2 # SQUID Web Proxy Cache http://www.squid-cache.org/
3 # ----------------------------------------------------------
5 # Squid is the result of efforts by numerous individuals from
6 # the Internet community; see the CONTRIBUTORS file for full
7 # details. Many organizations have provided support for Squid's
8 # development; see the SPONSORS file for full details. Squid is
9 # Copyrighted (C) 2000 by the Regents of the University of
10 # California; see the COPYRIGHT file for full details. Squid
11 # incorporates software developed and/or copyrighted by other
12 # sources; see the CREDITS file for full details.
14 # This program is free software; you can redistribute it and/or modify
15 # it under the terms of the GNU General Public License as published by
16 # the Free Software Foundation; either version 2 of the License, or
17 # (at your option) any later version.
19 # This program is distributed in the hope that it will be useful,
20 # but WITHOUT ANY WARRANTY; without even the implied warranty of
21 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 # GNU General Public License for more details.
24 # You should have received a copy of the GNU General Public License
25 # along with this program; if not, write to the Free Software
26 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
31 ----------------------------
33 This is the default Squid configuration file. You may wish
34 to look at the Squid home page (http://www.squid-cache.org/)
35 for the FAQ and other documentation.
37 The default Squid config file shows what the defaults for
38 various options happen to be. If you don't need to change the
39 default, you shouldn't uncomment the line. Doing so may cause
40 run-time problems. In some cases "none" refers to no default
41 setting at all, while in other cases it refers to a valid
42 option - the comments for that keyword indicate if this is the
48 Configuration options can be included using the "include" directive.
49 Include takes a list of files to include. Quoting and wildcards is
54 include /path/to/included/file/squid.acl.config
56 Includes can be nested up to a hard-coded depth of 16 levels.
57 This arbitrary restriction is to prevent recursive include references
58 from causing Squid entering an infinite loop whilst trying to load
62 Conditional configuration
64 If-statements can be used to make configuration directives
68 ... regular configuration directives ...
70 ... regular configuration directives ...]
73 The else part is optional. The keywords "if", "else", and "endif"
74 must be typed on their own lines, as if they were regular
75 configuration directives.
77 These individual conditions types are supported:
80 Always evaluates to true.
82 Always evaluates to false.
84 Equality comparison of two integer numbers.
89 The following SMP-related preprocessor macros can be used.
91 ${process_name} expands to the current Squid process "name"
92 (e.g., squid1, squid2, or cache1).
94 ${process_number} expands to the current Squid process
95 identifier, which is an integer number (e.g., 1, 2, 3) unique
96 across all Squid processes.
100 OPTIONS FOR AUTHENTICATION
101 -----------------------------------------------------------------------------
109 This is used to define parameters for the various authentication
110 schemes supported by Squid.
112 format: auth_param scheme parameter [setting]
114 The order in which authentication schemes are presented to the client is
115 dependent on the order the scheme first appears in config file. IE
116 has a bug (it's not RFC 2617 compliant) in that it will use the basic
117 scheme if basic is the first entry presented, even if more secure
118 schemes are presented. For now use the order in the recommended
119 settings section below. If other browsers have difficulties (don't
120 recognize the schemes offered even if you are using basic) either
121 put basic first, or disable the other schemes (by commenting out their
124 Once an authentication scheme is fully configured, it can only be
125 shutdown by shutting squid down and restarting. Changes can be made on
126 the fly and activated with a reconfigure. I.E. You can change to a
127 different helper, but not unconfigure the helper completely.
129 Please note that while this directive defines how Squid processes
130 authentication it does not automatically activate authentication.
131 To use authentication you must in addition make use of ACLs based
132 on login name in http_access (proxy_auth, proxy_auth_regex or
133 external with %LOGIN used in the format tag). The browser will be
134 challenged for authentication on the first such acl encountered
135 in http_access processing and will also be re-challenged for new
136 login credentials if the request is being denied by a proxy_auth
139 WARNING: authentication can't be used in a transparently intercepting
140 proxy as the client then thinks it is talking to an origin server and
141 not the proxy. This is a limitation of bending the TCP/IP protocol to
142 transparently intercepting port 80, not a limitation in Squid.
143 Ports flagged 'transparent', 'intercept', or 'tproxy' have
144 authentication disabled.
146 === Parameters for the basic scheme follow. ===
149 Specify the command for the external authenticator. Such a program
150 reads a line containing "username password" and replies "OK" or
151 "ERR" in an endless loop. "ERR" responses may optionally be followed
152 by a error description available as %m in the returned error page.
153 If you use an authenticator, make sure you have 1 acl of type
156 By default, the basic authentication scheme is not used unless a
157 program is specified.
159 If you want to use the traditional NCSA proxy authentication, set
160 this line to something like
162 auth_param basic program @DEFAULT_PREFIX@/libexec/ncsa_auth @DEFAULT_PREFIX@/etc/passwd
165 HTTP uses iso-latin-1 as characterset, while some authentication
166 backends such as LDAP expects UTF-8. If this is set to on Squid will
167 translate the HTTP iso-latin-1 charset to UTF-8 before sending the
168 username & password to the helper.
170 "children" numberofchildren [startup=N] [idle=N] [concurrency=N]
171 The maximum number of authenticator processes to spawn. If you start too few
172 Squid will have to wait for them to process a backlog of credential
173 verifications, slowing it down. When password verifications are
174 done via a (slow) network you are likely to need lots of
175 authenticator processes.
177 The startup= and idle= options permit some skew in the exact amount
178 run. A minimum of startup=N will begin during startup and reconfigure
179 and Squid will start more in groups of up to idle=N in an attempt to meet
180 traffic needs and to keep idle=N free above those traffic needs up to
183 The concurrency= option sets the number of concurrent requests the
184 helper can process. The default of 0 is used for helpers who only
185 supports one request at a time. Setting this to a number greater than
186 0 changes the protocol used to include a channel number first on the
187 request/response line, allowing multiple requests to be sent to the
188 same helper in parallell without wating for the response.
189 Must not be set unless it's known the helper supports this.
191 auth_param basic children 20 startup=0 idle=1
194 Specifies the realm name which is to be reported to the
195 client for the basic proxy authentication scheme (part of
196 the text the user will see when prompted their username and
197 password). There is no default.
198 auth_param basic realm Squid proxy-caching web server
200 "credentialsttl" timetolive
201 Specifies how long squid assumes an externally validated
202 username:password pair is valid for - in other words how
203 often the helper program is called for that user. Set this
204 low to force revalidation with short lived passwords. Note
205 setting this high does not impact your susceptibility
206 to replay attacks unless you are using an one-time password
207 system (such as SecureID). If you are using such a system,
208 you will be vulnerable to replay attacks unless you also
209 use the max_user_ip ACL in an http_access rule.
211 "casesensitive" on|off
212 Specifies if usernames are case sensitive. Most user databases are
213 case insensitive allowing the same username to be spelled using both
214 lower and upper case letters, but some are case sensitive. This
215 makes a big difference for user_max_ip ACL processing and similar.
216 auth_param basic casesensitive off
218 === Parameters for the digest scheme follow ===
221 Specify the command for the external authenticator. Such
222 a program reads a line containing "username":"realm" and
223 replies with the appropriate H(A1) value hex encoded or
224 ERR if the user (or his H(A1) hash) does not exists.
225 See rfc 2616 for the definition of H(A1).
226 "ERR" responses may optionally be followed by a error description
227 available as %m in the returned error page.
229 By default, the digest authentication scheme is not used unless a
230 program is specified.
232 If you want to use a digest authenticator, set this line to
235 auth_param digest program @DEFAULT_PREFIX@/bin/digest_pw_auth @DEFAULT_PREFIX@/etc/digpass
238 HTTP uses iso-latin-1 as characterset, while some authentication
239 backends such as LDAP expects UTF-8. If this is set to on Squid will
240 translate the HTTP iso-latin-1 charset to UTF-8 before sending the
241 username & password to the helper.
243 "children" numberofchildren [startup=N] [idle=N] [concurrency=N]
244 The maximum number of authenticator processes to spawn (default 5).
245 If you start too few Squid will have to wait for them to
246 process a backlog of H(A1) calculations, slowing it down.
247 When the H(A1) calculations are done via a (slow) network
248 you are likely to need lots of authenticator processes.
250 The startup= and idle= options permit some skew in the exact amount
251 run. A minimum of startup=N will begin during startup and reconfigure
252 and Squid will start more in groups of up to idle=N in an attempt to meet
253 traffic needs and to keep idle=N free above those traffic needs up to
256 The concurrency= option sets the number of concurrent requests the
257 helper can process. The default of 0 is used for helpers who only
258 supports one request at a time. Setting this to a number greater than
259 0 changes the protocol used to include a channel number first on the
260 request/response line, allowing multiple requests to be sent to the
261 same helper in parallell without wating for the response.
262 Must not be set unless it's known the helper supports this.
264 auth_param digest children 20 startup=0 idle=1
267 Specifies the realm name which is to be reported to the
268 client for the digest proxy authentication scheme (part of
269 the text the user will see when prompted their username and
270 password). There is no default.
271 auth_param digest realm Squid proxy-caching web server
273 "nonce_garbage_interval" timeinterval
274 Specifies the interval that nonces that have been issued
275 to client_agent's are checked for validity.
277 "nonce_max_duration" timeinterval
278 Specifies the maximum length of time a given nonce will be
281 "nonce_max_count" number
282 Specifies the maximum number of times a given nonce can be
285 "nonce_strictness" on|off
286 Determines if squid requires strict increment-by-1 behavior
287 for nonce counts, or just incrementing (off - for use when
288 useragents generate nonce counts that occasionally miss 1
289 (ie, 1,2,4,6)). Default off.
291 "check_nonce_count" on|off
292 This directive if set to off can disable the nonce count check
293 completely to work around buggy digest qop implementations in
294 certain mainstream browser versions. Default on to check the
295 nonce count to protect from authentication replay attacks.
297 "post_workaround" on|off
298 This is a workaround to certain buggy browsers who sends
299 an incorrect request digest in POST requests when reusing
300 the same nonce as acquired earlier on a GET request.
302 === NTLM scheme options follow ===
305 Specify the command for the external NTLM authenticator.
306 Such a program reads exchanged NTLMSSP packets with
307 the browser via Squid until authentication is completed.
308 If you use an NTLM authenticator, make sure you have 1 acl
309 of type proxy_auth. By default, the NTLM authenticator_program
312 auth_param ntlm program @DEFAULT_PREFIX@/bin/ntlm_auth
314 "children" numberofchildren [startup=N] [idle=N]
315 The maximum number of authenticator processes to spawn (default 5).
316 If you start too few Squid will have to wait for them to
317 process a backlog of credential verifications, slowing it
318 down. When credential verifications are done via a (slow)
319 network you are likely to need lots of authenticator
322 The startup= and idle= options permit some skew in the exact amount
323 run. A minimum of startup=N will begin during startup and reconfigure
324 and Squid will start more in groups of up to idle=N in an attempt to meet
325 traffic needs and to keep idle=N free above those traffic needs up to
328 auth_param ntlm children 20 startup=0 idle=1
331 If you experience problems with PUT/POST requests when using the
332 Negotiate authentication scheme then you can try setting this to
333 off. This will cause Squid to forcibly close the connection on
334 the initial requests where the browser asks which schemes are
335 supported by the proxy.
337 auth_param ntlm keep_alive on
339 === Options for configuring the NEGOTIATE auth-scheme follow ===
342 Specify the command for the external Negotiate authenticator.
343 This protocol is used in Microsoft Active-Directory enabled setups with
344 the Microsoft Internet Explorer or Mozilla Firefox browsers.
345 Its main purpose is to exchange credentials with the Squid proxy
346 using the Kerberos mechanisms.
347 If you use a Negotiate authenticator, make sure you have at least
348 one acl of type proxy_auth active. By default, the negotiate
349 authenticator_program is not used.
350 The only supported program for this role is the ntlm_auth
351 program distributed as part of Samba, version 4 or later.
353 auth_param negotiate program @DEFAULT_PREFIX@/bin/ntlm_auth --helper-protocol=gss-spnego
355 "children" numberofchildren [startup=N] [idle=N]
356 The maximum number of authenticator processes to spawn (default 5).
357 If you start too few Squid will have to wait for them to
358 process a backlog of credential verifications, slowing it
359 down. When crendential verifications are done via a (slow)
360 network you are likely to need lots of authenticator
363 The startup= and idle= options permit some skew in the exact amount
364 run. A minimum of startup=N will begin during startup and reconfigure
365 and Squid will start more in groups of up to idle=N in an attempt to meet
366 traffic needs and to keep idle=N free above those traffic needs up to
369 auth_param negotiate children 20 startup=0 idle=1
372 If you experience problems with PUT/POST requests when using the
373 Negotiate authentication scheme then you can try setting this to
374 off. This will cause Squid to forcibly close the connection on
375 the initial requests where the browser asks which schemes are
376 supported by the proxy.
378 auth_param negotiate keep_alive on
383 #Recommended minimum configuration per scheme:
384 #auth_param negotiate program <uncomment and complete this line to activate>
385 #auth_param negotiate children 20 startup=0 idle=1
386 #auth_param negotiate keep_alive on
388 #auth_param ntlm program <uncomment and complete this line to activate>
389 #auth_param ntlm children 20 startup=0 idle=1
390 #auth_param ntlm keep_alive on
392 #auth_param digest program <uncomment and complete this line>
393 #auth_param digest children 20 startup=0 idle=1
394 #auth_param digest realm Squid proxy-caching web server
395 #auth_param digest nonce_garbage_interval 5 minutes
396 #auth_param digest nonce_max_duration 30 minutes
397 #auth_param digest nonce_max_count 50
399 #auth_param basic program <uncomment and complete this line>
400 #auth_param basic children 5 stratup=5 idle=1
401 #auth_param basic realm Squid proxy-caching web server
402 #auth_param basic credentialsttl 2 hours
405 NAME: authenticate_cache_garbage_interval
408 LOC: Config.authenticateGCInterval
410 The time period between garbage collection across the username cache.
411 This is a tradeoff between memory utilization (long intervals - say
412 2 days) and CPU (short intervals - say 1 minute). Only change if you
416 NAME: authenticate_ttl
419 LOC: Config.authenticateTTL
421 The time a user & their credentials stay in the logged in
422 user cache since their last request. When the garbage
423 interval passes, all user credentials that have passed their
424 TTL are removed from memory.
427 NAME: authenticate_ip_ttl
429 LOC: Config.authenticateIpTTL
432 If you use proxy authentication and the 'max_user_ip' ACL,
433 this directive controls how long Squid remembers the IP
434 addresses associated with each user. Use a small value
435 (e.g., 60 seconds) if your users might change addresses
436 quickly, as is the case with dialups. You might be safe
437 using a larger value (e.g., 2 hours) in a corporate LAN
438 environment with relatively static address assignments.
443 -----------------------------------------------------------------------------
446 NAME: external_acl_type
447 TYPE: externalAclHelper
448 LOC: Config.externalAclHelperList
451 This option defines external acl classes using a helper program
452 to look up the status
454 external_acl_type name [options] FORMAT.. /path/to/helper [helper arguments..]
458 ttl=n TTL in seconds for cached results (defaults to 3600
461 TTL for cached negative lookups (default same
464 Maximum number of acl helper processes spawned to service
465 external acl lookups of this type. (default 20)
467 Minimum number of acl helper processes to spawn during
468 startup and reconfigure to service external acl lookups
469 of this type. (default 0)
471 Number of acl helper processes to keep ahead of traffic
472 loads. Squid will spawn this many at once whenever load
473 rises above the capabilities of existing processes.
474 Up to the value of children-max. (default 1)
475 concurrency=n concurrency level per process. Only used with helpers
476 capable of processing more than one query at a time.
477 cache=n limit the result cache size, default is unbounded.
478 grace=n Percentage remaining of TTL where a refresh of a
479 cached entry should be initiated without needing to
480 wait for a new reply. (default is for no grace period)
481 protocol=2.5 Compatibility mode for Squid-2.5 external acl helpers
482 ipv4 / ipv6 IP-mode used to communicate to this helper.
483 For compatability with older configurations and helpers
484 the default is currently 'ipv4'.
486 FORMAT specifications
488 %LOGIN Authenticated user login name
489 %EXT_USER Username from external acl
490 %IDENT Ident user name
492 %SRCPORT Client source port
495 %PROTO Requested protocol
497 %PATH Requested URL path
498 %METHOD Request method
499 %MYADDR Squid interface address
500 %MYPORT Squid http_port number
501 %PATH Requested URL-path (including query-string if any)
502 %USER_CERT SSL User certificate in PEM format
503 %USER_CERTCHAIN SSL User certificate chain in PEM format
504 %USER_CERT_xx SSL User certificate subject attribute xx
505 %USER_CA_xx SSL User certificate issuer attribute xx
507 %>{Header} HTTP request header "Header"
509 HTTP request header "Hdr" list member "member"
511 HTTP request header list member using ; as
512 list separator. ; can be any non-alphanumeric
515 %<{Header} HTTP reply header "Header"
517 HTTP reply header "Hdr" list member "member"
519 HTTP reply header list member using ; as
520 list separator. ; can be any non-alphanumeric
523 In addition to the above, any string specified in the referencing
524 acl will also be included in the helper request line, after the
525 specified formats (see the "acl external" directive)
527 The helper receives lines per the above format specification,
528 and returns lines starting with OK or ERR indicating the validity
529 of the request and optionally followed by additional keywords with
532 General result syntax:
534 OK/ERR keyword=value ...
538 user= The users name (login)
539 password= The users password (for login= cache_peer option)
540 message= Message describing the reason. Available as %o
542 tag= Apply a tag to a request (for both ERR and OK results)
543 Only sets a tag, does not alter existing tags.
544 log= String to be logged in access.log. Available as
545 %ea in logformat specifications
547 If protocol=3.0 (the default) then URL escaping is used to protect
548 each value in both requests and responses.
550 If using protocol=2.5 then all values need to be enclosed in quotes
551 if they may contain whitespace, or the whitespace escaped using \.
552 And quotes or \ characters within the keyword value must be \ escaped.
554 When using the concurrency= option the protocol is changed by
555 introducing a query channel tag infront of the request/response.
556 The query channel tag is a number between 0 and concurrency-1.
564 Defining an Access List
566 Every access list definition must begin with an aclname and acltype,
567 followed by either type-specific arguments or a quoted filename that
570 acl aclname acltype argument ...
571 acl aclname acltype "file" ...
573 When using "file", the file should contain one item per line.
575 By default, regular expressions are CASE-SENSITIVE. To make
576 them case-insensitive, use the -i option.
578 Some acl types require suspending the current request in order
579 to access some external data source.
580 Those which do are marked with the tag [slow], those which
581 don't are marked as [fast].
582 See http://wiki.squid-cache.org/SquidFaq/SquidAcl
583 for further information
585 ***** ACL TYPES AVAILABLE *****
587 acl aclname src ip-address/netmask ... # clients IP address [fast]
588 acl aclname src addr1-addr2/netmask ... # range of addresses [fast]
589 acl aclname dst ip-address/netmask ... # URL host's IP address [slow]
590 acl aclname myip ip-address/netmask ... # local socket IP address [fast]
592 acl aclname arp mac-address ... (xx:xx:xx:xx:xx:xx notation)
593 # The arp ACL requires the special configure option --enable-arp-acl.
594 # Furthermore, the ARP ACL code is not portable to all operating systems.
595 # It works on Linux, Solaris, Windows, FreeBSD, and some
596 # other *BSD variants.
599 # NOTE: Squid can only determine the MAC address for clients that are on
600 # the same subnet. If the client is on a different subnet,
601 # then Squid cannot find out its MAC address.
603 acl aclname srcdomain .foo.com ...
604 # reverse lookup, from client IP [slow]
605 acl aclname dstdomain .foo.com ...
606 # Destination server from URL [fast]
607 acl aclname srcdom_regex [-i] \.foo\.com ...
608 # regex matching client name [slow]
609 acl aclname dstdom_regex [-i] \.foo\.com ...
610 # regex matching server [fast]
612 # For dstdomain and dstdom_regex a reverse lookup is tried if a IP
613 # based URL is used and no match is found. The name "none" is used
614 # if the reverse lookup fails.
616 acl aclname src_as number ...
617 acl aclname dst_as number ...
619 # Except for access control, AS numbers can be used for
620 # routing of requests to specific caches. Here's an
621 # example for routing all requests for AS#1241 and only
622 # those to mycache.mydomain.net:
623 # acl asexample dst_as 1241
624 # cache_peer_access mycache.mydomain.net allow asexample
625 # cache_peer_access mycache_mydomain.net deny all
627 acl aclname peername myPeer ...
629 # match against a named cache_peer entry
630 # set unique name= on cache_peer lines for reliable use.
632 acl aclname time [day-abbrevs] [h1:m1-h2:m2]
642 # h1:m1 must be less than h2:m2
644 acl aclname url_regex [-i] ^http:// ...
645 # regex matching on whole URL [fast]
646 acl aclname urlpath_regex [-i] \.gif$ ...
647 # regex matching on URL path [fast]
649 acl aclname port 80 70 21 0-1024... # destination TCP port [fast]
651 acl aclname myport 3128 ... # local socket TCP port [fast]
652 acl aclname myportname 3128 ... # http(s)_port name [fast]
654 acl aclname proto HTTP FTP ... # request protocol [fast]
656 acl aclname method GET POST ... # HTTP request method [fast]
658 acl aclname http_status 200 301 500- 400-403 ...
659 # status code in reply [fast]
661 acl aclname browser [-i] regexp ...
662 # pattern match on User-Agent header (see also req_header below) [fast]
664 acl aclname referer_regex [-i] regexp ...
665 # pattern match on Referer header [fast]
666 # Referer is highly unreliable, so use with care
668 acl aclname ident username ...
669 acl aclname ident_regex [-i] pattern ...
670 # string match on ident output [slow]
671 # use REQUIRED to accept any non-null ident.
673 acl aclname proxy_auth [-i] username ...
674 acl aclname proxy_auth_regex [-i] pattern ...
675 # perform http authentication challenge to the client and match against
676 # supplied credentials [slow]
678 # takes a list of allowed usernames.
679 # use REQUIRED to accept any valid username.
681 # Will use proxy authentication in forward-proxy scenarios, and plain
682 # http authenticaiton in reverse-proxy scenarios
684 # NOTE: when a Proxy-Authentication header is sent but it is not
685 # needed during ACL checking the username is NOT logged
688 # NOTE: proxy_auth requires a EXTERNAL authentication program
689 # to check username/password combinations (see
690 # auth_param directive).
692 # NOTE: proxy_auth can't be used in a transparent/intercepting proxy
693 # as the browser needs to be configured for using a proxy in order
694 # to respond to proxy authentication.
696 acl aclname snmp_community string ...
697 # A community string to limit access to your SNMP Agent [fast]
700 # acl snmppublic snmp_community public
702 acl aclname maxconn number
703 # This will be matched when the client's IP address has
704 # more than <number> HTTP connections established. [fast]
706 acl aclname max_user_ip [-s] number
707 # This will be matched when the user attempts to log in from more
708 # than <number> different ip addresses. The authenticate_ip_ttl
709 # parameter controls the timeout on the ip entries. [fast]
710 # If -s is specified the limit is strict, denying browsing
711 # from any further IP addresses until the ttl has expired. Without
712 # -s Squid will just annoy the user by "randomly" denying requests.
713 # (the counter is reset each time the limit is reached and a
715 # NOTE: in acceleration mode or where there is mesh of child proxies,
716 # clients may appear to come from multiple addresses if they are
717 # going through proxy farms, so a limit of 1 may cause user problems.
719 acl aclname random probability
720 # Pseudo-randomly match requests. Based on the probability given.
721 # Probability may be written as a decimal (0.333), fraction (1/3)
722 # or ratio of matches:non-matches (3:5).
724 acl aclname req_mime_type [-i] mime-type ...
725 # regex match against the mime type of the request generated
726 # by the client. Can be used to detect file upload or some
727 # types HTTP tunneling requests [fast]
728 # NOTE: This does NOT match the reply. You cannot use this
729 # to match the returned file type.
731 acl aclname req_header header-name [-i] any\.regex\.here
732 # regex match against any of the known request headers. May be
733 # thought of as a superset of "browser", "referer" and "mime-type"
736 acl aclname rep_mime_type [-i] mime-type ...
