_service_net # clientside_tos 0x20 good_service_net # # Note: This feature is incompatible with qos_flows. Any TOS values set here # will be overwritten by TOS values in qos_flows. # # The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or # "default" to use whatever default your host has. # Note that only multiples of 4 are usable as the two rightmost bits have # been redefined for use by ECN (RFC 3168 section 23.1). # The squid parser will enforce this by masking away the ECN bits. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # none # TAG: tcp_outgoing_mark # Note: This option is only available if Squid is rebuilt with the # Packet MARK (Linux) # # Allows you to apply a Netfilter mark value to outgoing packets # on the server side, based on an ACL. # # tcp_outgoing_mark mark-value [!]aclname ... # # Example where normal_service_net uses the mark value 0x00 # and good_service_net uses 0x20 # # acl normal_service_net src 10.0.0.0/24 # acl good_service_net src 10.0.1.0/24 # tcp_outgoing_mark 0x00 normal_service_net # tcp_outgoing_mark 0x20 good_service_net # # Only fast ACLs are supported. #Default: # none # TAG: clientside_mark # Note: This option is only available if Squid is rebuilt with the # Packet MARK (Linux) # # Allows you to apply a Netfilter mark value to packets being transmitted # on the client-side, based on an ACL. # # clientside_mark mark-value [!]aclname ... # # Example where normal_service_net uses the mark value 0x00 # and good_service_net uses 0x20 # # acl normal_service_net src 10.0.0.0/24 # acl good_service_net src 10.0.1.0/24 # clientside_mark 0x00 normal_service_net # clientside_mark 0x20 good_service_net # # Note: This feature is incompatible with qos_flows. Any mark values set here # will be overwritten by mark values in qos_flows. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # none # TAG: qos_flows # Allows you to select a TOS/DSCP value to mark outgoing # connections to the client, based on where the reply was sourced. # For platforms using netfilter, allows you to set a netfilter mark # value instead of, or in addition to, a TOS value. # # By default this functionality is disabled. To enable it with the default # settings simply use "qos_flows mark" or "qos_flows tos". Default # settings will result in the netfilter mark or TOS value being copied # from the upstream connection to the client. Note that it is the connection # CONNMARK value not the packet MARK value that is copied. # # It is not currently possible to copy the mark or TOS value from the # client to the upstream connection request. # # TOS values really only have local significance - so you should # know what you're specifying. For more information, see RFC2474, # RFC2475, and RFC3260. # # The TOS/DSCP byte must be exactly that - a octet value 0 - 255. # Note that only multiples of 4 are usable as the two rightmost bits have # been redefined for use by ECN (RFC 3168 section 23.1). # The squid parser will enforce this by masking away the ECN bits. # # Mark values can be any unsigned 32-bit integer value. # # This setting is configured by setting the following values: # # tos|mark Whether to set TOS or netfilter mark values # # local-hit=0xFF Value to mark local cache hits. # # sibling-hit=0xFF Value to mark hits from sibling peers. # # parent-hit=0xFF Value to mark hits from parent peers. # # miss=0xFF[/mask] Value to mark cache misses. Takes precedence # over the preserve-miss feature (see below), unless # mask is specified, in which case only the bits # specified in the mask are written. # # The TOS variant of the following features are only possible on Linux # and require your kernel to be patched with the TOS preserving ZPH # patch, available from http://zph.bratcheda.org # No patch is needed to preserve the netfilter mark, which will work # with all variants of netfilter. # # disable-preserve-miss # This option disables the preservation of the TOS or netfilter # mark. By default, the existing TOS or netfilter mark value of # the response coming from the remote server will be retained # and masked with miss-mark. # NOTE: in the case of a netfilter mark, the mark must be set on # the connection (using the CONNMARK target) not on the packet # (MARK target). # # miss-mask=0xFF # Allows you to mask certain bits in the TOS or mark value # received from the remote server, before copying the value to # the TOS sent towards clients. # Default for tos: 0xFF (TOS from server is not changed). # Default for mark: 0xFFFFFFFF (mark from server is not changed). # # All of these features require the --enable-zph-qos compilation flag # (enabled by default). Netfilter marking also requires the # libnetfilter_conntrack libraries (--with-netfilter-conntrack) and # libcap 2.09+ (--with-libcap). # #Default: # none # TAG: tcp_outgoing_address # Allows you to map requests to different outgoing IP addresses # based on the username or source address of the user making # the request. # # tcp_outgoing_address ipaddr [[!]aclname] ... # # For example; # Forwarding clients with dedicated IPs for certain subnets. # # acl normal_service_net src 10.0.0.0/24 # acl good_service_net src 10.0.2.0/24 # # tcp_outgoing_address 2001:db8::c001 good_service_net # tcp_outgoing_address 10.1.0.2 good_service_net # # tcp_outgoing_address 2001:db8::beef normal_service_net # tcp_outgoing_address 10.1.0.1 normal_service_net # # tcp_outgoing_address 2001:db8::1 # tcp_outgoing_address 10.1.0.3 # # Processing proceeds in the order specified, and stops at first fully # matching line. # # Squid will add an implicit IP version test to each line. # Requests going to IPv4 websites will use the outgoing 10.1.0.* addresses. # Requests going to IPv6 websites will use the outgoing 2001:db8:* addresses. # # # NOTE: The use of this directive using client dependent ACLs is # incompatible with the use of server side persistent connections. To # ensure correct results it is best to set server_persistent_connections # to off when using this directive in such configurations. # # NOTE: The use of this directive to set a local IP on outgoing TCP links # is incompatible with using TPROXY to set client IP out outbound TCP links. # When needing to contact peers use the no-tproxy cache_peer option and the # client_dst_passthru directive re-enable normal forwarding such as this. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Address selection is performed by the operating system. # TAG: host_verify_strict # Regardless of this option setting, when dealing with intercepted # traffic, Squid always verifies that the destination IP address matches # the Host header domain or IP (called 'authority form URL'). # # This enforcement is performed to satisfy a MUST-level requirement in # RFC 2616 section 14.23: "The Host field value MUST represent the naming # authority of the origin server or gateway given by the original URL". # # When set to ON: # Squid always responds with an HTTP 409 (Conflict) error # page and logs a security warning if there is no match. # # Squid verifies that the destination IP address matches # the Host header for forward-proxy and reverse-proxy traffic # as well. For those traffic types, Squid also enables the # following checks, comparing the corresponding Host header # and Request-URI components: # # * The host names (domain or IP) must be identical, # but valueless or missing Host header disables all checks. # For the two host names to match, both must be either IP # or FQDN. # # * Port numbers must be identical, but if a port is missing # the scheme-default port is assumed. # # # When set to OFF (the default): # Squid allows suspicious requests to continue but logs a # security warning and blocks caching of the response. # # * Forward-proxy traffic is not checked at all. # # * Reverse-proxy traffic is not checked at all. # # * Intercepted traffic which passes verification is handled # according to client_dst_passthru. # # * Intercepted requests which fail verification are sent # to the client original destination instead of DIRECT. # This overrides 'client_dst_passthru off'. # # For now suspicious intercepted CONNECT requests are always # responded to with an HTTP 409 (Conflict) error page. # # # SECURITY NOTE: # # As described in CVE-2009-0801 when the Host: header alone is used # to determine the destination of a request it becomes trivial for # malicious scripts on remote websites to bypass browser same-origin # security policy and sandboxing protections. # # The cause of this is that such applets are allowed to perform their # own HTTP stack, in which case the same-origin policy of the browser # sandbox only verifies that the applet tries to contact the same IP # as from where it was loaded at the IP level. The Host: header may # be different from the connected IP and approved origin. # #Default: # host_verify_strict off # TAG: client_dst_passthru # With NAT or TPROXY intercepted traffic Squid may pass the request # directly to the original client destination IP or seek a faster # source using the HTTP Host header. # # Using Host to locate alternative servers can provide faster # connectivity with a range of failure recovery options. # But can also lead to connectivity trouble when the client and # server are attempting stateful interactions unaware of the proxy. # # This option (on by default) prevents alternative DNS entries being # located to send intercepted traffic DIRECT to an origin server. # The clients original destination IP and port will be used instead. # # Regardless of this option setting, when dealing with intercepted # traffic Squid will verify the Host: header and any traffic which # fails Host verification will be treated as if this option were ON. # # see host_verify_strict for details on the verification process. #Default: # client_dst_passthru on # TLS OPTIONS # ----------------------------------------------------------------------------- # TAG: tls_outgoing_options # disable Do not support https:// URLs. # # cert=/path/to/client/certificate # A client X.509 certificate to use when connecting. # # key=/path/to/client/private_key # The private key corresponding to the cert= above. # # If key= is not specified cert= is assumed to # reference a PEM file containing both the certificate # and private key. # # cipher=... The list of valid TLS ciphers to use. # # min-version=1.N # The minimum TLS protocol version to permit. # To control SSLv3 use the options= parameter. # Supported Values: 1.0 (default), 1.1, 1.2, 1.3 # # options=... Specify various TLS/SSL implementation options. # # OpenSSL options most important are: # # NO_SSLv3 Disallow the use of SSLv3 # # SINGLE_DH_USE # Always create a new key when using # temporary/ephemeral DH key exchanges # # NO_TICKET # Disable use of RFC5077 session tickets. # Some servers may have problems # understanding the TLS extension due # to ambiguous specification in RFC4507. # # ALL Enable various bug workarounds # suggested as "harmless" by OpenSSL # Be warned that this reduces SSL/TLS # strength to some attacks. # # See the OpenSSL SSL_CTX_set_options documentation # for a more complete list. # # GnuTLS options most important are: # # %NO_TICKETS # Disable use of RFC5077 session tickets. # Some servers may have problems # understanding the TLS extension due # to ambiguous specification in RFC4507. # # See the GnuTLS Priority Strings documentation # for a more complete list. # http://www.gnutls.org/manual/gnutls.html#Priority-Strings # # # cafile= PEM file containing CA certificates to use when verifying # the peer certificate. May be repeated to load multiple files. # # capath= A directory containing additional CA certificates to # use when verifying the peer certificate. # Requires OpenSSL or LibreSSL. # # crlfile=... A certificate revocation list file to use when # verifying the peer certificate. # # flags=... Specify various flags modifying the TLS implementation: # # DONT_VERIFY_PEER # Accept certificates even if they fail to # verify. # DONT_VERIFY_DOMAIN # Don't verify the peer certificate # matches the server name # # default-ca[=off] # Whether to use the system Trusted CAs. Default is ON. # # domain= The peer name as advertised in its certificate. # Used for verifying the correctness of the received peer # certificate. If not specified the peer hostname will be # used. #Default: # tls_outgoing_options min-version=1.0 # SSL OPTIONS # ----------------------------------------------------------------------------- # TAG: ssl_unclean_shutdown # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Some browsers (especially MSIE) bugs out on SSL shutdown # messages. #Default: # ssl_unclean_shutdown off # TAG: ssl_engine # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # The OpenSSL engine to use. You will need to set this if you # would like to use hardware SSL acceleration for example. #Default: # none # TAG: sslproxy_session_ttl # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Sets the timeout value for SSL sessions #Default: # sslproxy_session_ttl 300 # TAG: sslproxy_session_cache_size # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Sets the cache size to use for ssl session #Default: # sslproxy_session_cache_size 2 MB # TAG: sslproxy_foreign_intermediate_certs # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Many origin servers fail to send their full server certificate # chain for verification, assuming the client already has or can # easily locate any missing intermediate certificates. # # Squid uses the certificates from the specified file to fill in # these missing chains when trying to validate origin server # certificate chains. # # The file is expected to contain zero or more PEM-encoded # intermediate certificates. These certificates are not treated # as trusted root certificates, and any self-signed certificate in # this file will be ignored. #Default: # none # TAG: sslproxy_cert_sign_hash # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Sets the hashing algorithm to use when signing generated certificates. # Valid algorithm names depend on the OpenSSL library used. The following # names are usually available: sha1, sha256, sha512, and md5. Please see # your OpenSSL library manual for the available hashes. By default, Squids # that support this option use sha256 hashes. # # Squid does not forcefully purge cached certificates that were generated # with an algorithm other than the currently configured one. They remain # in the cache, subject to the regular cache eviction policy, and become # useful if the algorithm changes again. #Default: # none # TAG: ssl_bump # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # This option is consulted when a CONNECT request is received on # an http_port (or a new connection is intercepted at an # https_port), provided that port was configured with an ssl-bump # flag. The subsequent data on the connection is either treated as # HTTPS and decrypted OR tunneled at TCP level without decryption, # depending on the first matching bumping "action". # # ssl_bump <action> [!]acl ... # # The following bumping actions are currently supported: # # splice # Become a TCP tunnel without decrypting proxied traffic. # This is the default action. # # bump # When used on step SslBump1, establishes a secure connection # with the client first, then connect to the server. # When used on step SslBump2 or SslBump3, establishes a secure # connection with the server and, using a mimicked server # certificate, with the client. # # peek # Receive client (step SslBump1) or server (step SslBump2) # certificate while preserving the possibility of splicing the # connection. Peeking at the server certificate (during step 2) # usually precludes bumping of the connection at step 3. # # stare # Receive client (step SslBump1) or server (step SslBump2) # certificate while preserving the possibility of bumping the # connection. Staring at the server certificate (during step 2) # usually precludes splicing of the connection at step 3. # # terminate # Close client and server connections. # # Backward compatibility actions available at step SslBump1: # # client-first # Bump the connection. Establish a secure connection with the # client first, then connect to the server. This old mode does # not allow Squid to mimic server SSL certificate and does not # work with intercepted SSL connections. # # server-first # Bump the connection. Establish a secure connection with the # server first, then establish a secure connection with the # client, using a mimicked server certificate. Works with both # CONNECT requests and intercepted SSL connections, but does # not allow to make decisions based on SSL handshake info. # # peek-and-splice # Decide whether to bump or splice the connection based on # client-to-squid and server-to-squid SSL hello messages. # XXX: Remove. # # none # Same as the "splice" action. # # All ssl_bump rules are evaluated at each of the supported bumping # steps. Rules with actions that are impossible at the current step are # ignored. The first matching ssl_bump action wins and is applied at the # end of the current step. If no rules match, the splice action is used. # See the at_step ACL for a list of the supported SslBump steps. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # # See also: http_port ssl-bump, https_port ssl-bump, and acl at_step. # # # # Example: Bump all TLS connections except those originating from # # localhost or those going to example.com. # # acl broken_sites ssl::server_name .example.com # ssl_bump splice localhost # ssl_bump splice broken_sites # ssl_bump bump all #Default: # Become a TCP tunnel without decrypting proxied traffic. # TAG: sslproxy_cert_error # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Use this ACL to bypass server certificate validation errors. # # For example, the following lines will bypass all validation errors # when talking to servers for example.com. All other # validation errors will result in ERR_SECURE_CONNECT_FAIL error. # # acl BrokenButTrustedServers dstdomain example.com # sslproxy_cert_error allow BrokenButTrustedServers # sslproxy_cert_error deny all # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # Using slow acl types may result in server crashes # # Without this option, all server certificate validation errors # terminate the transaction to protect Squid and the client. # # SQUID_X509_V_ERR_INFINITE_VALIDATION error cannot be bypassed # but should not happen unless your OpenSSL library is buggy. # # SECURITY WARNING: # Bypassing validation errors is dangerous because an # error usually implies that the server cannot be trusted # and the connection may be insecure. # # See also: sslproxy_flags and DONT_VERIFY_PEER. #Default: # Server certificate errors terminate the transaction. # TAG: sslproxy_cert_sign # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # # sslproxy_cert_sign <signing algorithm> acl ... # # The following certificate signing algorithms are supported: # # signTrusted # Sign using the configured CA certificate which is usually # placed in and trusted by end-user browsers. This is the # default for trusted origin server certificates. # # signUntrusted # Sign to guarantee an X509_V_ERR_CERT_UNTRUSTED browser error. # This is the default for untrusted origin server certificates # that are not self-signed (see ssl::certUntrusted). # # signSelf # Sign using a self-signed certificate with the right CN to # generate a X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT error in the # browser. This is the default for self-signed origin server # certificates (see ssl::certSelfSigned). # # This clause only supports fast acl types. # # When sslproxy_cert_sign acl(s) match, Squid uses the corresponding # signing algorithm to generate the certificate and ignores all # subsequent sslproxy_cert_sign options (the first match wins). If no # acl(s) match, the default signing algorithm is determined by errors # detected when obtaining and validating the origin server certificate. # # WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can # be used with sslproxy_cert_adapt, but if and only if Squid is bumping a # CONNECT request that carries a domain name. In all other cases (CONNECT # to an IP address or an intercepted SSL connection), Squid cannot detect # the domain mismatch at certificate generation time when # bump-server-first is used. #Default: # none # TAG: sslproxy_cert_adapt # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # # sslproxy_cert_adapt <adaptation algorithm> acl ... # # The following certificate adaptation algorithms are supported: # # setValidAfter # Sets the "Not After" property to the "Not After" property of # the CA certificate used to sign generated certificates. # # setValidBefore # Sets the "Not Before" property to the "Not Before" property of # the CA certificate used to sign generated certificates. # # setCommonName or setCommonName{CN} # Sets Subject.CN property to the host name specified as a # CN parameter or, if no explicit CN parameter was specified, # extracted from the CONNECT request. It is a misconfiguration # to use setCommonName without an explicit parameter for # intercepted or tproxied SSL connections. # # This clause only supports fast acl types. # # Squid first groups sslproxy_cert_adapt options by adaptation algorithm. # Within a group, when sslproxy_cert_adapt acl(s) match, Squid uses the # corresponding adaptation algorithm to generate the certificate and # ignores all subsequent sslproxy_cert_adapt options in that algorithm's # group (i.e., the first match wins within each algorithm group). If no # acl(s) match, the default mimicking action takes place. # # WARNING: SQUID_X509_V_ERR_DOMAIN_MISMATCH and ssl:certDomainMismatch can # be used with sslproxy_cert_adapt, but if and only if Squid is bumping a # CONNECT request that carries a domain name. In all other cases (CONNECT # to an IP address or an intercepted SSL connection), Squid cannot detect # the domain mismatch at certificate generation time when # bump-server-first is used. #Default: # none # TAG: sslpassword_program # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Specify a program used for entering SSL key passphrases # when using encrypted SSL certificate keys. If not specified # keys must either be unencrypted, or Squid started with the -N # option to allow it to query interactively for the passphrase. # # The key file name is given as argument to the program allowing # selection of the right password if you have multiple encrypted # keys. #Default: # none # OPTIONS RELATING TO EXTERNAL SSL_CRTD # ----------------------------------------------------------------------------- # TAG: sslcrtd_program # Note: This option is only available if Squid is rebuilt with the # --enable-ssl-crtd # # Specify the location and options of the executable for certificate # generator. # # /usr/lib/squid/security_file_certgen program can use a disk cache to improve response # times on repeated requests. To enable caching, specify -s and -M # parameters. If those parameters are not given, the program generates # a new certificate on every request. # # For more information use: # /usr/lib/squid/security_file_certgen -h #Default: # sslcrtd_program /usr/lib/squid/security_file_certgen -s /var/spool/squid/ssl_db -M 4MB # TAG: sslcrtd_children # Note: This option is only available if Squid is rebuilt with the # --enable-ssl-crtd # # Specifies the maximum number of certificate generation processes that # Squid may spawn (numberofchildren) and several related options. Using # too few of these helper processes (a.k.a. "helpers") creates request # queues. Using too many helpers wastes your system resources. Squid # does not support spawning more than 32 helpers. # # Usage: numberofchildren [option]... # # The startup= and idle= options allow some measure of skew in your # tuning. # # startup=N # # Sets the minimum number of processes to spawn when Squid # starts or reconfigures. When set to zero the first request will # cause spawning of the first child process to handle it. # # Starting too few children temporary slows Squid under load while it # tries to spawn enough additional processes to cope with traffic. # # idle=N # # Sets a minimum of how many processes Squid is to try and keep available # at all times. When traffic begins to rise above what the existing # processes can handle this many more will be spawned up to the maximum # configured. A minimum setting of 1 is required. # # queue-size=N # # Sets the maximum number of queued requests. A request is queued when # no existing child is idle and no new child can be started due to # numberofchildren limit. If the queued requests exceed queue size for # more than 3 minutes squid aborts its operation. The default value is # set to 2*numberofchildren. # # You must have at least one ssl_crtd process. #Default: # sslcrtd_children 32 startup=5 idle=1 # TAG: sslcrtvalidator_program # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Specify the location and options of the executable for ssl_crt_validator # process. # # Usage: sslcrtvalidator_program [ttl=n] [cache=n] path ... # # Options: # ttl=n TTL in seconds for cached results. The default is 60 secs # cache=n limit the result cache size. The default value is 2048 #Default: # none # TAG: sslcrtvalidator_children # Note: This option is only available if Squid is rebuilt with the # --with-openssl # # Specifies the maximum number of certificate validation processes that # Squid may spawn (numberofchildren) and several related options. Using # too few of these helper processes (a.k.a. "helpers") creates request # queues. Using too many helpers wastes your system resources. Squid # does not support spawning more than 32 helpers. # # Usage: numberofchildren [option]... # # The startup= and idle= options allow some measure of skew in your # tuning. # # startup=N # # Sets the minimum number of processes to spawn when Squid # starts or reconfigures. When set to zero the first request will # cause spawning of the first child process to handle it. # # Starting too few children temporary slows Squid under load while it # tries to spawn enough additional processes to cope with traffic. # # idle=N # # Sets a minimum of how many processes Squid is to try and keep available # at all times. When traffic begins to rise above what the existing # processes can handle this many more will be spawned up to the maximum # configured. A minimum setting of 1 is required. # # concurrency= # # The number of requests each certificate validator helper can handle in # parallel. A value of 0 indicates the certficate validator does not # support concurrency. Defaults to 1. # # When this directive is set to a value >= 1 then the protocol # used to communicate with the helper is modified to include # a request ID in front of the request/response. The request # ID from the request must be echoed back with the response # to that request. # # queue-size=N # # Sets the maximum number of queued requests. A request is queued when # no existing child can accept it due to concurrency limit and no new # child can be started due to numberofchildren limit. If the queued # requests exceed queue size for more than 3 minutes squid aborts its # operation. The default value is set to 2*numberofchildren. # # You must have at least one ssl_crt_validator process. #Default: # sslcrtvalidator_children 32 startup=5 idle=1 concurrency=1 # OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM # ----------------------------------------------------------------------------- # TAG: cache_peer # To specify other caches in a hierarchy, use the format: # # cache_peer hostname type http-port icp-port [options] # # For example, # # # proxy icp # # hostname type port port options # # -------------------- -------- ----- ----- ----------- # cache_peer parent.foo.net parent 3128 3130 default # cache_peer sib1.foo.net sibling 3128 3130 proxy-only # cache_peer sib2.foo.net sibling 3128 3130 proxy-only # cache_peer example.com parent 80 0 default # cache_peer cdn.example.com sibling 3128 0 # # type: either 'parent', 'sibling', or 'multicast'. # # proxy-port: The port number where the peer accept HTTP requests. # For other Squid proxies this is usually 3128 # For web servers this is usually 80 # # icp-port: Used for querying neighbor caches about objects. # Set to 0 if the peer does not support ICP or HTCP. # See ICP and HTCP options below for additional details. # # # ==== ICP OPTIONS ==== # # You MUST also set icp_port and icp_access explicitly when using these options. # The defaults will prevent peer traffic using ICP. # # # no-query Disable ICP queries to this neighbor. # # multicast-responder # Indicates the named peer is a member of a multicast group. # ICP queries will not be sent directly to the peer, but ICP # replies will be accepted from it. # # closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward # CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes. # # background-ping # To only send ICP queries to this neighbor infrequently. # This is used to keep the neighbor round trip time updated # and is usually used in conjunction with weighted-round-robin. # # # ==== HTCP OPTIONS ==== # # You MUST also set htcp_port and htcp_access explicitly when using these options. # The defaults will prevent peer traffic using HTCP. # # # htcp Send HTCP, instead of ICP, queries to the neighbor. # You probably also want to set the "icp-port" to 4827 # instead