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 option.
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 ssl-bump 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
1907 instead of 3130. This directive accepts a comma separated
1908 list of options described below.
1910 htcp=oldsquid Send HTCP to old Squid versions (2.5 or earlier).
1912 htcp=no-clr Send HTCP to the neighbor but without
1913 sending any CLR requests. This cannot be used with
1916 htcp=only-clr Send HTCP to the neighbor but ONLY CLR requests.
1917 This cannot be used with no-clr.
1920 Send HTCP to the neighbor including CLRs but only when
1921 they do not result from PURGE requests.
1924 Forward any HTCP CLR requests this proxy receives to the peer.
1927 ==== PEER SELECTION METHODS ====
1929 The default peer selection method is ICP, with the first responding peer
1930 being used as source. These options can be used for better load balancing.
1933 default This is a parent cache which can be used as a "last-resort"
1934 if a peer cannot be located by any of the peer-selection methods.
1935 If specified more than once, only the first is used.
1937 round-robin Load-Balance parents which should be used in a round-robin
1938 fashion in the absence of any ICP queries.
1939 weight=N can be used to add bias.
1941 weighted-round-robin
1942 Load-Balance parents which should be used in a round-robin
1943 fashion with the frequency of each parent being based on the
1944 round trip time. Closer parents are used more often.
1945 Usually used for background-ping parents.
1946 weight=N can be used to add bias.
1948 carp Load-Balance parents which should be used as a CARP array.
1949 The requests will be distributed among the parents based on the
1950 CARP load balancing hash function based on their weight.
1952 userhash Load-balance parents based on the client proxy_auth or ident username.
1954 sourcehash Load-balance parents based on the client source IP.
1957 To be used only for cache peers of type "multicast".
1958 ALL members of this multicast group have "sibling"
1959 relationship with it, not "parent". This is to a mulicast
1960 group when the requested object would be fetched only from
1961 a "parent" cache, anyway. It's useful, e.g., when
1962 configuring a pool of redundant Squid proxies, being
1963 members of the same multicast group.
1966 ==== PEER SELECTION OPTIONS ====
1968 weight=N use to affect the selection of a peer during any weighted
1969 peer-selection mechanisms.
1970 The weight must be an integer; default is 1,
1971 larger weights are favored more.
1972 This option does not affect parent selection if a peering
1973 protocol is not in use.
1975 basetime=N Specify a base amount to be subtracted from round trip
1977 It is subtracted before division by weight in calculating
1978 which parent to fectch from. If the rtt is less than the
1979 base time the rtt is set to a minimal value.
1981 ttl=N Specify a IP multicast TTL to use when sending an ICP
1982 queries to this address.
1983 Only useful when sending to a multicast group.
1984 Because we don't accept ICP replies from random
1985 hosts, you must configure other group members as
1986 peers with the 'multicast-responder' option.
1988 no-delay To prevent access to this neighbor from influencing the
1991 digest-url=URL Tell Squid to fetch the cache digest (if digests are
1992 enabled) for this host from the specified URL rather
1993 than the Squid default location.
1996 ==== ACCELERATOR / REVERSE-PROXY OPTIONS ====
1998 originserver Causes this parent to be contacted as an origin server.
1999 Meant to be used in accelerator setups when the peer
2003 Set the Host header of requests forwarded to this peer.
2004 Useful in accelerator setups where the server (peer)
2005 expects a certain domain name but clients may request
2006 others. ie example.com or www.example.com
2008 no-digest Disable request of cache digests.
2011 Disables requesting ICMP RTT database (NetDB).
2014 ==== AUTHENTICATION OPTIONS ====
2017 If this is a personal/workgroup proxy and your parent
2018 requires proxy authentication.
2020 Note: The string can include URL escapes (i.e. %20 for
2021 spaces). This also means % must be written as %%.
2024 Send login details received from client to this peer.
2025 Both Proxy- and WWW-Authorization headers are passed
2026 without alteration to the peer.
2027 Authentication is not required by Squid for this to work.
2029 Note: This will pass any form of authentication but
2030 only Basic auth will work through a proxy unless the
2031 connection-auth options are also used.
2033 login=PASS Send login details received from client to this peer.
2034 Authentication is not required by this option.
2036 If there are no client-provided authentication headers
2037 to pass on, but username and password are available
2038 from an external ACL user= and password= result tags
2039 they may be sent instead.
2041 Note: To combine this with proxy_auth both proxies must
2042 share the same user database as HTTP only allows for
2043 a single login (one for proxy, one for origin server).
2044 Also be warned this will expose your users proxy
2045 password to the peer. USE WITH CAUTION
2048 Send the username to the upstream cache, but with a
2049 fixed password. This is meant to be used when the peer
2050 is in another administrative domain, but it is still
2051 needed to identify each user.
2052 The star can optionally be followed by some extra
2053 information which is added to the username. This can
2054 be used to identify this proxy to the peer, similar to
2055 the login=username:password option above.
2058 If this is a personal/workgroup proxy and your parent
2059 requires a secure proxy authentication.
2060 The first principal from the default keytab or defined by
2061 the environment variable KRB5_KTNAME will be used.