737 # regex match against the mime type of the reply received by
738 # squid. Can be used to detect file download or some
739 # types HTTP tunneling requests. [fast]
740 # NOTE: This has no effect in http_access rules. It only has
741 # effect in rules that affect the reply data stream such as
744 acl aclname rep_header header-name [-i] any\.regex\.here
745 # regex match against any of the known reply headers. May be
746 # thought of as a superset of "browser", "referer" and "mime-type"
749 acl aclname external class_name [arguments...]
750 # external ACL lookup via a helper class defined by the
751 # external_acl_type directive [slow]
753 acl aclname user_cert attribute values...
754 # match against attributes in a user SSL certificate
755 # attribute is one of DN/C/O/CN/L/ST [fast]
757 acl aclname ca_cert attribute values...
758 # match against attributes a users issuing CA SSL certificate
759 # attribute is one of DN/C/O/CN/L/ST [fast]
761 acl aclname ext_user username ...
762 acl aclname ext_user_regex [-i] pattern ...
763 # string match on username returned by external acl helper [slow]
764 # use REQUIRED to accept any non-null user name.
766 acl aclname tag tagvalue ...
767 # string match on tag returned by external acl helper [slow]
769 acl aclname hier_code codename ...
770 # string match against squid hierarchy code(s); [fast]
771 # e.g., DIRECT, PARENT_HIT, NONE, etc.
773 # NOTE: This has no effect in http_access rules. It only has
774 # effect in rules that affect the reply data stream such as
778 acl macaddress arp 09:00:2b:23:45:67
779 acl myexample dst_as 1241
780 acl password proxy_auth REQUIRED
781 acl fileupload req_mime_type -i ^multipart/form-data$
782 acl javascript rep_mime_type -i ^application/x-javascript$
786 # Recommended minimum configuration:
788 acl manager proto cache_object
789 acl localhost src 127.0.0.1/32 ::1
790 acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1
792 # Example rule allowing access from your local networks.
793 # Adapt to list your (internal) IP networks from where browsing
795 acl localnet src 10.0.0.0/8 # RFC1918 possible internal network
796 acl localnet src 172.16.0.0/12 # RFC1918 possible internal network
797 acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
798 acl localnet src fc00::/7 # RFC 4193 local private network range
799 acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines
801 acl SSL_ports port 443
802 acl Safe_ports port 80 # http
803 acl Safe_ports port 21 # ftp
804 acl Safe_ports port 443 # https
805 acl Safe_ports port 70 # gopher
806 acl Safe_ports port 210 # wais
807 acl Safe_ports port 1025-65535 # unregistered ports
808 acl Safe_ports port 280 # http-mgmt
809 acl Safe_ports port 488 # gss-http
810 acl Safe_ports port 591 # filemaker
811 acl Safe_ports port 777 # multiling http
812 acl CONNECT method CONNECT
816 NAME: follow_x_forwarded_for
818 IFDEF: FOLLOW_X_FORWARDED_FOR
819 LOC: Config.accessList.followXFF
821 DEFAULT_IF_NONE: deny all
823 Allowing or Denying the X-Forwarded-For header to be followed to
824 find the original source of a request.
826 Requests may pass through a chain of several other proxies
827 before reaching us. The X-Forwarded-For header will contain a
828 comma-separated list of the IP addresses in the chain, with the
829 rightmost address being the most recent.
831 If a request reaches us from a source that is allowed by this
832 configuration item, then we consult the X-Forwarded-For header
833 to see where that host received the request from. If the
834 X-Forwarded-For header contains multiple addresses, we continue
835 backtracking until we reach an address for which we are not allowed
836 to follow the X-Forwarded-For header, or until we reach the first
837 address in the list. For the purpose of ACL used in the
838 follow_x_forwarded_for directive the src ACL type always matches
839 the address we are testing and srcdomain matches its rDNS.
841 The end result of this process is an IP address that we will
842 refer to as the indirect client address. This address may
843 be treated as the client address for access control, ICAP, delay
844 pools and logging, depending on the acl_uses_indirect_client,
845 icap_uses_indirect_client, delay_pool_uses_indirect_client,
846 log_uses_indirect_client and tproxy_uses_indirect_client options.
848 This clause only supports fast acl types.
849 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
851 SECURITY CONSIDERATIONS:
853 Any host for which we follow the X-Forwarded-For header
854 can place incorrect information in the header, and Squid
855 will use the incorrect information as if it were the
856 source address of the request. This may enable remote
857 hosts to bypass any access control restrictions that are
858 based on the client's source addresses.
862 acl localhost src 127.0.0.1
863 acl my_other_proxy srcdomain .proxy.example.com
864 follow_x_forwarded_for allow localhost
865 follow_x_forwarded_for allow my_other_proxy
868 NAME: acl_uses_indirect_client
871 IFDEF: FOLLOW_X_FORWARDED_FOR
873 LOC: Config.onoff.acl_uses_indirect_client
875 Controls whether the indirect client address
876 (see follow_x_forwarded_for) is used instead of the
877 direct client address in acl matching.
880 NAME: delay_pool_uses_indirect_client
883 IFDEF: FOLLOW_X_FORWARDED_FOR&&DELAY_POOLS
885 LOC: Config.onoff.delay_pool_uses_indirect_client
887 Controls whether the indirect client address
888 (see follow_x_forwarded_for) is used instead of the
889 direct client address in delay pools.
892 NAME: log_uses_indirect_client
895 IFDEF: FOLLOW_X_FORWARDED_FOR
897 LOC: Config.onoff.log_uses_indirect_client
899 Controls whether the indirect client address
900 (see follow_x_forwarded_for) is used instead of the
901 direct client address in the access log.
904 NAME: tproxy_uses_indirect_client
907 IFDEF: FOLLOW_X_FORWARDED_FOR&&LINUX_NETFILTER
909 LOC: Config.onoff.tproxy_uses_indirect_client
911 Controls whether the indirect client address
912 (see follow_x_forwarded_for) is used instead of the
913 direct client address when spoofing the outgoing client.
915 This has no effect on requests arriving in non-tproxy
918 SECURITY WARNING: Usage of this option is dangerous
919 and should not be used trivially. Correct configuration
920 of folow_x_forewarded_for with a limited set of trusted
921 sources is required to prevent abuse of your proxy.
926 LOC: Config.accessList.http
928 DEFAULT_IF_NONE: deny all
930 Allowing or Denying access based on defined access lists
932 Access to the HTTP port:
933 http_access allow|deny [!]aclname ...
935 NOTE on default values:
937 If there are no "access" lines present, the default is to deny
940 If none of the "access" lines cause a match, the default is the
941 opposite of the last line in the list. If the last line was
942 deny, the default is allow. Conversely, if the last line
943 is allow, the default will be deny. For these reasons, it is a
944 good idea to have an "deny all" entry at the end of your access
945 lists to avoid potential confusion.
947 This clause supports both fast and slow acl types.
948 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
953 # Recommended minimum Access Permission configuration:
955 # Only allow cachemgr access from localhost
956 http_access allow manager localhost
957 http_access deny manager
959 # Deny requests to certain unsafe ports
960 http_access deny !Safe_ports
962 # Deny CONNECT to other than secure SSL ports
963 http_access deny CONNECT !SSL_ports
965 # We strongly recommend the following be uncommented to protect innocent
966 # web applications running on the proxy server who think the only
967 # one who can access services on "localhost" is a local user
968 #http_access deny to_localhost
971 # INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
974 # Example rule allowing access from your local networks.
975 # Adapt localnet in the ACL section to list your (internal) IP networks
976 # from where browsing should be allowed
977 http_access allow localnet
978 http_access allow localhost
980 # And finally deny all other access to this proxy
985 NAME: adapted_http_access http_access2
987 LOC: Config.accessList.adapted_http
990 Allowing or Denying access based on defined access lists
992 Essentially identical to http_access, but runs after redirectors
993 and ICAP/eCAP adaptation. Allowing access control based on their
996 If not set then only http_access is used.
999 NAME: http_reply_access
1001 LOC: Config.accessList.reply
1004 Allow replies to client requests. This is complementary to http_access.
1006 http_reply_access allow|deny [!] aclname ...
1008 NOTE: if there are no access lines present, the default is to allow
1011 If none of the access lines cause a match the opposite of the
1012 last line will apply. Thus it is good practice to end the rules
1013 with an "allow all" or "deny all" entry.
1015 This clause supports both fast and slow acl types.
1016 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1021 LOC: Config.accessList.icp
1023 DEFAULT_IF_NONE: deny all
1025 Allowing or Denying access to the ICP port based on defined
1028 icp_access allow|deny [!]aclname ...
1030 See http_access for details
1032 This clause only supports fast acl types.
1033 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1035 # Allow ICP queries from local networks only
1036 #icp_access allow localnet
1037 #icp_access deny all
1043 LOC: Config.accessList.htcp
1045 DEFAULT_IF_NONE: deny all
1047 Allowing or Denying access to the HTCP port based on defined
1050 htcp_access allow|deny [!]aclname ...
1052 See http_access for details
1054 NOTE: The default if no htcp_access lines are present is to
1055 deny all traffic. This default may cause problems with peers
1056 using the htcp or htcp-oldsquid options.
1058 This clause only supports fast acl types.
1059 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1061 # Allow HTCP queries from local networks only
1062 #htcp_access allow localnet
1063 #htcp_access deny all
1066 NAME: htcp_clr_access
1069 LOC: Config.accessList.htcp_clr
1071 DEFAULT_IF_NONE: deny all
1073 Allowing or Denying access to purge content using HTCP based
1074 on defined access lists
1076 htcp_clr_access allow|deny [!]aclname ...
1078 See http_access for details
1080 This clause only supports fast acl types.
1081 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1083 # Allow HTCP CLR requests from trusted peers
1084 acl htcp_clr_peer src 172.16.1.2
1085 htcp_clr_access allow htcp_clr_peer
1090 LOC: Config.accessList.miss
1093 Use to force your neighbors to use you as a sibling instead of
1094 a parent. For example:
1096 acl localclients src 172.16.0.0/16
1097 miss_access allow localclients
1098 miss_access deny !localclients
1100 This means only your local clients are allowed to fetch
1101 MISSES and all other clients can only fetch HITS.
1103 By default, allow all clients who passed the http_access rules
1104 to fetch MISSES from us.
1106 This clause only supports fast acl types.
1107 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1110 NAME: ident_lookup_access
1114 DEFAULT_IF_NONE: deny all
1115 LOC: Ident::TheConfig.identLookup
1117 A list of ACL elements which, if matched, cause an ident
1118 (RFC 931) lookup to be performed for this request. For
1119 example, you might choose to always perform ident lookups
1120 for your main multi-user Unix boxes, but not for your Macs
1121 and PCs. By default, ident lookups are not performed for
1124 To enable ident lookups for specific client addresses, you
1125 can follow this example:
1127 acl ident_aware_hosts src 198.168.1.0/24
1128 ident_lookup_access allow ident_aware_hosts
1129 ident_lookup_access deny all
1131 Only src type ACL checks are fully supported. A srcdomain
1132 ACL might work at times, but it will not always provide
1135 This clause only supports fast acl types.
1136 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1139 NAME: reply_body_max_size
1140 COMMENT: size [acl acl...]
1143 LOC: Config.ReplyBodySize
1145 This option specifies the maximum size of a reply body. It can be
1146 used to prevent users from downloading very large files, such as
1147 MP3's and movies. When the reply headers are received, the
1148 reply_body_max_size lines are processed, and the first line where
1149 all (if any) listed ACLs are true is used as the maximum body size
1152 This size is checked twice. First when we get the reply headers,
1153 we check the content-length value. If the content length value exists
1154 and is larger than the allowed size, the request is denied and the
1155 user receives an error message that says "the request or reply
1156 is too large." If there is no content-length, and the reply
1157 size exceeds this limit, the client's connection is just closed
1158 and they will receive a partial reply.
1160 WARNING: downstream caches probably can not detect a partial reply
1161 if there is no content-length header, so they will cache
1162 partial responses and give them out as hits. You should NOT
1163 use this option if you have downstream caches.
1165 WARNING: A maximum size smaller than the size of squid's error messages
1166 will cause an infinite loop and crash squid. Ensure that the smallest
1167 non-zero value you use is greater that the maximum header size plus
1168 the size of your largest error page.
1170 If you set this parameter none (the default), there will be
1173 Configuration Format is:
1174 reply_body_max_size SIZE UNITS [acl ...]
1176 reply_body_max_size 10 MB
1182 -----------------------------------------------------------------------------
1185 NAME: http_port ascii_port
1186 TYPE: http_port_list
1188 LOC: Config.Sockaddr.http
1190 Usage: port [mode] [options]
1191 hostname:port [mode] [options]
1192 1.2.3.4:port [mode] [options]
1194 The socket addresses where Squid will listen for HTTP client
1195 requests. You may specify multiple socket addresses.
1196 There are three forms: port alone, hostname with port, and
1197 IP address with port. If you specify a hostname or IP
1198 address, Squid binds the socket to that specific
1199 address. Most likely, you do not need to bind to a specific
1200 address, so you can use the port number alone.
1202 If you are running Squid in accelerator mode, you
1203 probably want to listen on port 80 also, or instead.
1205 The -a command line option may be used to specify additional
1206 port(s) where Squid listens for proxy request. Such ports will
1207 be plain proxy ports with no options.
1209 You may specify multiple socket addresses on multiple lines.
1213 intercept Support for IP-Layer interception of
1214 outgoing requests without browser settings.
1215 NP: disables authentication and IPv6 on the port.
1217 tproxy Support Linux TPROXY for spoofing outgoing
1218 connections using the client IP address.
1219 NP: disables authentication and maybe IPv6 on the port.
1221 accel Accelerator mode. Also needs at least one of
1222 vhost / vport / defaultsite.
1224 sslbump Intercept each CONNECT request matching ssl_bump ACL,
1225 establish secure connection with the client and with
1226 the server, decrypt HTTP messages as they pass through
1227 Squid, and treat them as unencrypted HTTP messages,
1228 becoming the man-in-the-middle.
1230 The ssl_bump option is required to fully enable
1231 the SslBump feature.
1233 Omitting the mode flag causes default forward proxy mode to be used.
1236 Accelerator Mode Options:
1238 allow-direct Allow direct forwarding in accelerator mode. Normally
1239 accelerated requests are denied direct forwarding as if
1240 never_direct was used.
1242 defaultsite=domainname
1243 What to use for the Host: header if it is not present
1244 in a request. Determines what site (not origin server)
1245 accelerators should consider the default.
1248 vhost Using the Host header for virtual domain support.
1249 Also uses the port as specified in Host: header.
1251 vport IP based virtual host support. Using the http_port number
1252 in passed on Host: headers.
1254 vport=NN Uses the specified port number rather than the
1257 protocol= Protocol to reconstruct accelerated requests with.
1258 Defaults to http://.
1260 ignore-cc Ignore request Cache-Control headers.
1262 Warning: This option violates HTTP specifications if
1263 used in non-accelerator setups.
1266 SSL Bump Mode Options:
1268 cert= Path to SSL certificate (PEM format).
1270 key= Path to SSL private key file (PEM format)
1271 if not specified, the certificate file is
1272 assumed to be a combined certificate and
1275 version= The version of SSL/TLS supported
1276 1 automatic (default)
1281 cipher= Colon separated list of supported ciphers.
1283 options= Various SSL engine options. The most important
1285 NO_SSLv2 Disallow the use of SSLv2
1286 NO_SSLv3 Disallow the use of SSLv3
1287 NO_TLSv1 Disallow the use of TLSv1
1288 SINGLE_DH_USE Always create a new key when using
1289 temporary/ephemeral DH key exchanges
1290 See src/ssl_support.c or OpenSSL SSL_CTX_set_options
1291 documentation for a complete list of options.
1293 clientca= File containing the list of CAs to use when
1294 requesting a client certificate.
1296 cafile= File containing additional CA certificates to
1297 use when verifying client certificates. If unset
1298 clientca will be used.
1300 capath= Directory containing additional CA certificates
1301 and CRL lists to use when verifying client certificates.
1303 crlfile= File of additional CRL lists to use when verifying
1304 the client certificate, in addition to CRLs stored in
1305 the capath. Implies VERIFY_CRL flag below.
1307 dhparams= File containing DH parameters for temporary/ephemeral
1310 sslflags= Various flags modifying the use of SSL:
1312 Don't request client certificates
1313 immediately, but wait until acl processing
1314 requires a certificate (not yet implemented).
1316 Don't use the default CA lists built in
1319 Don't allow for session reuse. Each connection
1320 will result in a new SSL session.
1322 Verify CRL lists when accepting client
1325 Verify CRL lists for all certificates in the
1326 client certificate chain.
1328 sslcontext= SSL session ID context identifier.
1333 connection-auth[=on|off]
1334 use connection-auth=off to tell Squid to prevent
1335 forwarding Microsoft connection oriented authentication
1336 (NTLM, Negotiate and Kerberos)
1338 disable-pmtu-discovery=
1339 Control Path-MTU discovery usage:
1340 off lets OS decide on what to do (default).
1341 transparent disable PMTU discovery when transparent
1343 always disable always PMTU discovery.
1345 In many setups of transparently intercepting proxies
1346 Path-MTU discovery can not work on traffic towards the
1347 clients. This is the case when the intercepting device
1348 does not fully track connections and fails to forward
1349 ICMP must fragment messages to the cache server. If you
1350 have such setup and experience that certain clients
1351 sporadically hang or never complete requests set
1352 disable-pmtu-discovery option to 'transparent'.
1354 name= Specifies a internal name for the port. Defaults to
1355 the port specification (port or addr:port)
1357 tcpkeepalive[=idle,interval,timeout]
1358 Enable TCP keepalive probes of idle connections.
1359 In seconds; idle is the initial time before TCP starts
1360 probing the connection, interval how often to probe, and
1361 timeout the time before giving up.
1363 If you run Squid on a dual-homed machine with an internal
1364 and an external interface we recommend you to specify the
1365 internal address:port in http_port. This way Squid will only be
1366 visible on the internal address.
1370 # Squid normally listens to port 3128
1371 http_port @DEFAULT_HTTP_PORT@
1377 TYPE: https_port_list
1379 LOC: Config.Sockaddr.https
1381 Usage: [ip:]port cert=certificate.pem [key=key.pem] [options...]
1383 The socket address where Squid will listen for HTTPS client
1386 This is really only useful for situations where you are running
1387 squid in accelerator mode and you want to do the SSL work at the
1390 You may specify multiple socket addresses on multiple lines,
1391 each with their own SSL certificate and/or options.
1395 accel Accelerator mode. Also needs at least one of
1396 defaultsite or vhost.
1398 defaultsite= The name of the https site presented on
1399 this port. Implies accel.
1401 vhost Accelerator mode using Host header for virtual
1402 domain support. Requires a wildcard certificate
1403 or other certificate valid for more than one domain.
1406 protocol= Protocol to reconstruct accelerated requests with.
1409 cert= Path to SSL certificate (PEM format).
1411 key= Path to SSL private key file (PEM format)
1412 if not specified, the certificate file is
1413 assumed to be a combined certificate and
1416 version= The version of SSL/TLS supported
1417 1 automatic (default)
1422 cipher= Colon separated list of supported ciphers.
1424 options= Various SSL engine options. The most important
1426 NO_SSLv2 Disallow the use of SSLv2
1427 NO_SSLv3 Disallow the use of SSLv3
1428 NO_TLSv1 Disallow the use of TLSv1
1429 SINGLE_DH_USE Always create a new key when using
1430 temporary/ephemeral DH key exchanges
1431 See src/ssl_support.c or OpenSSL SSL_CTX_set_options
1432 documentation for a complete list of options.
1434 clientca= File containing the list of CAs to use when
1435 requesting a client certificate.
1437 cafile= File containing additional CA certificates to
1438 use when verifying client certificates. If unset
1439 clientca will be used.
1441 capath= Directory containing additional CA certificates
1442 and CRL lists to use when verifying client certificates.
1444 crlfile= File of additional CRL lists to use when verifying
1445 the client certificate, in addition to CRLs stored in
1446 the capath. Implies VERIFY_CRL flag below.
1448 dhparams= File containing DH parameters for temporary/ephemeral
1451 sslflags= Various flags modifying the use of SSL:
1453 Don't request client certificates
1454 immediately, but wait until acl processing
1455 requires a certificate (not yet implemented).
1457 Don't use the default CA lists built in
1460 Don't allow for session reuse. Each connection
1461 will result in a new SSL session.
1463 Verify CRL lists when accepting client
1466 Verify CRL lists for all certificates in the
1467 client certificate chain.
1469 sslcontext= SSL session ID context identifier.
1471 vport Accelerator with IP based virtual host support.
1473 vport=NN As above, but uses specified port number rather
1474 than the https_port number. Implies accel.
1476 name= Specifies a internal name for the port. Defaults to
1477 the port specification (port or addr:port)
1481 NAME: tcp_outgoing_tos tcp_outgoing_ds tcp_outgoing_dscp
1484 LOC: Config.accessList.outgoing_tos
1486 Allows you to select a TOS/Diffserv value to mark outgoing
1487 connections with, based on the username or source address
1490 tcp_outgoing_tos ds-field [!]aclname ...
1492 Example where normal_service_net uses the TOS value 0x00
1493 and good_service_net uses 0x20
1495 acl normal_service_net src 10.0.0.0/255.255.255.0
1496 acl good_service_net src 10.0.1.0/255.255.255.0
1497 tcp_outgoing_tos 0x00 normal_service_net
1498 tcp_outgoing_tos 0x20 good_service_net
1500 TOS/DSCP values really only have local significance - so you should
1501 know what you're specifying. For more information, see RFC2474,
1502 RFC2475, and RFC3260.
1504 The TOS/DSCP byte must be exactly that - a octet value 0 - 255, or
1505 "default" to use whatever default your host has. Note that in
1506 practice often only values 0 - 63 is usable as the two highest bits
1507 have been redefined for use by ECN (RFC3168).
1509 Processing proceeds in the order specified, and stops at first fully
1512 Note: The use of this directive using client dependent ACLs is
1513 incompatible with the use of server side persistent connections. To
1514 ensure correct results it is best to set server_persisten_connections
1515 to off when using this directive in such configurations.
1518 NAME: clientside_tos
1521 LOC: Config.accessList.clientside_tos
1523 Allows you to select a TOS/Diffserv value to mark client-side
1524 connections with, based on the username or source address
1532 LOC: Ip::Qos::TheConfig
1534 Allows you to select a TOS/DSCP value to mark outgoing
1535 connections with, based on where the reply was sourced.
1537 TOS values really only have local significance - so you should
1538 know what you're specifying. For more information, see RFC2474,
1539 RFC2475, and RFC3260.
1541 The TOS/DSCP byte must be exactly that - octet value 0x00-0xFF.
1542 Note that in practice often only values up to 0x3F are usable
1543 as the two highest bits have been redefined for use by ECN
1546 This setting is configured by setting the source TOS values:
1548 local-hit=0xFF Value to mark local cache hits.
1550 sibling-hit=0xFF Value to mark hits from sibling peers.
1552 parent-hit=0xFF Value to mark hits from parent peers.
1555 NOTE: 'miss' preserve feature is only possible on Linux at this time.
1557 For the following to work correctly, you will need to patch your
1558 linux kernel with the TOS preserving ZPH patch.
1559 The kernel patch can be downloaded from http://zph.bratcheda.org
1561 disable-preserve-miss
1562 By default, the existing TOS value of the response coming
1563 from the remote server will be retained and masked with
1564 miss-mark. This option disables that feature.
1567 Allows you to mask certain bits in the TOS received from the
1568 remote server, before copying the value to the TOS sent
1570 Default: 0xFF (TOS from server is not changed).
1574 NAME: tcp_outgoing_address
1577 LOC: Config.accessList.outgoing_address
1579 Allows you to map requests to different outgoing IP addresses
1580 based on the username or source address of the user making
1583 tcp_outgoing_address ipaddr [[!]aclname] ...
1585 Example where requests from 10.0.0.0/24 will be forwarded
1586 with source address 10.1.0.1, 10.0.2.0/24 forwarded with
1587 source address 10.1.0.2 and the rest will be forwarded with
1588 source address 10.1.0.3.