of 3130. This directive accepts a comma separated # list of options described below. # # htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier). # # htcp=no-clr Send HTCP to the neighbor but without # sending any CLR requests. This cannot be used with # only-clr. # # htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests. # This cannot be used with no-clr. # # htcp=no-purge-clr # Send HTCP to the neighbor including CLRs but only when # they do not result from PURGE requests. # # htcp=forward-clr # Forward any HTCP CLR requests this proxy receives to the peer. # # # ==== PEER SELECTION METHODS ==== # # The default peer selection method is ICP, with the first responding peer # being used as source. These options can be used for better load balancing. # # # default This is a parent cache which can be used as a "last-resort" # if a peer cannot be located by any of the peer-selection methods. # If specified more than once, only the first is used. # # round-robin Load-Balance parents which should be used in a round-robin # fashion in the absence of any ICP queries. # weight=N can be used to add bias. # # weighted-round-robin # Load-Balance parents which should be used in a round-robin # fashion with the frequency of each parent being based on the # round trip time. Closer parents are used more often. # Usually used for background-ping parents. # weight=N can be used to add bias. # # carp Load-Balance parents which should be used as a CARP array. # The requests will be distributed among the parents based on the # CARP load balancing hash function based on their weight. # # userhash Load-balance parents based on the client proxy_auth or ident username. # # sourcehash Load-balance parents based on the client source IP. # # multicast-siblings # To be used only for cache peers of type "multicast". # ALL members of this multicast group have "sibling" # relationship with it, not "parent". This is to a multicast # group when the requested object would be fetched only from # a "parent" cache, anyway. It's useful, e.g., when # configuring a pool of redundant Squid proxies, being # members of the same multicast group. # # # ==== PEER SELECTION OPTIONS ==== # # weight=N use to affect the selection of a peer during any weighted # peer-selection mechanisms. # The weight must be an integer; default is 1, # larger weights are favored more. # This option does not affect parent selection if a peering # protocol is not in use. # # basetime=N Specify a base amount to be subtracted from round trip # times of parents. # It is subtracted before division by weight in calculating # which parent to fectch from. If the rtt is less than the # base time the rtt is set to a minimal value. # # ttl=N Specify a TTL to use when sending multicast ICP queries # to this address. # Only useful when sending to a multicast group. # Because we don't accept ICP replies from random # hosts, you must configure other group members as # peers with the 'multicast-responder' option. # # no-delay To prevent access to this neighbor from influencing the # delay pools. # # digest-url=URL Tell Squid to fetch the cache digest (if digests are # enabled) for this host from the specified URL rather # than the Squid default location. # # # ==== CARP OPTIONS ==== # # carp-key=key-specification # use a different key than the full URL to hash against the peer. # the key-specification is a comma-separated list of the keywords # scheme, host, port, path, params # Order is not important. # # ==== ACCELERATOR / REVERSE-PROXY OPTIONS ==== # # originserver Causes this parent to be contacted as an origin server. # Meant to be used in accelerator setups when the peer # is a web server. # # forceddomain=name # Set the Host header of requests forwarded to this peer. # Useful in accelerator setups where the server (peer) # expects a certain domain name but clients may request # others. ie example.com or www.example.com # # no-digest Disable request of cache digests. # # no-netdb-exchange # Disables requesting ICMP RTT database (NetDB). # # # ==== AUTHENTICATION OPTIONS ==== # # login=user:password # If this is a personal/workgroup proxy and your parent # requires proxy authentication. # # Note: The string can include URL escapes (i.e. %20 for # spaces). This also means % must be written as %%. # # login=PASSTHRU # Send login details received from client to this peer. # Both Proxy- and WWW-Authorization headers are passed # without alteration to the peer. # Authentication is not required by Squid for this to work. # # Note: This will pass any form of authentication but # only Basic auth will work through a proxy unless the # connection-auth options are also used. # # login=PASS Send login details received from client to this peer. # Authentication is not required by this option. # # If there are no client-provided authentication headers # to pass on, but username and password are available # from an external ACL user= and password= result tags # they may be sent instead. # # Note: To combine this with proxy_auth both proxies must # share the same user database as HTTP only allows for # a single login (one for proxy, one for origin server). # Also be warned this will expose your users proxy # password to the peer. USE WITH CAUTION # # login=*:password # Send the username to the upstream cache, but with a # fixed password. This is meant to be used when the peer # is in another administrative domain, but it is still # needed to identify each user. # The star can optionally be followed by some extra # information which is added to the username. This can # be used to identify this proxy to the peer, similar to # the login=username:password option above. # # login=NEGOTIATE # If this is a personal/workgroup proxy and your parent # requires a secure proxy authentication. # The first principal from the default keytab or defined by # the environment variable KRB5_KTNAME will be used. # # WARNING: The connection may transmit requests from multiple # clients. Negotiate often assumes end-to-end authentication # and a single-client. Which is not strictly true here. # # login=NEGOTIATE:principal_name # If this is a personal/workgroup proxy and your parent # requires a secure proxy authentication. # The principal principal_name from the default keytab or # defined by the environment variable KRB5_KTNAME will be # used. # # WARNING: The connection may transmit requests from multiple # clients. Negotiate often assumes end-to-end authentication # and a single-client. Which is not strictly true here. # # connection-auth=on|off # Tell Squid that this peer does or not support Microsoft # connection oriented authentication, and any such # challenges received from there should be ignored. # Default is auto to automatically determine the status # of the peer. # # auth-no-keytab # Do not use a keytab to authenticate to a peer when # login=NEGOTIATE is specified. Let the GSSAPI # implementation determine which already existing # credentials cache to use instead. # # # ==== SSL / HTTPS / TLS OPTIONS ==== # # tls Encrypt connections to this peer with TLS. # # sslcert=/path/to/ssl/certificate # A client X.509 certificate to use when connecting to # this peer. # # sslkey=/path/to/ssl/key # The private key corresponding to sslcert above. # # If sslkey= is not specified sslcert= is assumed to # reference a PEM file containing both the certificate # and private key. # # sslcipher=... The list of valid SSL ciphers to use when connecting # to this peer. # # tls-min-version=1.N # The minimum TLS protocol version to permit. To control # SSLv3 use the tls-options= parameter. # Supported Values: 1.0 (default), 1.1, 1.2 # # tls-options=... Specify various TLS implementation options. # # OpenSSL options most important are: # # NO_SSLv3 Disallow the use of SSLv3 # # SINGLE_DH_USE # Always create a new key when using # temporary/ephemeral DH key exchanges # # NO_TICKET # Disable use of RFC5077 session tickets. # Some servers may have problems # understanding the TLS extension due # to ambiguous specification in RFC4507. # # ALL Enable various bug workarounds # suggested as "harmless" by OpenSSL # Be warned that this reduces SSL/TLS # strength to some attacks. # # See the OpenSSL SSL_CTX_set_options documentation for a # more complete list. # # GnuTLS options most important are: # # %NO_TICKETS # Disable use of RFC5077 session tickets. # Some servers may have problems # understanding the TLS extension due # to ambiguous specification in RFC4507. # # See the GnuTLS Priority Strings documentation # for a more complete list. # http://www.gnutls.org/manual/gnutls.html#Priority-Strings # # tls-cafile= PEM file containing CA certificates to use when verifying # the peer certificate. May be repeated to load multiple files. # # sslcapath=... A directory containing additional CA certificates to # use when verifying the peer certificate. # Requires OpenSSL or LibreSSL. # # sslcrlfile=... A certificate revocation list file to use when # verifying the peer certificate. # # sslflags=... Specify various flags modifying the SSL implementation: # # DONT_VERIFY_PEER # Accept certificates even if they fail to # verify. # # DONT_VERIFY_DOMAIN # Don't verify the peer certificate # matches the server name # # ssldomain= The peer name as advertised in it's certificate. # Used for verifying the correctness of the received peer # certificate. If not specified the peer hostname will be # used. # # front-end-https[=off|on|auto] # Enable the "Front-End-Https: On" header needed when # using Squid as a SSL frontend in front of Microsoft OWA. # See MS KB document Q307347 for details on this header. # If set to auto the header will only be added if the # request is forwarded as a https:// URL. # # tls-default-ca[=off] # Whether to use the system Trusted CAs. Default is ON. # # tls-no-npn Do not use the TLS NPN extension to advertise HTTP/1.1. # # ==== GENERAL OPTIONS ==== # # connect-timeout=N # A peer-specific connect timeout. # Also see the peer_connect_timeout directive. # # connect-fail-limit=N # How many times connecting to a peer must fail before # it is marked as down. Standby connection failures # count towards this limit. Default is 10. # # allow-miss Disable Squid's use of only-if-cached when forwarding # requests to siblings. This is primarily useful when # icp_hit_stale is used by the sibling. Excessive use # of this option may result in forwarding loops. One way # to prevent peering loops when using this option, is to # deny cache peer usage on requests from a peer: # acl fromPeer ... # cache_peer_access peerName deny fromPeer # # max-conn=N Limit the number of concurrent connections the Squid # may open to this peer, including already opened idle # and standby connections. There is no peer-specific # connection limit by default. # # A peer exceeding the limit is not used for new # requests unless a standby connection is available. # # max-conn currently works poorly with idle persistent # connections: When a peer reaches its max-conn limit, # and there are idle persistent connections to the peer, # the peer may not be selected because the limiting code # does not know whether Squid can reuse those idle # connections. # # standby=N Maintain a pool of N "hot standby" connections to an # UP peer, available for requests when no idle # persistent connection is available (or safe) to use. # By default and with zero N, no such pool is maintained. # N must not exceed the max-conn limit (if any). # # At start or after reconfiguration, Squid opens new TCP # standby connections until there are N connections # available and then replenishes the standby pool as # opened connections are used up for requests. A used # connection never goes back to the standby pool, but # may go to the regular idle persistent connection pool # shared by all peers and origin servers. # # Squid never opens multiple new standby connections # concurrently. This one-at-a-time approach minimizes # flooding-like effect on peers. Furthermore, just a few # standby connections should be sufficient in most cases # to supply most new requests with a ready-to-use # connection. # # Standby connections obey server_idle_pconn_timeout. # For the feature to work as intended, the peer must be # configured to accept and keep them open longer than # the idle timeout at the connecting Squid, to minimize # race conditions typical to idle used persistent # connections. Default request_timeout and # server_idle_pconn_timeout values ensure such a # configuration. # # name=xxx Unique name for the peer. # Required if you have multiple peers on the same host # but different ports. # This name can be used in cache_peer_access and similar # directives to identify the peer. # Can be used by outgoing access controls through the # peername ACL type. # # no-tproxy Do not use the client-spoof TPROXY support when forwarding # requests to this peer. Use normal address selection instead. # This overrides the spoof_client_ip ACL. # # proxy-only objects fetched from the peer will not be stored locally. # #Default: # none # TAG: cache_peer_access # Restricts usage of cache_peer proxies. # # Usage: # cache_peer_access peer-name allow|deny [!]aclname ... # # For the required peer-name parameter, use either the value of the # cache_peer name=value parameter or, if name=value is missing, the # cache_peer hostname parameter. # # This directive narrows down the selection of peering candidates, but # does not determine the order in which the selected candidates are # contacted. That order is determined by the peer selection algorithms # (see PEER SELECTION sections in the cache_peer documentation). # # If a deny rule matches, the corresponding peer will not be contacted # for the current transaction -- Squid will not send ICP queries and # will not forward HTTP requests to that peer. An allow match leaves # the corresponding peer in the selection. The first match for a given # peer wins for that peer. # # The relative order of cache_peer_access directives for the same peer # matters. The relative order of any two cache_peer_access directives # for different peers does not matter. To ease interpretation, it is a # good idea to group cache_peer_access directives for the same peer # together. # # A single cache_peer_access directive may be evaluated multiple times # for a given transaction because individual peer selection algorithms # may check it independently from each other. These redundant checks # may be optimized away in future Squid versions. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # #Default: # No peer usage restrictions. # TAG: neighbor_type_domain # Modify the cache_peer neighbor type when passing requests # about specific domains to the peer. # # Usage: # neighbor_type_domain neighbor parent|sibling domain domain ... # # For example: # cache_peer foo.example.com parent 3128 3130 # neighbor_type_domain foo.example.com sibling .au .de # # The above configuration treats all requests to foo.example.com as a # parent proxy unless the request is for a .au or .de ccTLD domain name. #Default: # The peer type from cache_peer directive is used for all requests to that peer. # TAG: dead_peer_timeout (seconds) # This controls how long Squid waits to declare a peer cache # as "dead." If there are no ICP replies received in this # amount of time, Squid will declare the peer dead and not # expect to receive any further ICP replies. However, it # continues to send ICP queries, and will mark the peer as # alive upon receipt of the first subsequent ICP reply. # # This timeout also affects when Squid expects to receive ICP # replies from peers. If more than 'dead_peer' seconds have # passed since the last ICP reply was received, Squid will not # expect to receive an ICP reply on the next query. Thus, if # your time between requests is greater than this timeout, you # will see a lot of requests sent DIRECT to origin servers # instead of to your parents. #Default: # dead_peer_timeout 10 seconds # TAG: forward_max_tries # Limits the number of attempts to forward the request. # # For the purpose of this limit, Squid counts all high-level request # forwarding attempts, including any same-destination retries after # certain persistent connection failures and any attempts to use a # different peer. However, low-level connection reopening attempts # (enabled using connect_retries) are not counted. # # See also: forward_timeout and connect_retries. #Default: # forward_max_tries 25 # MEMORY CACHE OPTIONS # ----------------------------------------------------------------------------- # TAG: cache_mem (bytes) # NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE. # IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL # USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER # THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS. # # 'cache_mem' specifies the ideal amount of memory to be used # for: # * In-Transit objects # * Hot Objects # * Negative-Cached objects # # Data for these objects are stored in 4 KB blocks. This # parameter specifies the ideal upper limit on the total size of # 4 KB blocks allocated. In-Transit objects take the highest # priority. # # In-transit objects have priority over the others. When # additional space is needed for incoming data, negative-cached # and hot objects will be released. In other words, the # negative-cached and hot objects will fill up any unused space # not needed for in-transit objects. # # If circumstances require, this limit will be exceeded. # Specifically, if your incoming request rate requires more than # 'cache_mem' of memory to hold in-transit objects, Squid will # exceed this limit to satisfy the new requests. When the load # decreases, blocks will be freed until the high-water mark is # reached. Thereafter, blocks will be used to store hot # objects. # # If shared memory caching is enabled, Squid does not use the shared # cache space for in-transit objects, but they still consume as much # local memory as they need. For more details about the shared memory # cache, see memory_cache_shared. #Default: # cache_mem 256 MB # TAG: maximum_object_size_in_memory (bytes) # Objects greater than this size will not be attempted to kept in # the memory cache. This should be set high enough to keep objects # accessed frequently in memory to improve performance whilst low # enough to keep larger objects from hoarding cache_mem. #Default: # maximum_object_size_in_memory 512 KB # TAG: memory_cache_shared on|off # Controls whether the memory cache is shared among SMP workers. # # The shared memory cache is meant to occupy cache_mem bytes and replace # the non-shared memory cache, although some entities may still be # cached locally by workers for now (e.g., internal and in-transit # objects may be served from a local memory cache even if shared memory # caching is enabled). # # By default, the memory cache is shared if and only if all of the # following conditions are satisfied: Squid runs in SMP mode with # multiple workers, cache_mem is positive, and Squid environment # supports required IPC primitives (e.g., POSIX shared memory segments # and GCC-style atomic operations). # # To avoid blocking locks, shared memory uses opportunistic algorithms # that do not guarantee that every cachable entity that could have been # shared among SMP workers will actually be shared. #Default: # "on" where supported if doing memory caching with multiple SMP workers. # TAG: memory_cache_mode # Controls which objects to keep in the memory cache (cache_mem) # # always Keep most recently fetched objects in memory (default) # # disk Only disk cache hits are kept in memory, which means # an object must first be cached on disk and then hit # a second time before cached in memory. # # network Only objects fetched from network is kept in memory #Default: # Keep the most recently fetched objects in memory # TAG: memory_replacement_policy # The memory replacement policy parameter determines which # objects are purged from memory when memory space is needed. # # See cache_replacement_policy for details on algorithms. #Default: # memory_replacement_policy lru # DISK CACHE OPTIONS # ----------------------------------------------------------------------------- # TAG: cache_replacement_policy # The cache replacement policy parameter determines which # objects are evicted (replaced) when disk space is needed. # # lru : Squid's original list based LRU policy # heap GDSF : Greedy-Dual Size Frequency # heap LFUDA: Least Frequently Used with Dynamic Aging # heap LRU : LRU policy implemented using a heap # # Applies to any cache_dir lines listed below this directive. # # The LRU policies keeps recently referenced objects. # # The heap GDSF policy optimizes object hit rate by keeping smaller # popular objects in cache so it has a better chance of getting a # hit. It achieves a lower byte hit rate than LFUDA though since # it evicts larger (possibly popular) objects. # # The heap LFUDA policy keeps popular objects in cache regardless of # their size and thus optimizes byte hit rate at the expense of # hit rate since one large, popular object will prevent many # smaller, slightly less popular objects from being cached. # # Both policies utilize a dynamic aging mechanism that prevents # cache pollution that can otherwise occur with frequency-based # replacement policies. # # NOTE: if using the LFUDA replacement policy you should increase # the value of maximum_object_size above its default of 4 MB to # to maximize the potential byte hit rate improvement of LFUDA. # # For more information about the GDSF and LFUDA cache replacement # policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html # and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html. #Default: # cache_replacement_policy lru # TAG: minimum_object_size (bytes) # Objects smaller than this size will NOT be saved on disk. The # value is specified in bytes, and the default is 0 KB, which # means all responses can be stored. #Default: # no limit # TAG: maximum_object_size (bytes) # Set the default value for max-size parameter on any cache_dir. # The value is specified in bytes, and the default is 4 MB. # # If you wish to get a high BYTES hit ratio, you should probably # increase this (one 32 MB object hit counts for 3200 10KB # hits). # # If you wish to increase hit ratio more than you want to # save bandwidth you should leave this low. # # NOTE: if using the LFUDA replacement policy you should increase # this value to maximize the byte hit rate improvement of LFUDA! # See cache_replacement_policy for a discussion of this policy. #Default: # maximum_object_size 4 MB # TAG: cache_dir # Format: # cache_dir Type Directory-Name Fs-specific-data [options] # # You can specify multiple cache_dir lines to spread the # cache among different disk partitions. # # Type specifies the kind of storage system to use. Only "ufs" # is built by default. To enable any of the other storage systems # see the --enable-storeio configure option. # # 'Directory' is a top-level directory where cache swap # files will be stored. If you want to use an entire disk # for caching, this can be the mount-point directory. # The directory must exist and be writable by the Squid # process. Squid will NOT create this directory for you. # # In SMP configurations, cache_dir must not precede the workers option # and should use configuration macros or conditionals to give each # worker interested in disk caching a dedicated cache directory. # # # ==== The ufs store type ==== # # "ufs" is the old well-known Squid storage format that has always # been there. # # Usage: # cache_dir ufs Directory-Name Mbytes L1 L2 [options] # # 'Mbytes' is the amount of disk space (MB) to use under this # directory. The default is 100 MB. Change this to suit your # configuration. Do NOT put the size of your disk drive here. # Instead, if you want Squid to use the entire disk drive, # subtract 20% and use that value. # # 'L1' is the number of first-level subdirectories which # will be created under the 'Directory'. The default is 16. # # 'L2' is the number of second-level subdirectories which # will be created under each first-level directory. The default # is 256. # # # ==== The aufs store type ==== # # "aufs" uses the same storage format as "ufs", utilizing # POSIX-threads to avoid blocking the main Squid process on # disk-I/O. This was formerly known in Squid as async-io. # # Usage: # cache_dir aufs Directory-Name Mbytes L1 L2 [options] # # see argument descriptions under ufs above # # # ==== The diskd store type ==== # # "diskd" uses the same storage format as "ufs", utilizing a # separate process to avoid blocking the main Squid process on # disk-I/O. # # Usage: # cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n] # # see argument descriptions under ufs above # # Q1 specifies the number of unacknowledged I/O requests when Squid # stops opening new files. If this many messages are in the queues, # Squid won't open new files. Default is 64 # # Q2 specifies the number of unacknowledged messages when Squid # starts blocking. If this many messages are in the queues, # Squid blocks until it receives some replies. Default is 72 # # When Q1 < Q2 (the default), the cache directory is optimized # for lower response time at the expense of a decrease in hit # ratio. If Q1 > Q2, the cache directory is optimized for # higher hit ratio at the expense of an increase in response # time. # # # ==== The rock store type ==== # # Usage: # cache_dir rock Directory-Name Mbytes [options] # # The Rock Store type is a database-style storage. All cached # entries are stored in a "database" file, using fixed-size slots. # A single entry occupies one or more slots. # # If possible, Squid using Rock Store creates a dedicated kid # process called "disker" to avoid blocking Squid worker(s) on disk # I/O. One disker kid is created for each rock cache_dir. Diskers # are created only when Squid, running in daemon mode, has support # for the IpcIo disk I/O module. # # swap-timeout=msec: Squid will not start writing a miss to or # reading a hit from disk if it estimates that the swap operation # will take more than the specified number of milliseconds. By # default and when set to zero, disables the disk I/O time limit # enforcement. Ignored when using blocking I/O module because # blocking synchronous I/O does not allow Squid to estimate the # expected swap wait time. # # max-swap-rate=swaps/sec: Artificially limits disk access using # the specified I/O rate limit. Swap out requests that # would cause the average I/O rate to exceed the limit are # delayed. Individual swap in requests (i.e., hits or reads) are # not delayed, but they do contribute to measured swap rate and # since they are placed in the same FIFO queue as swap out # requests, they may wait longer if max-swap-rate is smaller. # This is necessary on file systems that buffer "too # many" writes and then start blocking Squid and other processes # while committing those writes to disk. Usually used together # with swap-timeout to avoid excessive delays and queue overflows # when disk demand exceeds available disk "bandwidth". By default # and when set to zero, disables the disk I/O rate limit # enforcement. Currently supported by IpcIo module only. # # slot-size=bytes: The size of a database "record" used for # storing cached responses. A cached response occupies at least # one slot and all database I/O is done using individual slots so # increasing this parameter leads to more disk space waste while # decreasing it leads to more disk I/O overheads. Should be a # multiple of your operating system I/O page size. Defaults to # 16KBytes. A housekeeping header is stored with each slot and # smaller slot-sizes will be rejected. The header is smaller than # 100 bytes. # # # ==== COMMON OPTIONS ==== # # no-store no new objects should be stored to this cache_dir. # # min-size=n the minimum object size in bytes this cache_dir # will accept. It's used to restrict a cache_dir # to only store large objects (e.g. AUFS) while # other stores are optimized for smaller objects # (e.g. Rock). # Defaults to 0. # # max-size=n the maximum object size in bytes this cache_dir # supports. # The value in maximum_object_size directive sets # the default unless more specific details are # available (ie a small store capacity). # # Note: To make optimal use of the max-size limits you should order # the cache_dir lines with the smallest max-size value first. # #Default: # No disk cache. Store cache ojects only in memory. # # Uncomment and adjust the following to add a disk cache directory. #cache_dir ufs /var/spool/squid 100 16 256 # TAG: store_dir_select_algorithm # How Squid selects which cache_dir to use when the response # object will fit into more than one. # # Regardless of which algorithm is used the cache_dir min-size # and max-size parameters are obeyed. As such they can affect # the selection algorithm by limiting the set of considered # cache_dir. # # Algorithms: # # least-load # # This algorithm is suited to caches with similar cache_dir # sizes and disk speeds. # # The disk with the least I/O pending is selected. # When there are multiple disks with the same I/O load ranking # the cache_dir with most available capacity is selected. # # When a mix of cache_dir sizes are configured the faster disks # have a naturally lower I/O loading and larger disks have more # capacity. So space used to store objects and data throughput # may be very unbalanced towards larger disks. # # # round-robin # # This algorithm is suited to caches with unequal cache_dir # disk sizes. # # Each cache_dir is selected in a rotation. The next suitable # cache_dir is used. # # Available cache_dir capacity is only considered in relation # to whether the object will fit and meets the min-size and # max-size parameters. # # Disk I/O loading is only considered to prevent overload on slow # disks. This algorithm does not spread objects by size, so any # I/O loading per-disk may appear very unbalanced and volatile. # # If several cache_dirs use similar min-size, max-size, or other # limits to to reject certain responses, then do not group such # cache_dir lines together, to avoid round-robin selection bias # towards the first cache_dir after the group. Instead, interleave # cache_dir lines from different groups. For example: # # store_dir_select_algorithm round-robin # cache_dir rock /hdd1 ... min-size=100000 # cache_dir rock /ssd1 ... max-size=99999 # cache_dir rock /hdd2 ... min-size=100000 # cache_dir rock /ssd2 ... max-size=99999 # cache_dir rock /hdd3 ... min-size=100000 # cache_dir rock /ssd3 ... max-size=99999 #Default: # store_dir_select_algorithm least-load # TAG: max_open_disk_fds # To avoid having disk as the I/O bottleneck Squid can optionally # bypass the on-disk cache if more than this amount of disk file # descriptors are open. # # A value of 0 indicates no limit. #Default: # no limit # TAG: cache_swap_low (percent, 0-100) # The low-water mark for AUFS/UFS/diskd cache object eviction by # the cache_replacement_policy algorithm. # # Removal begins when the swap (disk) usage of a cache_dir is # above this low-water mark and attempts to maintain utilization # near the low-water mark. # # As swap utilization increases towards the high-water mark set # by cache_swap_high object eviction becomes more agressive. # # The value difference in percentages between low- and high-water # marks represent an eviction rate of 300 objects per second and # the rate continues to scale in agressiveness by multiples of # this above the high-water mark. # # Defaults are 90% and 95%. If you have a large cache, 5% could be # hundreds of MB. If this is the case you may wish to set these # numbers closer together. # # See also cache_swap_high and cache_replacement_policy #Default: # cache_swap_low 90 # TAG: cache_swap_high (percent, 0-100) # The high-water mark for AUFS/UFS/diskd cache object eviction by # the cache_replacement_policy algorithm. # # Removal begins when the swap (disk) usage of a cache_dir is # above the low-water mark set by cache_swap_low and attempts to # maintain utilization near the low-water mark. # # As swap utilization increases towards this high-water mark object # eviction becomes more agressive. # # The value difference in percentages between low- and high-water # marks represent an eviction rate of 300 objects per second and # the rate continues to scale in agressiveness by multiples of # this above the high-water mark. # # Defaults are 90% and 95%. If you have a large cache, 5% could be # hundreds of MB. If this is the case you may wish to set these # numbers closer together. # # See also cache_swap_low and cache_replacement_policy #Default: # cache_swap_high 95 # LOGFILE OPTIONS # ----------------------------------------------------------------------------- # TAG: logformat # Usage: # # logformat <name> <format specification> # # Defines an access log format. # # The <format specification> is a string with embedded % format codes # # % format codes all follow the same basic structure where all # components but the formatcode are optional and usually unnecessary, # especially when dealing with common codes. # # % [encoding] [-] [[0]width] [{arg}] formatcode [{arg}] # # encoding escapes or otherwise protects "special" characters: # # " Quoted string encoding where quote(") and # backslash(\) characters are \-escaped while # CR, LF, and TAB characters are encoded as \r, # \n, and \t two-character sequences. # # [ Custom Squid encoding where percent(%), square # brackets([]), backslash(\) and characters with # codes outside of [32,126] range are %-encoded. # SP is not encoded. Used by log_mime_hdrs. # # # URL encoding (a.k.a. percent-encoding) where # all URL unsafe and control characters (per RFC # 1738) are %-encoded. # # / Shell-like encoding where quote(") and # backslash(\) characters are \-escaped while CR # and LF characters are encoded as \r and \n # two-character sequences. Values containing SP # character(s) are surrounded by quotes("). # # ' Raw/as-is encoding with no escaping/quoting. # # Default encoding: When no explicit encoding is # specified, each %code determines its own encoding. # Most %codes use raw/as-is encoding, but some codes use # a so called "pass-through URL encoding" where all URL # unsafe and control characters (per RFC 1738) are # %-encoded, but the percent character(%) is left as is. # # - left aligned # # width minimum and/or maximum field width: # [width_min][.width_max] # When minimum starts with 0, the field is zero-padded. # String values exceeding maximum width are truncated. # # {arg} argument such as header name etc. This field may be # placed before or after the token, but not both at once. # # Format codes: # # % a literal % character # sn Unique sequence number per log line entry # err_code The ID of an error response served by Squid or # a similar internal error identifier. # err_detail Additional err_code-dependent error information. # note The annotation specified by the argument. Also # logs the adaptation meta headers set by the # adaptation_meta configuration parameter. # If no argument given all annotations logged. # The argument may include a separator to use with # annotation values: # name[:separator] # By default, multiple note values are separated with "," # and multiple notes are separated with "\r\n". # When logging named notes with %{name}note, the # explicitly configured separator is used between note # values. When logging all notes with %note, the # explicitly configured separator is used between # individual notes. There is currently no way to # specify both value and notes separators when logging # all notes with %note. # # Connection related format codes: # # >a Client source IP address # >A Client FQDN # >p Client source port # >eui Client source EUI (MAC address, EUI-48 or EUI-64 identifier) # >la Local IP address the client connected to # >lp Local port number the client connected to # >qos Client connection TOS/DSCP value set by Squid # >nfmark Client connection netfilter mark set by Squid # # la Local listening IP address the client connection was connected to. # lp Local listening port number the client connection was connected to. # # <a Server IP address of the last server or peer connection # <A Server FQDN or peer name # <p Server port number of the last server or peer connection # <la Local IP address of the last server or peer connection # <lp Local port number of the last server or peer connection # <qos Server connection TOS/DSCP value set by Squid # <nfmark Server connection netfilter mark set by Squid # # >handshake Raw client handshake # Initial client bytes received by Squid on a newly # accepted TCP connection or inside a just established # CONNECT tunnel. Squid stops accumulating handshake # bytes as soon as the handshake parser succeeds or # fails (determining whether the client is using the # expected protocol). # # For HTTP clients, the handshake is the request line. # For TLS clients, the handshake consists of all TLS # records up to and including the TLS record that # contains the last byte of the first ClientHello # message. For clients using an unsupported protocol, # this field contains the bytes received by Squid at the # time of the handshake parsing failure. # # See the on_unsupported_protocol directive for more # information on Squid handshake traffic expectations. # # Current support is limited to these contexts: # - http_port connections, but only when the # on_unsupported_protocol directive is in use. # - https_port connections (and CONNECT tunnels) that # are subject to the ssl_bump peek or stare action. # # To protect binary handshake data, this field is always # base64-encoded (RFC 4648 Section 4). If logformat # field encoding is configured, that encoding is applied # on top of base64. Otherwise, the computed base64 value # is recorded as is. # # Time related format codes: # # ts Seconds since epoch # tu subsecond time (milliseconds) # tl Local time. Optional strftime format argument # default %d/%b/%Y:%H:%M:%S %z # tg GMT time. Optional strftime format argument # default %d/%b/%Y:%H:%M:%S %z # tr Response time (milliseconds) # dt Total time spent making DNS lookups (milliseconds) # tS Approximate master transaction start time in # <full seconds since epoch>.<fractional seconds> format. # Currently, Squid considers the master transaction # started when a complete HTTP request header initiating # the transaction is received from the client. This is # the same value that Squid uses to calculate transaction # response time when logging %tr to access.log. Currently, # Squid uses millisecond resolution for %tS values, # similar to the default access.log "current time" field # (%ts.%03tu). # # Access Control related format codes: # # et Tag returned by external acl # ea Log string returned by external acl # un User name (any available) # ul User name from authentication # ue User name from external acl helper # ui User name from ident # un A user name. Expands to the first available name # from the following list of information sources: # - authenticated user name, like %ul # - user name supplied by an external ACL, like %ue # - SSL client name, like %us # - ident user name, like %ui # credentials Client credentials. The exact meaning depends on # the authentication scheme: For Basic authentication, # it is the password; for Digest, the realm sent by the # client; for NTLM and Negotiate, the client challenge # or client credentials prefixed with "YR " or "KK ". # # HTTP related format codes: # # REQUEST # # [http::]rm Request method (GET/POST etc) # [http::]>rm Request method from client # [http::]<rm Request method sent to server or peer # # [http::]ru Request URL received (or computed) and sanitized # # Logs request URI received from the client, a # request adaptation service, or a request # redirector (whichever was applied last). # # Computed URLs are URIs of internally generated # requests and various "error:..." URIs. # # Honors strip_query_terms and uri_whitespace. # # This field is not encoded by default. Encoding # this field using variants of %-encoding will # clash with uri_whitespace modifications that # also use %-encoding. # # [http::]>ru Request URL received from the client (or computed) # # Computed URLs are URIs of internally generated # requests and various "error:..." URIs. # # Unlike %ru, this request URI is not affected # by request adaptation, URL rewriting services, # and strip_query_terms. # # Honors uri_whitespace. # # This field is using pass-through URL encoding # by default. Encoding this field using other # variants of %-encoding will clash with # uri_whitespace modifications that also use # %-encoding. # # [http::]<ru Request URL sent to server or peer # [http::]>rs Request URL scheme from client # [http::]<rs Request URL scheme sent to server or peer # [http::]>rd Request URL domain from client # [http::]<rd Request URL domain sent to server or peer # [http::]>rP Request URL port from client # [http::]<rP Request URL port sent to server or peer # [http::]rp Request URL path excluding hostname # [http::]>rp Request URL path excluding hostname from client # [http::]<rp Request URL path excluding hostname sent to server or peer # [http::]rv Request protocol version # [http::]>rv Request protocol version from client # [http::]<rv Request protocol version sent to server or peer # # [http::]>h Original received request header. # Usually differs from the request header sent by # Squid, although most fields are often preserved. # Accepts optional header field name/value filter # argument using name[:[separator]element] format. # [http::]>ha Received request header after adaptation and # redirection (pre-cache REQMOD vectoring point). # Usually differs from the request header sent by # Squid, although most fields are often preserved. # Optional header name argument as for >h # # RESPONSE # # [http::]<Hs HTTP status code received from the next hop # [http::]>Hs HTTP status code sent to the client # # [http::]<h Reply header. Optional header name argument # as for >h # # [http::]mt MIME content type # # # SIZE COUNTERS # # [http::]st Total size of request + reply traffic with client # [http::]>st Total size of request received from client. # Excluding chunked encoding bytes. # [http::]<st Total size of reply sent to client (after adaptation) # # [http::]>sh Size of request headers received from client # [http::]<sh Size of reply headers sent to client (after adaptation) # # [http::]<sH Reply high offset sent # [http::]<sS Upstream object size # # [http::]<bs Number of HTTP-equivalent message body bytes # received from the next hop, excluding chunked # transfer encoding and control messages. # Generated FTP/Gopher listings are treated as # received bodies. # # TIMING # # [http::]<pt Peer response time in milliseconds. The timer starts # when the last request byte is sent to the next hop # and stops when the last response byte is received. # [http::]<tt Total time in milliseconds. The timer # starts with the first connect request (or write I/O) # sent to the first selected peer. The timer stops # with the last I/O with the last peer. # # Squid handling related format codes: # # Ss Squid request status (TCP_MISS etc) # Sh Squid hierarchy status (DEFAULT_PARENT etc) # # SSL-related format codes: # # ssl::bump_mode SslBump decision for the transaction: # # For CONNECT requests that initiated bumping of # a connection and for any request received on # an already bumped connection, Squid logs the # corresponding SslBump mode ("splice", "bump", # "peek", "stare", "terminate", "server-first" # or "client-first"). See the ssl_bump option # for more information about these modes. # # A "none" token is logged for requests that # triggered "ssl_bump" ACL evaluation matching # a "none" rule. # # In all other cases, a single dash ("-") is # logged. # # ssl::>sni SSL client SNI sent to Squid. # # ssl::>cert_subject # The Subject field of the received client # SSL certificate or a dash ('-') if Squid has # received an invalid/malformed certificate or # no certificate at all. Consider encoding the # logged value because Subject often has spaces. # # ssl::>cert_issuer # The Issuer field of the received client # SSL certificate or a dash ('-') if Squid has # received an invalid/malformed certificate or # no certificate at all. Consider encoding the # logged value because Issuer often has spaces. # # ssl::<cert_subject # The Subject field of the received server # TLS certificate or a dash ('-') if this is # not available. Consider encoding the logged # value because Subject often has spaces. # # ssl::<cert_issuer # The Issuer field of the received server # TLS certificate or a dash ('-') if this is # not available. Consider encoding the logged # value because Issuer often has spaces. # # ssl::<cert_errors # The list of certificate validation errors # detected by Squid (including OpenSSL and # certificate validation helper components). The # errors are listed in the discovery order. By # default, the error codes are separated by ':'. # Accepts an optional separator argument. # # %ssl::>negotiated_version The negotiated TLS version of the # client connection. # # %ssl::<negotiated_version The negotiated TLS version of the # last server or peer connection. # # %ssl::>received_hello_version The TLS version of the Hello # message received from TLS client. # # %ssl::<received_hello_version The TLS version of the Hello # message received from TLS server. # # %ssl::>received_supported_version The maximum TLS version # supported by the TLS client. # # %ssl::<received_supported_version The maximum TLS version # supported by the TLS server. # # %ssl::>negotiated_cipher The negotiated cipher of the # client connection. # # %ssl::<negotiated_cipher The negotiated cipher of the # last server or peer connection. # # If ICAP is enabled, the following code becomes available (as # well as ICAP log codes documented with the icap_log option): # # icap::tt Total ICAP processing time for the HTTP # transaction. The timer ticks when ICAP # ACLs are checked and when ICAP # transaction is in progress. # # If adaptation is enabled the following codes become available: # # adapt::<last_h The header of the last ICAP response or # meta-information from the last eCAP # transaction related to the HTTP transaction. # Like <h, accepts an optional header name # argument. # # adapt::sum_trs Summed adaptation transaction response # times recorded as a comma-separated list in # the order of transaction start time. Each time # value is recorded as an integer number, # representing response time of one or more # adaptation (ICAP or eCAP) transaction in # milliseconds. When a failed transaction is # being retried or repeated, its time is not # logged individually but added to the # replacement (next) transaction. See also: # adapt::all_trs. # # adapt::all_trs All adaptation transaction response times. # Same as adaptation_strs but response times of # individual transactions are never added # together. Instead, all transaction response # times are recorded individually. # # You can prefix adapt::*_trs format codes with adaptation # service name in curly braces to record response time(s) specific # to that service. For example: %{my_service}adapt::sum_trs # # The default formats available (which do not need re-defining) are: # #logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %[un %Sh/%<a %mt #logformat common %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh #logformat combined %>a %[ui %[un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh #logformat referrer %ts.%03tu %>a %{Referer}>h %ru #logformat useragent %>a [%tl] "%{User-Agent}>h" # # NOTE: When the log_mime_hdrs directive is set to ON. # The squid, common and combined formats have a safely encoded copy # of the mime headers appended to each line within a pair of brackets. # # NOTE: The common and combined formats are not quite true to the Apache definition. # The logs from Squid contain an extra status and hierarchy code appended. # #Default: # The format definitions squid, common, combined, referrer, useragent are built in. # TAG: access_log # Configures whether and how Squid logs HTTP and ICP transactions. # If access logging is enabled, a single line is logged for every # matching HTTP or ICP request. The recommended directive formats are: # # access_log <module>:<place> [option ...] [acl acl ...] # access_log none [acl acl ...] # # The following directive format is accepted but may be deprecated: # access_log <module>:<place> [<logformat name> [acl acl ...]] # # In most cases, the first ACL name must not contain the '=' character # and should not be equal to an existing logformat name. You can always # start with an 'all' ACL to work around those restrictions. # # Will log to the specified module:place using the specified format (which # must be defined in a logformat directive) those entries which match # ALL the acl's specified (which must be defined in acl clauses). # If no acl is specified, all requests will be logged to this destination. # # ===== Available options for the recommended directive format ===== # # logformat=name Names log line format (either built-in or # defined by a logformat directive). Defaults # to 'squid'. # # buffer-size=64KB Defines approximate buffering limit for log # records (see buffered_logs). Squid should not # keep more than the specified size and, hence, # should flush records before the buffer becomes # full to avoid overflows under normal # conditions (the exact flushing algorithm is # module-dependent though). The on-error option # controls overflow handling. # # on-error=die|drop Defines action on unrecoverable errors. The # 'drop' action ignores (i.e., does not log) # affected log records. The default 'die' action # kills the affected worker. The drop action # support has not been tested for modules other # than tcp. # # rotate=N Specifies the number of log file rotations to # make when you run 'squid -k rotate'. The default # is to obey the logfile_rotate directive. Setting # rotate=0 will disable the file name rotation, # but the log files are still closed and re-opened. # This will enable you to rename the logfiles # yourself just before sending the rotate signal. # Only supported by the stdio module. # # ===== Modules Currently available ===== # # none Do not log any requests matching these ACL. # Do not specify Place or logformat name. # # stdio Write each log line to disk immediately at the completion of # each request. # Place: the filename and path to be written. # # daemon Very similar to stdio. But instead of writing to disk the log # line is passed to a daemon helper for asychronous handling instead. # Place: varies depending on the daemon. # # log_file_daemon Place: the file name and path to be written. # # syslog To log each request via syslog facility. # Place: The syslog facility and priority level for these entries. # Place Format: facility.priority # # where facility could be any of: # authpriv, daemon, local0 ... local7 or user. # # And priority could be any of: # err, warning, notice, info, debug. # # udp To send each log line as text data to a UDP receiver. # Place: The destination host name or IP and port. # Place Format: //host:port # # tcp To send each log line as text data to a TCP receiver. # Lines may be accumulated before sending (see buffered_logs). # Place: The destination host name or IP and port. # Place Format: //host:port # # Default: # access_log daemon:/var/log/squid/access.log squid #Default: # access_log daemon:/var/log/squid/access.log squid # TAG: icap_log # ICAP log files record ICAP transaction summaries, one line per # transaction. # # The icap_log option format is: # icap_log <filepath> [<logformat name> [acl acl ...]] # icap_log none [acl acl ...]] # # Please see access_log option documentation for details. The two # kinds of logs share the overall configuration approach and many # features. # # ICAP processing of a single HTTP message or transaction may # require multiple ICAP transactions. In such cases, multiple # ICAP transaction log lines will correspond to a single access # log line. # # ICAP log supports many access.log logformat %codes. In ICAP context, # HTTP message-related %codes are applied to the HTTP message embedded # in an ICAP message. Logformat "%http::>..." codes are used for HTTP # messages embedded in ICAP requests while "%http::<..." codes are used # for HTTP messages embedded in ICAP responses. For example: # # http::>h To-be-adapted HTTP message headers sent by Squid to # the ICAP service. For REQMOD transactions, these are # HTTP request headers. For RESPMOD, these are HTTP # response headers, but Squid currently cannot log them # (i.e., %http::>h will expand to "-" for RESPMOD). # # http::<h Adapted HTTP message headers sent by the ICAP # service to Squid (i.e., HTTP request headers in regular # REQMOD; HTTP response headers in RESPMOD and during # request satisfaction in REQMOD). # # ICAP OPTIONS transactions do not embed HTTP messages. # # Several logformat codes below deal with ICAP message bodies. An ICAP # message body, if any, typically includes a complete HTTP message # (required HTTP headers plus optional HTTP message body). When # computing HTTP message body size for these logformat codes, Squid # either includes or excludes chunked encoding overheads; see # code-specific documentation for details. # # For Secure ICAP services, all size-related information is currently # computed before/after TLS encryption/decryption, as if TLS was not # in use at all. # # The following format codes are also available for ICAP logs: # # icap::<A ICAP server IP address. Similar to <A. # # icap::<service_name ICAP service name from the icap_service # option in Squid configuration file. # # icap::ru ICAP Request-URI. Similar to ru. # # icap::rm ICAP request method (REQMOD, RESPMOD, or # OPTIONS). Similar to existing rm. # # icap::>st The total size of the ICAP request sent to the ICAP # server (ICAP headers + ICAP body), including chunking # metadata (if any). # # icap::<st The total size of the ICAP response received from the # ICAP server (ICAP headers + ICAP body), including # chunking metadata (if any). # # icap::<bs The size of the ICAP response body received from the # ICAP server, excluding chunking metadata (if any). # # icap::tr Transaction response time (in # milliseconds). The timer starts when # the ICAP transaction is created and # stops when the transaction is completed. # Similar to tr. # # icap::tio Transaction I/O time (in milliseconds). The # timer starts when the first ICAP request # byte is scheduled for sending. The timers # stops when the last byte of the ICAP response # is received. # # icap::to Transaction outcome: ICAP_ERR* for all # transaction errors, ICAP_OPT for OPTION # transactions, ICAP_ECHO for 204 # responses, ICAP_MOD for message # modification, and ICAP_SAT for request # satisfaction. Similar to Ss. # # icap::Hs ICAP response status code. Similar to Hs. # # icap::>h ICAP request header(s). Similar to >h. # # icap::<h ICAP response header(s). Similar to <h. # # The default ICAP log format, which can be used without an explicit # definition, is called icap_squid: # #logformat icap_squid %ts.%03tu %6icap::tr %>A %icap::to/%03icap::Hs %icap::<st %icap::rm %icap::ru %un -/%icap::<A - # # See also: logformat and %adapt::<last_h #Default: # none # TAG: logfile_daemon # Specify the path to the logfile-writing daemon. This daemon is # used to write the access and store logs, if configured. # # Squid sends a number of commands to the log daemon: # L<data>\n - logfile data # R\n - rotate file # T\n - truncate file # O\n - reopen file # F\n - flush file # r<n>\n - set rotate count to <n> # b<n>\n - 1 = buffer output, 0 = don't buffer output # # No responses is expected. #Default: # logfile_daemon /usr/lib/squid/log_file_daemon # TAG: stats_collection allow|deny acl acl... # This options allows you to control which requests gets accounted # in performance counters. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow logging for all transactions. # TAG: cache_store_log # Logs the activities of the storage manager. Shows which # objects are ejected from the cache, and which objects are # saved and for how long. # There are not really utilities to analyze this data, so you can safely # disable it (the default). # # Store log uses modular logging outputs. See access_log for the list # of modules supported. # # Example: # cache_store_log stdio:/var/log/squid/store.log # cache_store_log daemon:/var/log/squid/store.log #Default: # none # TAG: cache_swap_state # Location for the cache "swap.state" file. This index file holds # the metadata of objects saved on disk. It is used to rebuild # the cache during startup. Normally this file resides in each # 'cache_dir' directory, but you may specify an alternate # pathname here. Note you must give a full filename, not just # a directory. Since this is the index for the whole object # list you CANNOT periodically rotate it! # # If %s can be used in the file name it will be replaced with a # a representation of the cache_dir name where each / is replaced # with '.'