1590 acl normal_service_net src 10.0.0.0/24
1591 acl good_service_net src 10.0.2.0/24
1592 tcp_outgoing_address 10.1.0.1 normal_service_net
1593 tcp_outgoing_address 10.1.0.2 good_service_net
1594 tcp_outgoing_address 10.1.0.3
1596 Processing proceeds in the order specified, and stops at first fully
1599 Note: The use of this directive using client dependent ACLs is
1600 incompatible with the use of server side persistent connections. To
1601 ensure correct results it is best to set server_persistent_connections
1602 to off when using this directive in such configurations.
1604 Note: The use of this directive to set a local IP on outgoing TCP links
1605 is incompatible with using TPROXY to set client IP out outbound TCP links.
1606 When needing to contact peers use the no-tproxy cache_peer option to
1607 re-enable normal forwarding such as this.
1611 Squid is built with a capability of bridging the IPv4 and IPv6
1613 tcp_outgoing_address as exampled above breaks this bridging by forcing
1614 all outbound traffic through a certain IPv4 which may be on the wrong
1615 side of the IPv4/IPv6 boundary.
1617 To operate with tcp_outgoing_address and keep the bridging benefits
1618 an additional ACL needs to be used which ensures the IPv6-bound traffic
1619 is never forced or permitted out the IPv4 interface.
1621 acl to_ipv6 dst ipv6
1622 tcp_outgoing_address 2002::c001 good_service_net to_ipv6
1623 tcp_outgoing_address 10.1.0.2 good_service_net !to_ipv6
1625 tcp_outgoing_address 2002::beef normal_service_net to_ipv6
1626 tcp_outgoing_address 10.1.0.1 normal_service_net !to_ipv6
1628 tcp_outgoing_address 2002::1 to_ipv6
1629 tcp_outgoing_address 10.1.0.3 !to_ipv6
1632 'dst ipv6' bases its selection assuming DIRECT access.
1633 If peers are used the peername ACL are needed to select outgoing
1634 address which can link to the peer.
1636 'dst ipv6' is a slow ACL. It will only work here if 'dst' is used
1637 previously in the http_access rules to locate the destination IP.
1638 Some more magic may be needed for that:
1639 http_access allow to_ipv6 !all
1640 (meaning, allow if to IPv6 but not from anywhere ;)
1646 -----------------------------------------------------------------------------
1649 NAME: ssl_unclean_shutdown
1653 LOC: Config.SSL.unclean_shutdown
1655 Some browsers (especially MSIE) bugs out on SSL shutdown
1662 LOC: Config.SSL.ssl_engine
1665 The OpenSSL engine to use. You will need to set this if you
1666 would like to use hardware SSL acceleration for example.
1669 NAME: sslproxy_client_certificate
1672 LOC: Config.ssl_client.cert
1675 Client SSL Certificate to use when proxying https:// URLs
1678 NAME: sslproxy_client_key
1681 LOC: Config.ssl_client.key
1684 Client SSL Key to use when proxying https:// URLs
1687 NAME: sslproxy_version
1690 LOC: Config.ssl_client.version
1693 SSL version level to use when proxying https:// URLs
1696 NAME: sslproxy_options
1699 LOC: Config.ssl_client.options
1702 SSL engine options to use when proxying https:// URLs
1704 The most important being:
1706 NO_SSLv2 Disallow the use of SSLv2
1707 NO_SSLv3 Disallow the use of SSLv3
1708 NO_TLSv1 Disallow the use of TLSv1
1710 Always create a new key when using
1711 temporary/ephemeral DH key exchanges
1713 These options vary depending on your SSL engine.
1714 See the OpenSSL SSL_CTX_set_options documentation for a
1715 complete list of possible options.
1718 NAME: sslproxy_cipher
1721 LOC: Config.ssl_client.cipher
1724 SSL cipher list to use when proxying https:// URLs
1726 Colon separated list of supported ciphers.
1729 NAME: sslproxy_cafile
1732 LOC: Config.ssl_client.cafile
1735 file containing CA certificates to use when verifying server
1736 certificates while proxying https:// URLs
1739 NAME: sslproxy_capath
1742 LOC: Config.ssl_client.capath
1745 directory containing CA certificates to use when verifying
1746 server certificates while proxying https:// URLs
1752 LOC: Config.accessList.ssl_bump
1755 This ACL controls which CONNECT requests to an http_port
1756 marked with an sslBump flag are actually "bumped". Please
1757 see the sslBump flag of an http_port option for more details
1758 about decoding proxied SSL connections.
1760 By default, no requests are bumped.
1762 See also: http_port sslBump
1764 This clause only supports fast acl types.
1765 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1768 # Example: Bump all requests except those originating from localhost and
1769 # those going to webax.com or example.com sites.
1771 acl localhost src 127.0.0.1/32
1772 acl broken_sites dstdomain .webax.com
1773 acl broken_sites dstdomain .example.com
1774 ssl_bump deny localhost
1775 ssl_bump deny broken_sites
1779 NAME: sslproxy_flags
1782 LOC: Config.ssl_client.flags
1785 Various flags modifying the use of SSL while proxying https:// URLs:
1786 DONT_VERIFY_PEER Accept certificates that fail verification.
1787 For refined control, see sslproxy_cert_error.
1788 NO_DEFAULT_CA Don't use the default CA list built in
1793 NAME: sslproxy_cert_error
1796 LOC: Config.ssl_client.cert_error
1799 Use this ACL to bypass server certificate validation errors.
1801 For example, the following lines will bypass all validation errors
1802 when talking to servers located at 172.16.0.0/16. All other
1803 validation errors will result in ERR_SECURE_CONNECT_FAIL error.
1805 acl BrokenServersAtTrustedIP dst 172.16.0.0/16
1806 sslproxy_cert_error allow BrokenServersAtTrustedIP
1807 sslproxy_cert_error deny all
1809 This clause only supports fast acl types.
1810 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
1811 Using slow acl types may result in server crashes
1813 Without this option, all server certificate validation errors
1814 terminate the transaction. Bypassing validation errors is dangerous
1815 because an error usually implies that the server cannot be trusted and
1816 the connection may be insecure.
1818 See also: sslproxy_flags and DONT_VERIFY_PEER.
1820 Default setting: sslproxy_cert_error deny all
1825 NAME: sslpassword_program
1828 LOC: Config.Program.ssl_password
1831 Specify a program used for entering SSL key passphrases
1832 when using encrypted SSL certificate keys. If not specified
1833 keys must either be unencrypted, or Squid started with the -N
1834 option to allow it to query interactively for the passphrase.
1836 The key file name is given as argument to the program allowing
1837 selection of the right password if you have multiple encrypted
1842 OPTIONS WHICH AFFECT THE NEIGHBOR SELECTION ALGORITHM
1843 -----------------------------------------------------------------------------
1851 To specify other caches in a hierarchy, use the format:
1853 cache_peer hostname type http-port icp-port [options]
1858 # hostname type port port options
1859 # -------------------- -------- ----- ----- -----------
1860 cache_peer parent.foo.net parent 3128 3130 default
1861 cache_peer sib1.foo.net sibling 3128 3130 proxy-only
1862 cache_peer sib2.foo.net sibling 3128 3130 proxy-only
1863 cache_peer example.com parent 80 0 no-query default
1864 cache_peer cdn.example.com sibling 3128 0
1866 type: either 'parent', 'sibling', or 'multicast'.
1868 proxy-port: The port number where the peer accept HTTP requests.
1869 For other Squid proxies this is usually 3128
1870 For web servers this is usually 80
1872 icp-port: Used for querying neighbor caches about objects.
1873 Set to 0 if the peer does not support ICP or HTCP.
1874 See ICP and HTCP options below for additional details.
1877 ==== ICP OPTIONS ====
1879 You MUST also set icp_port and icp_access explicitly when using these options.
1880 The defaults will prevent peer traffic using ICP.
1883 no-query Disable ICP queries to this neighbor.
1886 Indicates the named peer is a member of a multicast group.
1887 ICP queries will not be sent directly to the peer, but ICP
1888 replies will be accepted from it.
1890 closest-only Indicates that, for ICP_OP_MISS replies, we'll only forward
1891 CLOSEST_PARENT_MISSes and never FIRST_PARENT_MISSes.
1894 To only send ICP queries to this neighbor infrequently.
1895 This is used to keep the neighbor round trip time updated
1896 and is usually used in conjunction with weighted-round-robin.
1899 ==== HTCP OPTIONS ====
1901 You MUST also set htcp_port and htcp_access explicitly when using these options.
1902 The defaults will prevent peer traffic using HTCP.
1905 htcp Send HTCP, instead of ICP, queries to the neighbor.
1906 You probably also want to set the "icp-port" to 4827
1909 htcp-oldsquid Send HTCP to old Squid versions.
1911 htcp-no-clr Send HTCP to the neighbor but without
1912 sending any CLR requests. This cannot be used with
1915 htcp-only-clr Send HTCP to the neighbor but ONLY CLR requests.
1916 This cannot be used with htcp-no-clr.
1919 Send HTCP to the neighbor including CLRs but only when
1920 they do not result from PURGE requests.
1923 Forward any HTCP CLR requests this proxy receives to the peer.
1926 ==== PEER SELECTION METHODS ====
1928 The default peer selection method is ICP, with the first responding peer
1929 being used as source. These options can be used for better load balancing.
1932 default This is a parent cache which can be used as a "last-resort"
1933 if a peer cannot be located by any of the peer-selection methods.
1934 If specified more than once, only the first is used.
1936 round-robin Load-Balance parents which should be used in a round-robin
1937 fashion in the absence of any ICP queries.
1938 weight=N can be used to add bias.
1940 weighted-round-robin
1941 Load-Balance parents which should be used in a round-robin
1942 fashion with the frequency of each parent being based on the
1943 round trip time. Closer parents are used more often.
1944 Usually used for background-ping parents.
1945 weight=N can be used to add bias.
1947 carp Load-Balance parents which should be used as a CARP array.
1948 The requests will be distributed among the parents based on the
1949 CARP load balancing hash function based on their weight.
1951 userhash Load-balance parents based on the client proxy_auth or ident username.
1953 sourcehash Load-balance parents based on the client source IP.
1956 To be used only for cache peers of type "multicast".
1957 ALL members of this multicast group have "sibling"
1958 relationship with it, not "parent". This is to a mulicast
1959 group when the requested object would be fetched only from
1960 a "parent" cache, anyway. It's useful, e.g., when
1961 configuring a pool of redundant Squid proxies, being
1962 members of the same multicast group.
1965 ==== PEER SELECTION OPTIONS ====
1967 weight=N use to affect the selection of a peer during any weighted
1968 peer-selection mechanisms.
1969 The weight must be an integer; default is 1,
1970 larger weights are favored more.
1971 This option does not affect parent selection if a peering
1972 protocol is not in use.
1974 basetime=N Specify a base amount to be subtracted from round trip
1976 It is subtracted before division by weight in calculating
1977 which parent to fectch from. If the rtt is less than the
1978 base time the rtt is set to a minimal value.
1980 ttl=N Specify a IP multicast TTL to use when sending an ICP
1981 queries to this address.
1982 Only useful when sending to a multicast group.
1983 Because we don't accept ICP replies from random
1984 hosts, you must configure other group members as
1985 peers with the 'multicast-responder' option.
1987 no-delay To prevent access to this neighbor from influencing the
1990 digest-url=URL Tell Squid to fetch the cache digest (if digests are
1991 enabled) for this host from the specified URL rather
1992 than the Squid default location.
1995 ==== ACCELERATOR / REVERSE-PROXY OPTIONS ====
1997 originserver Causes this parent to be contacted as an origin server.
1998 Meant to be used in accelerator setups when the peer
2002 Set the Host header of requests forwarded to this peer.
2003 Useful in accelerator setups where the server (peer)
2004 expects a certain domain name but clients may request
2005 others. ie example.com or www.example.com
2007 no-digest Disable request of cache digests.
2010 Disables requesting ICMP RTT database (NetDB).
2013 ==== AUTHENTICATION OPTIONS ====
2016 If this is a personal/workgroup proxy and your parent
2017 requires proxy authentication.
2019 Note: The string can include URL escapes (i.e. %20 for
2020 spaces). This also means % must be written as %%.
2023 Send login details received from client to this peer.
2024 Both Proxy- and WWW-Authorization headers are passed
2025 without alteration to the peer.
2026 Authentication is not required by Squid for this to work.
2028 Note: This will pass any form of authentication but
2029 only Basic auth will work through a proxy unless the
2030 connection-auth options are also used.
2032 login=PASS Send login details received from client to this peer.
2033 Authentication is not required by this option.
2035 If there are no client-provided authentication headers
2036 to pass on, but username and password are available
2037 from an external ACL user= and password= result tags
2038 they may be sent instead.
2040 Note: To combine this with proxy_auth both proxies must
2041 share the same user database as HTTP only allows for
2042 a single login (one for proxy, one for origin server).
2043 Also be warned this will expose your users proxy
2044 password to the peer. USE WITH CAUTION
2047 Send the username to the upstream cache, but with a
2048 fixed password. This is meant to be used when the peer
2049 is in another administrative domain, but it is still
2050 needed to identify each user.
2051 The star can optionally be followed by some extra
2052 information which is added to the username. This can
2053 be used to identify this proxy to the peer, similar to
2054 the login=username:password option above.
2057 If this is a personal/workgroup proxy and your parent
2058 requires a secure proxy authentication.
2059 The first principal from the default keytab or defined by
2060 the environment variable KRB5_KTNAME will be used.
2062 login=NEGOTIATE:principal_name
2063 If this is a personal/workgroup proxy and your parent
2064 requires a secure proxy authentication.
2065 The principal principal_name from the default keytab or
2066 defined by the environment variable KRB5_KTNAME will be
2069 connection-auth=on|off
2070 Tell Squid that this peer does or not support Microsoft
2071 connection oriented authentication, and any such
2072 challenges received from there should be ignored.
2073 Default is auto to automatically determine the status
2077 ==== SSL / HTTPS / TLS OPTIONS ====
2079 ssl Encrypt connections to this peer with SSL/TLS.
2081 sslcert=/path/to/ssl/certificate
2082 A client SSL certificate to use when connecting to
2085 sslkey=/path/to/ssl/key
2086 The private SSL key corresponding to sslcert above.
2087 If 'sslkey' is not specified 'sslcert' is assumed to
2088 reference a combined file containing both the
2089 certificate and the key.
2092 The SSL version to use when connecting to this peer
2093 1 = automatic (default)
2098 sslcipher=... The list of valid SSL ciphers to use when connecting
2101 ssloptions=... Specify various SSL engine options:
2102 NO_SSLv2 Disallow the use of SSLv2
2103 NO_SSLv3 Disallow the use of SSLv3
2104 NO_TLSv1 Disallow the use of TLSv1
2105 See src/ssl_support.c or the OpenSSL documentation for
2106 a more complete list.
2108 sslcafile=... A file containing additional CA certificates to use
2109 when verifying the peer certificate.
2111 sslcapath=... A directory containing additional CA certificates to
2112 use when verifying the peer certificate.
2114 sslcrlfile=... A certificate revocation list file to use when
2115 verifying the peer certificate.
2117 sslflags=... Specify various flags modifying the SSL implementation:
2120 Accept certificates even if they fail to
2123 Don't use the default CA list built in
2126 Don't verify the peer certificate
2127 matches the server name
2129 ssldomain= The peer name as advertised in it's certificate.
2130 Used for verifying the correctness of the received peer
2131 certificate. If not specified the peer hostname will be
2135 Enable the "Front-End-Https: On" header needed when
2136 using Squid as a SSL frontend in front of Microsoft OWA.
2137 See MS KB document Q307347 for details on this header.
2138 If set to auto the header will only be added if the
2139 request is forwarded as a https:// URL.
2142 ==== GENERAL OPTIONS ====
2145 A peer-specific connect timeout.
2146 Also see the peer_connect_timeout directive.
2148 connect-fail-limit=N
2149 How many times connecting to a peer must fail before
2150 it is marked as down. Default is 10.
2152 allow-miss Disable Squid's use of only-if-cached when forwarding
2153 requests to siblings. This is primarily useful when
2154 icp_hit_stale is used by the sibling. To extensive use
2155 of this option may result in forwarding loops, and you
2156 should avoid having two-way peerings with this option.
2157 For example to deny peer usage on requests from peer
2158 by denying cache_peer_access if the source is a peer.
2160 max-conn=N Limit the amount of connections Squid may open to this
2163 name=xxx Unique name for the peer.
2164 Required if you have multiple peers on the same host
2165 but different ports.
2166 This name can be used in cache_peer_access and similar
2167 directives to dentify the peer.
2168 Can be used by outgoing access controls through the
2171 no-tproxy Do not use the client-spoof TPROXY support when forwarding
2172 requests to this peer. Use normal address selection instead.
2174 proxy-only objects fetched from the peer will not be stored locally.
2178 NAME: cache_peer_domain cache_host_domain
2183 Use to limit the domains for which a neighbor cache will be
2186 cache_peer_domain cache-host domain [domain ...]
2187 cache_peer_domain cache-host !domain
2189 For example, specifying
2191 cache_peer_domain parent.foo.net .edu
2193 has the effect such that UDP query packets are sent to
2194 'bigserver' only when the requested object exists on a
2195 server in the .edu domain. Prefixing the domainname
2196 with '!' means the cache will be queried for objects
2199 NOTE: * Any number of domains may be given for a cache-host,
2200 either on the same or separate lines.
2201 * When multiple domains are given for a particular
2202 cache-host, the first matched domain is applied.
2203 * Cache hosts with no domain restrictions are queried
2205 * There are no defaults.
2206 * There is also a 'cache_peer_access' tag in the ACL
2210 NAME: cache_peer_access
2215 Similar to 'cache_peer_domain' but provides more flexibility by
2218 cache_peer_access cache-host allow|deny [!]aclname ...
2220 The syntax is identical to 'http_access' and the other lists of
2221 ACL elements. See the comments for 'http_access' below, or
2222 the Squid FAQ (http://wiki.squid-cache.org/SquidFaq/SquidAcl).
2225 NAME: neighbor_type_domain
2226 TYPE: hostdomaintype
2230 usage: neighbor_type_domain neighbor parent|sibling domain domain ...
2232 Modifying the neighbor type for specific domains is now
2233 possible. You can treat some domains differently than the
2234 default neighbor type specified on the 'cache_peer' line.
2235 Normally it should only be necessary to list domains which
2236 should be treated differently because the default neighbor type
2237 applies for hostnames which do not match domains listed here.
2240 cache_peer cache.foo.org parent 3128 3130
2241 neighbor_type_domain cache.foo.org sibling .com .net
2242 neighbor_type_domain cache.foo.org sibling .au .de
2245 NAME: dead_peer_timeout
2249 LOC: Config.Timeout.deadPeer
2251 This controls how long Squid waits to declare a peer cache
2252 as "dead." If there are no ICP replies received in this
2253 amount of time, Squid will declare the peer dead and not
2254 expect to receive any further ICP replies. However, it
2255 continues to send ICP queries, and will mark the peer as
2256 alive upon receipt of the first subsequent ICP reply.
2258 This timeout also affects when Squid expects to receive ICP
2259 replies from peers. If more than 'dead_peer' seconds have
2260 passed since the last ICP reply was received, Squid will not
2261 expect to receive an ICP reply on the next query. Thus, if
2262 your time between requests is greater than this timeout, you
2263 will see a lot of requests sent DIRECT to origin servers
2264 instead of to your parents.
2267 NAME: forward_max_tries
2270 LOC: Config.forward_max_tries
2272 Controls how many different forward paths Squid will try
2273 before giving up. See also forward_timeout.
2276 NAME: hierarchy_stoplist
2279 LOC: Config.hierarchy_stoplist
2281 A list of words which, if found in a URL, cause the object to
2282 be handled directly by this cache. In other words, use this
2283 to not query neighbor caches for certain objects. You may
2284 list this option multiple times.
2285 Note: never_direct overrides this option.
2288 # We recommend you to use at least the following line.
2289 hierarchy_stoplist cgi-bin ?
2294 MEMORY CACHE OPTIONS
2295 -----------------------------------------------------------------------------
2302 LOC: Config.memMaxSize
2304 NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE.
2305 IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL
2306 USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER
2307 THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS.
2309 'cache_mem' specifies the ideal amount of memory to be used
2311 * In-Transit objects
2313 * Negative-Cached objects
2315 Data for these objects are stored in 4 KB blocks. This
2316 parameter specifies the ideal upper limit on the total size of
2317 4 KB blocks allocated. In-Transit objects take the highest
2320 In-transit objects have priority over the others. When
2321 additional space is needed for incoming data, negative-cached
2322 and hot objects will be released. In other words, the
2323 negative-cached and hot objects will fill up any unused space
2324 not needed for in-transit objects.
2326 If circumstances require, this limit will be exceeded.
2327 Specifically, if your incoming request rate requires more than
2328 'cache_mem' of memory to hold in-transit objects, Squid will
2329 exceed this limit to satisfy the new requests. When the load
2330 decreases, blocks will be freed until the high-water mark is
2331 reached. Thereafter, blocks will be used to store hot
2335 NAME: maximum_object_size_in_memory
2339 LOC: Config.Store.maxInMemObjSize
2341 Objects greater than this size will not be attempted to kept in
2342 the memory cache. This should be set high enough to keep objects
2343 accessed frequently in memory to improve performance whilst low
2344 enough to keep larger objects from hoarding cache_mem.
2347 NAME: memory_cache_mode
2352 Controls which objects to keep in the memory cache (cache_mem)
2354 always Keep most recently fetched objects in memory (default)
2356 disk Only disk cache hits are kept in memory, which means
2357 an object must first be cached on disk and then hit
2358 a second time before cached in memory.
2360 network Only objects fetched from network is kept in memory
2363 NAME: memory_replacement_policy
2365 LOC: Config.memPolicy
2368 The memory replacement policy parameter determines which
2369 objects are purged from memory when memory space is needed.
2371 See cache_replacement_policy for details.
2376 -----------------------------------------------------------------------------
2379 NAME: cache_replacement_policy
2381 LOC: Config.replPolicy
2384 The cache replacement policy parameter determines which
2385 objects are evicted (replaced) when disk space is needed.
2387 lru : Squid's original list based LRU policy
2388 heap GDSF : Greedy-Dual Size Frequency
2389 heap LFUDA: Least Frequently Used with Dynamic Aging
2390 heap LRU : LRU policy implemented using a heap
2392 Applies to any cache_dir lines listed below this.
2394 The LRU policies keeps recently referenced objects.
2396 The heap GDSF policy optimizes object hit rate by keeping smaller
2397 popular objects in cache so it has a better chance of getting a
2398 hit. It achieves a lower byte hit rate than LFUDA though since
2399 it evicts larger (possibly popular) objects.
2401 The heap LFUDA policy keeps popular objects in cache regardless of
2402 their size and thus optimizes byte hit rate at the expense of
2403 hit rate since one large, popular object will prevent many
2404 smaller, slightly less popular objects from being cached.
2406 Both policies utilize a dynamic aging mechanism that prevents
2407 cache pollution that can otherwise occur with frequency-based
2408 replacement policies.
2410 NOTE: if using the LFUDA replacement policy you should increase
2411 the value of maximum_object_size above its default of 4096 KB to
2412 to maximize the potential byte hit rate improvement of LFUDA.
2414 For more information about the GDSF and LFUDA cache replacement
2415 policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
2416 and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
2422 LOC: Config.cacheSwap
2426 cache_dir Type Directory-Name Fs-specific-data [options]
2428 You can specify multiple cache_dir lines to spread the
2429 cache among different disk partitions.
2431 Type specifies the kind of storage system to use. Only "ufs"
2432 is built by default. To enable any of the other storage systems
2433 see the --enable-storeio configure option.
2435 'Directory' is a top-level directory where cache swap
2436 files will be stored. If you want to use an entire disk
2437 for caching, this can be the mount-point directory.
2438 The directory must exist and be writable by the Squid
2439 process. Squid will NOT create this directory for you.
2443 "ufs" is the old well-known Squid storage format that has always
2446 cache_dir ufs Directory-Name Mbytes L1 L2 [options]
2448 'Mbytes' is the amount of disk space (MB) to use under this
2449 directory. The default is 100 MB. Change this to suit your
2450 configuration. Do NOT put the size of your disk drive here.
2451 Instead, if you want Squid to use the entire disk drive,
2452 subtract 20% and use that value.
2454 'L1' is the number of first-level subdirectories which
2455 will be created under the 'Directory'. The default is 16.
2457 'L2' is the number of second-level subdirectories which
2458 will be created under each first-level directory. The default
2461 The aufs store type:
2463 "aufs" uses the same storage format as "ufs", utilizing
2464 POSIX-threads to avoid blocking the main Squid process on
2465 disk-I/O. This was formerly known in Squid as async-io.
2467 cache_dir aufs Directory-Name Mbytes L1 L2 [options]
2469 see argument descriptions under ufs above
2471 The diskd store type:
2473 "diskd" uses the same storage format as "ufs", utilizing a
2474 separate process to avoid blocking the main Squid process on
2477 cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
2479 see argument descriptions under ufs above
2481 Q1 specifies the number of unacknowledged I/O requests when Squid
2482 stops opening new files. If this many messages are in the queues,
2483 Squid won't open new files. Default is 64
2485 Q2 specifies the number of unacknowledged messages when Squid
2486 starts blocking. If this many messages are in the queues,
2487 Squid blocks until it receives some replies. Default is 72
2489 When Q1 < Q2 (the default), the cache directory is optimized
2490 for lower response time at the expense of a decrease in hit
2491 ratio. If Q1 > Q2, the cache directory is optimized for
2492 higher hit ratio at the expense of an increase in response
2495 The coss store type:
2497 NP: COSS filesystem in Squid-3 has been deemed too unstable for
2498 production use and has thus been removed from this release.
2499 We hope that it can be made usable again soon.
2501 block-size=n defines the "block size" for COSS cache_dir's.
2502 Squid uses file numbers as block numbers. Since file numbers
2503 are limited to 24 bits, the block size determines the maximum
2504 size of the COSS partition. The default is 512 bytes, which
2505 leads to a maximum cache_dir size of 512<<24, or 8 GB. Note
2506 you should not change the coss block size after Squid
2507 has written some objects to the cache_dir.
2509 The coss file store has changed from 2.5. Now it uses a file
2510 called 'stripe' in the directory names in the config - and
2511 this will be created by squid -z.
2515 no-store, no new objects should be stored to this cache_dir
2517 max-size=n, refers to the max object size this storedir supports.
2518 It is used to initially choose the storedir to dump the object.
2519 Note: To make optimal use of the max-size limits you should order
2520 the cache_dir lines with the smallest max-size value first and the
2521 ones with no max-size specification last.
2523 Note for coss, max-size must be less than COSS_MEMBUF_SZ,
2524 which can be changed with the --with-coss-membuf-size=N configure
2528 # Uncomment and adjust the following to add a disk cache directory.
2529 #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256
2533 NAME: store_dir_select_algorithm
2535 LOC: Config.store_dir_select_algorithm
2538 Set this to 'round-robin' as an alternative.
2541 NAME: max_open_disk_fds
2543 LOC: Config.max_open_disk_fds
2546 To avoid having disk as the I/O bottleneck Squid can optionally
2547 bypass the on-disk cache if more than this amount of disk file
2548 descriptors are open.
2550 A value of 0 indicates no limit.
2553 NAME: minimum_object_size
2557 LOC: Config.Store.minObjectSize
2559 Objects smaller than this size will NOT be saved on disk. The
2560 value is specified in kilobytes, and the default is 0 KB, which
2561 means there is no minimum.
2564 NAME: maximum_object_size
2568 LOC: Config.Store.maxObjectSize
2570 Objects larger than this size will NOT be saved on disk. The
2571 value is specified in kilobytes, and the default is 4MB. If
2572 you wish to get a high BYTES hit ratio, you should probably
2573 increase this (one 32 MB object hit counts for 3200 10KB
2574 hits). If you wish to increase speed more than your want to
2575 save bandwidth you should leave this low.
2577 NOTE: if using the LFUDA replacement policy you should increase
2578 this value to maximize the byte hit rate improvement of LFUDA!
2579 See replacement_policy below for a discussion of this policy.
2582 NAME: cache_swap_low
2583 COMMENT: (percent, 0-100)
2586 LOC: Config.Swap.lowWaterMark
2589 NAME: cache_swap_high
2590 COMMENT: (percent, 0-100)
2593 LOC: Config.Swap.highWaterMark
2596 The low- and high-water marks for cache object replacement.
2597 Replacement begins when the swap (disk) usage is above the
2598 low-water mark and attempts to maintain utilization near the
2599 low-water mark. As swap utilization gets close to high-water
2600 mark object eviction becomes more aggressive. If utilization is
2601 close to the low-water mark less replacement is done each time.
2603 Defaults are 90% and 95%. If you have a large cache, 5% could be
2604 hundreds of MB. If this is the case you may wish to set these
2605 numbers closer together.
2610 -----------------------------------------------------------------------------
2615 LOC: Config.Log.logformats
2620 logformat <name> <format specification>
2622 Defines an access log format.
2624 The <format specification> is a string with embedded % format codes
2626 % format codes all follow the same basic structure where all but
2627 the formatcode is optional. Output strings are automatically escaped
2628 as required according to their context and the output format
2629 modifiers are usually not needed, but can be specified if an explicit
2630 output format is desired.
2632 % ["|[|'|#] [-] [[0]width] [{argument}] formatcode
2634 " output in quoted string format
2635 [ output in squid text log format as used by log_mime_hdrs
2636 # output in URL quoted format
2640 width field width. If starting with 0 the
2641 output is zero padded
2642 {arg} argument such as header name etc
2646 % a literal % character
2647 >a Client source IP address
2649 >p Client source port
2650 <A Server IP address or peer name
2651 la Local IP address (http_port)
2652 lp Local port number (http_port)
2653 <lp Local port number of the last server or peer connection
2654 sn Unique sequence number per log line entry
2655 ts Seconds since epoch
2656 tu subsecond time (milliseconds)
2657 tl Local time. Optional strftime format argument
2658 default %d/%b/%Y:%H:%M:%S %z
2659 tg GMT time. Optional strftime format argument
2660 default %d/%b/%Y:%H:%M:%S %z
2661 tr Response time (milliseconds)
2662 dt Total time spent making DNS lookups (milliseconds)
2664 HTTP cache related format codes:
2666 [http::]>h Original request header. Optional header name argument
2667 on the format header[:[separator]element]
2668 [http::]>ha The HTTP request headers after adaptation and redirection.
2669 Optional header name argument as for >h
2670 [http::]<h Reply header. Optional header name argument
2672 [http::]un User name
2673 [http::]ul User name from authentication
2674 [http::]ui User name from ident
2675 [http::]us User name from SSL
2676 [http::]ue User name from external acl helper
2677 [http::]>Hs HTTP status code sent to the client
2678 [http::]<Hs HTTP status code received from the next hop
2679 [http::]<bs Number of HTTP-equivalent message body bytes
2680 received from the next hop, excluding chunked
2681 transfer encoding and control messages.
2682 Generated FTP/Gopher listings are treated as
2684 [http::]Ss Squid request status (TCP_MISS etc)
2685 [http::]Sh Squid hierarchy status (DEFAULT_PARENT etc)
2686 [http::]mt MIME content type
2687 [http::]rm Request method (GET/POST etc)
2688 [http::]ru Request URL
2689 [http::]rp Request URL-Path excluding hostname
2690 [http::]rv Request protocol version
2691 [http::]et Tag returned by external acl
2692 [http::]ea Log string returned by external acl
2693 [http::]<st Sent reply size including HTTP headers
2694 [http::]>st Received request size including HTTP headers. In the
2695 case of chunked requests the chunked encoding metadata
2697 [http::]>sh Received HTTP request headers size
2698 [http::]<sh Sent HTTP reply headers size
2699 [http::]st Request+Reply size including HTTP headers
2700 [http::]<sH Reply high offset sent
2701 [http::]<sS Upstream object size
2702 [http::]<pt Peer response time in milliseconds. The timer starts
2703 when the last request byte is sent to the next hop
2704 and stops when the last response byte is received.
2705 [http::]<tt Total server-side time in milliseconds. The timer
2706 starts with the first connect request (or write I/O)
2707 sent to the first selected peer. The timer stops
2708 with the last I/O with the last peer.
2710 If ICAP is enabled, the following two codes become available (as
2711 well as ICAP log codes documented with the icap_log option):
2713 icap::tt Total ICAP processing time for the HTTP
2714 transaction. The timer ticks when ICAP
2715 ACLs are checked and when ICAP
2716 transaction is in progress.
2718 icap::<last_h The header of the last ICAP response
2719 related to the HTTP transaction. Like
2720 <h, accepts an optional header name
2721 argument. Will not change semantics
2722 when multiple ICAP transactions per HTTP
2723 transaction are supported.
2725 If adaptation is enabled the following two codes become available:
2727 adapt::sum_trs Summed adaptation transaction response
2728 times recorded as a comma-separated list in
2729 the order of transaction start time. Each time
2730 value is recorded as an integer number,
2731 representing response time of one or more
2732 adaptation (ICAP or eCAP) transaction in
2733 milliseconds. When a failed transaction is
2734 being retried or repeated, its time is not
2735 logged individually but added to the
2736 replacement (next) transaction. See also:
2739 adapt::all_trs All adaptation transaction response times.
2740 Same as adaptation_strs but response times of
2741 individual transactions are never added
2742 together. Instead, all transaction response
2743 times are recorded individually.
2745 You can prefix adapt::*_trs format codes with adaptation
2746 service name in curly braces to record response time(s) specific
2747 to that service. For example: %{my_service}adapt::sum_trs
2749 The default formats available (which do not need re-defining) are:
2751 logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %un %Sh/%<A %mt
2752 logformat squidmime %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %un %Sh/%<A %mt [%>h] [%<h]
2753 logformat common %>a %ui %un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh
2754 logformat combined %>a %ui %un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
2757 NAME: access_log cache_access_log
2759 LOC: Config.Log.accesslogs
2761 DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid
2763 These files log client request activities. Has a line every HTTP or
2764 ICP request. The format is:
2765 access_log <module>:<place> [<logformat name> [acl acl ...]]
2766 access_log none [acl acl ...]]
2768 Will log to the specified module:place using the specified format (which
2769 must be defined in a logformat directive) those entries which match
2770 ALL the acl's specified (which must be defined in acl clauses).
2771 If no acl is specified, all requests will be logged to this destination.
2773 ===== Modules Currently available =====
2775 none Do not log any requests matchign these ACL.
2776 Do not specify Place or logformat name.
2778 stdio Write each log line to disk immediately at the completion of
2780 Place: the filename and path to be written.
2782 daemon Very similar to stdio. But instead of writing to disk the log
2783 line is passed to a daemon helper for asychronous handling instead.
2784 Place: varies depending on the daemon.
2786 log_file_daemon Place: the file name and path to be written.
2788 syslog To log each request via syslog facility.
2789 Place: The syslog facility and priority level for these entries.
2790 Place Format: facility.priority
2792 where facility could be any of:
2793 authpriv, daemon, local0 ... local7 or user.
2795 And priority could be any of:
2796 err, warning, notice, info, debug.
2798 udp To send each log line as text data to a UDP receiver.
2799 Place: The destination host name or IP and port.
2800 Place Format: \\host:port
2802 tcp To send each log line as text data to a TCP receiver.
2803 Place: The destination host name or IP and port.
2804 Place Format: \\host:port
2807 access_log daemon:@DEFAULT_ACCESS_LOG@ squid
2813 LOC: Config.Log.icaplogs
2816 ICAP log files record ICAP transaction summaries, one line per
2819 The icap_log option format is:
2820 icap_log <filepath> [<logformat name> [acl acl ...]]
2821 icap_log none [acl acl ...]]
2823 Please see access_log option documentation for details. The two
2824 kinds of logs share the overall configuration approach and many
2827 ICAP processing of a single HTTP message or transaction may
2828 require multiple ICAP transactions. In such cases, multiple
2829 ICAP transaction log lines will correspond to a single access
2832 ICAP log uses logformat codes that make sense for an ICAP
2833 transaction. Header-related codes are applied to the HTTP header
2834 embedded in an ICAP server response, with the following caveats:
2835 For REQMOD, there is no HTTP response header unless the ICAP
2836 server performed request satisfaction. For RESPMOD, the HTTP
2837 request header is the header sent to the ICAP server. For
2838 OPTIONS, there are no HTTP headers.
2840 The following format codes are also available for ICAP logs:
2842 icap::<A ICAP server IP address. Similar to <A.
2844 icap::<service_name ICAP service name from the icap_service
2845 option in Squid configuration file.
2847 icap::ru ICAP Request-URI. Similar to ru.
2849 icap::rm ICAP request method (REQMOD, RESPMOD, or
2850 OPTIONS). Similar to existing rm.
2852 icap::>st Bytes sent to the ICAP server (TCP payload
2853 only; i.e., what Squid writes to the socket).
2855 icap::<st Bytes received from the ICAP server (TCP
2856 payload only; i.e., what Squid reads from
2859 icap::<bs Number of message body bytes received from the
2860 ICAP server. ICAP message body, if any, usually
2861 includes encapsulated HTTP message headers and
2862 possibly encapsulated HTTP message body. The
2863 HTTP body part is dechunked before its size is
2866 icap::tr Transaction response time (in
2867 milliseconds). The timer starts when
2868 the ICAP transaction is created and
2869 stops when the transaction is completed.
2872 icap::tio Transaction I/O time (in milliseconds). The
2873 timer starts when the first ICAP request
2874 byte is scheduled for sending. The timers
2875 stops when the last byte of the ICAP response
2878 icap::to Transaction outcome: ICAP_ERR* for all
2879 transaction errors, ICAP_OPT for OPTION
2880 transactions, ICAP_ECHO for 204
2881 responses, ICAP_MOD for message
2882 modification, and ICAP_SAT for request
2883 satisfaction. Similar to Ss.
2885 icap::Hs ICAP response status code. Similar to Hs.
2887 icap::>h ICAP request header(s). Similar to >h.
2889 icap::<h ICAP response header(s). Similar to <h.
2891 The default ICAP log format, which can be used without an explicit
2892 definition, is called icap_squid:
2894 logformat icap_squid %ts.%03tu %6icap::tr %>a %icap::to/%03icap::Hs %icap::<size %icap::rm %icap::ru% %un -/%icap::<A -
2896 See also: logformat, log_icap, and %icap::<last_h
2899 NAME: logfile_daemon
2901 DEFAULT: @DEFAULT_LOGFILED@
2902 LOC: Log::TheConfig.logfile_daemon
2904 Specify the path to the logfile-writing daemon. This daemon is
2905 used to write the access and store logs, if configured.
2907 Squid sends a number of commands to the log daemon:
2908 L<data>\n - logfile data
2913 r<n>\n - set rotate count to <n>
2914 b<n>\n - 1 = buffer output, 0 = don't buffer output
2916 No responses is expected.
2921 LOC: Config.accessList.log
2923 COMMENT: allow|deny acl acl...
2925 This options allows you to control which requests gets logged
2926 to access.log (see access_log directive). Requests denied for
2927 logging will also not be accounted for in performance counters.
2929 This clause only supports fast acl types.
2930 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2936 LOC: Config.accessList.icap
2939 This options allows you to control which requests get logged
2940 to icap.log. See the icap_log directive for ICAP log details.
2943 NAME: cache_store_log
2946 LOC: Config.Log.store
2948 Logs the activities of the storage manager. Shows which
2949 objects are ejected from the cache, and which objects are
2950 saved and for how long. To disable, enter "none" or remove the line.
2951 There are not really utilities to analyze this data, so you can safely
2955 cache_store_log @DEFAULT_STORE_LOG@
2958 NAME: cache_swap_state cache_swap_log
2960 LOC: Config.Log.swap
2963 Location for the cache "swap.state" file. This index file holds
2964 the metadata of objects saved on disk. It is used to rebuild
2965 the cache during startup. Normally this file resides in each
2966 'cache_dir' directory, but you may specify an alternate
2967 pathname here. Note you must give a full filename, not just
2968 a directory. Since this is the index for the whole object
2969 list you CANNOT periodically rotate it!
2971 If %s can be used in the file name it will be replaced with a
2972 a representation of the cache_dir name where each / is replaced
2973 with '.'. This is needed to allow adding/removing cache_dir
2974 lines when cache_swap_log is being used.
2976 If have more than one 'cache_dir', and %s is not used in the name
2977 these swap logs will have names such as:
2983 The numbered extension (which is added automatically)
2984 corresponds to the order of the 'cache_dir' lines in this
2985 configuration file. If you change the order of the 'cache_dir'
2986 lines in this file, these index files will NOT correspond to
2987 the correct 'cache_dir' entry (unless you manually rename
2988 them). We recommend you do NOT use this option. It is
2989 better to keep these index files in each 'cache_dir' directory.
2992 NAME: logfile_rotate
2995 LOC: Config.Log.rotateNumber
2997 Specifies the number of logfile rotations to make when you
2998 type 'squid -k rotate'. The default is 10, which will rotate
2999 with extensions 0 through 9. Setting logfile_rotate to 0 will
3000 disable the file name rotation, but the logfiles are still closed
3001 and re-opened. This will enable you to rename the logfiles
3002 yourself just before sending the rotate signal.
3004 Note, the 'squid -k rotate' command normally sends a USR1
3005 signal to the running squid process. In certain situations
3006 (e.g. on Linux with Async I/O), USR1 is used for other
3007 purposes, so -k rotate uses another signal. It is best to get
3008 in the habit of using 'squid -k rotate' instead of 'kill -USR1
3011 Note, from Squid-3.1 this option has no effect on the cache.log,
3012 that log can be rotated separately by using debug_options
3015 NAME: emulate_httpd_log
3019 LOC: Config.onoff.common_log
3021 The Cache can emulate the log file format which many 'httpd'
3022 programs use. To disable/enable this emulation, set
3023 emulate_httpd_log to 'off' or 'on'. The default
3024 is to use the native log format since it includes useful
3025 information Squid-specific log analyzers use.
3028 NAME: log_ip_on_direct
3032 LOC: Config.onoff.log_ip_on_direct
3034 Log the destination IP address in the hierarchy log tag when going
3035 direct. Earlier Squid versions logged the hostname here. If you
3036 prefer the old way set this to off.
3041 DEFAULT: @DEFAULT_MIME_TABLE@
3042 LOC: Config.mimeTablePathname
3044 Pathname to Squid's MIME table. You shouldn't need to change
3045 this, but the default file contains examples and formatting
3046 information if you do.
3052 LOC: Config.onoff.log_mime_hdrs
3055 The Cache can record both the request and the response MIME
3056 headers for each HTTP transaction. The headers are encoded
3057 safely and will appear as two bracketed fields at the end of
3058 the access log (for either the native or httpd-emulated log
3059 formats). To enable this logging set log_mime_hdrs to 'on'.
3064 LOC: Config.Log.useragent
3066 IFDEF: USE_USERAGENT_LOG
3068 Squid will write the User-Agent field from HTTP requests
3069 to the filename specified here. By default useragent_log
3073 NAME: referer_log referrer_log
3075 LOC: Config.Log.referer
3077 IFDEF: USE_REFERER_LOG
3079 Squid will write the Referer field from HTTP requests to the
3080 filename specified here. By default referer_log is disabled.
3081 Note that "referer" is actually a misspelling of "referrer"
3082 however the misspelt version has been accepted into the HTTP RFCs
3088 DEFAULT: @DEFAULT_PID_FILE@
3089 LOC: Config.pidFilename
3091 A filename to write the process-id to. To disable, enter "none".
3098 LOC: Config.onoff.log_fqdn
3100 Turn this on if you wish to log fully qualified domain names
3101 in the access.log. To do this Squid does a DNS lookup of all
3102 IP's connecting to it. This can (in some situations) increase
3103 latency, which makes your cache seem slower for interactive
3107 NAME: client_netmask
3109 LOC: Config.Addrs.client_netmask
3112 A netmask for client addresses in logfiles and cachemgr output.
3113 Change this to protect the privacy of your cache clients.
3114 A netmask of 255.255.255.0 will log all IP's in that range with
3115 the last digit set to '0'.
3122 LOC: Config.Log.forward
3124 Logs the server-side requests.
3126 This is currently work in progress.
3129 NAME: strip_query_terms
3131 LOC: Config.onoff.strip_query_terms
3134 By default, Squid strips query terms from requested URLs before
3135 logging. This protects your user's privacy.
3142 LOC: Config.onoff.buffered_logs
3144 cache.log log file is written with stdio functions, and as such
3145 it can be buffered or unbuffered. By default it will be unbuffered.
3146 Buffering it can speed up the writing slightly (though you are
3147 unlikely to need to worry unless you run with tons of debugging
3148 enabled in which case performance will suffer badly anyway..).
3151 NAME: netdb_filename
3153 DEFAULT: @DEFAULT_NETDB_FILE@
3154 LOC: Config.netdbFilename
3157 A filename where Squid stores it's netdb state between restarts.
3158 To disable, enter "none".
3162 OPTIONS FOR TROUBLESHOOTING
3163 -----------------------------------------------------------------------------
3169 DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@
3170 LOC: Debug::cache_log
3172 Cache logging file. This is where general information about
3173 your cache's behavior goes. You can increase the amount of data
3174 logged to this file and how often its rotated with "debug_options"
3180 LOC: Debug::debugOptions
3182 Logging options are set as section,level where each source file
3183 is assigned a unique section. Lower levels result in less
3184 output, Full debugging (level 9) can result in a very large
3185 log file, so be careful.
3187 The magic word "ALL" sets debugging levels for all sections.
3188 We recommend normally running with "ALL,1".
3190 The rotate=N option can be used to keep more or less of these logs
3191 than would otherwise be kept by logfile_rotate.
3192 For most uses a single log should be enough to monitor current
3193 events affecting Squid.
3198 LOC: Config.coredump_dir
3200 DEFAULT_IF_NONE: none
3202 By default Squid leaves core files in the directory from where
3203 it was started. If you set 'coredump_dir' to a directory
3204 that exists, Squid will chdir() to that directory at startup
3205 and coredump files will be left there.
3209 # Leave coredumps in the first cache dir
3210 coredump_dir @DEFAULT_SWAP_DIR@
3216 OPTIONS FOR FTP GATEWAYING
3217 -----------------------------------------------------------------------------
3223 LOC: Config.Ftp.anon_user
3225 If you want the anonymous login password to be more informative
3226 (and enable the use of picky ftp servers), set this to something
3227 reasonable for your domain, like wwwuser@somewhere.net
3229 The reason why this is domainless by default is the
3230 request can be made on the behalf of a user in any domain,
3231 depending on how the cache is used.
3232 Some ftp server also validate the email address is valid
3233 (for example perl.com).
3239 LOC: Config.Ftp.passive
3241 If your firewall does not allow Squid to use passive
3242 connections, turn off this option.
3244 Use of ftp_epsv_all option requires this to be ON.
3250 LOC: Config.Ftp.epsv_all
3252 FTP Protocol extensions permit the use of a special "EPSV ALL" command.
3254 NATs may be able to put the connection on a "fast path" through the
3255 translator, as the EPRT command will never be used and therefore,
3256 translation of the data portion of the segments will never be needed.
3258 When a client only expects to do two-way FTP transfers this may be
3260 If squid finds that it must do a three-way FTP transfer after issuing
3261 an EPSV ALL command, the FTP session will fail.
3263 If you have any doubts about this option do not use it.
3264 Squid will nicely attempt all other connection methods.
3266 Requires ftp_passive to be ON (default) for any effect.
3272 LOC: Config.Ftp.epsv
3274 FTP Protocol extensions permit the use of a special "EPSV" command.
3276 NATs may be able to put the connection on a "fast path" through the
3277 translator using EPSV, as the EPRT command will never be used
3278 and therefore, translation of the data portion of the segments
3279 will never be needed.
3281 Turning this OFF will prevent EPSV being attempted.
3282 WARNING: Doing so will convert Squid back to the old behavior with all
3283 the related problems with external NAT devices/layers.
3285 Requires ftp_passive to be ON (default) for any effect.
3288 NAME: ftp_sanitycheck
3291 LOC: Config.Ftp.sanitycheck
3293 For security and data integrity reasons Squid by default performs
3294 sanity checks of the addresses of FTP data connections ensure the
3295 data connection is to the requested server. If you need to allow
3296 FTP connections to servers using another IP address for the data
3297 connection turn this off.
3300 NAME: ftp_telnet_protocol
3303 LOC: Config.Ftp.telnet
3305 The FTP protocol is officially defined to use the telnet protocol
3306 as transport channel for the control connection. However, many
3307 implementations are broken and does not respect this aspect of
3310 If you have trouble accessing files with ASCII code 255 in the
3311 path or similar problems involving this ASCII code you can
3312 try setting this directive to off. If that helps, report to the
3313 operator of the FTP server in question that their FTP server
3314 is broken and does not follow the FTP standard.