. This is needed to allow adding/removing cache_dir # lines when cache_swap_log is being used. # # If have more than one 'cache_dir', and %s is not used in the name # these swap logs will have names such as: # # cache_swap_log.00 # cache_swap_log.01 # cache_swap_log.02 # # The numbered extension (which is added automatically) # corresponds to the order of the 'cache_dir' lines in this # configuration file. If you change the order of the 'cache_dir' # lines in this file, these index files will NOT correspond to # the correct 'cache_dir' entry (unless you manually rename # them). We recommend you do NOT use this option. It is # better to keep these index files in each 'cache_dir' directory. #Default: # Store the journal inside its cache_dir # TAG: logfile_rotate # Specifies the default number of logfile rotations to make when you # type 'squid -k rotate'. The default is 10, which will rotate # with extensions 0 through 9. Setting logfile_rotate to 0 will # disable the file name rotation, but the logfiles are still closed # and re-opened. This will enable you to rename the logfiles # yourself just before sending the rotate signal. # # Note, from Squid-3.1 this option is only a default for cache.log, # that log can be rotated separately by using debug_options. # # Note, from Squid-4 this option is only a default for access.log # recorded by stdio: module. Those logs can be rotated separately by # using the rotate=N option on their access_log directive. # # Note, the 'squid -k rotate' command normally sends a USR1 # signal to the running squid process. In certain situations # (e.g. on Linux with Async I/O), USR1 is used for other # purposes, so -k rotate uses another signal. It is best to get # in the habit of using 'squid -k rotate' instead of 'kill -USR1 # <pid>'. # # Note, for Debian/Linux the default of logfile_rotate is # zero, since it includes external logfile-rotation methods. #Default: # logfile_rotate 0 # TAG: mime_table # Path to Squid's icon configuration file. # # You shouldn't need to change this, but the default file contains # examples and formatting information if you do. #Default: # mime_table /usr/share/squid/mime.conf # TAG: log_mime_hdrs on|off # The Cache can record both the request and the response MIME # headers for each HTTP transaction. The headers are encoded # safely and will appear as two bracketed fields at the end of # the access log (for either the native or httpd-emulated log # formats). To enable this logging set log_mime_hdrs to 'on'. #Default: # log_mime_hdrs off # TAG: pid_filename # A filename to write the process-id to. To disable, enter "none". #Default: # pid_filename /run/squid.pid # TAG: client_netmask # A netmask for client addresses in logfiles and cachemgr output. # Change this to protect the privacy of your cache clients. # A netmask of 255.255.255.0 will log all IP's in that range with # the last digit set to '0'. #Default: # Log full client IP address # TAG: strip_query_terms # By default, Squid strips query terms from requested URLs before # logging. This protects your user's privacy and reduces log size. # # When investigating HIT/MISS or other caching behaviour you # will need to disable this to see the full URL used by Squid. #Default: # strip_query_terms on # TAG: buffered_logs on|off # Whether to write/send access_log records ASAP or accumulate them and # then write/send them in larger chunks. Buffering may improve # performance because it decreases the number of I/Os. However, # buffering increases the delay before log records become available to # the final recipient (e.g., a disk file or logging daemon) and, # hence, increases the risk of log records loss. # # Note that even when buffered_logs are off, Squid may have to buffer # records if it cannot write/send them immediately due to pending I/Os # (e.g., the I/O writing the previous log record) or connectivity loss. # # Currently honored by 'daemon' and 'tcp' access_log modules only. #Default: # buffered_logs off # TAG: netdb_filename # Where Squid stores it's netdb journal. # When enabled this journal preserves netdb state between restarts. # # To disable, enter "none". #Default: # netdb_filename stdio:/var/spool/squid/netdb.state # OPTIONS FOR TROUBLESHOOTING # ----------------------------------------------------------------------------- # TAG: cache_log # Squid administrative logging file. # # This is where general information about Squid behavior goes. You can # increase the amount of data logged to this file and how often it is # rotated with "debug_options" #Default: # cache_log /var/log/squid/cache.log # TAG: debug_options # Logging options are set as section,level where each source file # is assigned a unique section. Lower levels result in less # output, Full debugging (level 9) can result in a very large # log file, so be careful. # # The magic word "ALL" sets debugging levels for all sections. # The default is to run with "ALL,1" to record important warnings. # # The rotate=N option can be used to keep more or less of these logs # than would otherwise be kept by logfile_rotate. # For most uses a single log should be enough to monitor current # events affecting Squid. #Default: # Log all critical and important messages. # TAG: coredump_dir # By default Squid leaves core files in the directory from where # it was started. If you set 'coredump_dir' to a directory # that exists, Squid will chdir() to that directory at startup # and coredump files will be left there. # #Default: # Use the directory from where Squid was started. # # Leave coredumps in the first cache dir coredump_dir /var/spool/squid # OPTIONS FOR FTP GATEWAYING # ----------------------------------------------------------------------------- # TAG: ftp_user # If you want the anonymous login password to be more informative # (and enable the use of picky FTP servers), set this to something # reasonable for your domain, like wwwuser@somewhere.net # # The reason why this is domainless by default is the # request can be made on the behalf of a user in any domain, # depending on how the cache is used. # Some FTP server also validate the email address is valid # (for example perl.com). #Default: # ftp_user Squid@ # TAG: ftp_passive # If your firewall does not allow Squid to use passive # connections, turn off this option. # # Use of ftp_epsv_all option requires this to be ON. #Default: # ftp_passive on # TAG: ftp_epsv_all # FTP Protocol extensions permit the use of a special "EPSV ALL" command. # # NATs may be able to put the connection on a "fast path" through the # translator, as the EPRT command will never be used and therefore, # translation of the data portion of the segments will never be needed. # # When a client only expects to do two-way FTP transfers this may be # useful. # If squid finds that it must do a three-way FTP transfer after issuing # an EPSV ALL command, the FTP session will fail. # # If you have any doubts about this option do not use it. # Squid will nicely attempt all other connection methods. # # Requires ftp_passive to be ON (default) for any effect. #Default: # ftp_epsv_all off # TAG: ftp_epsv # FTP Protocol extensions permit the use of a special "EPSV" command. # # NATs may be able to put the connection on a "fast path" through the # translator using EPSV, as the EPRT command will never be used # and therefore, translation of the data portion of the segments # will never be needed. # # EPSV is often required to interoperate with FTP servers on IPv6 # networks. On the other hand, it may break some IPv4 servers. # # By default, EPSV may try EPSV with any FTP server. To fine tune # that decision, you may restrict EPSV to certain clients or servers # using ACLs: # # ftp_epsv allow|deny al1 acl2 ... # # WARNING: Disabling EPSV may cause problems with external NAT and IPv6. # # Only fast ACLs are supported. # Requires ftp_passive to be ON (default) for any effect. #Default: # none # TAG: ftp_eprt # FTP Protocol extensions permit the use of a special "EPRT" command. # # This extension provides a protocol neutral alternative to the # IPv4-only PORT command. When supported it enables active FTP data # channels over IPv6 and efficient NAT handling. # # Turning this OFF will prevent EPRT being attempted and will skip # straight to using PORT for IPv4 servers. # # Some devices are known to not handle this extension correctly and # may result in crashes. Devices which suport EPRT enough to fail # cleanly will result in Squid attempting PORT anyway. This directive # should only be disabled when EPRT results in device failures. # # WARNING: Doing so will convert Squid back to the old behavior with all # the related problems with external NAT devices/layers and IPv4-only FTP. #Default: # ftp_eprt on # TAG: ftp_sanitycheck # For security and data integrity reasons Squid by default performs # sanity checks of the addresses of FTP data connections ensure the # data connection is to the requested server. If you need to allow # FTP connections to servers using another IP address for the data # connection turn this off. #Default: # ftp_sanitycheck on # TAG: ftp_telnet_protocol # The FTP protocol is officially defined to use the telnet protocol # as transport channel for the control connection. However, many # implementations are broken and does not respect this aspect of # the FTP protocol. # # If you have trouble accessing files with ASCII code 255 in the # path or similar problems involving this ASCII code you can # try setting this directive to off. If that helps, report to the # operator of the FTP server in question that their FTP server # is broken and does not follow the FTP standard. #Default: # ftp_telnet_protocol on # OPTIONS FOR EXTERNAL SUPPORT PROGRAMS # ----------------------------------------------------------------------------- # TAG: diskd_program # Specify the location of the diskd executable. # Note this is only useful if you have compiled in # diskd as one of the store io modules. #Default: # diskd_program /usr/lib/squid/diskd # TAG: unlinkd_program # Specify the location of the executable for file deletion process. #Default: # unlinkd_program /usr/lib/squid/unlinkd # TAG: pinger_program # Specify the location of the executable for the pinger process. #Default: # pinger_program /usr/lib/squid/pinger # TAG: pinger_enable # Control whether the pinger is active at run-time. # Enables turning ICMP pinger on and off with a simple # squid -k reconfigure. #Default: # pinger_enable on # OPTIONS FOR URL REWRITING # ----------------------------------------------------------------------------- # TAG: url_rewrite_program # Specify the location of the executable URL rewriter to use. # Since they can perform almost any function there isn't one included. # # For each requested URL, the rewriter will receive on line with the format # # [channel-ID <SP>] URL [<SP> extras]<NL> # # See url_rewrite_extras on how to send "extras" with optional values to # the helper. # After processing the request the helper must reply using the following format: # # [channel-ID <SP>] result [<SP> kv-pairs] # # The result code can be: # # OK status=30N url="..." # Redirect the URL to the one supplied in 'url='. # 'status=' is optional and contains the status code to send # the client in Squids HTTP response. It must be one of the # HTTP redirect status codes: 301, 302, 303, 307, 308. # When no status is given Squid will use 302. # # OK rewrite-url="..." # Rewrite the URL to the one supplied in 'rewrite-url='. # The new URL is fetched directly by Squid and returned to # the client as the response to its request. # # OK # When neither of url= and rewrite-url= are sent Squid does # not change the URL. # # ERR # Do not change the URL. # # BH # An internal error occurred in the helper, preventing # a result being identified. The 'message=' key name is # reserved for delivering a log message. # # # In addition to the above kv-pairs Squid also understands the following # optional kv-pairs received from URL rewriters: # clt_conn_tag=TAG # Associates a TAG with the client TCP connection. # The TAG is treated as a regular annotation but persists across # future requests on the client connection rather than just the # current request. A helper may update the TAG during subsequent # requests be returning a new kv-pair. # # When using the concurrency= option the protocol is changed by # introducing a query channel tag in front of the request/response. # The query channel tag is a number between 0 and concurrency-1. # This value must be echoed back unchanged to Squid as the first part # of the response relating to its request. # # WARNING: URL re-writing ability should be avoided whenever possible. # Use the URL redirect form of response instead. # # Re-write creates a difference in the state held by the client # and server. Possibly causing confusion when the server response # contains snippets of its view state. Embeded URLs, response # and content Location headers, etc. are not re-written by this # interface. # # By default, a URL rewriter is not used. #Default: # none # TAG: url_rewrite_children # Specifies the maximum number of redirector processes that Squid may # spawn (numberofchildren) and several related options. Using too few of # these helper processes (a.k.a. "helpers") creates request queues. # Using too many helpers wastes your system resources. # # Usage: numberofchildren [option]... # # The startup= and idle= options allow some measure of skew in your # tuning. # # startup= # # Sets a minimum of how many processes are to be spawned when Squid # starts or reconfigures. When set to zero the first request will # cause spawning of the first child process to handle it. # # Starting too few will cause an initial slowdown in traffic as Squid # attempts to simultaneously spawn enough processes to cope. # # idle= # # Sets a minimum of how many processes Squid is to try and keep available # at all times. When traffic begins to rise above what the existing # processes can handle this many more will be spawned up to the maximum # configured. A minimum setting of 1 is required. # # concurrency= # # The number of requests each redirector helper can handle in # parallel. Defaults to 0 which indicates the redirector # is a old-style single threaded redirector. # # When this directive is set to a value >= 1 then the protocol # used to communicate with the helper is modified to include # an ID in front of the request/response. The ID from the request # must be echoed back with the response to that request. # # queue-size=N # # Sets the maximum number of queued requests. A request is queued when # no existing child can accept it due to concurrency limit and no new # child can be started due to numberofchildren limit. The default # maximum is zero if url_rewrite_bypass is enabled and # 2*numberofchildren otherwise. If the queued requests exceed queue size # and redirector_bypass configuration option is set, then redirector is # bypassed. Otherwise, Squid is allowed to temporarily exceed the # configured maximum, marking the affected helper as "overloaded". If # the helper overload lasts more than 3 minutes, the action prescribed # by the on-persistent-overload option applies. # # on-persistent-overload=action # # Specifies Squid reaction to a new helper request arriving when the helper # has been overloaded for more that 3 minutes already. The number of queued # requests determines whether the helper is overloaded (see the queue-size # option). # # Two actions are supported: # # die Squid worker quits. This is the default behavior. # # ERR Squid treats the helper request as if it was # immediately submitted, and the helper immediately # replied with an ERR response. This action has no effect # on the already queued and in-progress helper requests. #Default: # url_rewrite_children 20 startup=0 idle=1 concurrency=0 # TAG: url_rewrite_host_header # To preserve same-origin security policies in browsers and # prevent Host: header forgery by redirectors Squid rewrites # any Host: header in redirected requests. # # If you are running an accelerator this may not be a wanted # effect of a redirector. This directive enables you disable # Host: alteration in reverse-proxy traffic. # # WARNING: Entries are cached on the result of the URL rewriting # process, so be careful if you have domain-virtual hosts. # # WARNING: Squid and other software verifies the URL and Host # are matching, so be careful not to relay through other proxies # or inspecting firewalls with this disabled. #Default: # url_rewrite_host_header on # TAG: url_rewrite_access # If defined, this access list specifies which requests are # sent to the redirector processes. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow, unless rules exist in squid.conf. # TAG: url_rewrite_bypass # When this is 'on', a request will not go through the # redirector if all the helpers are busy. If this is 'off' and the # redirector queue grows too large, the action is prescribed by the # on-persistent-overload option. You should only enable this if the # redirectors are not critical to your caching system. If you use # redirectors for access control, and you enable this option, # users may have access to pages they should not # be allowed to request. # # Enabling this option sets the default url_rewrite_children queue-size # option value to 0. #Default: # url_rewrite_bypass off # TAG: url_rewrite_extras # Specifies a string to be append to request line format for the # rewriter helper. "Quoted" format values may contain spaces and # logformat %macros. In theory, any logformat %macro can be used. # In practice, a %macro expands as a dash (-) if the helper request is # sent before the required macro information is available to Squid. #Default: # url_rewrite_extras "%>a/%>A %un %>rm myip=%la myport=%lp" # TAG: url_rewrite_timeout # Squid times active requests to redirector. The timeout value and Squid # reaction to a timed out request are configurable using the following # format: # # url_rewrite_timeout timeout time-units on_timeout=<action> [response=<quoted-response>] # # supported timeout actions: # fail Squid return a ERR_GATEWAY_FAILURE error page # # bypass Do not re-write the URL # # retry Send the lookup to the helper again # # use_configured_response # Use the <quoted-response> as helper response #Default: # Squid waits for the helper response forever # OPTIONS FOR STORE ID # ----------------------------------------------------------------------------- # TAG: store_id_program # Specify the location of the executable StoreID helper to use. # Since they can perform almost any function there isn't one included. # # For each requested URL, the helper will receive one line with the format # # [channel-ID <SP>] URL [<SP> extras]<NL> # # # After processing the request the helper must reply using the following format: # # [channel-ID <SP>] result [<SP> kv-pairs] # # The result code can be: # # OK store-id="..." # Use the StoreID supplied in 'store-id='. # # ERR # The default is to use HTTP request URL as the store ID. # # BH # An internal error occurred in the helper, preventing # a result being identified. # # In addition to the above kv-pairs Squid also understands the following # optional kv-pairs received from URL rewriters: # clt_conn_tag=TAG # Associates a TAG with the client TCP connection. # Please see url_rewrite_program related documentation for this # kv-pair # # Helper programs should be prepared to receive and possibly ignore # additional whitespace-separated tokens on each input line. # # When using the concurrency= option the protocol is changed by # introducing a query channel tag in front of the request/response. # The query channel tag is a number between 0 and concurrency-1. # This value must be echoed back unchanged to Squid as the first part # of the response relating to its request. # # NOTE: when using StoreID refresh_pattern will apply to the StoreID # returned from the helper and not the URL. # # WARNING: Wrong StoreID value returned by a careless helper may result # in the wrong cached response returned to the user. # # By default, a StoreID helper is not used. #Default: # none # TAG: store_id_extras # Specifies a string to be append to request line format for the # StoreId helper. "Quoted" format values may contain spaces and # logformat %macros. In theory, any logformat %macro can be used. # In practice, a %macro expands as a dash (-) if the helper request is # sent before the required macro information is available to Squid. #Default: # store_id_extras "%>a/%>A %un %>rm myip=%la myport=%lp" # TAG: store_id_children # Specifies the maximum number of StoreID helper processes that Squid # may spawn (numberofchildren) and several related options. Using # too few of these helper processes (a.k.a. "helpers") creates request # queues. Using too many helpers wastes your system resources. # # Usage: numberofchildren [option]... # # The startup= and idle= options allow some measure of skew in your # tuning. # # startup= # # Sets a minimum of how many processes are to be spawned when Squid # starts or reconfigures. When set to zero the first request will # cause spawning of the first child process to handle it. # # Starting too few will cause an initial slowdown in traffic as Squid # attempts to simultaneously spawn enough processes to cope. # # idle= # # Sets a minimum of how many processes Squid is to try and keep available # at all times. When traffic begins to rise above what the existing # processes can handle this many more will be spawned up to the maximum # configured. A minimum setting of 1 is required. # # concurrency= # # The number of requests each storeID helper can handle in # parallel. Defaults to 0 which indicates the helper # is a old-style single threaded program. # # When this directive is set to a value >= 1 then the protocol # used to communicate with the helper is modified to include # an ID in front of the request/response. The ID from the request # must be echoed back with the response to that request. # # queue-size=N # # Sets the maximum number of queued requests to N. A request is queued # when no existing child can accept it due to concurrency limit and no # new child can be started due to numberofchildren limit. The default # maximum is 2*numberofchildren. If the queued requests exceed queue # size and redirector_bypass configuration option is set, then # redirector is bypassed. Otherwise, Squid is allowed to temporarily # exceed the configured maximum, marking the affected helper as # "overloaded". If the helper overload lasts more than 3 minutes, the # action prescribed by the on-persistent-overload option applies. # # on-persistent-overload=action # # Specifies Squid reaction to a new helper request arriving when the helper # has been overloaded for more that 3 minutes already. The number of queued # requests determines whether the helper is overloaded (see the queue-size # option). # # Two actions are supported: # # die Squid worker quits. This is the default behavior. # # ERR Squid treats the helper request as if it was # immediately submitted, and the helper immediately # replied with an ERR response. This action has no effect # on the already queued and in-progress helper requests. #Default: # store_id_children 20 startup=0 idle=1 concurrency=0 # TAG: store_id_access # If defined, this access list specifies which requests are # sent to the StoreID processes. By default all requests # are sent. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow, unless rules exist in squid.conf. # TAG: store_id_bypass # When this is 'on', a request will not go through the # helper if all helpers are busy. If this is 'off' and the helper # queue grows too large, the action is prescribed by the # on-persistent-overload option. You should only enable this if the # helpers are not critical to your caching system. If you use # helpers for critical caching components, and you enable this # option, users may not get objects from cache. # This options sets default queue-size option of the store_id_children # to 0. #Default: # store_id_bypass on # OPTIONS FOR TUNING THE CACHE # ----------------------------------------------------------------------------- # TAG: cache # Requests denied by this directive will not be served from the cache # and their responses will not be stored in the cache. This directive # has no effect on other transactions and on already cached responses. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # # This and the two other similar caching directives listed below are # checked at different transaction processing stages, have different # access to response information, affect different cache operations, # and differ in slow ACLs support: # # * cache: Checked before Squid makes a hit/miss determination. # No access to reply information! # Denies both serving a hit and storing a miss. # Supports both fast and slow ACLs. # * send_hit: Checked after a hit was detected. # Has access to reply (hit) information. # Denies serving a hit only. # Supports fast ACLs only. # * store_miss: Checked before storing a cachable miss. # Has access to reply (miss) information. # Denies storing a miss only. # Supports fast ACLs only. # # If you are not sure which of the three directives to use, apply the # following decision logic: # # * If your ACL(s) are of slow type _and_ need response info, redesign. # Squid does not support that particular combination at this time. # Otherwise: # * If your directive ACL(s) are of slow type, use "cache"; and/or # * if your directive ACL(s) need no response info, use "cache". # Otherwise: # * If you do not want the response cached, use store_miss; and/or # * if you do not want a hit on a cached response, use send_hit. #Default: # By default, this directive is unused and has no effect. # TAG: send_hit # Responses denied by this directive will not be served from the cache # (but may still be cached, see store_miss). This directive has no # effect on the responses it allows and on the cached objects. # # Please see the "cache" directive for a summary of differences among # store_miss, send_hit, and cache directives. # # Unlike the "cache" directive, send_hit only supports fast acl # types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # # For example: # # # apply custom Store ID mapping to some URLs # acl MapMe dstdomain .c.example.com # store_id_program ... # store_id_access allow MapMe # # # but prevent caching of special responses # # such as 302 redirects that cause StoreID loops # acl Ordinary http_status 200-299 # store_miss deny MapMe !Ordinary # # # and do not serve any previously stored special responses # # from the cache (in case they were already cached before # # the above store_miss rule was in effect). # send_hit deny MapMe !Ordinary #Default: # By default, this directive is unused and has no effect. # TAG: store_miss # Responses denied by this directive will not be cached (but may still # be served from the cache, see send_hit). This directive has no # effect on the responses it allows and on the already cached responses. # # Please see the "cache" directive for a summary of differences among # store_miss, send_hit, and cache directives. See the # send_hit directive for a usage example. # # Unlike the "cache" directive, store_miss only supports fast acl # types. See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # By default, this directive is unused and has no effect. # TAG: max_stale time-units # This option puts an upper limit on how stale content Squid # will serve from the cache if cache validation fails. # Can be overriden by the refresh_pattern max-stale option. #Default: # max_stale 1 week # TAG: refresh_pattern # usage: refresh_pattern [-i] regex min percent max [options] # # By default, regular expressions are CASE-SENSITIVE. To make # them case-insensitive, use the -i option. # # 'Min' is the time (in minutes) an object without an explicit # expiry time should be considered fresh. The recommended # value is 0, any higher values may cause dynamic applications # to be erroneously cached unless the application designer # has taken the appropriate actions. # # 'Percent' is a percentage of the objects age (time since last # modification age) an object without explicit expiry time # will be considered fresh. # # 'Max' is an upper limit on how long objects without an explicit # expiry time will be considered fresh. The value is also used # to form Cache-Control: max-age header for a request sent from # Squid to origin/parent. # # options: override-expire # override-lastmod # reload-into-ims # ignore-reload # ignore-no-store # ignore-private # max-stale=NN # refresh-ims # store-stale # # override-expire enforces min age even if the server # sent an explicit expiry time (e.g., with the # Expires: header or Cache-Control: max-age). Doing this # VIOLATES the HTTP standard. Enabling this feature # could make you liable for problems which it causes. # # Note: override-expire does not enforce staleness - it only extends # freshness / min. If the server returns a Expires time which # is longer than your max time, Squid will still consider # the object fresh for that period of time. # # override-lastmod enforces min age even on objects # that were modified recently. # # reload-into-ims changes a client no-cache or ``reload'' # request for a cached entry into a conditional request using # If-Modified-Since and/or If-None-Match headers, provided the # cached entry has a Last-Modified and/or a strong ETag header. # Doing this VIOLATES the HTTP standard. Enabling this feature # could make you liable for problems which it causes. # # ignore-reload ignores a client no-cache or ``reload'' # header. Doing this VIOLATES the HTTP standard. Enabling # this feature could make you liable for problems which # it causes. # # ignore-no-store ignores any ``Cache-control: no-store'' # headers received from a server. Doing this VIOLATES # the HTTP standard. Enabling this feature could make you # liable for problems which it causes. # # ignore-private ignores any ``Cache-control: private'' # headers received from a server. Doing this VIOLATES # the HTTP standard. Enabling this feature could make you # liable for problems which it causes. # # refresh-ims causes squid to contact the origin server # when a client issues an If-Modified-Since request. This # ensures that the client will receive an updated version # if one is available. # # store-stale stores responses even if they don't have explicit # freshness or a validator (i.e., Last-Modified or an ETag) # present, or if they're already stale. By default, Squid will # not cache such responses because they usually can't be # reused. Note that such responses will be stale by default. # # max-stale=NN provide a maximum staleness factor. Squid won't # serve objects more stale than this even if it failed to # validate the object. Default: use the max_stale global limit. # # Basically a cached object is: # # FRESH if expire > now, else STALE # STALE if age > max # FRESH if lm-factor < percent, else STALE # FRESH if age < min # else STALE # # The refresh_pattern lines are checked in the order listed here. # The first entry which matches is used. If none of the entries # match the default will be used. # # Note, you must uncomment all the default lines if you want # to change one. The default setting is only active if none is # used. # # # # Add any of your own refresh_pattern entries above these. # refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 refresh_pattern . 