3318 OPTIONS FOR EXTERNAL SUPPORT PROGRAMS
3319 -----------------------------------------------------------------------------
3324 DEFAULT: @DEFAULT_DISKD@
3325 LOC: Config.Program.diskd
3327 Specify the location of the diskd executable.
3328 Note this is only useful if you have compiled in
3329 diskd as one of the store io modules.
3332 NAME: unlinkd_program
3335 DEFAULT: @DEFAULT_UNLINKD@
3336 LOC: Config.Program.unlinkd
3338 Specify the location of the executable for file deletion process.
3341 NAME: pinger_program
3343 DEFAULT: @DEFAULT_PINGER@
3344 LOC: Config.pinger.program
3347 Specify the location of the executable for the pinger process.
3353 LOC: Config.pinger.enable
3356 Control whether the pinger is active at run-time.
3357 Enables turning ICMP pinger on and off with a simple
3358 squid -k reconfigure.
3363 OPTIONS FOR URL REWRITING
3364 -----------------------------------------------------------------------------
3367 NAME: url_rewrite_program redirect_program
3369 LOC: Config.Program.redirect
3372 Specify the location of the executable for the URL rewriter.
3373 Since they can perform almost any function there isn't one included.
3375 For each requested URL rewriter will receive on line with the format
3377 URL <SP> client_ip "/" fqdn <SP> user <SP> method [<SP> kvpairs]<NL>
3379 In the future, the rewriter interface will be extended with
3380 key=value pairs ("kvpairs" shown above). Rewriter programs
3381 should be prepared to receive and possibly ignore additional
3382 whitespace-separated tokens on each input line.
3384 And the rewriter may return a rewritten URL. The other components of
3385 the request line does not need to be returned (ignored if they are).
3387 The rewriter can also indicate that a client-side redirect should
3388 be performed to the new URL. This is done by prefixing the returned
3389 URL with "301:" (moved permanently) or 302: (moved temporarily).
3391 By default, a URL rewriter is not used.
3394 NAME: url_rewrite_children redirect_children
3395 TYPE: HelperChildConfig
3396 DEFAULT: 20 startup=0 idle=1 concurrency=0
3397 LOC: Config.redirectChildren
3399 The maximum number of redirector processes to spawn. If you limit
3400 it too few Squid will have to wait for them to process a backlog of
3401 URLs, slowing it down. If you allow too many they will use RAM
3402 and other system resources noticably.
3404 The startup= and idle= options allow some measure of skew in your
3409 Sets a minimum of how many processes are to be spawned when Squid
3410 starts or reconfigures. When set to zero the first request will
3411 cause spawning of the first child process to handle it.
3413 Starting too few will cause an initial slowdown in traffic as Squid
3414 attempts to simultaneously spawn enough processes to cope.
3418 Sets a minimum of how many processes Squid is to try and keep available
3419 at all times. When traffic begins to rise above what the existing
3420 processes can handle this many more will be spawned up to the maximum
3421 configured. A minimum setting of 1 is required.
3425 The number of requests each redirector helper can handle in
3426 parallel. Defaults to 0 which indicates the redirector
3427 is a old-style single threaded redirector.
3429 When this directive is set to a value >= 1 then the protocol
3430 used to communicate with the helper is modified to include
3431 a request ID in front of the request/response. The request
3432 ID from the request must be echoed back with the response
3436 NAME: url_rewrite_host_header redirect_rewrites_host_header
3439 LOC: Config.onoff.redir_rewrites_host
3441 By default Squid rewrites any Host: header in redirected
3442 requests. If you are running an accelerator this may
3443 not be a wanted effect of a redirector.
3445 WARNING: Entries are cached on the result of the URL rewriting
3446 process, so be careful if you have domain-virtual hosts.
3449 NAME: url_rewrite_access redirector_access
3452 LOC: Config.accessList.redirector
3454 If defined, this access list specifies which requests are
3455 sent to the redirector processes. By default all requests
3458 This clause supports both fast and slow acl types.
3459 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3462 NAME: url_rewrite_bypass redirector_bypass
3464 LOC: Config.onoff.redirector_bypass
3467 When this is 'on', a request will not go through the
3468 redirector if all redirectors are busy. If this is 'off'
3469 and the redirector queue grows too large, Squid will exit
3470 with a FATAL error and ask you to increase the number of
3471 redirectors. You should only enable this if the redirectors
3472 are not critical to your caching system. If you use
3473 redirectors for access control, and you enable this option,
3474 users may have access to pages they should not
3475 be allowed to request.
3479 OPTIONS FOR TUNING THE CACHE
3480 -----------------------------------------------------------------------------
3483 NAME: cache no_cache
3486 LOC: Config.accessList.noCache
3488 A list of ACL elements which, if matched and denied, cause the request to
3489 not be satisfied from the cache and the reply to not be cached.
3490 In other words, use this to force certain objects to never be cached.
3492 You must use the words 'allow' or 'deny' to indicate whether items
3493 matching the ACL should be allowed or denied into the cache.
3495 Default is to allow all to be cached.
3497 This clause supports both fast and slow acl types.
3498 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3501 NAME: refresh_pattern
3502 TYPE: refreshpattern
3506 usage: refresh_pattern [-i] regex min percent max [options]
3508 By default, regular expressions are CASE-SENSITIVE. To make
3509 them case-insensitive, use the -i option.
3511 'Min' is the time (in minutes) an object without an explicit
3512 expiry time should be considered fresh. The recommended
3513 value is 0, any higher values may cause dynamic applications
3514 to be erroneously cached unless the application designer
3515 has taken the appropriate actions.
3517 'Percent' is a percentage of the objects age (time since last
3518 modification age) an object without explicit expiry time
3519 will be considered fresh.
3521 'Max' is an upper limit on how long objects without an explicit
3522 expiry time will be considered fresh.
3524 options: override-expire
3530 ignore-must-revalidate
3536 override-expire enforces min age even if the server
3537 sent an explicit expiry time (e.g., with the
3538 Expires: header or Cache-Control: max-age). Doing this
3539 VIOLATES the HTTP standard. Enabling this feature
3540 could make you liable for problems which it causes.
3542 Note: override-expire does not enforce staleness - it only extends
3543 freshness / min. If the server returns a Expires time which
3544 is longer than your max time, Squid will still consider
3545 the object fresh for that period of time.
3547 override-lastmod enforces min age even on objects
3548 that were modified recently.
3550 reload-into-ims changes client no-cache or ``reload''
3551 to If-Modified-Since requests. Doing this VIOLATES the
3552 HTTP standard. Enabling this feature could make you
3553 liable for problems which it causes.
3555 ignore-reload ignores a client no-cache or ``reload''
3556 header. Doing this VIOLATES the HTTP standard. Enabling
3557 this feature could make you liable for problems which
3560 ignore-no-cache ignores any ``Pragma: no-cache'' and
3561 ``Cache-control: no-cache'' headers received from a server.
3562 The HTTP RFC never allows the use of this (Pragma) header
3563 from a server, only a client, though plenty of servers
3566 ignore-no-store ignores any ``Cache-control: no-store''
3567 headers received from a server. Doing this VIOLATES
3568 the HTTP standard. Enabling this feature could make you
3569 liable for problems which it causes.
3571 ignore-must-revalidate ignores any ``Cache-Control: must-revalidate``
3572 headers received from a server. Doing this VIOLATES
3573 the HTTP standard. Enabling this feature could make you
3574 liable for problems which it causes.
3576 ignore-private ignores any ``Cache-control: private''
3577 headers received from a server. Doing this VIOLATES
3578 the HTTP standard. Enabling this feature could make you
3579 liable for problems which it causes.
3581 ignore-auth caches responses to requests with authorization,
3582 as if the originserver had sent ``Cache-control: public''
3583 in the response header. Doing this VIOLATES the HTTP standard.
3584 Enabling this feature could make you liable for problems which
3587 refresh-ims causes squid to contact the origin server
3588 when a client issues an If-Modified-Since request. This
3589 ensures that the client will receive an updated version
3590 if one is available.
3592 store-stale stores responses even if they don't have explicit
3593 freshness or a validator (i.e., Last-Modified or an ETag)
3594 present, or if they're already stale. By default, Squid will
3595 not cache such responses because they usually can't be
3596 reused. Note that such responses will be stale by default.
3598 Basically a cached object is:
3600 FRESH if expires < now, else STALE
3602 FRESH if lm-factor < percent, else STALE
3606 The refresh_pattern lines are checked in the order listed here.
3607 The first entry which matches is used. If none of the entries
3608 match the default will be used.
3610 Note, you must uncomment all the default lines if you want
3611 to change one. The default setting is only active if none is
3616 # Add any of your own refresh_pattern entries above these.
3617 refresh_pattern ^ftp: 1440 20% 10080
3618 refresh_pattern ^gopher: 1440 0% 1440
3619 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
3620 refresh_pattern . 0 20% 4320
3624 NAME: quick_abort_min
3628 LOC: Config.quickAbort.min
3631 NAME: quick_abort_max
3635 LOC: Config.quickAbort.max
3638 NAME: quick_abort_pct
3642 LOC: Config.quickAbort.pct
3644 The cache by default continues downloading aborted requests
3645 which are almost completed (less than 16 KB remaining). This
3646 may be undesirable on slow (e.g. SLIP) links and/or very busy
3647 caches. Impatient users may tie up file descriptors and
3648 bandwidth by repeatedly requesting and immediately aborting
3651 When the user aborts a request, Squid will check the
3652 quick_abort values to the amount of data transfered until
3655 If the transfer has less than 'quick_abort_min' KB remaining,
3656 it will finish the retrieval.
3658 If the transfer has more than 'quick_abort_max' KB remaining,
3659 it will abort the retrieval.
3661 If more than 'quick_abort_pct' of the transfer has completed,
3662 it will finish the retrieval.
3664 If you do not want any retrieval to continue after the client
3665 has aborted, set both 'quick_abort_min' and 'quick_abort_max'
3668 If you want retrievals to always continue if they are being
3669 cached set 'quick_abort_min' to '-1 KB'.
3672 NAME: read_ahead_gap
3673 COMMENT: buffer-size
3675 LOC: Config.readAheadGap
3678 The amount of data the cache will buffer ahead of what has been
3679 sent to the client when retrieving an object from another server.
3683 IFDEF: HTTP_VIOLATIONS
3686 LOC: Config.negativeTtl
3689 Set the Default Time-to-Live (TTL) for failed requests.
3690 Certain types of failures (such as "connection refused" and
3691 "404 Not Found") are able to be negatively-cached for a short time.
3692 Modern web servers should provide Expires: header, however if they
3693 do not this can provide a minimum TTL.
3694 The default is not to cache errors with unknown expiry details.
3696 Note that this is different from negative caching of DNS lookups.
3698 WARNING: Doing this VIOLATES the HTTP standard. Enabling
3699 this feature could make you liable for problems which it
3703 NAME: positive_dns_ttl
3706 LOC: Config.positiveDnsTtl
3709 Upper limit on how long Squid will cache positive DNS responses.
3710 Default is 6 hours (360 minutes). This directive must be set
3711 larger than negative_dns_ttl.
3714 NAME: negative_dns_ttl
3717 LOC: Config.negativeDnsTtl
3720 Time-to-Live (TTL) for negative caching of failed DNS lookups.
3721 This also sets the lower cache limit on positive lookups.
3722 Minimum value is 1 second, and it is not recommendable to go
3723 much below 10 seconds.
3726 NAME: range_offset_limit
3727 COMMENT: size [acl acl...]
3729 LOC: Config.rangeOffsetLimit
3732 usage: (size) [units] [[!]aclname]
3734 Sets an upper limit on how far (number of bytes) into the file
3735 a Range request may be to cause Squid to prefetch the whole file.
3736 If beyond this limit, Squid forwards the Range request as it is and
3737 the result is NOT cached.
3739 This is to stop a far ahead range request (lets say start at 17MB)
3740 from making Squid fetch the whole object up to that point before
3741 sending anything to the client.
3743 Multiple range_offset_limit lines may be specified, and they will
3744 be searched from top to bottom on each request until a match is found.
3745 The first match found will be used. If no line matches a request, the
3746 default limit of 0 bytes will be used.
3748 'size' is the limit specified as a number of units.
3750 'units' specifies whether to use bytes, KB, MB, etc.
3751 If no units are specified bytes are assumed.
3753 A size of 0 causes Squid to never fetch more than the
3754 client requested. (default)
3756 A size of 'none' causes Squid to always fetch the object from the
3757 beginning so it may cache the result. (2.0 style)
3759 'aclname' is the name of a defined ACL.
3761 NP: Using 'none' as the byte value here will override any quick_abort settings
3762 that may otherwise apply to the range request. The range request will
3763 be fully fetched from start to finish regardless of the client
3764 actions. This affects bandwidth usage.
3767 NAME: minimum_expiry_time
3770 LOC: Config.minimum_expiry_time
3773 The minimum caching time according to (Expires - Date)
3774 Headers Squid honors if the object can't be revalidated
3775 defaults to 60 seconds. In reverse proxy environments it
3776 might be desirable to honor shorter object lifetimes. It
3777 is most likely better to make your server return a
3778 meaningful Last-Modified header however. In ESI environments
3779 where page fragments often have short lifetimes, this will
3780 often be best set to 0.
3783 NAME: store_avg_object_size
3787 LOC: Config.Store.avgObjectSize
3789 Average object size, used to estimate number of objects your
3790 cache can hold. The default is 13 KB.
3793 NAME: store_objects_per_bucket
3796 LOC: Config.Store.objectsPerBucket
3798 Target number of objects per bucket in the store hash table.
3799 Lowering this value increases the total number of buckets and
3800 also the storage maintenance rate. The default is 20.
3805 -----------------------------------------------------------------------------
3808 NAME: request_header_max_size
3812 LOC: Config.maxRequestHeaderSize
3814 This specifies the maximum size for HTTP headers in a request.
3815 Request headers are usually relatively small (about 512 bytes).
3816 Placing a limit on the request header size will catch certain
3817 bugs (for example with persistent connections) and possibly
3818 buffer-overflow or denial-of-service attacks.
3821 NAME: reply_header_max_size
3825 LOC: Config.maxReplyHeaderSize
3827 This specifies the maximum size for HTTP headers in a reply.
3828 Reply headers are usually relatively small (about 512 bytes).
3829 Placing a limit on the reply header size will catch certain
3830 bugs (for example with persistent connections) and possibly
3831 buffer-overflow or denial-of-service attacks.
3834 NAME: request_body_max_size
3838 LOC: Config.maxRequestBodySize
3840 This specifies the maximum size for an HTTP request body.
3841 In other words, the maximum size of a PUT/POST request.
3842 A user who attempts to send a request with a body larger
3843 than this limit receives an "Invalid Request" error message.
3844 If you set this parameter to a zero (the default), there will
3845 be no limit imposed.
3848 NAME: chunked_request_body_max_size
3852 LOC: Config.maxChunkedRequestBodySize
3854 A broken or confused HTTP/1.1 client may send a chunked HTTP
3855 request to Squid. Squid does not have full support for that
3856 feature yet. To cope with such requests, Squid buffers the
3857 entire request and then dechunks request body to create a
3858 plain HTTP/1.0 request with a known content length. The plain
3859 request is then used by the rest of Squid code as usual.
3861 The option value specifies the maximum size of the buffer used
3862 to hold the request before the conversion. If the chunked
3863 request size exceeds the specified limit, the conversion
3864 fails, and the client receives an "unsupported request" error,
3865 as if dechunking was disabled.
3867 Dechunking is enabled by default. To disable conversion of
3868 chunked requests, set the maximum to zero.
3870 Request dechunking feature and this option in particular are a
3871 temporary hack. When chunking requests and responses are fully
3872 supported, there will be no need to buffer a chunked request.
3876 IFDEF: HTTP_VIOLATIONS
3879 LOC: Config.accessList.brokenPosts
3881 A list of ACL elements which, if matched, causes Squid to send
3882 an extra CRLF pair after the body of a PUT/POST request.
3884 Some HTTP servers has broken implementations of PUT/POST,
3885 and rely on an extra CRLF pair sent by some WWW clients.
3887 Quote from RFC2616 section 4.1 on this matter:
3889 Note: certain buggy HTTP/1.0 client implementations generate an
3890 extra CRLF's after a POST request. To restate what is explicitly
3891 forbidden by the BNF, an HTTP/1.1 client must not preface or follow
3892 a request with an extra CRLF.
3894 This clause only supports fast acl types.
3895 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3898 acl buggy_server url_regex ^http://....
3899 broken_posts allow buggy_server
3902 NAME: icap_uses_indirect_client
3905 IFDEF: FOLLOW_X_FORWARDED_FOR&&ICAP_CLIENT
3907 LOC: Adaptation::Icap::TheConfig.icap_uses_indirect_client
3909 Controls whether the indirect client address
3910 (see follow_x_forwarded_for) instead of the
3911 direct client address is passed to an ICAP
3912 server as "X-Client-IP".
3916 IFDEF: HTTP_VIOLATIONS
3920 LOC: Config.onoff.via
3922 If set (default), Squid will include a Via header in requests and
3923 replies as required by RFC2616.
3929 LOC: Config.onoff.ie_refresh
3932 Microsoft Internet Explorer up until version 5.5 Service
3933 Pack 1 has an issue with transparent proxies, wherein it
3934 is impossible to force a refresh. Turning this on provides
3935 a partial fix to the problem, by causing all IMS-REFRESH
3936 requests from older IE versions to check the origin server
3937 for fresh content. This reduces hit ratio by some amount
3938 (~10% in my experience), but allows users to actually get
3939 fresh content when they want it. Note because Squid
3940 cannot tell if the user is using 5.5 or 5.5SP1, the behavior
3941 of 5.5 is unchanged from old versions of Squid (i.e. a
3942 forced refresh is impossible). Newer versions of IE will,
3943 hopefully, continue to have the new behavior and will be
3944 handled based on that assumption. This option defaults to
3945 the old Squid behavior, which is better for hit ratios but
3946 worse for clients using IE, if they need to be able to
3947 force fresh content.
3950 NAME: vary_ignore_expire
3953 LOC: Config.onoff.vary_ignore_expire
3956 Many HTTP servers supporting Vary gives such objects
3957 immediate expiry time with no cache-control header
3958 when requested by a HTTP/1.0 client. This option
3959 enables Squid to ignore such expiry times until
3960 HTTP/1.1 is fully implemented.
3962 WARNING: If turned on this may eventually cause some
3963 varying objects not intended for caching to get cached.
3966 NAME: request_entities
3968 LOC: Config.onoff.request_entities
3971 Squid defaults to deny GET and HEAD requests with request entities,
3972 as the meaning of such requests are undefined in the HTTP standard
3973 even if not explicitly forbidden.
3975 Set this directive to on if you have clients which insists
3976 on sending request entities in GET or HEAD requests. But be warned
3977 that there is server software (both proxies and web servers) which
3978 can fail to properly process this kind of request which may make you
3979 vulnerable to cache pollution attacks if enabled.
3982 NAME: request_header_access
3983 IFDEF: HTTP_VIOLATIONS
3984 TYPE: http_header_access[]
3985 LOC: Config.request_header_access
3988 Usage: request_header_access header_name allow|deny [!]aclname ...
3990 WARNING: Doing this VIOLATES the HTTP standard. Enabling
3991 this feature could make you liable for problems which it
3994 This option replaces the old 'anonymize_headers' and the
3995 older 'http_anonymizer' option with something that is much
3996 more configurable. This new method creates a list of ACLs
3997 for each header, allowing you very fine-tuned header
4000 This option only applies to request headers, i.e., from the
4001 client to the server.
4003 You can only specify known headers for the header name.
4004 Other headers are reclassified as 'Other'. You can also
4005 refer to all the headers with 'All'.
4007 For example, to achieve the same behavior as the old
4008 'http_anonymizer standard' option, you should use:
4010 request_header_access From deny all
4011 request_header_access Referer deny all
4012 request_header_access Server deny all
4013 request_header_access User-Agent deny all
4014 request_header_access WWW-Authenticate deny all
4015 request_header_access Link deny all
4017 Or, to reproduce the old 'http_anonymizer paranoid' feature
4020 request_header_access Allow allow all
4021 request_header_access Authorization allow all
4022 request_header_access WWW-Authenticate allow all
4023 request_header_access Proxy-Authorization allow all
4024 request_header_access Proxy-Authenticate allow all
4025 request_header_access Cache-Control allow all
4026 request_header_access Content-Encoding allow all
4027 request_header_access Content-Length allow all
4028 request_header_access Content-Type allow all
4029 request_header_access Date allow all
4030 request_header_access Expires allow all
4031 request_header_access Host allow all
4032 request_header_access If-Modified-Since allow all
4033 request_header_access Last-Modified allow all
4034 request_header_access Location allow all
4035 request_header_access Pragma allow all
4036 request_header_access Accept allow all
4037 request_header_access Accept-Charset allow all
4038 request_header_access Accept-Encoding allow all
4039 request_header_access Accept-Language allow all
4040 request_header_access Content-Language allow all
4041 request_header_access Mime-Version allow all
4042 request_header_access Retry-After allow all
4043 request_header_access Title allow all
4044 request_header_access Connection allow all
4045 request_header_access Proxy-Connection allow all
4046 request_header_access All deny all
4048 although many of those are HTTP reply headers, and so should be
4049 controlled with the reply_header_access directive.
4051 By default, all headers are allowed (no anonymizing is
4055 NAME: reply_header_access
4056 IFDEF: HTTP_VIOLATIONS
4057 TYPE: http_header_access[]
4058 LOC: Config.reply_header_access
4061 Usage: reply_header_access header_name allow|deny [!]aclname ...
4063 WARNING: Doing this VIOLATES the HTTP standard. Enabling
4064 this feature could make you liable for problems which it
4067 This option only applies to reply headers, i.e., from the
4068 server to the client.
4070 This is the same as request_header_access, but in the other
4073 This option replaces the old 'anonymize_headers' and the
4074 older 'http_anonymizer' option with something that is much
4075 more configurable. This new method creates a list of ACLs
4076 for each header, allowing you very fine-tuned header
4079 You can only specify known headers for the header name.
4080 Other headers are reclassified as 'Other'. You can also
4081 refer to all the headers with 'All'.
4083 For example, to achieve the same behavior as the old
4084 'http_anonymizer standard' option, you should use:
4086 reply_header_access From deny all
4087 reply_header_access Referer deny all
4088 reply_header_access Server deny all
4089 reply_header_access User-Agent deny all
4090 reply_header_access WWW-Authenticate deny all
4091 reply_header_access Link deny all
4093 Or, to reproduce the old 'http_anonymizer paranoid' feature
4096 reply_header_access Allow allow all
4097 reply_header_access Authorization allow all
4098 reply_header_access WWW-Authenticate allow all
4099 reply_header_access Proxy-Authorization allow all
4100 reply_header_access Proxy-Authenticate allow all
4101 reply_header_access Cache-Control allow all
4102 reply_header_access Content-Encoding allow all
4103 reply_header_access Content-Length allow all
4104 reply_header_access Content-Type allow all
4105 reply_header_access Date allow all
4106 reply_header_access Expires allow all
4107 reply_header_access Host allow all
4108 reply_header_access If-Modified-Since allow all
4109 reply_header_access Last-Modified allow all
4110 reply_header_access Location allow all
4111 reply_header_access Pragma allow all
4112 reply_header_access Accept allow all
4113 reply_header_access Accept-Charset allow all
4114 reply_header_access Accept-Encoding allow all
4115 reply_header_access Accept-Language allow all
4116 reply_header_access Content-Language allow all
4117 reply_header_access Mime-Version allow all
4118 reply_header_access Retry-After allow all
4119 reply_header_access Title allow all
4120 reply_header_access Connection allow all
4121 reply_header_access Proxy-Connection allow all
4122 reply_header_access All deny all
4124 although the HTTP request headers won't be usefully controlled
4125 by this directive -- see request_header_access for details.