0 20% 4320 # TAG: quick_abort_min (KB) #Default: # quick_abort_min 16 KB # TAG: quick_abort_max (KB) #Default: # quick_abort_max 16 KB # TAG: quick_abort_pct (percent) # The cache by default continues downloading aborted requests # which are almost completed (less than 16 KB remaining). This # may be undesirable on slow (e.g. SLIP) links and/or very busy # caches. Impatient users may tie up file descriptors and # bandwidth by repeatedly requesting and immediately aborting # downloads. # # When the user aborts a request, Squid will check the # quick_abort values to the amount of data transferred until # then. # # If the transfer has less than 'quick_abort_min' KB remaining, # it will finish the retrieval. # # If the transfer has more than 'quick_abort_max' KB remaining, # it will abort the retrieval. # # If more than 'quick_abort_pct' of the transfer has completed, # it will finish the retrieval. # # If you do not want any retrieval to continue after the client # has aborted, set both 'quick_abort_min' and 'quick_abort_max' # to '0 KB'. # # If you want retrievals to always continue if they are being # cached set 'quick_abort_min' to '-1 KB'. #Default: # quick_abort_pct 95 # TAG: read_ahead_gap buffer-size # The amount of data the cache will buffer ahead of what has been # sent to the client when retrieving an object from another server. #Default: # read_ahead_gap 16 KB # TAG: negative_ttl time-units # Set the Default Time-to-Live (TTL) for failed requests. # Certain types of failures (such as "connection refused" and # "404 Not Found") are able to be negatively-cached for a short time. # Modern web servers should provide Expires: header, however if they # do not this can provide a minimum TTL. # The default is not to cache errors with unknown expiry details. # # Note that this is different from negative caching of DNS lookups. # # WARNING: Doing this VIOLATES the HTTP standard. Enabling # this feature could make you liable for problems which it # causes. #Default: # negative_ttl 0 seconds # TAG: positive_dns_ttl time-units # Upper limit on how long Squid will cache positive DNS responses. # Default is 6 hours (360 minutes). This directive must be set # larger than negative_dns_ttl. #Default: # positive_dns_ttl 6 hours # TAG: negative_dns_ttl time-units # Time-to-Live (TTL) for negative caching of failed DNS lookups. # This also sets the lower cache limit on positive lookups. # Minimum value is 1 second, and it is not recommendable to go # much below 10 seconds. #Default: # negative_dns_ttl 1 minutes # TAG: range_offset_limit size [acl acl...] # usage: (size) [units] [[!]aclname] # # Sets an upper limit on how far (number of bytes) into the file # a Range request may be to cause Squid to prefetch the whole file. # If beyond this limit, Squid forwards the Range request as it is and # the result is NOT cached. # # This is to stop a far ahead range request (lets say start at 17MB) # from making Squid fetch the whole object up to that point before # sending anything to the client. # # Multiple range_offset_limit lines may be specified, and they will # be searched from top to bottom on each request until a match is found. # The first match found will be used. If no line matches a request, the # default limit of 0 bytes will be used. # # 'size' is the limit specified as a number of units. # # 'units' specifies whether to use bytes, KB, MB, etc. # If no units are specified bytes are assumed. # # A size of 0 causes Squid to never fetch more than the # client requested. (default) # # A size of 'none' causes Squid to always fetch the object from the # beginning so it may cache the result. (2.0 style) # # 'aclname' is the name of a defined ACL. # # NP: Using 'none' as the byte value here will override any quick_abort settings # that may otherwise apply to the range request. The range request will # be fully fetched from start to finish regardless of the client # actions. This affects bandwidth usage. #Default: # none # TAG: minimum_expiry_time (seconds) # The minimum caching time according to (Expires - Date) # headers Squid honors if the object can't be revalidated. # The default is 60 seconds. # # In reverse proxy environments it might be desirable to honor # shorter object lifetimes. It is most likely better to make # your server return a meaningful Last-Modified header however. # # In ESI environments where page fragments often have short # lifetimes, this will often be best set to 0. #Default: # minimum_expiry_time 60 seconds # TAG: store_avg_object_size (bytes) # Average object size, used to estimate number of objects your # cache can hold. The default is 13 KB. # # This is used to pre-seed the cache index memory allocation to # reduce expensive reallocate operations while handling clients # traffic. Too-large values may result in memory allocation during # peak traffic, too-small values will result in wasted memory. # # Check the cache manager 'info' report metrics for the real # object sizes seen by your Squid before tuning this. #Default: # store_avg_object_size 13 KB # TAG: store_objects_per_bucket # Target number of objects per bucket in the store hash table. # Lowering this value increases the total number of buckets and # also the storage maintenance rate. The default is 20. #Default: # store_objects_per_bucket 20 # HTTP OPTIONS # ----------------------------------------------------------------------------- # TAG: request_header_max_size (KB) # This directives limits the header size of a received HTTP request # (including request-line). Increasing this limit beyond its 64 KB default # exposes certain old Squid code to various denial-of-service attacks. This # limit also applies to received FTP commands. # # This limit has no direct affect on Squid memory consumption. # # Squid does not check this limit when sending requests. #Default: # request_header_max_size 64 KB # TAG: reply_header_max_size (KB) # This directives limits the header size of a received HTTP response # (including status-line). Increasing this limit beyond its 64 KB default # exposes certain old Squid code to various denial-of-service attacks. This # limit also applies to FTP command responses. # # Squid also checks this limit when loading hit responses from disk cache. # # Squid does not check this limit when sending responses. #Default: # reply_header_max_size 64 KB # TAG: request_body_max_size (bytes) # This specifies the maximum size for an HTTP request body. # In other words, the maximum size of a PUT/POST request. # A user who attempts to send a request with a body larger # than this limit receives an "Invalid Request" error message. # If you set this parameter to a zero (the default), there will # be no limit imposed. # # See also client_request_buffer_max_size for an alternative # limitation on client uploads which can be configured. #Default: # No limit. # TAG: client_request_buffer_max_size (bytes) # This specifies the maximum buffer size of a client request. # It prevents squid eating too much memory when somebody uploads # a large file. #Default: # client_request_buffer_max_size 512 KB # TAG: broken_posts # A list of ACL elements which, if matched, causes Squid to send # an extra CRLF pair after the body of a PUT/POST request. # # Some HTTP servers has broken implementations of PUT/POST, # and rely on an extra CRLF pair sent by some WWW clients. # # Quote from RFC2616 section 4.1 on this matter: # # Note: certain buggy HTTP/1.0 client implementations generate an # extra CRLF's after a POST request. To restate what is explicitly # forbidden by the BNF, an HTTP/1.1 client must not preface or follow # a request with an extra CRLF. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # #Example: # acl buggy_server url_regex ^http://.... # broken_posts allow buggy_server #Default: # Obey RFC 2616. # TAG: adaptation_uses_indirect_client on|off # Controls whether the indirect client IP address (instead of the direct # client IP address) is passed to adaptation services. # # See also: follow_x_forwarded_for adaptation_send_client_ip #Default: # adaptation_uses_indirect_client on # TAG: via on|off # If set (default), Squid will include a Via header in requests and # replies as required by RFC2616. #Default: # via on # TAG: vary_ignore_expire on|off # Many HTTP servers supporting Vary gives such objects # immediate expiry time with no cache-control header # when requested by a HTTP/1.0 client. This option # enables Squid to ignore such expiry times until # HTTP/1.1 is fully implemented. # # WARNING: If turned on this may eventually cause some # varying objects not intended for caching to get cached. #Default: # vary_ignore_expire off # TAG: request_entities # Squid defaults to deny GET and HEAD requests with request entities, # as the meaning of such requests are undefined in the HTTP standard # even if not explicitly forbidden. # # Set this directive to on if you have clients which insists # on sending request entities in GET or HEAD requests. But be warned # that there is server software (both proxies and web servers) which # can fail to properly process this kind of request which may make you # vulnerable to cache pollution attacks if enabled. #Default: # request_entities off # TAG: request_header_access # Usage: request_header_access header_name allow|deny [!]aclname ... # # WARNING: Doing this VIOLATES the HTTP standard. Enabling # this feature could make you liable for problems which it # causes. # # This option replaces the old 'anonymize_headers' and the # older 'http_anonymizer' option with something that is much # more configurable. A list of ACLs for each header name allows # removal of specific header fields under specific conditions. # # This option only applies to outgoing HTTP request headers (i.e., # headers sent by Squid to the next HTTP hop such as a cache peer # or an origin server). The option has no effect during cache hit # detection. The equivalent adaptation vectoring point in ICAP # terminology is post-cache REQMOD. # # The option is applied to individual outgoing request header # fields. For each request header field F, Squid uses the first # qualifying sets of request_header_access rules: # # 1. Rules with header_name equal to F's name. # 2. Rules with header_name 'Other', provided F's name is not # on the hard-coded list of commonly used HTTP header names. # 3. Rules with header_name 'All'. # # Within that qualifying rule set, rule ACLs are checked as usual. # If ACLs of an "allow" rule match, the header field is allowed to # go through as is. If ACLs of a "deny" rule match, the header is # removed and request_header_replace is then checked to identify # if the removed header has a replacement. If no rules within the # set have matching ACLs, the header field is left as is. # # For example, to achieve the same behavior as the old # 'http_anonymizer standard' option, you should use: # # request_header_access From deny all # request_header_access Referer deny all # request_header_access User-Agent deny all # # Or, to reproduce the old 'http_anonymizer paranoid' feature # you should use: # # request_header_access Authorization allow all # request_header_access Proxy-Authorization allow all # request_header_access Cache-Control allow all # request_header_access Content-Length allow all # request_header_access Content-Type allow all # request_header_access Date allow all # request_header_access Host allow all # request_header_access If-Modified-Since allow all # request_header_access Pragma allow all # request_header_access Accept allow all # request_header_access Accept-Charset allow all # request_header_access Accept-Encoding allow all # request_header_access Accept-Language allow all # request_header_access Connection allow all # request_header_access All deny all # # HTTP reply headers are controlled with the reply_header_access directive. # # By default, all headers are allowed (no anonymizing is performed). #Default: # No limits. # TAG: reply_header_access # Usage: reply_header_access header_name allow|deny [!]aclname ... # # WARNING: Doing this VIOLATES the HTTP standard. Enabling # this feature could make you liable for problems which it # causes. # # This option only applies to reply headers, i.e., from the # server to the client. # # This is the same as request_header_access, but in the other # direction. Please see request_header_access for detailed # documentation. # # For example, to achieve the same behavior as the old # 'http_anonymizer standard' option, you should use: # # reply_header_access Server deny all # reply_header_access WWW-Authenticate deny all # reply_header_access Link deny all # # Or, to reproduce the old 'http_anonymizer paranoid' feature # you should use: # # reply_header_access Allow allow all # reply_header_access WWW-Authenticate allow all # reply_header_access Proxy-Authenticate allow all # reply_header_access Cache-Control allow all # reply_header_access Content-Encoding allow all # reply_header_access Content-Length allow all # reply_header_access Content-Type allow all # reply_header_access Date allow all # reply_header_access Expires allow all # reply_header_access Last-Modified allow all # reply_header_access Location allow all # reply_header_access Pragma allow all # reply_header_access Content-Language allow all # reply_header_access Retry-After allow all # reply_header_access Title allow all # reply_header_access Content-Disposition allow all # reply_header_access Connection allow all # reply_header_access All deny all # # HTTP request headers are controlled with the request_header_access directive. # # By default, all headers are allowed (no anonymizing is # performed). #Default: # No limits. # TAG: request_header_replace # Usage: request_header_replace header_name message # Example: request_header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit) # # This option allows you to change the contents of headers # denied with request_header_access above, by replacing them # with some fixed string. # # This only applies to request headers, not reply headers. # # By default, headers are removed if denied. #Default: # none # TAG: reply_header_replace # Usage: reply_header_replace header_name message # Example: reply_header_replace Server Foo/1.0 # # This option allows you to change the contents of headers # denied with reply_header_access above, by replacing them # with some fixed string. # # This only applies to reply headers, not request headers. # # By default, headers are removed if denied. #Default: # none # TAG: request_header_add # Usage: request_header_add field-name field-value [ acl ... ] # Example: request_header_add X-Client-CA "CA=%ssl::>cert_issuer" all # # This option adds header fields to outgoing HTTP requests (i.e., # request headers sent by Squid to the next HTTP hop such as a # cache peer or an origin server). The option has no effect during # cache hit detection. The equivalent adaptation vectoring point # in ICAP terminology is post-cache REQMOD. # # Field-name is a token specifying an HTTP header name. If a # standard HTTP header name is used, Squid does not check whether # the new header conflicts with any existing headers or violates # HTTP rules. If the request to be modified already contains a # field with the same name, the old field is preserved but the # header field values are not merged. # # Field-value is either a token or a quoted string. If quoted # string format is used, then the surrounding quotes are removed # while escape sequences and %macros are processed. # # One or more Squid ACLs may be specified to restrict header # injection to matching requests. As always in squid.conf, all # ACLs in the ACL list must be satisfied for the insertion to # happen. The request_header_add supports fast ACLs only. # # See also: reply_header_add. #Default: # none # TAG: reply_header_add # Usage: reply_header_add field-name field-value [ acl ... ] # Example: reply_header_add X-Client-CA "CA=%ssl::>cert_issuer" all # # This option adds header fields to outgoing HTTP responses (i.e., response # headers delivered by Squid to the client). This option has no effect on # cache hit detection. The equivalent adaptation vectoring point in # ICAP terminology is post-cache RESPMOD. This option does not apply to # successful CONNECT replies. # # Field-name is a token specifying an HTTP header name. If a # standard HTTP header name is used, Squid does not check whether # the new header conflicts with any existing headers or violates # HTTP rules. If the response to be modified already contains a # field with the same name, the old field is preserved but the # header field values are not merged. # # Field-value is either a token or a quoted string. If quoted # string format is used, then the surrounding quotes are removed # while escape sequences and %macros are processed. # # One or more Squid ACLs may be specified to restrict header # injection to matching responses. As always in squid.conf, all # ACLs in the ACL list must be satisfied for the insertion to # happen. The reply_header_add option supports fast ACLs only. # # See also: request_header_add. #Default: # none # TAG: note # This option used to log custom information about the master # transaction. For example, an admin may configure Squid to log # which "user group" the transaction belongs to, where "user group" # will be determined based on a set of ACLs and not [just] # authentication information. # Values of key/value pairs can be logged using %{key}note macros: # # note key value acl ... # logformat myFormat ... %{key}note ... # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # none # TAG: relaxed_header_parser on|off|warn # In the default "on" setting Squid accepts certain forms # of non-compliant HTTP messages where it is unambiguous # what the sending application intended even if the message # is not correctly formatted. The messages is then normalized # to the correct form when forwarded by Squid. # # If set to "warn" then a warning will be emitted in cache.log # each time such HTTP error is encountered. # # If set to "off" then such HTTP errors will cause the request # or response to be rejected. #Default: # relaxed_header_parser on # TAG: collapsed_forwarding (on|off) # This option controls whether Squid is allowed to merge multiple # potentially cachable requests for the same URI before Squid knows # whether the response is going to be cachable. # # When enabled, instead of forwarding each concurrent request for # the same URL, Squid just sends the first of them. The other, so # called "collapsed" requests, wait for the response to the first # request and, if it happens to be cachable, use that response. # Here, "concurrent requests" means "received after the first # request headers were parsed and before the corresponding response # headers were parsed". # # This feature is disabled by default: enabling collapsed # forwarding needlessly delays forwarding requests that look # cachable (when they are collapsed) but then need to be forwarded # individually anyway because they end up being for uncachable # content. However, in some cases, such as acceleration of highly # cachable content with periodic or grouped expiration times, the # gains from collapsing [large volumes of simultaneous refresh # requests] outweigh losses from such delays. # # Squid collapses two kinds of requests: regular client requests # received on one of the listening ports and internal "cache # revalidation" requests which are triggered by those regular # requests hitting a stale cached object. Revalidation collapsing # is currently disabled for Squid instances containing SMP-aware # disk or memory caches and for Vary-controlled cached objects. #Default: # collapsed_forwarding off # TAG: collapsed_forwarding_shared_entries_limit (number of entries) # This limits the size of a table used for sharing information # about collapsible entries among SMP workers. Limiting sharing # too much results in cache content duplication and missed # collapsing opportunities. Using excessively large values # wastes shared memory. # # The limit should be significantly larger then the number of # concurrent collapsible entries one wants to share. For a cache # that handles less than 5000 concurrent requests, the default # setting of 16384 should be plenty. # # If the limit is set to zero, it disables sharing of collapsed # forwarding between SMP workers. #Default: # collapsed_forwarding_shared_entries_limit 16384 # TIMEOUTS # ----------------------------------------------------------------------------- # TAG: forward_timeout time-units # This parameter specifies how long Squid should at most attempt in # finding a forwarding path for the request before giving up. #Default: # forward_timeout 4 minutes # TAG: connect_timeout time-units # This parameter specifies how long to wait for the TCP connect to # the requested server or peer to complete before Squid should # attempt to find another path where to forward the request. #Default: # connect_timeout 1 minute # TAG: peer_connect_timeout time-units # This parameter specifies how long to wait for a pending TCP # connection to a peer cache. The default is 30 seconds. You # may also set different timeout values for individual neighbors # with the 'connect-timeout' option on a 'cache_peer' line. #Default: # peer_connect_timeout 30 seconds # TAG: read_timeout time-units # Applied on peer server connections. # # After each successful read(), the timeout will be extended by this # amount. If no data is read again after this amount of time, # the request is aborted and logged with ERR_READ_TIMEOUT. # # The default is 15 minutes. #Default: # read_timeout 15 minutes # TAG: write_timeout time-units # This timeout is tracked for all connections that have data # available for writing and are waiting for the socket to become # ready. After each successful write, the timeout is extended by # the configured amount. If Squid has data to write but the # connection is not ready for the configured duration, the # transaction associated with the connection is terminated. The # default is 15 minutes. #Default: # write_timeout 15 minutes # TAG: request_timeout # How long to wait for complete HTTP request headers after initial # connection establishment. #Default: # request_timeout 5 minutes # TAG: request_start_timeout # How long to wait for the first request byte after initial # connection establishment. #Default: # request_start_timeout 5 minutes # TAG: client_idle_pconn_timeout # How long to wait for the next HTTP request on a persistent # client connection after the previous request completes. #Default: # client_idle_pconn_timeout 2 minutes # TAG: ftp_client_idle_timeout # How long to wait for an FTP request on a connection to Squid ftp_port. # Many FTP clients do not deal with idle connection closures well, # necessitating a longer default timeout than client_idle_pconn_timeout # used for incoming HTTP requests. #Default: # ftp_client_idle_timeout 30 minutes # TAG: client_lifetime time-units # The maximum amount of time a client (browser) is allowed to # remain connected to the cache process. This protects the Cache # from having a lot of sockets (and hence file descriptors) tied up # in a CLOSE_WAIT state from remote clients that go away without # properly shutting down (either because of a network failure or # because of a poor client implementation). The default is one # day, 1440 minutes. # # NOTE: The default value is intended to be much larger than any # client would ever need to be connected to your cache. You # should probably change client_lifetime only as a last resort. # If you seem to have many client connections tying up # filedescriptors, we recommend first tuning the read_timeout, # request_timeout, persistent_request_timeout and quick_abort values. #Default: # client_lifetime 1 day # TAG: pconn_lifetime time-units # Desired maximum lifetime of a persistent connection. # When set, Squid will close a now-idle persistent connection that # exceeded configured lifetime instead of moving the connection into # the idle connection pool (or equivalent). No effect on ongoing/active # transactions. Connection lifetime is the time period from the # connection acceptance or opening time until "now". # # This limit is useful in environments with long-lived connections # where Squid configuration or environmental factors change during a # single connection lifetime. If unrestricted, some connections may # last for hours and even days, ignoring those changes that should # have affected their behavior or their existence. # # Currently, a new lifetime value supplied via Squid reconfiguration # has no effect on already idle connections unless they become busy. # # When set to '0' this limit is not used. #Default: # pconn_lifetime 0 seconds # TAG: half_closed_clients # Some clients may shutdown the sending side of their TCP # connections, while leaving their receiving sides open. Sometimes, # Squid can not tell the difference between a half-closed and a # fully-closed TCP connection. # # By default, Squid will immediately close client connections when # read(2) returns "no more data to read." # # Change this option to 'on' and Squid will keep open connections # until a read(2) or write(2) on the socket returns an error. # This may show some benefits for reverse proxies. But if not # it is recommended to leave OFF. #Default: # half_closed_clients off # TAG: server_idle_pconn_timeout # Timeout for idle persistent connections to servers and other # proxies. #Default: # server_idle_pconn_timeout 1 minute # TAG: ident_timeout # Maximum time to wait for IDENT lookups to complete. # # If this is too high, and you enabled IDENT lookups from untrusted # users, you might be susceptible to denial-of-service by having # many ident requests going at once. #Default: # ident_timeout 10 seconds # TAG: shutdown_lifetime time-units # When SIGTERM or SIGHUP is received, the cache is put into # "shutdown pending" mode until all active sockets are closed. # This value is the lifetime to set for all open descriptors # during shutdown mode. Any active clients after this many # seconds will receive a 'timeout' message. #Default: # shutdown_lifetime 30 seconds # ADMINISTRATIVE PARAMETERS # ----------------------------------------------------------------------------- # TAG: cache_mgr # Email-address of local cache manager who will receive # mail if the cache dies. The default is "webmaster". #Default: # cache_mgr webmaster # TAG: mail_from # From: email-address for mail sent when the cache dies. # The default is to use 'squid@unique_hostname'. # # See also: unique_hostname directive. #Default: # none # TAG: mail_program # Email program used to send mail if the cache dies. # The default is "mail". The specified program must comply # with the standard Unix mail syntax: # mail-program recipient < mailfile # # Optional command line options can be specified. #Default: # mail_program mail # TAG: cache_effective_user # If you start Squid as root, it will change its effective/real # UID/GID to the user specified below. The default is to change # to UID of proxy. # see also; cache_effective_group #Default: # cache_effective_user proxy # TAG: cache_effective_group # Squid sets the GID to the effective user's default group ID # (taken from the password file) and supplementary group list # from the groups membership. # # If you want Squid to run with a specific GID regardless of # the group memberships of the effective user then set this # to the group (or GID) you want Squid to run as. When set # all other group privileges of the effective user are ignored # and only this GID is effective. If Squid is not started as # root the user starting Squid MUST be member of the specified # group. # # This option is not recommended by the Squid Team. # Our preference is for administrators to configure a secure # user account for squid with UID/GID matching system policies. #Default: # Use system group memberships of the cache_effective_user account # TAG: httpd_suppress_version_string on|off # Suppress Squid version string info in HTTP headers and HTML error pages. #Default: # httpd_suppress_version_string off # TAG: visible_hostname # If you want to present a special hostname in error messages, etc, # define this. Otherwise, the return value of gethostname() # will be used. If you have multiple caches in a cluster and # get errors about IP-forwarding you must set them to have individual # names with this setting. #Default: # Automatically detect the system host name # TAG: unique_hostname # If you want to have multiple machines with the same # 'visible_hostname' you must give each machine a different # 'unique_hostname' so forwarding loops can be detected. #Default: # Copy the value from visible_hostname # TAG: hostname_aliases # A list of other DNS names your cache has. #Default: # none # TAG: umask # Minimum umask which should be enforced while the proxy # is running, in addition to the umask set at startup. # # For a traditional octal representation of umasks, start # your value with 0. #Default: # umask 027 # OPTIONS FOR THE CACHE REGISTRATION SERVICE # ----------------------------------------------------------------------------- # # This section contains parameters for the (optional) cache # announcement service. This service is provided to help # cache administrators locate one another in order to join or # create cache hierarchies. # # An 'announcement' message is sent (via UDP) to the registration # service by Squid. By default, the announcement message is NOT # SENT unless you enable it with 'announce_period' below. # # The announcement message includes your hostname, plus the # following information from this configuration file: # # http_port # icp_port # cache_mgr # # All current information is processed regularly and made # available on the Web at http://www.ircache.net/Cache/Tracker/. # TAG: announce_period # This is how frequently to send cache announcements. # # To enable announcing your cache, just set an announce period. # # Example: # announce_period 1 day #Default: # Announcement messages disabled. # TAG: announce_host # Set the hostname where announce registration messages will be sent. # # See also announce_port and announce_file #Default: # announce_host tracker.ircache.net # TAG: announce_file # The contents of this file will be included in the announce # registration messages. #Default: # none # TAG: announce_port # Set the port where announce registration messages will be sent. # # See also announce_host and announce_file #Default: # announce_port 3131 # HTTPD-ACCELERATOR OPTIONS # ----------------------------------------------------------------------------- # TAG: httpd_accel_surrogate_id # Surrogates (http://www.esi.org/architecture_spec_1.0.html) # need an identification token to allow control targeting. Because # a farm of surrogates may all perform the same tasks, they may share # an identification token. #Default: # visible_hostname is used if no specific ID is set. # TAG: http_accel_surrogate_remote on|off # Remote surrogates (such as those in a CDN) honour the header # "Surrogate-Control: no-store-remote". # # Set this to on to have squid behave as a remote surrogate. #Default: # http_accel_surrogate_remote off # TAG: esi_parser libxml2|expat # Note: This option is only available if Squid is rebuilt with the # --enable-esi # # Selects the XML parsing library to use when interpreting responses with # Edge Side Includes. # # To disable ESI handling completely, ./configure Squid with --disable-esi. #Default: # Selects libxml2 if available at ./configure time or libexpat otherwise. # DELAY POOL PARAMETERS # ----------------------------------------------------------------------------- # TAG: delay_pools # This represents the number of delay pools to be used. For example, # if you have one class 2 delay pool and one class 3 delays pool, you # have a total of 2 delay pools. # # See also delay_parameters, delay_class, delay_access for pool # configuration details. #Default: # delay_pools 0 # TAG: delay_class # This defines the class of each delay pool. There must be exactly one # delay_class line for each delay pool. For example, to define two # delay pools, one of class 2 and one of class 3, the settings above # and here would be: # # Example: # delay_pools 4 # 4 delay pools # delay_class 1 2 # pool 1 is a class 2 pool # delay_class 2 3 # pool 2 is a class 3 pool # delay_class 3 4 # pool 3 is a class 4 pool # delay_class 4 5 # pool 4 is a class 5 pool # # The delay pool classes are: # # class 1 Everything is limited by a single aggregate # bucket. # # class 2 Everything is limited by a single aggregate # bucket as well as an "individual" bucket chosen # from bits 25 through 32 of the IPv4 address. # # class 3 Everything is limited by a single aggregate # bucket as well as a "network" bucket chosen # from bits 17 through 24 of the IP address and a # "individual" bucket chosen from bits 17 through # 32 of the IPv4 address. # # class 4 Everything in a class 3 delay pool, with an # additional limit on a per user basis. This # only takes effect if the username is established # in advance - by forcing authentication in your # http_access rules. # # class 5 Requests are grouped according their tag (see # external_acl's tag= reply). # # # Each pool also requires a delay_parameters directive to configure the pool size # and speed limits used whenever the pool is applied to a request. Along with # a set of delay_access directives to determine when it is used. # # NOTE: If an IP address is a.b.c.d # -> bits 25 through 32 are "d" # -> bits 17 through 24 are "c" # -> bits 17 through 32 are "c * 256 + d" # # NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to # IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic. # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # # See also delay_parameters and delay_access. #Default: # none # TAG: delay_access # This is used to determine which delay pool a request falls into. # # delay_access is sorted per pool and the matching starts with pool 1, # then pool 2, ..., and finally pool N. The first delay pool where the # request is allowed is selected for the request. If it does not allow # the request to any pool then the request is not delayed (default). # # For example, if you want some_big_clients in delay # pool 1 and lotsa_little_clients in delay pool 2: # # delay_access 1 allow some_big_clients # delay_access 1 deny all # delay_access 2 allow lotsa_little_clients # delay_access 2 deny all # delay_access 3 allow authenticated_clients # # See also delay_parameters and delay_class. # #Default: # Deny using the pool, unless allow rules exist in squid.conf for the pool. # TAG: delay_parameters # This defines the parameters for a delay pool. Each delay pool has # a number of "buckets" associated with it, as explained in the # description of delay_class. # # For a class 1 delay pool, the syntax is: # delay_class pool 1 # delay_parameters pool aggregate # # For a class 2 delay pool: # delay_class pool 2 # delay_parameters pool aggregate individual # # For a class 3 delay pool: # delay_class pool 3 # delay_parameters pool aggregate network individual # # For a class 4 delay pool: # delay_class pool 4 # delay_parameters pool aggregate network individual user # # For a class 5 delay pool: # delay_class pool 5 # delay_parameters pool tagrate # # The option variables are: # # pool a pool number - ie, a number between 1 and the # number specified in delay_pools as used in # delay_class lines. # # aggregate the speed limit parameters for the aggregate bucket # (class 1, 2, 3). # # individual the speed limit parameters for the individual # buckets (class 2, 3). # # network the speed limit parameters for the network buckets # (class 3). # # user the speed limit parameters for the user buckets # (class 4). # # tagrate the speed limit parameters for the tag buckets # (class 5). # # A pair of delay parameters is written restore/maximum, where restore is # the number of bytes (not bits - modem and network speeds are usually # quoted in bits) per second placed into the bucket, and maximum is the # maximum number of bytes which can be in the bucket at any time. # # There must be one delay_parameters line for each delay pool. # # # For example, if delay pool number 1 is a class 2 delay pool as in the # above example, and is being used to strictly limit each host to 64Kbit/sec # (plus overheads), with no overall limit, the line is: # # delay_parameters 1 none 8000/8000 # # Note that 8 x 8K Byte/sec -> 64K bit/sec. # # Note that the word 'none' is used to represent no limit. # # # And, if delay pool number 2 is a class 3 delay pool as in the above # example, and you want to limit it to a total of 256Kbit/sec (strict limit) # with each 8-bit network permitted 64Kbit/sec (strict limit) and each # individual host permitted 4800bit/sec with a bucket maximum size of 64Kbits # to permit a decent web page to be downloaded at a decent speed # (if the network is not being limited due to overuse) but slow down # large downloads more significantly: # # delay_parameters 2 32000/32000 8000/8000 600/8000 # # Note that 8 x 32K Byte/sec -> 256K bit/sec. # 8 x 8K Byte/sec -> 64K bit/sec. # 8 x 600 Byte/sec -> 4800 bit/sec. # # # Finally, for a class 4 delay pool as in the example - each user will # be limited to 128Kbits/sec no matter how many workstations they are logged into.: # # delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000 # # # See also delay_class and delay_access. # #Default: # none # TAG: delay_initial_bucket_level (percent, 0-100) # The initial bucket percentage is used to determine how much is put # in each bucket when squid starts, is reconfigured, or first notices # a host accessing it (in class 2 and class 3, individual hosts and # networks only have buckets associated with them once they have been # "seen" by squid). #Default: # delay_initial_bucket_level 50 # CLIENT DELAY POOL PARAMETERS # ----------------------------------------------------------------------------- # TAG: client_delay_pools # This option specifies the number of client delay pools used. It must # preceed other client_delay_* options. # # Example: # client_delay_pools 2 # # See also client_delay_parameters and client_delay_access. #Default: # client_delay_pools 0 # TAG: client_delay_initial_bucket_level (percent, 0-no_limit) # This option determines the initial bucket size as a percentage of # max_bucket_size from client_delay_parameters. Buckets are created # at the time of the "first" connection from the matching IP. Idle # buckets are periodically deleted up. # # You can specify more than 100 percent but note that such "oversized" # buckets are not refilled until their size goes down to max_bucket_size # from client_delay_parameters. # # Example: # client_delay_initial_bucket_level 50 #Default: # client_delay_initial_bucket_level 50 # TAG: client_delay_parameters # # This option configures client-side bandwidth limits using the # following format: # # client_delay_parameters pool speed_limit max_bucket_size # # pool is an integer ID used for client_delay_access matching. # # speed_limit is bytes added to the bucket per second. # # max_bucket_size is the maximum size of a bucket, enforced after any # speed_limit additions. # # Please see the delay_parameters option for more information and # examples. # # Example: # client_delay_parameters 1 1024 2048 # client_delay_parameters 2 51200 16384 # # See also client_delay_access. # #Default: # none # TAG: client_delay_access # This option determines the client-side delay pool for the # request: # # client_delay_access pool_ID allow|deny acl_name # # All client_delay_access options are checked in their pool ID # order, starting with pool 1. The first checked pool with allowed # request is selected for the request. If no ACL matches or there # are no client_delay_access options, the request bandwidth is not # limited. # # The ACL-selected pool is then used to find the # client_delay_parameters for the request. Client-side pools are # not used to aggregate clients. Clients are always aggregated # based on their source IP addresses (one bucket per source IP). # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # Additionally, only the client TCP connection details are available. # ACLs testing HTTP properties will not work. # # Please see delay_access for more examples. # # Example: # client_delay_access 1 allow low_rate_network # client_delay_access 2 allow vips_network # # # See also client_delay_parameters and client_delay_pools. #Default: # Deny use of the pool, unless allow rules exist in squid.conf for the pool. # WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS # ----------------------------------------------------------------------------- # TAG: wccp_router # Use this option to define your WCCP ``home'' router for # Squid. # # wccp_router supports a single WCCP(v1) router # # wccp2_router supports multiple WCCPv2 routers # # only one of the two may be used at the same time and defines # which version of WCCP to use. #Default: # WCCP disabled. # TAG: wccp2_router # Use this option to define your WCCP ``home'' router for # Squid. # # wccp_router supports a single WCCP(v1) router # # wccp2_router supports multiple WCCPv2 routers # # only one of the two may be used at the same time and defines # which version of WCCP to use. #Default: # WCCPv2 disabled. # TAG: wccp_version # This directive is only relevant if you need to set up WCCP(v1) # to some very old and end-of-life Cisco routers. In all other # setups it must be left unset or at the default setting. # It defines an internal version in the WCCP(v1) protocol, # with version 4 being the officially documented protocol. # # According to some users, Cisco IOS 11.2 and earlier only # support WCCP version 3. If you're using that or an earlier # version of IOS, you may need to change this value to 3, otherwise # do not specify this parameter. #Default: # wccp_version 4 # TAG: wccp2_rebuild_wait # If this is enabled Squid will wait for the cache dir rebuild to finish # before sending the first wccp2 HereIAm packet #Default: # wccp2_rebuild_wait on # TAG: wccp2_forwarding_method # WCCP2 allows the setting of forwarding methods between the # router/switch and the cache. Valid values are as follows: # # gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel) # l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting) # # Currently (as of IOS 12.4) cisco routers only support GRE. # Cisco switches only support the L2 redirect assignment method. #Default: # wccp2_forwarding_method gre # TAG: wccp2_return_method # WCCP2 allows the setting of return methods between the # router/switch and the cache for packets that the cache # decides not to handle. Valid values are as follows: # # gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel) # l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting) # # Currently (as of IOS 12.4) cisco routers only support GRE. # Cisco switches only support the L2 redirect assignment. # # If the "ip wccp redirect exclude in" command has been # enabled on the cache interface, then it is still safe for # the proxy server to use a l2 redirect method even if this # option is set to GRE. #Default: # wccp2_return_method gre # TAG: wccp2_assignment_method # WCCP2 allows the setting of methods to assign the WCCP hash # Valid values are as follows: # # hash - Hash assignment # mask - Mask assignment # # As a general rule, cisco routers support the hash assignment method # and cisco switches support the mask assignment method. #Default: # wccp2_assignment_method hash # TAG: wccp2_service # WCCP2 allows for multiple traffic services. There are two # types: "standard" and "dynamic". The standard type defines # one service id - http (id 0). The dynamic service ids can be from # 51 to 255 inclusive. In order to use a dynamic service id # one must define the type of traffic to be redirected; this is done # using the wccp2_service_info option. # # The "standard" type does not require a wccp2_service_info option, # just specifying the service id will suffice. # # MD5 service authentication can be enabled by adding # "password=<password>" to the end of this service declaration. # # Examples: # # wccp2_service standard 0 # for the 'web-cache' standard service # wccp2_service dynamic 80 # a dynamic service type which will be # # fleshed out with subsequent options. # wccp2_service standard 0 password=foo #Default: # Use the 'web-cache' standard service. # TAG: wccp2_service_info # Dynamic WCCPv2 services require further information to define the # traffic you wish to have diverted. # # The format is: # # wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>.. # priority=<priority> ports=<port>,<port>.. # # The relevant WCCPv2 flags: # + src_ip_hash, dst_ip_hash # + source_port_hash, dst_port_hash # + src_ip_alt_hash, dst_ip_alt_hash # + src_port_alt_hash, dst_port_alt_hash # + ports_source # # The port list can be one to eight entries. # # Example: # # wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source # priority=240 ports=80 # # Note: the service id must have been defined by a previous # 'wccp2_service dynamic <id>' entry. #Default: # none # TAG: wccp2_weight # Each cache server gets assigned a set of the destination # hash proportional to their weight. #Default: # wccp2_weight 10000 # TAG: wccp_address # Use this option if you require WCCP(v1) to use a specific # interface address. # # The default behavior is to not bind to any specific address. #Default: # Address selected by the operating system. # TAG: wccp2_address # Use this option if you require WCCPv2 to use a specific # interface address. # # The default behavior is to not bind to any specific address. #Default: # Address selected by the operating system. # PERSISTENT CONNECTION HANDLING # ----------------------------------------------------------------------------- # # Also see "pconn_timeout" in the TIMEOUTS section # TAG: client_persistent_connections # Persistent connection support for clients. # Squid uses persistent connections (when allowed). You can use # this option to disable persistent connections with clients. #Default: # client_persistent_connections on # TAG: server_persistent_connections # Persistent connection support for servers. # Squid uses persistent connections (when allowed). You can use # this option to disable persistent connections with servers. #Default: # server_persistent_connections on # TAG: persistent_connection_after_error # With this directive the use of persistent connections after # HTTP errors can be disabled. Useful if you have clients # who fail to handle errors on persistent connections proper. #Default: # persistent_connection_after_error on # TAG: detect_broken_pconn # Some servers have been found to incorrectly signal the use # of HTTP/1.0 persistent connections even on replies not # compatible, causing significant delays. This server problem # has mostly been seen on redirects. # # By enabling this directive Squid attempts to detect such # broken replies and automatically assume the reply is finished # after 10 seconds timeout. #Default: # detect_broken_pconn off # CACHE DIGEST OPTIONS # ----------------------------------------------------------------------------- # TAG: digest_generation # This controls whether the server will generate a Cache Digest # of its contents. By default, Cache Digest generation is # enabled if Squid is compiled with --enable-cache-digests defined. #Default: # digest_generation on # TAG: digest_bits_per_entry # This is the number of bits of the server's Cache Digest which # will be associated with the Digest entry for a given HTTP # Method and URL (public key) combination. The default is 5. #Default: # digest_bits_per_entry 5 # TAG: digest_rebuild_period (seconds) # This is the wait time between Cache Digest rebuilds. #Default: # digest_rebuild_period 1 hour # TAG: digest_rewrite_period (seconds) # This is the wait time between Cache Digest writes to # disk. #Default: # digest_rewrite_period 1 hour # TAG: digest_swapout_chunk_size (bytes) # This is the number of bytes of the Cache Digest to write to # disk at a time. It defaults to 4096 bytes (4KB), the Squid # default swap page. #Default: # digest_swapout_chunk_size 4096 bytes # TAG: digest_rebuild_chunk_percentage (percent, 0-100) # This is the percentage of the Cache Digest to be scanned at a # time. By default it is set to 10% of the Cache Digest. #Default: # digest_rebuild_chunk_percentage 10 # SNMP OPTIONS # ----------------------------------------------------------------------------- # TAG: snmp_port # The port number where Squid listens for SNMP requests. To enable # SNMP support set this to a suitable port number. Port number # 3401 is often used for the Squid SNMP agent. By default it's # set to "0" (disabled) # # Example: # snmp_port 3401 #Default: # SNMP disabled. # TAG: snmp_access # Allowing or denying access to the SNMP port. # # All access to the agent is denied by default. # usage: # # snmp_access allow|deny [!]aclname ... # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # #Example: # snmp_access allow snmppublic localhost # snmp_access deny all #Default: # Deny, unless rules exist in squid.conf. # TAG: snmp_incoming_address # Just like 'udp_incoming_address', but for the SNMP port. # # snmp_incoming_address is used for the SNMP socket receiving # messages from SNMP agents. # # The default snmp_incoming_address is to listen on all # available network interfaces. #Default: # Accept SNMP packets from all machine interfaces. # TAG: snmp_outgoing_address # Just like 'udp_outgoing_address', but for the SNMP port. # # snmp_outgoing_address is used for SNMP packets returned to SNMP # agents. # # If snmp_outgoing_address is not set it will use the same socket # as snmp_incoming_address. Only change this if you want to have # SNMP replies sent using another address than where this Squid # listens for SNMP queries. # # NOTE, snmp_incoming_address and snmp_outgoing_address can not have # the same value since they both use the same port. #Default: # Use snmp_incoming_address or an address selected by the operating system. # ICP OPTIONS # ----------------------------------------------------------------------------- # TAG: icp_port # The port number where Squid sends and receives ICP queries to # and from neighbor caches. The standard UDP port for ICP is 3130. # # Example: # icp_port 3130 #Default: # ICP disabled. # TAG: htcp_port # The port number where Squid sends and receives HTCP queries to # and from neighbor caches. To turn it on you want to set it to # 4827. # # Example: # htcp_port 4827 #Default: # HTCP disabled. # TAG: log_icp_queries on|off # If set, ICP queries are logged to access.log. You may wish # do disable this if your ICP load is VERY high to speed things # up or to simplify log analysis. #Default: # log_icp_queries on # TAG: udp_incoming_address # udp_incoming_address is used for UDP packets received from other # caches. # # The default behavior is to not bind to any specific address. # # Only change this if you want to have all UDP queries received on # a specific interface/address. # # NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS # modules. Altering it will affect all of them in the same manner. # # see also; udp_outgoing_address # # NOTE, udp_incoming_address and udp_outgoing_address can not # have the same value since they both use the same port. #Default: # Accept packets from all machine interfaces. # TAG: udp_outgoing_address # udp_outgoing_address is used for UDP packets sent out to other # caches. # # The default behavior is to not bind to any specific address. # # Instead it will use the same socket as udp_incoming_address. # Only change this if you want to have UDP queries sent using another # address than where this Squid listens for UDP queries from other # caches. # # NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS # modules. Altering it will affect all of them in the same manner. # # see also; udp_incoming_address # # NOTE, udp_incoming_address and udp_outgoing_address can not # have the same value since they both use the same port. #Default: # Use udp_incoming_address or an address selected by the operating system. # TAG: icp_hit_stale on|off # If you want to return ICP_HIT for stale cache objects, set this # option to 'on'. If you have sibling relationships with caches # in other administrative domains, this should be 'off'. If you only # have sibling relationships with caches under your control, # it is probably okay to set this to 'on'. # If set to 'on', your siblings should use the option "allow-miss" # on their cache_peer lines for connecting to you. #Default: # icp_hit_stale off # TAG: minimum_direct_hops # If using the ICMP pinging stuff, do direct fetches for sites # which are no more than this many hops away. #Default: # minimum_direct_hops 4 # TAG: minimum_direct_rtt (msec) # If using the ICMP pinging stuff, do direct fetches for sites # which are no more than this many rtt milliseconds away. #Default: # minimum_direct_rtt 400 # TAG: netdb_low # The low water mark for the ICMP measurement database. # # Note: high watermark controlled by netdb_high directive. # # These watermarks are counts, not percents. The defaults are # (low) 900 and (high) 1000. When the high water mark is # reached, database entries will be deleted until the low # mark is reached. #Default: # netdb_low 900 # TAG: netdb_high # The high water mark for the ICMP measurement database. # # Note: low watermark controlled by netdb_low directive. # # These watermarks are counts, not percents. The defaults are # (low) 900 and (high) 1000. When the high water mark is # reached, database entries will be deleted until the low # mark is reached. #Default: # netdb_high 1000 # TAG: netdb_ping_period # The minimum period for measuring a site. There will be at # least this much delay between successive pings to the same # network. The default is five minutes. #Default: # netdb_ping_period 5 minutes # TAG: query_icmp on|off # If you want to ask your peers to include ICMP data in their ICP # replies, enable this option. # # If your peer has configured Squid (during compilation) with # '--enable-icmp' that peer will send ICMP pings to origin server # sites of the URLs it receives. If you enable this option the # ICP replies from that peer will include the ICMP data (if available). # Then, when choosing a parent cache, Squid will choose the parent with # the minimal RTT to the origin server. When this happens, the # hierarchy field of the access.log will be # "CLOSEST_PARENT_MISS". This option is off by default. #Default: # query_icmp off # TAG: test_reachability on|off # When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH # instead of ICP_MISS if the target host is NOT in the ICMP # database, or has a zero RTT. #Default: # test_reachability off # TAG: icp_query_timeout (msec) # Normally Squid will automatically determine an optimal ICP # query timeout value based on the round-trip-time of recent ICP # queries. If you want to override the value determined by # Squid, set this 'icp_query_timeout' to a non-zero value. This # value is specified in MILLISECONDS, so, to use a 2-second # timeout (the old default), you would write: # # icp_query_timeout 2000 #Default: # Dynamic detection. # TAG: maximum_icp_query_timeout (msec) # Normally the ICP query timeout is determined dynamically. But # sometimes it can lead to very large values (say 5 seconds). # Use this option to put an upper limit on the dynamic timeout # value. Do NOT use this option to always use a fixed (instead # of a dynamic) timeout value. To set a fixed timeout see the # 'icp_query_timeout' directive. #Default: # maximum_icp_query_timeout 2000 # TAG: minimum_icp_query_timeout (msec) # Normally the ICP query timeout is determined dynamically. But # sometimes it can lead to very small timeouts, even lower than # the normal latency variance on your link due to traffic. # Use this option to put an lower limit on the dynamic timeout # value. Do NOT use this option to always use a fixed (instead # of a dynamic) timeout value. To set a fixed timeout see the # 'icp_query_timeout' directive. #Default: # minimum_icp_query_timeout 5 # TAG: background_ping_rate time-units # Controls how often the ICP pings are sent to siblings that # have background-ping set. #Default: # background_ping_rate 10 seconds # MULTICAST ICP OPTIONS # ----------------------------------------------------------------------------- # TAG: mcast_groups # This tag specifies a list of multicast groups which your server # should join to receive multicasted ICP queries. # # NOTE! Be very careful what you put here! Be sure you # understand the difference between an ICP _query_ and an ICP # _reply_. This option is to be set only if you want to RECEIVE # multicast queries. Do NOT set this option to SEND multicast # ICP (use cache_peer for that). ICP replies are always sent via # unicast, so this option does not affect whether or not you will # receive replies from multicast group members. # # You must be very careful to NOT use a multicast address which # is already in use by another group of caches. # # If you are unsure about multicast, please read the Multicast # chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/). # # Usage: mcast_groups 239.128.16.128 224.0.1.20 # # By default, Squid doesn't listen on any multicast groups. #Default: # none # TAG: mcast_miss_addr # Note: This option is only available if Squid is rebuilt with the # -DMULTICAST_MISS_STREAM define # # If you enable this option, every "cache miss" URL will # be sent out on the specified multicast address. # # Do not enable this option unless you are are absolutely # certain you understand what you are doing. #Default: # disabled. # TAG: mcast_miss_ttl # Note: This option is only available if Squid is rebuilt with the # -DMULTICAST_MISS_STREAM define # # This is the time-to-live value for packets multicasted # when multicasting off cache miss URLs is enabled. By # default this is set to 'site scope', i.e. 16. #Default: # mcast_miss_ttl 16 # TAG: mcast_miss_port # Note: This option is only available if Squid is rebuilt with the # -DMULTICAST_MISS_STREAM define # # This is the port number to be used in conjunction with # 'mcast_miss_addr'. #Default: # mcast_miss_port 3135 # TAG: mcast_miss_encode_key # Note: This option is only available if Squid is rebuilt with the # -DMULTICAST_MISS_STREAM define # # The URLs that are sent in the multicast miss stream are # encrypted. This is the encryption key. #Default: # mcast_miss_encode_key XXXXXXXXXXXXXXXX # TAG: mcast_icp_query_timeout (msec) # For multicast peers, Squid regularly sends out ICP "probes" to # count how many other peers are listening on the given multicast # address. This value specifies how long Squid should wait to # count all the replies. The default is 2000 msec, or 2 # seconds. #Default: # mcast_icp_query_timeout 2000 # INTERNAL ICON OPTIONS # ----------------------------------------------------------------------------- # TAG: icon_directory # Where the icons are stored. These are normally kept in # /usr/share/squid/icons #Default: # icon_directory /usr/share/squid/icons # TAG: global_internal_static # This directive controls is Squid should intercept all requests for # /squid-internal-static/ no matter which host the URL is requesting # (default on setting), or if nothing special should be done for # such URLs (off setting). The purpose of this directive is to make # icons etc work better in complex cache hierarchies where it may # not always be possible for all corners in the cache mesh to reach # the server generating a directory listing. #Default: # global_internal_static on # TAG: short_icon_urls # If this is enabled Squid will use short URLs for icons. # If disabled it will revert to the old behavior of including # it's own name and port in the URL. # # If you run a complex cache hierarchy with a mix of Squid and # other proxies you may need to disable this directive. #Default: # short_icon_urls on # ERROR PAGE OPTIONS # ----------------------------------------------------------------------------- # TAG: error_directory # If you wish to create your own versions of the default # error files to customize them to suit your company copy # the error/template files to another directory and point # this tag at them. # # WARNING: This option will disable multi-language support # on error pages if used. # # The squid developers are interested in making squid available in # a wide variety of languages. If you are making translations for a # language that Squid does not currently provide please consider # contributing your translation back to the project. # http://wiki.squid-cache.org/Translations # # The squid developers working on translations are happy to supply drop-in # translated error files in exchange for any new language contributions. #Default: # Send error pages in the clients preferred language # TAG: error_default_language # Set the default language which squid will send error pages in # if no existing translation matches the clients language # preferences. # # If unset (default) generic English will be used. # # The squid developers are interested in making squid available in # a wide variety of languages. If you are interested in making # translations for any language see the squid wiki for details. # http://wiki.squid-cache.org/Translations #Default: # Generate English language pages. # TAG: error_log_languages # Log to cache.log what languages users are attempting to # auto-negotiate for translations. # # Successful negotiations are not logged. Only failures # have meaning to indicate that Squid may need an upgrade # of its error page translations. #Default: # error_log_languages on # TAG: err_page_stylesheet # CSS Stylesheet to pattern the display of Squid default error pages. # # For information on CSS see http://www.w3.org/Style/CSS/ #Default: # err_page_stylesheet /etc/squid/errorpage.css # TAG: err_html_text # HTML text to include in error messages. Make this a "mailto" # URL to your admin address, or maybe just a link to your # organizations Web page. # # To include this in your error messages, you must rewrite # the error template files (found in the "errors" directory). # Wherever you want the 'err_html_text' line to appear, # insert a %L tag in the error template file. #Default: # none # TAG: email_err_data on|off # If enabled, information about the occurred error will be # included in the mailto links of the ERR pages (if %W is set) # so that the email body contains the data. # Syntax is <A HREF="mailto:%w%W">%w</A> # # SECURITY WARNING: # Request headers and other included facts may contain # sensitive information about transaction history, the # Squid instance, and its environment which would be # unavailable to error recipients otherwise. #Default: # email_err_data off # TAG: deny_info # Usage: deny_info err_page_name acl # or deny_info http://... acl # or deny_info TCP_RESET acl # # This can be used to return a ERR_ page for requests which # do not pass the 'http_access' rules. Squid remembers the last # acl it evaluated in http_access, and if a 'deny_info' line exists # for that ACL Squid returns a corresponding error page. # # The acl is typically the last acl on the http_access deny line which # denied access. The exceptions to this rule are: # - When Squid needs to request authentication credentials. It's then # the first authentication related acl encountered # - When none of the http_access lines matches. It's then the last # acl processed on the last http_access line. # - When the decision to deny access was made by an adaptation service, # the acl name is the corresponding eCAP or ICAP service_name. # # NP: If providing your own custom error pages with error_directory # you may also specify them by your custom file name: # Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys # # By defaut Squid will send "403 Forbidden". A different 4xx or 5xx # may be specified by prefixing the file name with the code and a colon. # e.g. 404:ERR_CUSTOM_ACCESS_DENIED # # Alternatively you can tell Squid to reset the TCP connection # by specifying TCP_RESET. # # Or you can specify an error URL or URL pattern. The browsers will # get redirected to the specified URL after formatting tags have # been replaced. Redirect will be done with 302 or 307 according to # HTTP/1.1 specs. A different 3xx code may be specified by prefixing # the URL. e.g. 303:http://example.com/ # # URL FORMAT TAGS: # %a - username (if available. Password NOT included) # %B - FTP path URL # %e - Error number # %E - Error description # %h - Squid hostname # %H - Request domain name # %i - Client IP Address # %M - Request Method # %O - Unescaped message result from external ACL helper # %o - Message result from external ACL helper # %p - Request Port number # %P - Request Protocol name # %R - Request URL path # %T - Timestamp in RFC 1123 format # %U - Full canonical URL from client # (HTTPS URLs terminate with *) # %u - Full canonical URL from client # %w - Admin email from squid.conf # %x - Error name # %% - Literal percent (%) code # #Default: # none # OPTIONS INFLUENCING REQUEST FORWARDING # ----------------------------------------------------------------------------- # TAG: nonhierarchical_direct # By default, Squid will send any non-hierarchical requests # (not cacheable request type) direct to origin servers. # # When this is set to "off", Squid will prefer to send these # requests to parents. # # Note that in most configurations, by turning this off you will only # add latency to these request without any improvement in global hit # ratio. # # This option only sets a preference. If the parent is unavailable a # direct connection to the origin server may still be attempted. To # completely prevent direct connections use never_direct. #Default: # nonhierarchical_direct on # TAG: prefer_direct # Normally Squid tries to use parents for most requests. If you for some # reason like it to first try going direct and only use a parent if # going direct fails set this to on. # # By combining nonhierarchical_direct off and prefer_direct on you # can set up Squid to use a parent as a backup path if going direct # fails. # # Note: If you want Squid to use parents for all requests see # the never_direct directive. prefer_direct only modifies how Squid # acts on cacheable requests. #Default: # prefer_direct off # TAG: cache_miss_revalidate on|off # RFC 7232 defines a conditional request mechanism to prevent # response objects being unnecessarily transferred over the network. # If that mechanism is used by the client and a cache MISS occurs # it can prevent new cache entries being created. # # This option determines whether Squid on cache MISS will pass the # client revalidation request to the server or tries to fetch new # content for caching. It can be useful while the cache is mostly # empty to more quickly have the cache populated by generating # non-conditional GETs. # # When set to 'on' (default), Squid will pass all client If-* headers # to the server. This permits server responses without a cacheable # payload to be delivered and on MISS no new cache entry is created. # # When set to 'off' and if the request is cacheable, Squid will # remove the clients If-Modified-Since and If-None-Match headers from # the request sent to the server. This requests a 200 status response # from the server to create a new cache entry with. #Default: # cache_miss_revalidate on # TAG: always_direct # Usage: always_direct allow|deny [!]aclname ... # # Here you can use ACL elements to specify requests which should # ALWAYS be forwarded by Squid to the origin servers without using # any peers. For example, to always directly forward requests for # local servers ignoring any parents or siblings you may have use # something like: # # acl local-servers dstdomain my.domain.net # always_direct allow local-servers # # To always forward FTP requests directly, use # # acl FTP proto FTP # always_direct allow FTP # # NOTE: There is a similar, but opposite option named # 'never_direct'. You need to be aware that "always_direct deny # foo" is NOT the same thing as "never_direct allow foo". You # may need to use a deny rule to exclude a more-specific case of # some other rule. Example: # # acl local-external dstdomain external.foo.net # acl local-servers dstdomain .foo.net # always_direct deny local-external # always_direct allow local-servers # # NOTE: If your goal is to make the client forward the request # directly to the origin server bypassing Squid then this needs # to be done in the client configuration. Squid configuration # can only tell Squid how Squid should fetch the object. # # NOTE: This directive is not related to caching. The replies # is cached as usual even if you use always_direct. To not cache # the replies see the 'cache' directive. # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Prevent any cache_peer being used for this request. # TAG: never_direct # Usage: never_direct allow|deny [!]aclname ... # # never_direct is the opposite of always_direct. Please read # the description for always_direct if you have not already. # # With 'never_direct' you can use ACL elements to specify # requests which should NEVER be forwarded directly to origin # servers. For example, to force the use of a proxy for all # requests, except those in your local domain use something like: # # acl local-servers dstdomain .foo.net # never_direct deny local-servers # never_direct allow all # # or if Squid is inside a firewall and there are local intranet # servers inside the firewall use something like: # # acl local-intranet dstdomain .foo.net # acl local-external dstdomain external.foo.net # always_direct deny local-external # always_direct allow local-intranet # never_direct allow all # # This clause supports both fast and slow acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. #Default: # Allow DNS results to be used for this request. # ADVANCED NETWORKING OPTIONS # ----------------------------------------------------------------------------- # TAG: incoming_udp_average # Heavy voodoo here. I can't even believe you are reading this. # Are you crazy? Don't even think about adjusting these unless # you understand the algorithms in comm_select.c first! #Default: # incoming_udp_average 6 # TAG: incoming_tcp_average # Heavy voodoo here. I can't even believe you are reading this. # Are you crazy? Don't even think about adjusting these unless # you understand the algorithms in comm_select.c first! #Default: # incoming_tcp_average 4 # TAG: incoming_dns_average # Heavy voodoo here. I can't even believe you are reading this. # Are you crazy? Don't even think about adjusting these unless # you understand the algorithms in comm_select.c first! #Default: # incoming_dns_average 4 # TAG: min_udp_poll_cnt # Heavy voodoo here. I can't even believe you are reading this. # Are you crazy? Don't even think about adjusting these unless # you understand the algorithms in comm_select.c first! #Default: # min_udp_poll_cnt 8 # TAG: min_dns_poll_cnt # Heavy voodoo here. I can't even believe you are reading this. # Are you crazy? Don't even think about adjusting these unless # you understand the algorithms in comm_select.c first! #Default: # min_dns_poll_cnt 8 # TAG: min_tcp_poll_cnt # Heavy voodoo here. I can't even believe you are reading this. # Are you crazy? Don't even think about adjusting these unless # you understand the algorithms in comm_select.c first! #Default: # min_tcp_poll_cnt 8 # TAG: accept_filter # FreeBSD: # # The name of an accept(2) filter to install on Squid's # listen socket(s). This feature is perhaps specific to # FreeBSD and requires support in the kernel. # # The 'httpready' filter delays delivering new connections # to Squid until a full HTTP request has been received. # See the accf_http(9) man page for details. # # The 'dataready' filter delays delivering new connections # to Squid until there is some data to process. # See the accf_dataready(9) man page for details. # # Linux: # # The 'data' filter delays delivering of new connections # to Squid until there is some data to process by TCP_ACCEPT_DEFER. # You may optionally specify a number of seconds to wait by # 'data=N' where N is the number of seconds. Defaults to 30 # if not specified. See the tcp(7) man page for details. #EXAMPLE: ## FreeBSD #accept_filter httpready ## Linux #accept_filter data #Default: # none # TAG: client_ip_max_connections # Set an absolute limit on the number of connections a single # client IP can use. Any more than this and Squid will begin to drop # new connections from the client until it closes some links. # # Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP # connections from the client. For finer control use the ACL access controls. # # Requires client_db to be enabled (the default). # # WARNING: This may noticably slow down traffic received via external proxies # or NAT devices and cause them to rebound error messages back to their clients. #Default: # No limit. # TAG: tcp_recv_bufsize (bytes) # Size of receive buffer to set for TCP sockets. Probably just # as easy to change your kernel's default. # Omit from squid.conf to use the default buffer size. #Default: # Use operating system TCP defaults. # ICAP OPTIONS # ----------------------------------------------------------------------------- # TAG: icap_enable on|off # If you want to enable the ICAP module support, set this to on. #Default: # icap_enable off # TAG: icap_connect_timeout # This parameter specifies how long to wait for the TCP connect to # the requested ICAP server to complete before giving up and either # terminating the HTTP transaction or bypassing the failure. # # The default for optional services is peer_connect_timeout. # The default for essential services is connect_timeout. # If this option is explicitly set, its value applies to all services. #Default: # none # TAG: icap_io_timeout time-units # This parameter specifies how long to wait for an I/O activity on # an established, active ICAP connection before giving up and # either terminating the HTTP transaction or bypassing the # failure. #Default: # Use read_timeout. # TAG: icap_service_failure_limit limit [in memory-depth time-units] # The limit specifies the number of failures that Squid tolerates # when establishing a new TCP connection with an ICAP service. If # the number of failures exceeds the limit, the ICAP service is # not used for new ICAP requests until it is time to refresh its # OPTIONS. # # A negative value disables the limit. Without the limit, an ICAP # service will not be considered down due to connectivity failures # between ICAP OPTIONS requests. # # Squid forgets ICAP service failures older than the specified # value of memory-depth. The memory fading algorithm # is approximate because Squid does not remember individual # errors but groups them instead, splitting the option # value into ten time slots of equal length. # # When memory-depth is 0 and by default this option has no # effect on service failure expiration. # # Squid always forgets failures when updating service settings # using an ICAP OPTIONS transaction, regardless of this option # setting. # # For example, # # suspend service usage after 10 failures in 5 seconds: # icap_service_failure_limit 10 in 5 seconds #Default: # icap_service_failure_limit 10 # TAG: icap_service_revival_delay # The delay specifies the number of seconds to wait after an ICAP # OPTIONS request failure before requesting the options again. The # failed ICAP service is considered "down" until fresh OPTIONS are # fetched. # # The actual delay cannot be smaller than the hardcoded minimum # delay of 30 seconds. #Default: # icap_service_revival_delay 180 # TAG: icap_preview_enable on|off # The ICAP Preview feature allows the ICAP server to handle the # HTTP message by looking only at the beginning of the message body # or even without receiving the body at all. In some environments, # previews greatly speedup ICAP processing. # # During an ICAP OPTIONS transaction, the server may tell Squid what # HTTP messages should be previewed and how big the preview should be. # Squid will not use Preview if the server did not request one. # # To disable ICAP Preview for all ICAP services, regardless of # individual ICAP server OPTIONS responses, set this option to "off". #Example: #icap_preview_enable off #Default: # icap_preview_enable on # TAG: icap_preview_size # The default size of preview data to be sent to the ICAP server. # This value might be overwritten on a per server basis by OPTIONS requests. #Default: # No preview sent. # TAG: icap_206_enable on|off # 206 (Partial Content) responses is an ICAP extension that allows the # ICAP agents to optionally combine adapted and original HTTP message # content. The decision to combine is postponed until the end of the # ICAP response. Squid supports Partial Content extension by default. # # Activation of the Partial Content extension is negotiated with each # ICAP service during OPTIONS exchange. Most ICAP servers should handle # negotation correctly even if they do not support the extension, but # some might fail. To disable Partial Content support for all ICAP # services and to avoid any negotiation, set this option to "off". # # Example: # icap_206_enable off #Default: # icap_206_enable on # TAG: icap_default_options_ttl # The default TTL value for ICAP OPTIONS responses that don't have # an Options-TTL header. #Default: # icap_default_options_ttl 60 # TAG: icap_persistent_connections on|off # Whether or not Squid should use persistent connections to # an ICAP server. #Default: # icap_persistent_connections on # TAG: adaptation_send_client_ip on|off # If enabled, Squid shares HTTP client IP information with adaptation # services. For ICAP, Squid adds the X-Client-IP header to ICAP requests. # For eCAP, Squid sets the libecap::metaClientIp transaction option. # # See also: adaptation_uses_indirect_client #Default: # adaptation_send_client_ip off # TAG: adaptation_send_username on|off # This sends authenticated HTTP client username (if available) to # the adaptation service. # # For ICAP, the username value is encoded based on the # icap_client_username_encode option and is sent using the header # specified by the icap_client_username_header option. #Default: # adaptation_send_username off # TAG: icap_client_username_header # ICAP request header name to use for adaptation_send_username. #Default: # icap_client_username_header X-Client-Username # TAG: icap_client_username_encode on|off # Whether to base64 encode the authenticated client username. #Default: # icap_client_username_encode off # TAG: icap_service # Defines a single ICAP service using the following format: # # icap_service id vectoring_point uri [option ...] # # id: ID # an opaque identifier or name which is used to direct traffic to # this specific service. Must be unique among all adaptation # services in squid.conf. # # vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache # This specifies at which point of transaction processing the # ICAP service should be activated. *_postcache vectoring points # are not yet supported. # # uri: icap://servername:port/servicepath # ICAP server and service location. # icaps://servername:port/servicepath # The "icap:" URI scheme is used for traditional ICAP server and # service location (default port is 1344, connections are not # encrypted). The "icaps:" URI scheme is for Secure ICAP # services that use SSL/TLS-encrypted ICAP connections (by # default, on port 11344). # # ICAP does not allow a single service to handle both REQMOD and RESPMOD # transactions. Squid does not enforce that requirement. You can specify # services with the same service_url and different vectoring_points. You # can even specify multiple identical services as long as their # service_names differ. # # To activate a service, use the adaptation_access directive. To group # services, use adaptation_service_chain and adaptation_service_set. # # Service options are separated by white space. ICAP services support # the following name=value options: # # bypass=on|off|1|0 # If set to 'on' or '1', the ICAP service is treated as # optional. If the service cannot be reached or malfunctions, # Squid will try to ignore any errors and process the message as # if the service was not enabled. No all ICAP errors can be # bypassed. If set to 0, the ICAP service is treated as # essential and all ICAP errors will result in an error page # returned to the HTTP client. # # Bypass is off by default: services are treated as essential. # # routing=on|off|1|0 # If set to 'on' or '1', the ICAP service is allowed to # dynamically change the current message adaptation plan by # returning a chain of services to be used next. The services # are specified using the X-Next-Services ICAP response header # value, formatted as a comma-separated list of service names. # Each named service should be configured in squid.conf. Other # services are ignored. An empty X-Next-Services value results # in an empty plan which ends the current adaptation. # # Dynamic adaptation plan may cross or cover multiple supported # vectoring points in their natural processing order. # # Routing is not allowed by default: the ICAP X-Next-Services # response header is ignored. # # ipv6=on|off # Only has effect on split-stack systems. The default on those systems # is to use IPv4-only connections. When set to 'on' this option will # make Squid use IPv6-only connections to contact this ICAP service. # # on-overload=block|bypass|wait|force # If the service Max-Connections limit has been reached, do # one of the following for each new ICAP transaction: # * block: send an HTTP error response to the client # * bypass: ignore the "over-connected" ICAP service # * wait: wait (in a FIFO queue) for an ICAP connection slot # * force: proceed, ignoring the Max-Connections limit # # In SMP mode with N workers, each worker assumes the service # connection limit is Max-Connections/N, even though not all # workers may use a given service. # # The default value is "bypass" if service is bypassable, # otherwise it is set to "wait". # # # max-conn=number # Use the given number as the Max-Connections limit, regardless # of the Max-Connections value given by the service, if any. # # connection-encryption=on|off # Determines the ICAP service effect on the connections_encrypted # ACL. # # The default is "on" for Secure ICAP services (i.e., those # with the icaps:// service URIs scheme) and "off" for plain ICAP # services. # # Does not affect ICAP connections (e.g., does not turn Secure # ICAP on or off). # # ==== ICAPS / TLS OPTIONS ==== # # These options are used for Secure ICAP (icaps://....) services only. # # tls-cert=/path/to/ssl/certificate # A client X.509 certificate to use when connecting to # this ICAP server. # # tls-key=/path/to/ssl/key # The private key corresponding to the previous # tls-cert= option. # # If tls-key= is not specified tls-cert= is assumed to # reference a PEM file containing both the certificate # and private key. # # tls-cipher=... The list of valid TLS/SSL ciphers to use when connecting # to this icap server. # # tls-min-version=1.N # The minimum TLS protocol version to permit. To control # SSLv3 use the tls-options= parameter. # Supported Values: 1.0 (default), 1.1, 1.2 # # tls-options=... Specify various OpenSSL library options: # # NO_SSLv3 Disallow the use of SSLv3 # # SINGLE_DH_USE # Always create a new key when using # temporary/ephemeral DH key exchanges # # ALL Enable various bug workarounds # suggested as "harmless" by OpenSSL # Be warned that this reduces SSL/TLS # strength to some attacks. # # See the OpenSSL SSL_CTX_set_options documentation for a # more complete list. Options relevant only to SSLv2 are # not supported. # # tls-cafile= PEM file containing CA certificates to use when verifying # the icap server certificate. # Use to specify intermediate CA certificate(s) if not sent # by the server. Or the full CA chain for the server when # using the tls-default-ca=off flag. # May be repeated to load multiple files. # # tls-capath=... A directory containing additional CA certificates to # use when verifying the icap server certificate. # Requires OpenSSL or LibreSSL. # # tls-crlfile=... A certificate revocation list file to use when # verifying the icap server certificate. # # tls-flags=... Specify various flags modifying the Squid TLS implementation: # # DONT_VERIFY_PEER # Accept certificates even if they fail to # verify. # DONT_VERIFY_DOMAIN # Don't verify the icap server certificate # matches the server name # # tls-default-ca[=off] # Whether to use the system Trusted CAs. Default is ON. # # tls-domain= The icap server name as advertised in it's certificate. # Used for verifying the correctness of the received icap # server certificate. If not specified the icap server # hostname extracted from ICAP URI will be used. # # Older icap_service format without optional named parameters is # deprecated but supported for backward compatibility. # #Example: #icap_service svcBlocker reqmod_precache icap://icap1.mydomain.net:1344/reqmod bypass=0 #icap_service svcLogger reqmod_precache icaps://icap2.mydomain.net:11344/reqmod routing=on #Default: # none # TAG: icap_class # This deprecated option was documented to define an ICAP service # chain, even though it actually defined a set of similar, redundant # services, and the chains were not supported. # # To define a set of redundant services, please use the # adaptation_service_set directive. For service chains, use # adaptation_service_chain. #Default: # none # TAG: icap_access # This option is deprecated. Please use adaptation_access, which # has the same ICAP functionality, but comes with better # documentation, and eCAP support. #Default: # none # eCAP OPTIONS # ----------------------------------------------------------------------------- # TAG: ecap_enable on|off # Controls whether eCAP support is enabled. #Default: # ecap_enable off # TAG: ecap_service # Defines a single eCAP service # # ecap_service id vectoring_point uri [option ...] # # id: ID # an opaque identifier or name which is used to direct traffic to # this specific service. Must be unique among all adaptation # services in squid.conf. # # vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache # This specifies at which point of transaction processing the # eCAP service should be activated. *_postcache vectoring points # are not yet supported. # # uri: ecap://vendor/service_name?custom&cgi=style¶meters=optional # Squid uses the eCAP service URI to match this configuration # line with one of the dynamically loaded services. Each loaded # eCAP service must have a unique URI. Obtain the right URI from # the service provider. # # To activate a service, use the adaptation_access directive. To group # services, use adaptation_service_chain and adaptation_service_set. # # Service options are separated by white space. eCAP services support # the following name=value options: # # bypass=on|off|1|0 # If set to 'on' or '1', the eCAP service is treated as optional. # If the service cannot be reached or malfunctions, Squid will try # to ignore any errors and process the message as if the service # was not enabled. No all eCAP errors can be bypassed. # If set to 'off' or '0', the eCAP service is treated as essential # and all eCAP errors will result in an error page returned to the # HTTP client. # # Bypass is off by default: services are treated as essential. # # routing=on|off|1|0 # If set to 'on' or '1', the eCAP service is allowed to # dynamically change the current message adaptation plan by # returning a chain of services to be used next. # # Dynamic adaptation plan may cross or cover multiple supported # vectoring points in their natural