4127 By default, all headers are allowed (no anonymizing is
4131 NAME: header_replace
4132 IFDEF: HTTP_VIOLATIONS
4133 TYPE: http_header_replace[]
4134 LOC: Config.request_header_access
4137 Usage: header_replace header_name message
4138 Example: header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit)
4140 This option allows you to change the contents of headers
4141 denied with header_access above, by replacing them with
4142 some fixed string. This replaces the old fake_user_agent
4145 This only applies to request headers, not reply headers.
4147 By default, headers are removed if denied.
4150 NAME: relaxed_header_parser
4151 COMMENT: on|off|warn
4153 LOC: Config.onoff.relaxed_header_parser
4156 In the default "on" setting Squid accepts certain forms
4157 of non-compliant HTTP messages where it is unambiguous
4158 what the sending application intended even if the message
4159 is not correctly formatted. The messages is then normalized
4160 to the correct form when forwarded by Squid.
4162 If set to "warn" then a warning will be emitted in cache.log
4163 each time such HTTP error is encountered.
4165 If set to "off" then such HTTP errors will cause the request
4166 or response to be rejected.
4169 NAME: ignore_expect_100
4171 IFDEF: HTTP_VIOLATIONS
4173 LOC: Config.onoff.ignore_expect_100
4176 This option makes Squid ignore any Expect: 100-continue header present
4177 in the request. RFC 2616 requires that Squid being unable to satisfy
4178 the response expectation MUST return a 417 error.
4180 Note: Enabling this is a HTTP protocol violation, but some clients may
4181 not handle it well..
4186 -----------------------------------------------------------------------------
4189 NAME: forward_timeout
4192 LOC: Config.Timeout.forward
4195 This parameter specifies how long Squid should at most attempt in
4196 finding a forwarding path for the request before giving up.
4199 NAME: connect_timeout
4202 LOC: Config.Timeout.connect
4205 This parameter specifies how long to wait for the TCP connect to
4206 the requested server or peer to complete before Squid should
4207 attempt to find another path where to forward the request.
4210 NAME: peer_connect_timeout
4213 LOC: Config.Timeout.peer_connect
4216 This parameter specifies how long to wait for a pending TCP
4217 connection to a peer cache. The default is 30 seconds. You
4218 may also set different timeout values for individual neighbors
4219 with the 'connect-timeout' option on a 'cache_peer' line.
4225 LOC: Config.Timeout.read
4228 The read_timeout is applied on server-side connections. After
4229 each successful read(), the timeout will be extended by this
4230 amount. If no data is read again after this amount of time,
4231 the request is aborted and logged with ERR_READ_TIMEOUT. The
4232 default is 15 minutes.
4238 LOC: Config.Timeout.write
4241 This timeout is tracked for all connections that have data
4242 available for writing and are waiting for the socket to become
4243 ready. After each successful write, the timeout is extended by
4244 the configured amount. If Squid has data to write but the
4245 connection is not ready for the configured duration, the
4246 transaction associated with the connection is terminated. The
4247 default is 15 minutes.
4250 NAME: request_timeout
4252 LOC: Config.Timeout.request
4255 How long to wait for an HTTP request after initial
4256 connection establishment.
4259 NAME: persistent_request_timeout
4261 LOC: Config.Timeout.persistent_request
4264 How long to wait for the next HTTP request on a persistent
4265 connection after the previous request completes.
4268 NAME: client_lifetime
4271 LOC: Config.Timeout.lifetime
4274 The maximum amount of time a client (browser) is allowed to
4275 remain connected to the cache process. This protects the Cache
4276 from having a lot of sockets (and hence file descriptors) tied up
4277 in a CLOSE_WAIT state from remote clients that go away without
4278 properly shutting down (either because of a network failure or
4279 because of a poor client implementation). The default is one
4282 NOTE: The default value is intended to be much larger than any
4283 client would ever need to be connected to your cache. You
4284 should probably change client_lifetime only as a last resort.
4285 If you seem to have many client connections tying up
4286 filedescriptors, we recommend first tuning the read_timeout,
4287 request_timeout, persistent_request_timeout and quick_abort values.
4290 NAME: half_closed_clients
4292 LOC: Config.onoff.half_closed_clients
4295 Some clients may shutdown the sending side of their TCP
4296 connections, while leaving their receiving sides open. Sometimes,
4297 Squid can not tell the difference between a half-closed and a
4298 fully-closed TCP connection.
4300 By default, Squid will immediately close client connections when
4301 read(2) returns "no more data to read."
4303 Change this option to 'on' and Squid will keep open connections
4304 until a read(2) or write(2) on the socket returns an error.
4305 This may show some benefits for reverse proxies. But if not
4306 it is recommended to leave OFF.
4311 LOC: Config.Timeout.pconn
4314 Timeout for idle persistent connections to servers and other
4321 LOC: Ident::TheConfig.timeout
4324 Maximum time to wait for IDENT lookups to complete.
4326 If this is too high, and you enabled IDENT lookups from untrusted
4327 users, you might be susceptible to denial-of-service by having
4328 many ident requests going at once.
4331 NAME: shutdown_lifetime
4334 LOC: Config.shutdownLifetime
4337 When SIGTERM or SIGHUP is received, the cache is put into
4338 "shutdown pending" mode until all active sockets are closed.
4339 This value is the lifetime to set for all open descriptors
4340 during shutdown mode. Any active clients after this many
4341 seconds will receive a 'timeout' message.
4345 ADMINISTRATIVE PARAMETERS
4346 -----------------------------------------------------------------------------
4352 LOC: Config.adminEmail
4354 Email-address of local cache manager who will receive
4355 mail if the cache dies. The default is "webmaster."
4361 LOC: Config.EmailFrom
4363 From: email-address for mail sent when the cache dies.
4364 The default is to use 'appname@unique_hostname'.
4365 Default appname value is "squid", can be changed into
4366 src/globals.h before building squid.
4372 LOC: Config.EmailProgram
4374 Email program used to send mail if the cache dies.
4375 The default is "mail". The specified program must comply
4376 with the standard Unix mail syntax:
4377 mail-program recipient < mailfile
4379 Optional command line options can be specified.
4382 NAME: cache_effective_user
4384 DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@
4385 LOC: Config.effectiveUser
4387 If you start Squid as root, it will change its effective/real
4388 UID/GID to the user specified below. The default is to change
4389 to UID of @DEFAULT_CACHE_EFFECTIVE_USER@.
4390 see also; cache_effective_group
4393 NAME: cache_effective_group
4396 LOC: Config.effectiveGroup
4398 Squid sets the GID to the effective user's default group ID
4399 (taken from the password file) and supplementary group list
4400 from the groups membership.
4402 If you want Squid to run with a specific GID regardless of
4403 the group memberships of the effective user then set this
4404 to the group (or GID) you want Squid to run as. When set
4405 all other group privileges of the effective user are ignored
4406 and only this GID is effective. If Squid is not started as
4407 root the user starting Squid MUST be member of the specified
4410 This option is not recommended by the Squid Team.
4411 Our preference is for administrators to configure a secure
4412 user account for squid with UID/GID matching system policies.
4415 NAME: httpd_suppress_version_string
4419 LOC: Config.onoff.httpd_suppress_version_string
4421 Suppress Squid version string info in HTTP headers and HTML error pages.
4424 NAME: visible_hostname
4426 LOC: Config.visibleHostname
4429 If you want to present a special hostname in error messages, etc,
4430 define this. Otherwise, the return value of gethostname()
4431 will be used. If you have multiple caches in a cluster and
4432 get errors about IP-forwarding you must set them to have individual
4433 names with this setting.
4436 NAME: unique_hostname
4438 LOC: Config.uniqueHostname
4441 If you want to have multiple machines with the same
4442 'visible_hostname' you must give each machine a different
4443 'unique_hostname' so forwarding loops can be detected.
4446 NAME: hostname_aliases
4448 LOC: Config.hostnameAliases
4451 A list of other DNS names your cache has.
4459 Minimum umask which should be enforced while the proxy
4460 is running, in addition to the umask set at startup.
4462 For a traditional octal representation of umasks, start
4467 OPTIONS FOR THE CACHE REGISTRATION SERVICE
4468 -----------------------------------------------------------------------------
4470 This section contains parameters for the (optional) cache
4471 announcement service. This service is provided to help
4472 cache administrators locate one another in order to join or
4473 create cache hierarchies.
4475 An 'announcement' message is sent (via UDP) to the registration
4476 service by Squid. By default, the announcement message is NOT
4477 SENT unless you enable it with 'announce_period' below.
4479 The announcement message includes your hostname, plus the
4480 following information from this configuration file:
4486 All current information is processed regularly and made
4487 available on the Web at http://www.ircache.net/Cache/Tracker/.
4490 NAME: announce_period
4492 LOC: Config.Announce.period
4495 This is how frequently to send cache announcements. The
4496 default is `0' which disables sending the announcement
4499 To enable announcing your cache, just set an announce period.
4502 announce_period 1 day
4507 DEFAULT: tracker.ircache.net
4508 LOC: Config.Announce.host
4514 LOC: Config.Announce.file
4520 LOC: Config.Announce.port
4522 announce_host and announce_port set the hostname and port
4523 number where the registration message will be sent.
4525 Hostname will default to 'tracker.ircache.net' and port will
4526 default default to 3131. If the 'filename' argument is given,
4527 the contents of that file will be included in the announce
4532 HTTPD-ACCELERATOR OPTIONS
4533 -----------------------------------------------------------------------------
4536 NAME: httpd_accel_surrogate_id
4539 LOC: Config.Accel.surrogate_id
4541 Surrogates (http://www.esi.org/architecture_spec_1.0.html)
4542 need an identification token to allow control targeting. Because
4543 a farm of surrogates may all perform the same tasks, they may share
4544 an identification token.
4546 The default ID is the visible_hostname
4549 NAME: http_accel_surrogate_remote
4553 LOC: Config.onoff.surrogate_is_remote
4555 Remote surrogates (such as those in a CDN) honour Surrogate-Control: no-store-remote.
4556 Set this to on to have squid behave as a remote surrogate.
4560 IFDEF: USE_SQUID_ESI
4561 COMMENT: libxml2|expat|custom
4563 LOC: ESIParser::Type
4566 ESI markup is not strictly XML compatible. The custom ESI parser
4567 will give higher performance, but cannot handle non ASCII character
4572 DELAY POOL PARAMETERS
4573 -----------------------------------------------------------------------------
4577 TYPE: delay_pool_count
4582 This represents the number of delay pools to be used. For example,
4583 if you have one class 2 delay pool and one class 3 delays pool, you
4584 have a total of 2 delay pools.
4588 TYPE: delay_pool_class
4593 This defines the class of each delay pool. There must be exactly one
4594 delay_class line for each delay pool. For example, to define two
4595 delay pools, one of class 2 and one of class 3, the settings above
4599 delay_pools 4 # 4 delay pools
4600 delay_class 1 2 # pool 1 is a class 2 pool
4601 delay_class 2 3 # pool 2 is a class 3 pool
4602 delay_class 3 4 # pool 3 is a class 4 pool
4603 delay_class 4 5 # pool 4 is a class 5 pool
4605 The delay pool classes are:
4607 class 1 Everything is limited by a single aggregate
4610 class 2 Everything is limited by a single aggregate
4611 bucket as well as an "individual" bucket chosen
4612 from bits 25 through 32 of the IPv4 address.
4614 class 3 Everything is limited by a single aggregate
4615 bucket as well as a "network" bucket chosen
4616 from bits 17 through 24 of the IP address and a
4617 "individual" bucket chosen from bits 17 through
4618 32 of the IPv4 address.
4620 class 4 Everything in a class 3 delay pool, with an
4621 additional limit on a per user basis. This
4622 only takes effect if the username is established
4623 in advance - by forcing authentication in your
4626 class 5 Requests are grouped according their tag (see
4627 external_acl's tag= reply).
4629 NOTE: If an IP address is a.b.c.d
4630 -> bits 25 through 32 are "d"
4631 -> bits 17 through 24 are "c"
4632 -> bits 17 through 32 are "c * 256 + d"
4634 NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to
4635 IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic.
4639 TYPE: delay_pool_access
4644 This is used to determine which delay pool a request falls into.
4646 delay_access is sorted per pool and the matching starts with pool 1,
4647 then pool 2, ..., and finally pool N. The first delay pool where the
4648 request is allowed is selected for the request. If it does not allow
4649 the request to any pool then the request is not delayed (default).
4651 For example, if you want some_big_clients in delay
4652 pool 1 and lotsa_little_clients in delay pool 2:
4655 delay_access 1 allow some_big_clients
4656 delay_access 1 deny all
4657 delay_access 2 allow lotsa_little_clients
4658 delay_access 2 deny all
4659 delay_access 3 allow authenticated_clients
4662 NAME: delay_parameters
4663 TYPE: delay_pool_rates
4668 This defines the parameters for a delay pool. Each delay pool has
4669 a number of "buckets" associated with it, as explained in the
4670 description of delay_class. For a class 1 delay pool, the syntax is:
4672 delay_parameters pool aggregate
4674 For a class 2 delay pool:
4676 delay_parameters pool aggregate individual
4678 For a class 3 delay pool:
4680 delay_parameters pool aggregate network individual
4682 For a class 4 delay pool:
4684 delay_parameters pool aggregate network individual user
4686 For a class 5 delay pool:
4688 delay_parameters pool tag
4690 The variables here are:
4692 pool a pool number - ie, a number between 1 and the
4693 number specified in delay_pools as used in
4696 aggregate the "delay parameters" for the aggregate bucket
4699 individual the "delay parameters" for the individual
4700 buckets (class 2, 3).
4702 network the "delay parameters" for the network buckets
4705 user the delay parameters for the user buckets
4708 tag the delay parameters for the tag buckets
4711 A pair of delay parameters is written restore/maximum, where restore is
4712 the number of bytes (not bits - modem and network speeds are usually
4713 quoted in bits) per second placed into the bucket, and maximum is the
4714 maximum number of bytes which can be in the bucket at any time.
4716 For example, if delay pool number 1 is a class 2 delay pool as in the
4717 above example, and is being used to strictly limit each host to 64kbps
4718 (plus overheads), with no overall limit, the line is:
4720 delay_parameters 1 -1/-1 8000/8000
4722 Note that the figure -1 is used to represent "unlimited".
4724 And, if delay pool number 2 is a class 3 delay pool as in the above
4725 example, and you want to limit it to a total of 256kbps (strict limit)
4726 with each 8-bit network permitted 64kbps (strict limit) and each
4727 individual host permitted 4800bps with a bucket maximum size of 64kb
4728 to permit a decent web page to be downloaded at a decent speed
4729 (if the network is not being limited due to overuse) but slow down
4730 large downloads more significantly:
4732 delay_parameters 2 32000/32000 8000/8000 600/8000
4734 There must be one delay_parameters line for each delay pool.
4736 Finally, for a class 4 delay pool as in the example - each user will
4737 be limited to 128Kb no matter how many workstations they are logged into.:
4739 delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000
4742 NAME: delay_initial_bucket_level
4743 COMMENT: (percent, 0-100)
4747 LOC: Config.Delay.initial
4749 The initial bucket percentage is used to determine how much is put
4750 in each bucket when squid starts, is reconfigured, or first notices
4751 a host accessing it (in class 2 and class 3, individual hosts and
4752 networks only have buckets associated with them once they have been
4757 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS
4758 -----------------------------------------------------------------------------
4763 LOC: Config.Wccp.router
4767 Use this option to define your WCCP ``home'' router for
4770 wccp_router supports a single WCCP(v1) router
4772 wccp2_router supports multiple WCCPv2 routers
4774 only one of the two may be used at the same time and defines
4775 which version of WCCP to use.
4779 TYPE: IpAddress_list
4780 LOC: Config.Wccp2.router
4784 Use this option to define your WCCP ``home'' router for
4787 wccp_router supports a single WCCP(v1) router
4789 wccp2_router supports multiple WCCPv2 routers
4791 only one of the two may be used at the same time and defines
4792 which version of WCCP to use.
4797 LOC: Config.Wccp.version
4801 This directive is only relevant if you need to set up WCCP(v1)
4802 to some very old and end-of-life Cisco routers. In all other
4803 setups it must be left unset or at the default setting.
4804 It defines an internal version in the WCCP(v1) protocol,
4805 with version 4 being the officially documented protocol.
4807 According to some users, Cisco IOS 11.2 and earlier only
4808 support WCCP version 3. If you're using that or an earlier
4809 version of IOS, you may need to change this value to 3, otherwise
4810 do not specify this parameter.
4813 NAME: wccp2_rebuild_wait
4815 LOC: Config.Wccp2.rebuildwait
4819 If this is enabled Squid will wait for the cache dir rebuild to finish
4820 before sending the first wccp2 HereIAm packet
4823 NAME: wccp2_forwarding_method
4825 LOC: Config.Wccp2.forwarding_method
4829 WCCP2 allows the setting of forwarding methods between the
4830 router/switch and the cache. Valid values are as follows:
4832 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
4833 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
4835 Currently (as of IOS 12.4) cisco routers only support GRE.
4836 Cisco switches only support the L2 redirect assignment method.
4839 NAME: wccp2_return_method
4841 LOC: Config.Wccp2.return_method
4845 WCCP2 allows the setting of return methods between the
4846 router/switch and the cache for packets that the cache
4847 decides not to handle. Valid values are as follows:
4849 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
4850 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
4852 Currently (as of IOS 12.4) cisco routers only support GRE.
4853 Cisco switches only support the L2 redirect assignment.
4855 If the "ip wccp redirect exclude in" command has been
4856 enabled on the cache interface, then it is still safe for
4857 the proxy server to use a l2 redirect method even if this
4858 option is set to GRE.
4861 NAME: wccp2_assignment_method
4863 LOC: Config.Wccp2.assignment_method
4867 WCCP2 allows the setting of methods to assign the WCCP hash
4868 Valid values are as follows:
4870 hash - Hash assignment
4871 mask - Mask assignment
4873 As a general rule, cisco routers support the hash assignment method
4874 and cisco switches support the mask assignment method.
4879 LOC: Config.Wccp2.info
4881 DEFAULT_IF_NONE: standard 0
4884 WCCP2 allows for multiple traffic services. There are two
4885 types: "standard" and "dynamic". The standard type defines
4886 one service id - http (id 0). The dynamic service ids can be from
4887 51 to 255 inclusive. In order to use a dynamic service id
4888 one must define the type of traffic to be redirected; this is done
4889 using the wccp2_service_info option.
4891 The "standard" type does not require a wccp2_service_info option,
4892 just specifying the service id will suffice.
4894 MD5 service authentication can be enabled by adding
4895 "password=<password>" to the end of this service declaration.
4899 wccp2_service standard 0 # for the 'web-cache' standard service
4900 wccp2_service dynamic 80 # a dynamic service type which will be
4901 # fleshed out with subsequent options.
4902 wccp2_service standard 0 password=foo
4905 NAME: wccp2_service_info
4906 TYPE: wccp2_service_info
4907 LOC: Config.Wccp2.info
4911 Dynamic WCCPv2 services require further information to define the
4912 traffic you wish to have diverted.
4916 wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>..
4917 priority=<priority> ports=<port>,<port>..
4919 The relevant WCCPv2 flags:
4920 + src_ip_hash, dst_ip_hash
4921 + source_port_hash, dst_port_hash
4922 + src_ip_alt_hash, dst_ip_alt_hash
4923 + src_port_alt_hash, dst_port_alt_hash
4926 The port list can be one to eight entries.
4930 wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source
4931 priority=240 ports=80
4933 Note: the service id must have been defined by a previous
4934 'wccp2_service dynamic <id>' entry.
4939 LOC: Config.Wccp2.weight
4943 Each cache server gets assigned a set of the destination
4944 hash proportional to their weight.
4949 LOC: Config.Wccp.address
4956 LOC: Config.Wccp2.address
4960 Use this option if you require WCCP to use a specific
4963 The default behavior is to not bind to any specific address.
4967 PERSISTENT CONNECTION HANDLING
4968 -----------------------------------------------------------------------------
4970 Also see "pconn_timeout" in the TIMEOUTS section
4973 NAME: client_persistent_connections
4975 LOC: Config.onoff.client_pconns
4979 NAME: server_persistent_connections
4981 LOC: Config.onoff.server_pconns
4984 Persistent connection support for clients and servers. By
4985 default, Squid uses persistent connections (when allowed)
4986 with its clients and servers. You can use these options to
4987 disable persistent connections with clients and/or servers.
4990 NAME: persistent_connection_after_error
4992 LOC: Config.onoff.error_pconns
4995 With this directive the use of persistent connections after
4996 HTTP errors can be disabled. Useful if you have clients
4997 who fail to handle errors on persistent connections proper.
5000 NAME: detect_broken_pconn
5002 LOC: Config.onoff.detect_broken_server_pconns
5005 Some servers have been found to incorrectly signal the use
5006 of HTTP/1.0 persistent connections even on replies not
5007 compatible, causing significant delays. This server problem
5008 has mostly been seen on redirects.
5010 By enabling this directive Squid attempts to detect such
5011 broken replies and automatically assume the reply is finished
5012 after 10 seconds timeout.
5016 CACHE DIGEST OPTIONS
5017 -----------------------------------------------------------------------------
5020 NAME: digest_generation
5021 IFDEF: USE_CACHE_DIGESTS
5023 LOC: Config.onoff.digest_generation
5026 This controls whether the server will generate a Cache Digest
5027 of its contents. By default, Cache Digest generation is
5028 enabled if Squid is compiled with --enable-cache-digests defined.
5031 NAME: digest_bits_per_entry
5032 IFDEF: USE_CACHE_DIGESTS
5034 LOC: Config.digest.bits_per_entry
5037 This is the number of bits of the server's Cache Digest which
5038 will be associated with the Digest entry for a given HTTP
5039 Method and URL (public key) combination. The default is 5.
5042 NAME: digest_rebuild_period
5043 IFDEF: USE_CACHE_DIGESTS
5046 LOC: Config.digest.rebuild_period
5049 This is the wait time between Cache Digest rebuilds.
5052 NAME: digest_rewrite_period
5054 IFDEF: USE_CACHE_DIGESTS
5056 LOC: Config.digest.rewrite_period
5059 This is the wait time between Cache Digest writes to
5063 NAME: digest_swapout_chunk_size
5066 IFDEF: USE_CACHE_DIGESTS
5067 LOC: Config.digest.swapout_chunk_size
5070 This is the number of bytes of the Cache Digest to write to
5071 disk at a time. It defaults to 4096 bytes (4KB), the Squid
5075 NAME: digest_rebuild_chunk_percentage
5076 COMMENT: (percent, 0-100)
5077 IFDEF: USE_CACHE_DIGESTS
5079 LOC: Config.digest.rebuild_chunk_percentage
5082 This is the percentage of the Cache Digest to be scanned at a
5083 time. By default it is set to 10% of the Cache Digest.
5088 -----------------------------------------------------------------------------
5093 LOC: Config.Port.snmp
5097 The port number where Squid listens for SNMP requests. To enable
5098 SNMP support set this to a suitable port number. Port number
5099 3401 is often used for the Squid SNMP agent. By default it's
5100 set to "0" (disabled)
5108 LOC: Config.accessList.snmp
5110 DEFAULT_IF_NONE: deny all
5113 Allowing or denying access to the SNMP port.
5115 All access to the agent is denied by default.
5118 snmp_access allow|deny [!]aclname ...
5120 This clause only supports fast acl types.
5121 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5123 snmp_access allow snmppublic localhost
5124 snmp_access deny all
5127 NAME: snmp_incoming_address
5129 LOC: Config.Addrs.snmp_incoming
5134 NAME: snmp_outgoing_address
5136 LOC: Config.Addrs.snmp_outgoing
5140 Just like 'udp_incoming_address', but for the SNMP port.
5142 snmp_incoming_address is used for the SNMP socket receiving
5143 messages from SNMP agents.
5144 snmp_outgoing_address is used for SNMP packets returned to SNMP
5147 The default snmp_incoming_address is to listen on all
5148 available network interfaces.
5150 If snmp_outgoing_address is not set it will use the same socket
5151 as snmp_incoming_address. Only change this if you want to have
5152 SNMP replies sent using another address than where this Squid
5153 listens for SNMP queries.
5155 NOTE, snmp_incoming_address and snmp_outgoing_address can not have
5156 the same value since they both use port 3401.
5161 -----------------------------------------------------------------------------
5164 NAME: icp_port udp_port
5167 LOC: Config.Port.icp
5169 The port number where Squid sends and receives ICP queries to
5170 and from neighbor caches. The standard UDP port for ICP is 3130.