processing order. # # Routing is not allowed by default. # # connection-encryption=on|off # Determines the eCAP service effect on the connections_encrypted # ACL. # # Defaults to "on", which does not taint the master transaction # w.r.t. that ACL. # # Does not affect eCAP API calls. # # Older ecap_service format without optional named parameters is # deprecated but supported for backward compatibility. # # #Example: #ecap_service s1 reqmod_precache ecap://filters.R.us/leakDetector?on_error=block bypass=off #ecap_service s2 respmod_precache ecap://filters.R.us/virusFilter config=/etc/vf.cfg bypass=on #Default: # none # TAG: loadable_modules # Instructs Squid to load the specified dynamic module(s) or activate # preloaded module(s). #Example: #loadable_modules /usr/lib/MinimalAdapter.so #Default: # none # MESSAGE ADAPTATION OPTIONS # ----------------------------------------------------------------------------- # TAG: adaptation_service_set # # Configures an ordered set of similar, redundant services. This is # useful when hot standby or backup adaptation servers are available. # # adaptation_service_set set_name service_name1 service_name2 ... # # The named services are used in the set declaration order. The first # applicable adaptation service from the set is used first. The next # applicable service is tried if and only if the transaction with the # previous service fails and the message waiting to be adapted is still # intact. # # When adaptation starts, broken services are ignored as if they were # not a part of the set. A broken service is a down optional service. # # The services in a set must be attached to the same vectoring point # (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD). # # If all services in a set are optional then adaptation failures are # bypassable. If all services in the set are essential, then a # transaction failure with one service may still be retried using # another service from the set, but when all services fail, the master # transaction fails as well. # # A set may contain a mix of optional and essential services, but that # is likely to lead to surprising results because broken services become # ignored (see above), making previously bypassable failures fatal. # Technically, it is the bypassability of the last failed service that # matters. # # See also: adaptation_access adaptation_service_chain # #Example: #adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup #adaptation service_set svcLogger loggerLocal loggerRemote #Default: # none # TAG: adaptation_service_chain # # Configures a list of complementary services that will be applied # one-by-one, forming an adaptation chain or pipeline. This is useful # when Squid must perform different adaptations on the same message. # # adaptation_service_chain chain_name service_name1 svc_name2 ... # # The named services are used in the chain declaration order. The first # applicable adaptation service from the chain is used first. The next # applicable service is applied to the successful adaptation results of # the previous service in the chain. # # When adaptation starts, broken services are ignored as if they were # not a part of the chain. A broken service is a down optional service. # # Request satisfaction terminates the adaptation chain because Squid # does not currently allow declaration of RESPMOD services at the # "reqmod_precache" vectoring point (see icap_service or ecap_service). # # The services in a chain must be attached to the same vectoring point # (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD). # # A chain may contain a mix of optional and essential services. If an # essential adaptation fails (or the failure cannot be bypassed for # other reasons), the master transaction fails. Otherwise, the failure # is bypassed as if the failed adaptation service was not in the chain. # # See also: adaptation_access adaptation_service_set # #Example: #adaptation_service_chain svcRequest requestLogger urlFilter leakDetector #Default: # none # TAG: adaptation_access # Sends an HTTP transaction to an ICAP or eCAP adaptation service. # # adaptation_access service_name allow|deny [!]aclname... # adaptation_access set_name allow|deny [!]aclname... # # At each supported vectoring point, the adaptation_access # statements are processed in the order they appear in this # configuration file. Statements pointing to the following services # are ignored (i.e., skipped without checking their ACL): # # - services serving different vectoring points # - "broken-but-bypassable" services # - "up" services configured to ignore such transactions # (e.g., based on the ICAP Transfer-Ignore header). # # When a set_name is used, all services in the set are checked # using the same rules, to find the first applicable one. See # adaptation_service_set for details. # # If an access list is checked and there is a match, the # processing stops: For an "allow" rule, the corresponding # adaptation service is used for the transaction. For a "deny" # rule, no adaptation service is activated. # # It is currently not possible to apply more than one adaptation # service at the same vectoring point to the same HTTP transaction. # # See also: icap_service and ecap_service # #Example: #adaptation_access service_1 allow all #Default: # Allow, unless rules exist in squid.conf. # TAG: adaptation_service_iteration_limit # Limits the number of iterations allowed when applying adaptation # services to a message. If your longest adaptation set or chain # may have more than 16 services, increase the limit beyond its # default value of 16. If detecting infinite iteration loops sooner # is critical, make the iteration limit match the actual number # of services in your longest adaptation set or chain. # # Infinite adaptation loops are most likely with routing services. # # See also: icap_service routing=1 #Default: # adaptation_service_iteration_limit 16 # TAG: adaptation_masterx_shared_names # For each master transaction (i.e., the HTTP request and response # sequence, including all related ICAP and eCAP exchanges), Squid # maintains a table of metadata. The table entries are (name, value) # pairs shared among eCAP and ICAP exchanges. The table is destroyed # with the master transaction. # # This option specifies the table entry names that Squid must accept # from and forward to the adaptation transactions. # # An ICAP REQMOD or RESPMOD transaction may set an entry in the # shared table by returning an ICAP header field with a name # specified in adaptation_masterx_shared_names. # # An eCAP REQMOD or RESPMOD transaction may set an entry in the # shared table by implementing the libecap::visitEachOption() API # to provide an option with a name specified in # adaptation_masterx_shared_names. # # Squid will store and forward the set entry to subsequent adaptation # transactions within the same master transaction scope. # # Only one shared entry name is supported at this time. # #Example: ## share authentication information among ICAP services #adaptation_masterx_shared_names X-Subscriber-ID #Default: # none # TAG: adaptation_meta # This option allows Squid administrator to add custom ICAP request # headers or eCAP options to Squid ICAP requests or eCAP transactions. # Use it to pass custom authentication tokens and other # transaction-state related meta information to an ICAP/eCAP service. # # The addition of a meta header is ACL-driven: # adaptation_meta name value [!]aclname ... # # Processing for a given header name stops after the first ACL list match. # Thus, it is impossible to add two headers with the same name. If no ACL # lists match for a given header name, no such header is added. For # example: # # # do not debug transactions except for those that need debugging # adaptation_meta X-Debug 1 needs_debugging # # # log all transactions except for those that must remain secret # adaptation_meta X-Log 1 !keep_secret # # # mark transactions from users in the "G 1" group # adaptation_meta X-Authenticated-Groups "G 1" authed_as_G1 # # The "value" parameter may be a regular squid.conf token or a "double # quoted string". Within the quoted string, use backslash (\) to escape # any character, which is currently only useful for escaping backslashes # and double quotes. For example, # "this string has one backslash (\\) and two \"quotes\"" # # Used adaptation_meta header values may be logged via %note # logformat code. If multiple adaptation_meta headers with the same name # are used during master transaction lifetime, the header values are # logged in the order they were used and duplicate values are ignored # (only the first repeated value will be logged). #Default: # none # TAG: icap_retry # This ACL determines which retriable ICAP transactions are # retried. Transactions that received a complete ICAP response # and did not have to consume or produce HTTP bodies to receive # that response are usually retriable. # # icap_retry allow|deny [!]aclname ... # # Squid automatically retries some ICAP I/O timeouts and errors # due to persistent connection race conditions. # # See also: icap_retry_limit #Default: # icap_retry deny all # TAG: icap_retry_limit # Limits the number of retries allowed. # # Communication errors due to persistent connection race # conditions are unavoidable, automatically retried, and do not # count against this limit. # # See also: icap_retry #Default: # No retries are allowed. # DNS OPTIONS # ----------------------------------------------------------------------------- # TAG: check_hostnames # For security and stability reasons Squid can check # hostnames for Internet standard RFC compliance. If you want # Squid to perform these checks turn this directive on. #Default: # check_hostnames off # TAG: allow_underscore # Underscore characters is not strictly allowed in Internet hostnames # but nevertheless used by many sites. Set this to off if you want # Squid to be strict about the standard. # This check is performed only when check_hostnames is set to on. #Default: # allow_underscore on # TAG: dns_retransmit_interval # Initial retransmit interval for DNS queries. The interval is # doubled each time all configured DNS servers have been tried. #Default: # dns_retransmit_interval 5 seconds # TAG: dns_timeout # DNS Query timeout. If no response is received to a DNS query # within this time all DNS servers for the queried domain # are assumed to be unavailable. #Default: # dns_timeout 30 seconds # TAG: dns_packet_max # Maximum number of bytes packet size to advertise via EDNS. # Set to "none" to disable EDNS large packet support. # # For legacy reasons DNS UDP replies will default to 512 bytes which # is too small for many responses. EDNS provides a means for Squid to # negotiate receiving larger responses back immediately without having # to failover with repeat requests. Responses larger than this limit # will retain the old behaviour of failover to TCP DNS. # # Squid has no real fixed limit internally, but allowing packet sizes # over 1500 bytes requires network jumbogram support and is usually not # necessary. # # WARNING: The RFC also indicates that some older resolvers will reply # with failure of the whole request if the extension is added. Some # resolvers have already been identified which will reply with mangled # EDNS response on occasion. Usually in response to many-KB jumbogram # sizes being advertised by Squid. # Squid will currently treat these both as an unable-to-resolve domain # even if it would be resolvable without EDNS. #Default: # EDNS disabled # TAG: dns_defnames on|off # Normally the RES_DEFNAMES resolver option is disabled # (see res_init(3)). This prevents caches in a hierarchy # from interpreting single-component hostnames locally. To allow # Squid to handle single-component names, enable this option. #Default: # Search for single-label domain names is disabled. # TAG: dns_multicast_local on|off # When set to on, Squid sends multicast DNS lookups on the local # network for domains ending in .local and .arpa. # This enables local servers and devices to be contacted in an # ad-hoc or zero-configuration network environment. #Default: # Search for .local and .arpa names is disabled. # TAG: dns_nameservers # Use this if you want to specify a list of DNS name servers # (IP addresses) to use instead of those given in your # /etc/resolv.conf file. # # On Windows platforms, if no value is specified here or in # the /etc/resolv.conf file, the list of DNS name servers are # taken from the Windows registry, both static and dynamic DHCP # configurations are supported. # # Example: dns_nameservers 10.0.0.1 192.172.0.4 #Default: # Use operating system definitions # TAG: hosts_file # Location of the host-local IP name-address associations # database. Most Operating Systems have such a file on different # default locations: # - Un*X & Linux: /etc/hosts # - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts # (%SystemRoot% value install default is c:\winnt) # - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts # (%SystemRoot% value install default is c:\windows) # - Windows 9x/Me: %windir%\hosts # (%windir% value is usually c:\windows) # - Cygwin: /etc/hosts # # The file contains newline-separated definitions, in the # form ip_address_in_dotted_form name [name ...] names are # whitespace-separated. Lines beginning with an hash (#) # character are comments. # # The file is checked at startup and upon configuration. # If set to 'none', it won't be checked. # If append_domain is used, that domain will be added to # domain-local (i.e. not containing any dot character) host # definitions. #Default: # hosts_file /etc/hosts # TAG: append_domain # Appends local domain name to hostnames without any dots in # them. append_domain must begin with a period. # # Be warned there are now Internet names with no dots in # them using only top-domain names, so setting this may # cause some Internet sites to become unavailable. # #Example: # append_domain .yourdomain.com #Default: # Use operating system definitions # TAG: ignore_unknown_nameservers # By default Squid checks that DNS responses are received # from the same IP addresses they are sent to. If they # don't match, Squid ignores the response and writes a warning # message to cache.log. You can allow responses from unknown # nameservers by setting this option to 'off'. #Default: # ignore_unknown_nameservers on # TAG: dns_v4_first # With the IPv6 Internet being as fast or faster than IPv4 Internet # for most networks Squid prefers to contact websites over IPv6. # # This option reverses the order of preference to make Squid contact # dual-stack websites over IPv4 first. Squid will still perform both # IPv6 and IPv4 DNS lookups before connecting. # # WARNING: # This option will restrict the situations under which IPv6 # connectivity is used (and tested), potentially hiding network # problems which would otherwise be detected and warned about. #Default: # dns_v4_first off # TAG: ipcache_size (number of entries) # Maximum number of DNS IP cache entries. #Default: # ipcache_size 1024 # TAG: ipcache_low (percent) #Default: # ipcache_low 90 # TAG: ipcache_high (percent) # The size, low-, and high-water marks for the IP cache. #Default: # ipcache_high 95 # TAG: fqdncache_size (number of entries) # Maximum number of FQDN cache entries. #Default: # fqdncache_size 1024 # MISCELLANEOUS # ----------------------------------------------------------------------------- # TAG: configuration_includes_quoted_values on|off # If set, Squid will recognize each "quoted string" after a configuration # directive as a single parameter. The quotes are stripped before the # parameter value is interpreted or used. # See "Values with spaces, quotes, and other special characters" # section for more details. #Default: # configuration_includes_quoted_values off # TAG: memory_pools on|off # If set, Squid will keep pools of allocated (but unused) memory # available for future use. If memory is a premium on your # system and you believe your malloc library outperforms Squid # routines, disable this. #Default: # memory_pools on # TAG: memory_pools_limit (bytes) # Used only with memory_pools on: # memory_pools_limit 50 MB # # If set to a non-zero value, Squid will keep at most the specified # limit of allocated (but unused) memory in memory pools. All free() # requests that exceed this limit will be handled by your malloc # library. Squid does not pre-allocate any memory, just safe-keeps # objects that otherwise would be free()d. Thus, it is safe to set # memory_pools_limit to a reasonably high value even if your # configuration will use less memory. # # If set to none, Squid will keep all memory it can. That is, there # will be no limit on the total amount of memory used for safe-keeping. # # To disable memory allocation optimization, do not set # memory_pools_limit to 0 or none. Set memory_pools to "off" instead. # # An overhead for maintaining memory pools is not taken into account # when the limit is checked. This overhead is close to four bytes per # object kept. However, pools may actually _save_ memory because of # reduced memory thrashing in your malloc library. #Default: # memory_pools_limit 5 MB # TAG: forwarded_for on|off|transparent|truncate|delete # If set to "on", Squid will append your client's IP address # in the HTTP requests it forwards. By default it looks like: # # X-Forwarded-For: 192.1.2.3 # # If set to "off", it will appear as # # X-Forwarded-For: unknown # # If set to "transparent", Squid will not alter the # X-Forwarded-For header in any way. # # If set to "delete", Squid will delete the entire # X-Forwarded-For header. # # If set to "truncate", Squid will remove all existing # X-Forwarded-For entries, and place the client IP as the sole entry. #Default: # forwarded_for on # TAG: cachemgr_passwd # Specify passwords for cachemgr operations. # # Usage: cachemgr_passwd password action action ... # # Some valid actions are (see cache manager menu for a full list): # 5min # 60min # asndb # authenticator # cbdata # client_list # comm_incoming # config * # counters # delay # digest_stats # dns # events # filedescriptors # fqdncache # histograms # http_headers # info # io # ipcache # mem # menu # netdb # non_peers # objects # offline_toggle * # pconn # peer_select # reconfigure * # redirector # refresh # server_list # shutdown * # store_digest # storedir # utilization # via_headers # vm_objects # # * Indicates actions which will not be performed without a # valid password, others can be performed if not listed here. # # To disable an action, set the password to "disable". # To allow performing an action without a password, set the # password to "none". # # Use the keyword "all" to set the same password for all actions. # #Example: # cachemgr_passwd secret shutdown # cachemgr_passwd lesssssssecret info stats/objects # cachemgr_passwd disable all #Default: # No password. Actions which require password are denied. # TAG: client_db on|off # If you want to disable collecting per-client statistics, # turn off client_db here. #Default: # client_db on # TAG: refresh_all_ims on|off # When you enable this option, squid will always check # the origin server for an update when a client sends an # If-Modified-Since request. Many browsers use IMS # requests when the user requests a reload, and this # ensures those clients receive the latest version. # # By default (off), squid may return a Not Modified response # based on the age of the cached version. #Default: # refresh_all_ims off # TAG: reload_into_ims on|off # When you enable this option, client no-cache or ``reload'' # requests will be changed to If-Modified-Since requests. # Doing this VIOLATES the HTTP standard. Enabling this # feature could make you liable for problems which it # causes. # # see also refresh_pattern for a more selective approach. #Default: # reload_into_ims off # TAG: connect_retries # Limits the number of reopening attempts when establishing a single # TCP connection. All these attempts must still complete before the # applicable connection opening timeout expires. # # By default and when connect_retries is set to zero, Squid does not # retry failed connection opening attempts. # # The (not recommended) maximum is 10 tries. An attempt to configure a # higher value results in the value of 10 being used (with a warning). # # Squid may open connections to retry various high-level forwarding # failures. For an outside observer, that activity may look like a # low-level connection reopening attempt, but those high-level retries # are governed by forward_max_tries instead. # # See also: connect_timeout, forward_timeout, icap_connect_timeout, # ident_timeout, and forward_max_tries. #Default: # Do not retry failed connections. # TAG: retry_on_error # If set to ON Squid will automatically retry requests when # receiving an error response with status 403 (Forbidden), # 500 (Internal Error), 501 or 503 (Service not available). # Status 502 and 504 (Gateway errors) are always retried. # # This is mainly useful if you are in a complex cache hierarchy to # work around access control errors. # # NOTE: This retry will attempt to find another working destination. # Which is different from the server which just failed. #Default: # retry_on_error off # TAG: as_whois_server # WHOIS server to query for AS numbers. NOTE: AS numbers are # queried only when Squid starts up, not for every request. #Default: # as_whois_server whois.ra.net # TAG: offline_mode # Enable this option and Squid will never try to validate cached # objects. #Default: # offline_mode off # TAG: uri_whitespace # What to do with requests that have whitespace characters in the # URI. Options: # # strip: The whitespace characters are stripped out of the URL. # This is the behavior recommended by RFC2396 and RFC3986 # for tolerant handling of generic URI. # NOTE: This is one difference between generic URI and HTTP URLs. # # deny: The request is denied. The user receives an "Invalid # Request" message. # This is the behaviour recommended by RFC2616 for safe # handling of HTTP request URL. # # allow: The request is allowed and the URI is not changed. The # whitespace characters remain in the URI. Note the # whitespace is passed to redirector processes if they # are in use. # Note this may be considered a violation of RFC2616 # request parsing where whitespace is prohibited in the # URL field. # # encode: The request is allowed and the whitespace characters are # encoded according to RFC1738. # # chop: The request is allowed and the URI is chopped at the # first whitespace. # # # NOTE the current Squid implementation of encode and chop violates # RFC2616 by not using a 301 redirect after altering the URL. #Default: # uri_whitespace strip # TAG: chroot # Specifies a directory where Squid should do a chroot() while # initializing. This also causes Squid to fully drop root # privileges after initializing. This means, for example, if you # use a HTTP port less than 1024 and try to reconfigure, you may # get an error saying that Squid can not open the port. #Default: # none # TAG: pipeline_prefetch # HTTP clients may send a pipeline of 1+N requests to Squid using a # single connection, without waiting for Squid to respond to the first # of those requests. This option limits the number of concurrent # requests Squid will try to handle in parallel. If set to N, Squid # will try to receive and process up to 1+N requests on the same # connection concurrently. # # Defaults to 0 (off) for bandwidth management and access logging # reasons. # # NOTE: pipelining requires persistent connections to clients. # # WARNING: pipelining breaks NTLM and Negotiate/Kerberos authentication. #Default: # Do not pre-parse pipelined requests. # TAG: high_response_time_warning (msec) # If the one-minute median response time exceeds this value, # Squid prints a WARNING with debug level 0 to get the # administrators attention. The value is in milliseconds. #Default: # disabled. # TAG: high_page_fault_warning # If the one-minute average page fault rate exceeds this # value, Squid prints a WARNING with debug level 0 to get # the administrators attention. The value is in page faults # per second. #Default: # disabled. # TAG: high_memory_warning # Note: This option is only available if Squid is rebuilt with the # GNU Malloc with mstats() # # If the memory usage (as determined by gnumalloc, if available and used) # exceeds this amount, Squid prints a WARNING with debug level 0 to get # the administrators attention. #Default: # disabled. # TAG: sleep_after_fork (microseconds) # When this is set to a non-zero value, the main Squid process # sleeps the specified number of microseconds after a fork() # system call. This sleep may help the situation where your # system reports fork() failures due to lack of (virtual) # memory. Note, however, if you have a lot of child # processes, these sleep delays will add up and your # Squid will not service requests for some amount of time # until all the child processes have been started. # On Windows value less then 1000 (1 milliseconds) are # rounded to 1000. #Default: # sleep_after_fork 0 # TAG: windows_ipaddrchangemonitor on|off # Note: This option is only available if Squid is rebuilt with the # MS Windows # # On Windows Squid by default will monitor IP address changes and will # reconfigure itself after any detected event. This is very useful for # proxies connected to internet with dial-up interfaces. # In some cases (a Proxy server acting as VPN gateway is one) it could be # desiderable to disable this behaviour setting this to 'off'. # Note: after changing this, Squid service must be restarted. #Default: # windows_ipaddrchangemonitor on # TAG: eui_lookup # Whether to lookup the EUI or MAC address of a connected client. #Default: # eui_lookup on # TAG: max_filedescriptors # Set the maximum number of filedescriptors, either below the # operating system default or up to the hard limit. # # Remove from squid.conf to inherit the current ulimit soft # limit setting. # # Note: Changing this requires a restart of Squid. Also # not all I/O types supports large values (eg on Windows). #Default: # Use operating system soft limit set by ulimit. # TAG: force_request_body_continuation # This option controls how Squid handles data upload requests from HTTP # and FTP agents that require a "Please Continue" control message response # to actually send the request body to Squid. It is mostly useful in # adaptation environments. # # When Squid receives an HTTP request with an "Expect: 100-continue" # header or an FTP upload command (e.g., STOR), Squid normally sends the # request headers or FTP command information to an adaptation service (or # peer) and waits for a response. Most adaptation services (and some # broken peers) may not respond to Squid at that stage because they may # decide to wait for the HTTP request body or FTP data transfer. However, # that request body or data transfer may never come because Squid has not # responded with the HTTP 100 or FTP 150 (Please Continue) control message # to the request sender yet! # # An allow match tells Squid to respond with the HTTP 100 or FTP 150 # (Please Continue) control message on its own, before forwarding the # request to an adaptation service or peer. Such a response usually forces # the request sender to proceed with sending the body. A deny match tells # Squid to delay that control response until the origin server confirms # that the request body is needed. Delaying is the default behavior. #Default: # Deny, unless rules exist in squid.conf. # TAG: server_pconn_for_nonretriable # This option provides fine-grained control over persistent connection # reuse when forwarding HTTP requests that Squid cannot retry. It is useful # in environments where opening new connections is very expensive # (e.g., all connections are secured with TLS with complex client and server # certificate validation) and race conditions associated with persistent # connections are very rare and/or only cause minor problems. # # HTTP prohibits retrying unsafe and non-idempotent requests (e.g., POST). # Squid limitations also prohibit retrying all requests with bodies (e.g., PUT). # By default, when forwarding such "risky" requests, Squid opens a new # connection to the server or cache_peer, even if there is an idle persistent # connection available. When Squid is configured to risk sending a non-retriable # request on a previously used persistent connection, and the server closes # the connection before seeing that risky request, the user gets an error response # from Squid. In most cases, that error response will be HTTP 502 (Bad Gateway) # with ERR_ZERO_SIZE_OBJECT or ERR_WRITE_ERROR (peer connection reset) error detail. # # If an allow rule matches, Squid reuses an available idle persistent connection # (if any) for the request that Squid cannot retry. If a deny rule matches, then # Squid opens a new connection for the request that Squid cannot retry. # # This option does not affect requests that Squid can retry. They will reuse idle # persistent connections (if any). # # This clause only supports fast acl types. # See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details. # # Example: # acl SpeedIsWorthTheRisk method POST # server_pconn_for_nonretriable allow SpeedIsWorthTheRisk #Default: # Open new connections for forwarding requests Squid cannot retry safely.
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