5171 Default is disabled (0).
5174 icp_port @DEFAULT_ICP_PORT@
5181 LOC: Config.Port.htcp
5183 The port number where Squid sends and receives HTCP queries to
5184 and from neighbor caches. To turn it on you want to set it to
5185 4827. By default it is set to "0" (disabled).
5191 NAME: log_icp_queries
5195 LOC: Config.onoff.log_udp
5197 If set, ICP queries are logged to access.log. You may wish
5198 do disable this if your ICP load is VERY high to speed things
5199 up or to simplify log analysis.
5202 NAME: udp_incoming_address
5204 LOC:Config.Addrs.udp_incoming
5207 udp_incoming_address is used for UDP packets received from other
5210 The default behavior is to not bind to any specific address.
5212 Only change this if you want to have all UDP queries received on
5213 a specific interface/address.
5215 NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS
5216 modules. Altering it will affect all of them in the same manner.
5218 see also; udp_outgoing_address
5220 NOTE, udp_incoming_address and udp_outgoing_address can not
5221 have the same value since they both use the same port.
5224 NAME: udp_outgoing_address
5226 LOC: Config.Addrs.udp_outgoing
5229 udp_outgoing_address is used for UDP packets sent out to other
5232 The default behavior is to not bind to any specific address.
5234 Instead it will use the same socket as udp_incoming_address.
5235 Only change this if you want to have UDP queries sent using another
5236 address than where this Squid listens for UDP queries from other
5239 NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS
5240 modules. Altering it will affect all of them in the same manner.
5242 see also; udp_incoming_address
5244 NOTE, udp_incoming_address and udp_outgoing_address can not
5245 have the same value since they both use the same port.
5252 LOC: Config.onoff.icp_hit_stale
5254 If you want to return ICP_HIT for stale cache objects, set this
5255 option to 'on'. If you have sibling relationships with caches
5256 in other administrative domains, this should be 'off'. If you only
5257 have sibling relationships with caches under your control,
5258 it is probably okay to set this to 'on'.
5259 If set to 'on', your siblings should use the option "allow-miss"
5260 on their cache_peer lines for connecting to you.
5263 NAME: minimum_direct_hops
5266 LOC: Config.minDirectHops
5268 If using the ICMP pinging stuff, do direct fetches for sites
5269 which are no more than this many hops away.
5272 NAME: minimum_direct_rtt
5275 LOC: Config.minDirectRtt
5277 If using the ICMP pinging stuff, do direct fetches for sites
5278 which are no more than this many rtt milliseconds away.
5284 LOC: Config.Netdb.low
5290 LOC: Config.Netdb.high
5292 The low and high water marks for the ICMP measurement
5293 database. These are counts, not percents. The defaults are
5294 900 and 1000. When the high water mark is reached, database
5295 entries will be deleted until the low mark is reached.
5298 NAME: netdb_ping_period
5300 LOC: Config.Netdb.period
5303 The minimum period for measuring a site. There will be at
5304 least this much delay between successive pings to the same
5305 network. The default is five minutes.
5312 LOC: Config.onoff.query_icmp
5314 If you want to ask your peers to include ICMP data in their ICP
5315 replies, enable this option.
5317 If your peer has configured Squid (during compilation) with
5318 '--enable-icmp' that peer will send ICMP pings to origin server
5319 sites of the URLs it receives. If you enable this option the
5320 ICP replies from that peer will include the ICMP data (if available).
5321 Then, when choosing a parent cache, Squid will choose the parent with
5322 the minimal RTT to the origin server. When this happens, the
5323 hierarchy field of the access.log will be
5324 "CLOSEST_PARENT_MISS". This option is off by default.
5327 NAME: test_reachability
5331 LOC: Config.onoff.test_reachability
5333 When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH
5334 instead of ICP_MISS if the target host is NOT in the ICMP
5335 database, or has a zero RTT.
5338 NAME: icp_query_timeout
5342 LOC: Config.Timeout.icp_query
5344 Normally Squid will automatically determine an optimal ICP
5345 query timeout value based on the round-trip-time of recent ICP
5346 queries. If you want to override the value determined by
5347 Squid, set this 'icp_query_timeout' to a non-zero value. This
5348 value is specified in MILLISECONDS, so, to use a 2-second
5349 timeout (the old default), you would write:
5351 icp_query_timeout 2000
5354 NAME: maximum_icp_query_timeout
5358 LOC: Config.Timeout.icp_query_max
5360 Normally the ICP query timeout is determined dynamically. But
5361 sometimes it can lead to very large values (say 5 seconds).
5362 Use this option to put an upper limit on the dynamic timeout
5363 value. Do NOT use this option to always use a fixed (instead
5364 of a dynamic) timeout value. To set a fixed timeout see the
5365 'icp_query_timeout' directive.
5368 NAME: minimum_icp_query_timeout
5372 LOC: Config.Timeout.icp_query_min
5374 Normally the ICP query timeout is determined dynamically. But
5375 sometimes it can lead to very small timeouts, even lower than
5376 the normal latency variance on your link due to traffic.
5377 Use this option to put an lower limit on the dynamic timeout
5378 value. Do NOT use this option to always use a fixed (instead
5379 of a dynamic) timeout value. To set a fixed timeout see the
5380 'icp_query_timeout' directive.
5383 NAME: background_ping_rate
5387 LOC: Config.backgroundPingRate
5389 Controls how often the ICP pings are sent to siblings that
5390 have background-ping set.
5394 MULTICAST ICP OPTIONS
5395 -----------------------------------------------------------------------------
5400 LOC: Config.mcast_group_list
5403 This tag specifies a list of multicast groups which your server
5404 should join to receive multicasted ICP queries.
5406 NOTE! Be very careful what you put here! Be sure you
5407 understand the difference between an ICP _query_ and an ICP
5408 _reply_. This option is to be set only if you want to RECEIVE
5409 multicast queries. Do NOT set this option to SEND multicast
5410 ICP (use cache_peer for that). ICP replies are always sent via
5411 unicast, so this option does not affect whether or not you will
5412 receive replies from multicast group members.
5414 You must be very careful to NOT use a multicast address which
5415 is already in use by another group of caches.
5417 If you are unsure about multicast, please read the Multicast
5418 chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/).
5420 Usage: mcast_groups 239.128.16.128 224.0.1.20
5422 By default, Squid doesn't listen on any multicast groups.
5425 NAME: mcast_miss_addr
5426 IFDEF: MULTICAST_MISS_STREAM
5428 LOC: Config.mcast_miss.addr
5431 If you enable this option, every "cache miss" URL will
5432 be sent out on the specified multicast address.
5434 Do not enable this option unless you are are absolutely
5435 certain you understand what you are doing.
5438 NAME: mcast_miss_ttl
5439 IFDEF: MULTICAST_MISS_STREAM
5441 LOC: Config.mcast_miss.ttl
5444 This is the time-to-live value for packets multicasted
5445 when multicasting off cache miss URLs is enabled. By
5446 default this is set to 'site scope', i.e. 16.
5449 NAME: mcast_miss_port
5450 IFDEF: MULTICAST_MISS_STREAM
5452 LOC: Config.mcast_miss.port
5455 This is the port number to be used in conjunction with
5459 NAME: mcast_miss_encode_key
5460 IFDEF: MULTICAST_MISS_STREAM
5462 LOC: Config.mcast_miss.encode_key
5463 DEFAULT: XXXXXXXXXXXXXXXX
5465 The URLs that are sent in the multicast miss stream are
5466 encrypted. This is the encryption key.
5469 NAME: mcast_icp_query_timeout
5473 LOC: Config.Timeout.mcast_icp_query
5475 For multicast peers, Squid regularly sends out ICP "probes" to
5476 count how many other peers are listening on the given multicast
5477 address. This value specifies how long Squid should wait to
5478 count all the replies. The default is 2000 msec, or 2
5483 INTERNAL ICON OPTIONS
5484 -----------------------------------------------------------------------------
5487 NAME: icon_directory
5489 LOC: Config.icons.directory
5490 DEFAULT: @DEFAULT_ICON_DIR@
5492 Where the icons are stored. These are normally kept in
5496 NAME: global_internal_static
5498 LOC: Config.onoff.global_internal_static
5501 This directive controls is Squid should intercept all requests for
5502 /squid-internal-static/ no matter which host the URL is requesting
5503 (default on setting), or if nothing special should be done for
5504 such URLs (off setting). The purpose of this directive is to make
5505 icons etc work better in complex cache hierarchies where it may
5506 not always be possible for all corners in the cache mesh to reach
5507 the server generating a directory listing.
5510 NAME: short_icon_urls
5512 LOC: Config.icons.use_short_names
5515 If this is enabled Squid will use short URLs for icons.
5516 If disabled it will revert to the old behavior of including
5517 it's own name and port in the URL.
5519 If you run a complex cache hierarchy with a mix of Squid and
5520 other proxies you may need to disable this directive.
5525 -----------------------------------------------------------------------------
5528 NAME: error_directory
5530 LOC: Config.errorDirectory
5533 If you wish to create your own versions of the default
5534 error files to customize them to suit your company copy
5535 the error/template files to another directory and point
5538 WARNING: This option will disable multi-language support
5539 on error pages if used.
5541 The squid developers are interested in making squid available in
5542 a wide variety of languages. If you are making translations for a
5543 language that Squid does not currently provide please consider
5544 contributing your translation back to the project.
5545 http://wiki.squid-cache.org/Translations
5547 The squid developers working on translations are happy to supply drop-in
5548 translated error files in exchange for any new language contributions.
5551 NAME: error_default_language
5552 IFDEF: USE_ERR_LOCALES
5554 LOC: Config.errorDefaultLanguage
5557 Set the default language which squid will send error pages in
5558 if no existing translation matches the clients language
5561 If unset (default) generic English will be used.
5563 The squid developers are interested in making squid available in
5564 a wide variety of languages. If you are interested in making
5565 translations for any language see the squid wiki for details.
5566 http://wiki.squid-cache.org/Translations
5569 NAME: error_log_languages
5570 IFDEF: USE_ERR_LOCALES
5572 LOC: Config.errorLogMissingLanguages
5575 Log to cache.log what languages users are attempting to
5576 auto-negotiate for translations.
5578 Successful negotiations are not logged. Only failures
5579 have meaning to indicate that Squid may need an upgrade
5580 of its error page translations.
5583 NAME: err_page_stylesheet
5585 LOC: Config.errorStylesheet
5586 DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css
5588 CSS Stylesheet to pattern the display of Squid default error pages.
5590 For information on CSS see http://www.w3.org/Style/CSS/
5595 LOC: Config.errHtmlText
5598 HTML text to include in error messages. Make this a "mailto"
5599 URL to your admin address, or maybe just a link to your
5600 organizations Web page.
5602 To include this in your error messages, you must rewrite
5603 the error template files (found in the "errors" directory).
5604 Wherever you want the 'err_html_text' line to appear,
5605 insert a %L tag in the error template file.
5608 NAME: email_err_data
5611 LOC: Config.onoff.emailErrData
5614 If enabled, information about the occurred error will be
5615 included in the mailto links of the ERR pages (if %W is set)
5616 so that the email body contains the data.
5617 Syntax is <A HREF="mailto:%w%W">%w</A>
5622 LOC: Config.denyInfoList
5625 Usage: deny_info err_page_name acl
5626 or deny_info http://... acl
5627 or deny_info TCP_RESET acl
5629 This can be used to return a ERR_ page for requests which
5630 do not pass the 'http_access' rules. Squid remembers the last
5631 acl it evaluated in http_access, and if a 'deny_info' line exists
5632 for that ACL Squid returns a corresponding error page.
5634 The acl is typically the last acl on the http_access deny line which
5635 denied access. The exceptions to this rule are:
5636 - When Squid needs to request authentication credentials. It's then
5637 the first authentication related acl encountered
5638 - When none of the http_access lines matches. It's then the last
5639 acl processed on the last http_access line.
5641 NP: If providing your own custom error pages with error_directory
5642 you may also specify them by your custom file name:
5643 Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys
5645 Alternatively you can tell Squid to reset the TCP connection
5646 by specifying TCP_RESET.
5648 Or you can specify an error URL or URL pattern. The browsers will
5649 get redirected (302) to the specified URL after formattgin tags have
5653 %a - username (if available. Password NOT included)
5656 %E - Error description
5658 %H - Request domain name
5659 %i - Client IP Address
5661 %o - Message result from external ACL helper
5662 %p - Request Port number
5663 %P - Request Protocol name
5664 %R - Request URL path
5665 %T - Timestamp in RFC 1123 format
5666 %U - Full canonical URL from client
5667 (HTTPS URLs terminate with *)
5668 %u - Full canonical URL from client
5669 %w - Admin email from squid.conf
5670 %% - Literal percent (%) code
5675 OPTIONS INFLUENCING REQUEST FORWARDING
5676 -----------------------------------------------------------------------------
5679 NAME: nonhierarchical_direct
5681 LOC: Config.onoff.nonhierarchical_direct
5684 By default, Squid will send any non-hierarchical requests
5685 (matching hierarchy_stoplist or not cacheable request type) direct
5688 If you set this to off, Squid will prefer to send these
5689 requests to parents.
5691 Note that in most configurations, by turning this off you will only
5692 add latency to these request without any improvement in global hit
5695 If you are inside an firewall see never_direct instead of
5701 LOC: Config.onoff.prefer_direct
5704 Normally Squid tries to use parents for most requests. If you for some
5705 reason like it to first try going direct and only use a parent if
5706 going direct fails set this to on.
5708 By combining nonhierarchical_direct off and prefer_direct on you
5709 can set up Squid to use a parent as a backup path if going direct
5712 Note: If you want Squid to use parents for all requests see
5713 the never_direct directive. prefer_direct only modifies how Squid
5714 acts on cacheable requests.
5719 LOC: Config.accessList.AlwaysDirect
5722 Usage: always_direct allow|deny [!]aclname ...
5724 Here you can use ACL elements to specify requests which should
5725 ALWAYS be forwarded by Squid to the origin servers without using
5726 any peers. For example, to always directly forward requests for
5727 local servers ignoring any parents or siblings you may have use
5730 acl local-servers dstdomain my.domain.net
5731 always_direct allow local-servers
5733 To always forward FTP requests directly, use
5736 always_direct allow FTP
5738 NOTE: There is a similar, but opposite option named
5739 'never_direct'. You need to be aware that "always_direct deny
5740 foo" is NOT the same thing as "never_direct allow foo". You
5741 may need to use a deny rule to exclude a more-specific case of
5742 some other rule. Example:
5744 acl local-external dstdomain external.foo.net
5745 acl local-servers dstdomain .foo.net
5746 always_direct deny local-external
5747 always_direct allow local-servers
5749 NOTE: If your goal is to make the client forward the request
5750 directly to the origin server bypassing Squid then this needs
5751 to be done in the client configuration. Squid configuration
5752 can only tell Squid how Squid should fetch the object.
5754 NOTE: This directive is not related to caching. The replies
5755 is cached as usual even if you use always_direct. To not cache
5756 the replies see the 'cache' directive.
5758 This clause supports both fast and slow acl types.
5759 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5764 LOC: Config.accessList.NeverDirect
5767 Usage: never_direct allow|deny [!]aclname ...
5769 never_direct is the opposite of always_direct. Please read
5770 the description for always_direct if you have not already.
5772 With 'never_direct' you can use ACL elements to specify
5773 requests which should NEVER be forwarded directly to origin
5774 servers. For example, to force the use of a proxy for all
5775 requests, except those in your local domain use something like:
5777 acl local-servers dstdomain .foo.net
5778 never_direct deny local-servers
5779 never_direct allow all
5781 or if Squid is inside a firewall and there are local intranet
5782 servers inside the firewall use something like:
5784 acl local-intranet dstdomain .foo.net
5785 acl local-external dstdomain external.foo.net
5786 always_direct deny local-external
5787 always_direct allow local-intranet
5788 never_direct allow all
5790 This clause supports both fast and slow acl types.
5791 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5795 ADVANCED NETWORKING OPTIONS
5796 -----------------------------------------------------------------------------
5799 NAME: incoming_icp_average
5802 LOC: Config.comm_incoming.icp_average
5805 NAME: incoming_http_average
5808 LOC: Config.comm_incoming.http_average
5811 NAME: incoming_dns_average
5814 LOC: Config.comm_incoming.dns_average
5817 NAME: min_icp_poll_cnt
5820 LOC: Config.comm_incoming.icp_min_poll
5823 NAME: min_dns_poll_cnt
5826 LOC: Config.comm_incoming.dns_min_poll
5829 NAME: min_http_poll_cnt
5832 LOC: Config.comm_incoming.http_min_poll
5834 Heavy voodoo here. I can't even believe you are reading this.
5835 Are you crazy? Don't even think about adjusting these unless
5836 you understand the algorithms in comm_select.c first!
5842 LOC: Config.accept_filter
5846 The name of an accept(2) filter to install on Squid's
5847 listen socket(s). This feature is perhaps specific to
5848 FreeBSD and requires support in the kernel.
5850 The 'httpready' filter delays delivering new connections
5851 to Squid until a full HTTP request has been received.
5852 See the accf_http(9) man page for details.
5854 The 'dataready' filter delays delivering new connections
5855 to Squid until there is some data to process.
5856 See the accf_dataready(9) man page for details.
5860 The 'data' filter delays delivering of new connections
5861 to Squid until there is some data to process by TCP_ACCEPT_DEFER.
5862 You may optionally specify a number of seconds to wait by
5863 'data=N' where N is the number of seconds. Defaults to 30
5864 if not specified. See the tcp(7) man page for details.
5867 accept_filter httpready
5872 NAME: client_ip_max_connections
5874 LOC: Config.client_ip_max_connections
5877 Set an absolute limit on the number of connections a single
5878 client IP can use. Any more than this and Squid will begin to drop
5879 new connections from the client until it closes some links.
5881 Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP
5882 connections from the client. For finer control use the ACL access controls.
5884 Requires client_db to be enabled (the default).
5886 WARNING: This may noticably slow down traffic received via external proxies
5887 or NAT devices and cause them to rebound error messages back to their clients.
5890 NAME: tcp_recv_bufsize
5894 LOC: Config.tcpRcvBufsz
5896 Size of receive buffer to set for TCP sockets. Probably just
5897 as easy to change your kernel's default. Set to zero to use
5898 the default buffer size.
5903 -----------------------------------------------------------------------------
5910 LOC: Adaptation::Icap::TheConfig.onoff
5913 If you want to enable the ICAP module support, set this to on.
5916 NAME: icap_connect_timeout
5919 LOC: Adaptation::Icap::TheConfig.connect_timeout_raw
5922 This parameter specifies how long to wait for the TCP connect to
5923 the requested ICAP server to complete before giving up and either
5924 terminating the HTTP transaction or bypassing the failure.
5926 The default for optional services is peer_connect_timeout.
5927 The default for essential services is connect_timeout.
5928 If this option is explicitly set, its value applies to all services.
5931 NAME: icap_io_timeout
5935 LOC: Adaptation::Icap::TheConfig.io_timeout_raw
5938 This parameter specifies how long to wait for an I/O activity on
5939 an established, active ICAP connection before giving up and
5940 either terminating the HTTP transaction or bypassing the
5943 The default is read_timeout.
5946 NAME: icap_service_failure_limit
5947 COMMENT: limit [in memory-depth time-units]
5948 TYPE: icap_service_failure_limit
5950 LOC: Adaptation::Icap::TheConfig
5953 The limit specifies the number of failures that Squid tolerates
5954 when establishing a new TCP connection with an ICAP service. If
5955 the number of failures exceeds the limit, the ICAP service is
5956 not used for new ICAP requests until it is time to refresh its
5959 A negative value disables the limit. Without the limit, an ICAP
5960 service will not be considered down due to connectivity failures
5961 between ICAP OPTIONS requests.
5963 Squid forgets ICAP service failures older than the specified
5964 value of memory-depth. The memory fading algorithm
5965 is approximate because Squid does not remember individual
5966 errors but groups them instead, splitting the option
5967 value into ten time slots of equal length.
5969 When memory-depth is 0 and by default this option has no
5970 effect on service failure expiration.
5972 Squid always forgets failures when updating service settings
5973 using an ICAP OPTIONS transaction, regardless of this option
5977 # suspend service usage after 10 failures in 5 seconds:
5978 icap_service_failure_limit 10 in 5 seconds
5981 NAME: icap_service_revival_delay
5984 LOC: Adaptation::Icap::TheConfig.service_revival_delay
5987 The delay specifies the number of seconds to wait after an ICAP
5988 OPTIONS request failure before requesting the options again. The
5989 failed ICAP service is considered "down" until fresh OPTIONS are
5992 The actual delay cannot be smaller than the hardcoded minimum
5993 delay of 30 seconds.
5996 NAME: icap_preview_enable
6000 LOC: Adaptation::Icap::TheConfig.preview_enable
6003 The ICAP Preview feature allows the ICAP server to handle the
6004 HTTP message by looking only at the beginning of the message body
6005 or even without receiving the body at all. In some environments,
6006 previews greatly speedup ICAP processing.
6008 During an ICAP OPTIONS transaction, the server may tell Squid what
6009 HTTP messages should be previewed and how big the preview should be.
6010 Squid will not use Preview if the server did not request one.
6012 To disable ICAP Preview for all ICAP services, regardless of
6013 individual ICAP server OPTIONS responses, set this option to "off".
6015 icap_preview_enable off
6018 NAME: icap_preview_size
6021 LOC: Adaptation::Icap::TheConfig.preview_size
6024 The default size of preview data to be sent to the ICAP server.
6025 -1 means no preview. This value might be overwritten on a per server
6026 basis by OPTIONS requests.
6029 NAME: icap_206_enable
6033 LOC: Adaptation::Icap::TheConfig.allow206_enable
6036 206 (Partial Content) responses is an ICAP extension that allows the
6037 ICAP agents to optionally combine adapted and original HTTP message
6038 content. The decision to combine is postponed until the end of the
6039 ICAP response. Squid supports Partial Content extension by default.
6041 Activation of the Partial Content extension is negotiated with each
6042 ICAP service during OPTIONS exchange. Most ICAP servers should handle
6043 negotation correctly even if they do not support the extension, but
6044 some might fail. To disable Partial Content support for all ICAP
6045 services and to avoid any negotiation, set this option to "off".
6051 NAME: icap_default_options_ttl
6054 LOC: Adaptation::Icap::TheConfig.default_options_ttl
6057 The default TTL value for ICAP OPTIONS responses that don't have
6058 an Options-TTL header.
6061 NAME: icap_persistent_connections
6065 LOC: Adaptation::Icap::TheConfig.reuse_connections
6068 Whether or not Squid should use persistent connections to
6072 NAME: icap_send_client_ip
6076 LOC: Adaptation::Icap::TheConfig.send_client_ip
6079 This adds the header "X-Client-IP" to ICAP requests.
6082 NAME: icap_send_client_username
6086 LOC: Adaptation::Icap::TheConfig.send_client_username
6089 This sends authenticated HTTP client username (if available) to
6090 the ICAP service. The username value is encoded based on the
6091 icap_client_username_encode option and is sent using the header
6092 specified by the icap_client_username_header option.
6095 NAME: icap_client_username_header
6098 LOC: Adaptation::Icap::TheConfig.client_username_header
6099 DEFAULT: X-Client-Username
6101 ICAP request header name to use for send_client_username.
6104 NAME: icap_client_username_encode
6108 LOC: Adaptation::Icap::TheConfig.client_username_encode
6111 Whether to base64 encode the authenticated client username.
6115 TYPE: icap_service_type
6117 LOC: Adaptation::Icap::TheConfig
6120 Defines a single ICAP service using the following format:
6122 icap_service service_name vectoring_point [options] service_url
6125 an opaque identifier which must be unique in squid.conf
6127 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
6128 This specifies at which point of transaction processing the
6129 ICAP service should be activated. *_postcache vectoring points
6130 are not yet supported.
6132 service_url: icap://servername:port/servicepath
6133 ICAP server and service location.
6135 ICAP does not allow a single service to handle both REQMOD and RESPMOD
6136 transactions. Squid does not enforce that requirement. You can specify
6137 services with the same service_url and different vectoring_points. You
6138 can even specify multiple identical services as long as their
6139 service_names differ.
6142 Service options are separated by white space. ICAP services support
6143 the following name=value options:
6146 If set to 'on' or '1', the ICAP service is treated as
6147 optional. If the service cannot be reached or malfunctions,
6148 Squid will try to ignore any errors and process the message as
6149 if the service was not enabled. No all ICAP errors can be
6150 bypassed. If set to 0, the ICAP service is treated as
6151 essential and all ICAP errors will result in an error page
6152 returned to the HTTP client.
6154 Bypass is off by default: services are treated as essential.
6157 If set to 'on' or '1', the ICAP service is allowed to
6158 dynamically change the current message adaptation plan by
6159 returning a chain of services to be used next. The services
6160 are specified using the X-Next-Services ICAP response header
6161 value, formatted as a comma-separated list of service names.
6162 Each named service should be configured in squid.conf and
6163 should have the same method and vectoring point as the current
6164 ICAP transaction. Services violating these rules are ignored.
6165 An empty X-Next-Services value results in an empty plan which
6166 ends the current adaptation.
6168 Routing is not allowed by default: the ICAP X-Next-Services
6169 response header is ignored.
6172 Only has effect on split-stack systems. The default on those systems
6173 is to use IPv4-only connections. When set to 'on' this option will
6174 make Squid use IPv6-only connections to contact this ICAP service.
6176 Older icap_service format without optional named parameters is
6177 deprecated but supported for backward compatibility.
6180 icap_service svcBlocker reqmod_precache bypass=0 icap://icap1.mydomain.net:1344/reqmod
6181 icap_service svcLogger reqmod_precache routing=on icap://icap2.mydomain.net:1344/respmod
6185 TYPE: icap_class_type
6190 This deprecated option was documented to define an ICAP service
6191 chain, even though it actually defined a set of similar, redundant
6192 services, and the chains were not supported.
6194 To define a set of redundant services, please use the
6195 adaptation_service_set directive. For service chains, use
6196 adaptation_service_chain.
6200 TYPE: icap_access_type
6205 This option is deprecated. Please use adaptation_access, which
6206 has the same ICAP functionality, but comes with better
6207 documentation, and eCAP support.
6212 -----------------------------------------------------------------------------
6219 LOC: Adaptation::Ecap::TheConfig.onoff
6222 Controls whether eCAP support is enabled.
6226 TYPE: ecap_service_type
6228 LOC: Adaptation::Ecap::TheConfig
6231 Defines a single eCAP service
6233 ecap_service servicename vectoring_point bypass service_url
6235 vectoring_point = reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
6236 This specifies at which point of transaction processing the
6237 eCAP service should be activated. *_postcache vectoring points
6238 are not yet supported.
6240 If set to 1, the eCAP service is treated as optional. If the
6241 service cannot be reached or malfunctions, Squid will try to
6242 ignore any errors and process the message as if the service
6243 was not enabled. No all eCAP errors can be bypassed.
6244 If set to 0, the eCAP service is treated as essential and all
6245 eCAP errors will result in an error page returned to the
6247 service_url = ecap://vendor/service_name?custom&cgi=style¶meters=optional
6250 ecap_service service_1 reqmod_precache 0 ecap://filters-R-us/leakDetector?on_error=block
6251 ecap_service service_2 respmod_precache 1 icap://filters-R-us/virusFilter?config=/etc/vf.cfg
6254 NAME: loadable_modules
6256 IFDEF: USE_LOADABLE_MODULES
6257 LOC: Config.loadable_module_names
6260 Instructs Squid to load the specified dynamic module(s) or activate
6261 preloaded module(s).
6263 loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so
6267 MESSAGE ADAPTATION OPTIONS
6268 -----------------------------------------------------------------------------
6271 NAME: adaptation_service_set
6272 TYPE: adaptation_service_set_type
6273 IFDEF: USE_ADAPTATION
6278 Configures an ordered set of similar, redundant services. This is
6279 useful when hot standby or backup adaptation servers are available.
6281 adaptation_service_set set_name service_name1 service_name2 ...
6283 The named services are used in the set declaration order. The first
6284 applicable adaptation service from the set is used first. The next
6285 applicable service is tried if and only if the transaction with the
6286 previous service fails and the message waiting to be adapted is still
6289 When adaptation starts, broken services are ignored as if they were
6290 not a part of the set. A broken service is a down optional service.
6292 The services in a set must be attached to the same vectoring point
6293 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
6295 If all services in a set are optional then adaptation failures are
6296 bypassable. If all services in the set are essential, then a
6297 transaction failure with one service may still be retried using
6298 another service from the set, but when all services fail, the master
6299 transaction fails as well.
6301 A set may contain a mix of optional and essential services, but that
6302 is likely to lead to surprising results because broken services become
6303 ignored (see above), making previously bypassable failures fatal.
6304 Technically, it is the bypassability of the last failed service that
6307 See also: adaptation_access adaptation_service_chain
6310 adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup
6311 adaptation service_set svcLogger loggerLocal loggerRemote
6314 NAME: adaptation_service_chain
6315 TYPE: adaptation_service_chain_type
6316 IFDEF: USE_ADAPTATION
6321 Configures a list of complementary services that will be applied
6322 one-by-one, forming an adaptation chain or pipeline. This is useful
6323 when Squid must perform different adaptations on the same message.
6325 adaptation_service_chain chain_name service_name1 svc_name2 ...
6327 The named services are used in the chain declaration order. The first
6328 applicable adaptation service from the chain is used first. The next
6329 applicable service is applied to the successful adaptation results of
6330 the previous service in the chain.
6332 When adaptation starts, broken services are ignored as if they were
6333 not a part of the chain. A broken service is a down optional service.
6335 Request satisfaction terminates the adaptation chain because Squid
6336 does not currently allow declaration of RESPMOD services at the
6337 "reqmod_precache" vectoring point (see icap_service or ecap_service).
6339 The services in a chain must be attached to the same vectoring point
6340 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
6342 A chain may contain a mix of optional and essential services. If an
6343 essential adaptation fails (or the failure cannot be bypassed for
6344 other reasons), the master transaction fails. Otherwise, the failure
6345 is bypassed as if the failed adaptation service was not in the chain.
6347 See also: adaptation_access adaptation_service_set
6350 adaptation_service_chain svcRequest requestLogger urlFilter leakDetector
6353 NAME: adaptation_access
6354 TYPE: adaptation_access_type
6355 IFDEF: USE_ADAPTATION
6359 Sends an HTTP transaction to an ICAP or eCAP adaptation service.
6361 adaptation_access service_name allow|deny [!]aclname...
6362 adaptation_access set_name allow|deny [!]aclname...
6364 At each supported vectoring point, the adaptation_access
6365 statements are processed in the order they appear in this
6366 configuration file. Statements pointing to the following services
6367 are ignored (i.e., skipped without checking their ACL):
6369 - services serving different vectoring points
6370 - "broken-but-bypassable" services
6371 - "up" services configured to ignore such transactions
6372 (e.g., based on the ICAP Transfer-Ignore header).
6374 When a set_name is used, all services in the set are checked
6375 using the same rules, to find the first applicable one. See
6376 adaptation_service_set for details.
6378 If an access list is checked and there is a match, the
6379 processing stops: For an "allow" rule, the corresponding
6380 adaptation service is used for the transaction. For a "deny"
6381 rule, no adaptation service is activated.
6383 It is currently not possible to apply more than one adaptation
6384 service at the same vectoring point to the same HTTP transaction.
6386 See also: icap_service and ecap_service
6389 adaptation_access service_1 allow all
6392 NAME: adaptation_service_iteration_limit
6394 IFDEF: USE_ADAPTATION
6395 LOC: Adaptation::Config::service_iteration_limit
6398 Limits the number of iterations allowed when applying adaptation
6399 services to a message. If your longest adaptation set or chain
6400 may have more than 16 services, increase the limit beyond its
6401 default value of 16. If detecting infinite iteration loops sooner
6402 is critical, make the iteration limit match the actual number
6403 of services in your longest adaptation set or chain.
6405 Infinite adaptation loops are most likely with routing services.
6407 See also: icap_service routing=1
6410 NAME: adaptation_masterx_shared_names
6412 IFDEF: USE_ADAPTATION
6413 LOC: Adaptation::Config::masterx_shared_name
6416 For each master transaction (i.e., the HTTP request and response
6417 sequence, including all related ICAP and eCAP exchanges), Squid
6418 maintains a table of metadata. The table entries are (name, value)
6419 pairs shared among eCAP and ICAP exchanges. The table is destroyed
6420 with the master transaction.
6422 This option specifies the table entry names that Squid must accept
6423 from and forward to the adaptation transactions.
6425 An ICAP REQMOD or RESPMOD transaction may set an entry in the
6426 shared table by returning an ICAP header field with a name
6427 specified in adaptation_masterx_shared_names. Squid will store
6428 and forward that ICAP header field to subsequent ICAP
6429 transactions within the same master transaction scope.
6431 Only one shared entry name is supported at this time.
6434 # share authentication information among ICAP services
6435 adaptation_masterx_shared_names X-Subscriber-ID
6441 LOC: Adaptation::Icap::TheConfig.repeat
6443 DEFAULT_IF_NONE: deny all
6445 This ACL determines which retriable ICAP transactions are
6446 retried. Transactions that received a complete ICAP response
6447 and did not have to consume or produce HTTP bodies to receive
6448 that response are usually retriable.
6450 icap_retry allow|deny [!]aclname ...
6452 Squid automatically retries some ICAP I/O timeouts and errors
6453 due to persistent connection race conditions.
6455 See also: icap_retry_limit
6458 NAME: icap_retry_limit
6461 LOC: Adaptation::Icap::TheConfig.repeat_limit
6464 Limits the number of retries allowed. When set to zero (default),
6465 no retries are allowed.
6467 Communication errors due to persistent connection race
6468 conditions are unavoidable, automatically retried, and do not
6469 count against this limit.
6471 See also: icap_retry
6477 -----------------------------------------------------------------------------
6480 NAME: check_hostnames
6483 LOC: Config.onoff.check_hostnames
6485 For security and stability reasons Squid can check
6486 hostnames for Internet standard RFC compliance. If you want
6487 Squid to perform these checks turn this directive on.
6490 NAME: allow_underscore
6493 LOC: Config.onoff.allow_underscore
6495 Underscore characters is not strictly allowed in Internet hostnames
6496 but nevertheless used by many sites. Set this to off if you want
6497 Squid to be strict about the standard.
6498 This check is performed only when check_hostnames is set to on.
6501 NAME: cache_dns_program
6503 IFDEF: USE_DNSSERVERS
6504 DEFAULT: @DEFAULT_DNSSERVER@
6505 LOC: Config.Program.dnsserver
6507 Specify the location of the executable for dnslookup process.
6511 TYPE: HelperChildConfig
6512 IFDEF: USE_DNSSERVERS
6513 DEFAULT: 32 startup=1 idle=1
6514 LOC: Config.dnsChildren
6516 The maximum number of processes spawn to service DNS name lookups.
6517 If you limit it too few Squid will have to wait for them to process
6518 a backlog of requests, slowing it down. If you allow too many they
6519 will use RAM and other system resources noticably.
6520 The maximum this may be safely set to is 32.
6522 The startup= and idle= options allow some measure of skew in your
6527 Sets a minimum of how many processes are to be spawned when Squid
6528 starts or reconfigures. When set to zero the first request will
6529 cause spawning of the first child process to handle it.
6531 Starting too few will cause an initial slowdown in traffic as Squid
6532 attempts to simultaneously spawn enough processes to cope.
6536 Sets a minimum of how many processes Squid is to try and keep available
6537 at all times. When traffic begins to rise above what the existing
6538 processes can handle this many more will be spawned up to the maximum
6539 configured. A minimum setting of 1 is required.
6542 NAME: dns_retransmit_interval
6545 LOC: Config.Timeout.idns_retransmit
6546 IFDEF: !USE_DNSSERVERS
6548 Initial retransmit interval for DNS queries. The interval is
6549 doubled each time all configured DNS servers have been tried.
6555 LOC: Config.Timeout.idns_query
6556 IFDEF: !USE_DNSSERVERS
6558 DNS Query timeout. If no response is received to a DNS query
6559 within this time all DNS servers for the queried domain
6560 are assumed to be unavailable.
6567 LOC: Config.onoff.res_defnames
6569 Normally the RES_DEFNAMES resolver option is disabled
6570 (see res_init(3)). This prevents caches in a hierarchy
6571 from interpreting single-component hostnames locally. To allow
6572 Squid to handle single-component names, enable this option.
6575 NAME: dns_nameservers
6578 LOC: Config.dns_nameservers
6580 Use this if you want to specify a list of DNS name servers
6581 (IP addresses) to use instead of those given in your
6582 /etc/resolv.conf file.
6583 On Windows platforms, if no value is specified here or in
6584 the /etc/resolv.conf file, the list of DNS name servers are
6585 taken from the Windows registry, both static and dynamic DHCP
6586 configurations are supported.
6588 Example: dns_nameservers 10.0.0.1 192.172.0.4
6593 DEFAULT: @DEFAULT_HOSTS@
6594 LOC: Config.etcHostsPath
6596 Location of the host-local IP name-address associations
6597 database. Most Operating Systems have such a file on different
6599 - Un*X & Linux: /etc/hosts
6600 - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts
6601 (%SystemRoot% value install default is c:\winnt)
6602 - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts
6603 (%SystemRoot% value install default is c:\windows)
6604 - Windows 9x/Me: %windir%\hosts
6605 (%windir% value is usually c:\windows)
6606 - Cygwin: /etc/hosts
6608 The file contains newline-separated definitions, in the
6609 form ip_address_in_dotted_form name [name ...] names are
6610 whitespace-separated. Lines beginning with an hash (#)
6611 character are comments.
6613 The file is checked at startup and upon configuration.
6614 If set to 'none', it won't be checked.
6615 If append_domain is used, that domain will be added to
6616 domain-local (i.e. not containing any dot character) host
6622 LOC: Config.appendDomain
6625 Appends local domain name to hostnames without any dots in
6626 them. append_domain must begin with a period.
6628 Be warned there are now Internet names with no dots in
6629 them using only top-domain names, so setting this may
6630 cause some Internet sites to become unavailable.
6633 append_domain .yourdomain.com
6636 NAME: ignore_unknown_nameservers
6638 LOC: Config.onoff.ignore_unknown_nameservers
6641 By default Squid checks that DNS responses are received
6642 from the same IP addresses they are sent to. If they
6643 don't match, Squid ignores the response and writes a warning
6644 message to cache.log. You can allow responses from unknown
6645 nameservers by setting this option to 'off'.
6648 NAME: dns_v4_fallback
6651 LOC: Config.onoff.dns_require_A
6653 Standard practice with DNS is to lookup either A or AAAA records
6654 and use the results if it succeeds. Only looking up the other if
6655 the first attempt fails or otherwise produces no results.
6657 That policy however will cause squid to produce error pages for some
6658 servers that advertise AAAA but are unreachable over IPv6.
6660 If this is ON squid will always lookup both AAAA and A, using both.
6661 If this is OFF squid will lookup AAAA and only try A if none found.
6663 WARNING: There are some possibly unwanted side-effects with this on:
6664 *) Doubles the load placed by squid on the DNS network.
6665 *) May negatively impact connection delay times.
6669 COMMENT: (number of entries)
6672 LOC: Config.ipcache.size
6679 LOC: Config.ipcache.low
6686 LOC: Config.ipcache.high
6688 The size, low-, and high-water marks for the IP cache.
6691 NAME: fqdncache_size
6692 COMMENT: (number of entries)
6695 LOC: Config.fqdncache.size
6697 Maximum number of FQDN cache entries.
6702 -----------------------------------------------------------------------------
6709 LOC: Config.onoff.mem_pools
6711 If set, Squid will keep pools of allocated (but unused) memory
6712 available for future use. If memory is a premium on your
6713 system and you believe your malloc library outperforms Squid
6714 routines, disable this.
6717 NAME: memory_pools_limit
6721 LOC: Config.MemPools.limit
6723 Used only with memory_pools on:
6724 memory_pools_limit 50 MB
6726 If set to a non-zero value, Squid will keep at most the specified
6727 limit of allocated (but unused) memory in memory pools. All free()
6728 requests that exceed this limit will be handled by your malloc
6729 library. Squid does not pre-allocate any memory, just safe-keeps
6730 objects that otherwise would be free()d. Thus, it is safe to set
6731 memory_pools_limit to a reasonably high value even if your
6732 configuration will use less memory.
6734 If set to none, Squid will keep all memory it can. That is, there
6735 will be no limit on the total amount of memory used for safe-keeping.
6737 To disable memory allocation optimization, do not set
6738 memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
6740 An overhead for maintaining memory pools is not taken into account
6741 when the limit is checked. This overhead is close to four bytes per
6742 object kept. However, pools may actually _save_ memory because of
6743 reduced memory thrashing in your malloc library.
6747 COMMENT: on|off|transparent|truncate|delete
6750 LOC: opt_forwarded_for
6752 If set to "on", Squid will append your client's IP address
6753 in the HTTP requests it forwards. By default it looks like:
6755 X-Forwarded-For: 192.1.2.3
6757 If set to "off", it will appear as
6759 X-Forwarded-For: unknown
6761 If set to "transparent", Squid will not alter the
6762 X-Forwarded-For header in any way.
6764 If set to "delete", Squid will delete the entire
6765 X-Forwarded-For header.
6767 If set to "truncate", Squid will remove all existing
6768 X-Forwarded-For entries, and place itself as the sole entry.
6771 NAME: cachemgr_passwd
6772 TYPE: cachemgrpasswd
6774 LOC: Config.passwd_list
6776 Specify passwords for cachemgr operations.
6778 Usage: cachemgr_passwd password action action ...
6780 Some valid actions are (see cache manager menu for a full list):
6820 * Indicates actions which will not be performed without a
6821 valid password, others can be performed if not listed here.
6823 To disable an action, set the password to "disable".
6824 To allow performing an action without a password, set the
6827 Use the keyword "all" to set the same password for all actions.
6830 cachemgr_passwd secret shutdown
6831 cachemgr_passwd lesssssssecret info stats/objects
6832 cachemgr_passwd disable all
6839 LOC: Config.onoff.client_db
6841 If you want to disable collecting per-client statistics,
6842 turn off client_db here.
6845 NAME: refresh_all_ims
6849 LOC: Config.onoff.refresh_all_ims
6851 When you enable this option, squid will always check
6852 the origin server for an update when a client sends an
6853 If-Modified-Since request. Many browsers use IMS
6854 requests when the user requests a reload, and this
6855 ensures those clients receive the latest version.
6857 By default (off), squid may return a Not Modified response
6858 based on the age of the cached version.
6861 NAME: reload_into_ims
6862 IFDEF: HTTP_VIOLATIONS
6866 LOC: Config.onoff.reload_into_ims
6868 When you enable this option, client no-cache or ``reload''
6869 requests will be changed to If-Modified-Since requests.
6870 Doing this VIOLATES the HTTP standard. Enabling this
6871 feature could make you liable for problems which it
6874 see also refresh_pattern for a more selective approach.
6877 NAME: maximum_single_addr_tries
6879 LOC: Config.retry.maxtries
6882 This sets the maximum number of connection attempts for a
6883 host that only has one address (for multiple-address hosts,
6884 each address is tried once).
6886 The default value is one attempt, the (not recommended)
6887 maximum is 255 tries. A warning message will be generated
6888 if it is set to a value greater than ten.
6890 Note: This is in addition to the request re-forwarding which
6891 takes place if Squid fails to get a satisfying response.
6894 NAME: retry_on_error
6896 LOC: Config.retry.onerror
6899 If set to on Squid will automatically retry requests when
6900 receiving an error response. This is mainly useful if you
6901 are in a complex cache hierarchy to work around access
6905 NAME: as_whois_server
6907 LOC: Config.as_whois_server
6908 DEFAULT: whois.ra.net
6909 DEFAULT_IF_NONE: whois.ra.net
6911 WHOIS server to query for AS numbers. NOTE: AS numbers are
6912 queried only when Squid starts up, not for every request.
6917 LOC: Config.onoff.offline
6920 Enable this option and Squid will never try to validate cached
6924 NAME: uri_whitespace
6925 TYPE: uri_whitespace
6926 LOC: Config.uri_whitespace
6929 What to do with requests that have whitespace characters in the
6932 strip: The whitespace characters are stripped out of the URL.
6933 This is the behavior recommended by RFC2396.
6934 deny: The request is denied. The user receives an "Invalid
6936 allow: The request is allowed and the URI is not changed. The
6937 whitespace characters remain in the URI. Note the
6938 whitespace is passed to redirector processes if they
6940 encode: The request is allowed and the whitespace characters are
6941 encoded according to RFC1738. This could be considered
6942 a violation of the HTTP/1.1
6943 RFC because proxies are not allowed to rewrite URI's.
6944 chop: The request is allowed and the URI is chopped at the
6945 first whitespace. This might also be considered a
6951 LOC: Config.chroot_dir
6954 Specifies a directory where Squid should do a chroot() while
6955 initializing. This also causes Squid to fully drop root
6956 privileges after initializing. This means, for example, if you
6957 use a HTTP port less than 1024 and try to reconfigure, you may
6958 get an error saying that Squid can not open the port.
6961 NAME: balance_on_multiple_ip
6963 LOC: Config.onoff.balance_on_multiple_ip
6966 Modern IP resolvers in squid sort lookup results by preferred access.
6967 By default squid will use these IP in order and only rotates to
6968 the next listed when the most preffered fails.
6970 Some load balancing servers based on round robin DNS have been
6971 found not to preserve user session state across requests
6972 to different IP addresses.
6974 Enabling this directive Squid rotates IP's per request.
6977 NAME: pipeline_prefetch
6979 LOC: Config.onoff.pipeline_prefetch
6982 To boost the performance of pipelined requests to closer
6983 match that of a non-proxied environment Squid can try to fetch
6984 up to two requests in parallel from a pipeline.
6986 Defaults to off for bandwidth management and access logging
6990 NAME: high_response_time_warning
6993 LOC: Config.warnings.high_rptm
6996 If the one-minute median response time exceeds this value,
6997 Squid prints a WARNING with debug level 0 to get the
6998 administrators attention. The value is in milliseconds.
7001 NAME: high_page_fault_warning
7003 LOC: Config.warnings.high_pf
7006 If the one-minute average page fault rate exceeds this
7007 value, Squid prints a WARNING with debug level 0 to get
7008 the administrators attention. The value is in page faults
7012 NAME: high_memory_warning
7014 LOC: Config.warnings.high_memory
7017 If the memory usage (as determined by mallinfo) exceeds
7018 this amount, Squid prints a WARNING with debug level 0 to get
7019 the administrators attention.
7022 NAME: sleep_after_fork
7023 COMMENT: (microseconds)
7025 LOC: Config.sleep_after_fork
7028 When this is set to a non-zero value, the main Squid process
7029 sleeps the specified number of microseconds after a fork()
7030 system call. This sleep may help the situation where your
7031 system reports fork() failures due to lack of (virtual)
7032 memory. Note, however, if you have a lot of child
7033 processes, these sleep delays will add up and your
7034 Squid will not service requests for some amount of time
7035 until all the child processes have been started.
7036 On Windows value less then 1000 (1 milliseconds) are
7040 NAME: windows_ipaddrchangemonitor
7041 IFDEF: _SQUID_MSWIN_
7045 LOC: Config.onoff.WIN32_IpAddrChangeMonitor
7047 On Windows Squid by default will monitor IP address changes and will
7048 reconfigure itself after any detected event. This is very useful for
7049 proxies connected to internet with dial-up interfaces.
7050 In some cases (a Proxy server acting as VPN gateway is one) it could be
7051 desiderable to disable this behaviour setting this to 'off'.
7052 Note: after changing this, Squid service must be restarted.
7057 IFDEF: USE_SQUID_EUI
7059 LOC: Eui::TheConfig.euiLookup
7061 Whether to lookup the EUI or MAC address of a connected client.
7064 NAME: max_filedescriptors max_filedesc
7067 LOC: Config.max_filedescriptors
7069 The maximum number of filedescriptors supported.
7071 The default "0" means Squid inherits the current ulimit setting.
7073 Note: Changing this requires a restart of Squid. Also
7074 not all comm loops supports large values.
7082 Number of main Squid processes or "workers" to fork and maintain.
7083 0: "no daemon" mode, like running "squid -N ..."
7084 1: "no SMP" mode, start one main Squid process daemon (default)
7085 N: start N main Squid process daemons (i.e., SMP mode)
7087 In SMP mode, each worker does nearly all what a single Squid daemon
7088 does (e.g., listen on http_port and forward HTTP requests).