2063 login=NEGOTIATE:principal_name
2064 If this is a personal/workgroup proxy and your parent
2065 requires a secure proxy authentication.
2066 The principal principal_name from the default keytab or
2067 defined by the environment variable KRB5_KTNAME will be
2070 connection-auth=on|off
2071 Tell Squid that this peer does or not support Microsoft
2072 connection oriented authentication, and any such
2073 challenges received from there should be ignored.
2074 Default is auto to automatically determine the status
2078 ==== SSL / HTTPS / TLS OPTIONS ====
2080 ssl Encrypt connections to this peer with SSL/TLS.
2082 sslcert=/path/to/ssl/certificate
2083 A client SSL certificate to use when connecting to
2086 sslkey=/path/to/ssl/key
2087 The private SSL key corresponding to sslcert above.
2088 If 'sslkey' is not specified 'sslcert' is assumed to
2089 reference a combined file containing both the
2090 certificate and the key.
2093 The SSL version to use when connecting to this peer
2094 1 = automatic (default)
2099 sslcipher=... The list of valid SSL ciphers to use when connecting
2102 ssloptions=... Specify various SSL engine options:
2103 NO_SSLv2 Disallow the use of SSLv2
2104 NO_SSLv3 Disallow the use of SSLv3
2105 NO_TLSv1 Disallow the use of TLSv1
2106 See src/ssl_support.c or the OpenSSL documentation for
2107 a more complete list.
2109 sslcafile=... A file containing additional CA certificates to use
2110 when verifying the peer certificate.
2112 sslcapath=... A directory containing additional CA certificates to
2113 use when verifying the peer certificate.
2115 sslcrlfile=... A certificate revocation list file to use when
2116 verifying the peer certificate.
2118 sslflags=... Specify various flags modifying the SSL implementation:
2121 Accept certificates even if they fail to
2124 Don't use the default CA list built in
2127 Don't verify the peer certificate
2128 matches the server name
2130 ssldomain= The peer name as advertised in it's certificate.
2131 Used for verifying the correctness of the received peer
2132 certificate. If not specified the peer hostname will be
2136 Enable the "Front-End-Https: On" header needed when
2137 using Squid as a SSL frontend in front of Microsoft OWA.
2138 See MS KB document Q307347 for details on this header.
2139 If set to auto the header will only be added if the
2140 request is forwarded as a https:// URL.
2143 ==== GENERAL OPTIONS ====
2146 A peer-specific connect timeout.
2147 Also see the peer_connect_timeout directive.
2149 connect-fail-limit=N
2150 How many times connecting to a peer must fail before
2151 it is marked as down. Default is 10.
2153 allow-miss Disable Squid's use of only-if-cached when forwarding
2154 requests to siblings. This is primarily useful when
2155 icp_hit_stale is used by the sibling. To extensive use
2156 of this option may result in forwarding loops, and you
2157 should avoid having two-way peerings with this option.
2158 For example to deny peer usage on requests from peer
2159 by denying cache_peer_access if the source is a peer.
2161 max-conn=N Limit the amount of connections Squid may open to this
2164 name=xxx Unique name for the peer.
2165 Required if you have multiple peers on the same host
2166 but different ports.
2167 This name can be used in cache_peer_access and similar
2168 directives to dentify the peer.
2169 Can be used by outgoing access controls through the
2172 no-tproxy Do not use the client-spoof TPROXY support when forwarding
2173 requests to this peer. Use normal address selection instead.
2175 proxy-only objects fetched from the peer will not be stored locally.
2179 NAME: cache_peer_domain cache_host_domain
2184 Use to limit the domains for which a neighbor cache will be
2187 cache_peer_domain cache-host domain [domain ...]
2188 cache_peer_domain cache-host !domain
2190 For example, specifying
2192 cache_peer_domain parent.foo.net .edu
2194 has the effect such that UDP query packets are sent to
2195 'bigserver' only when the requested object exists on a
2196 server in the .edu domain. Prefixing the domainname
2197 with '!' means the cache will be queried for objects
2200 NOTE: * Any number of domains may be given for a cache-host,
2201 either on the same or separate lines.
2202 * When multiple domains are given for a particular
2203 cache-host, the first matched domain is applied.
2204 * Cache hosts with no domain restrictions are queried
2206 * There are no defaults.
2207 * There is also a 'cache_peer_access' tag in the ACL
2211 NAME: cache_peer_access
2216 Similar to 'cache_peer_domain' but provides more flexibility by
2219 cache_peer_access cache-host allow|deny [!]aclname ...
2221 The syntax is identical to 'http_access' and the other lists of
2222 ACL elements. See the comments for 'http_access' below, or
2223 the Squid FAQ (http://wiki.squid-cache.org/SquidFaq/SquidAcl).
2226 NAME: neighbor_type_domain
2227 TYPE: hostdomaintype
2231 usage: neighbor_type_domain neighbor parent|sibling domain domain ...
2233 Modifying the neighbor type for specific domains is now
2234 possible. You can treat some domains differently than the
2235 default neighbor type specified on the 'cache_peer' line.
2236 Normally it should only be necessary to list domains which
2237 should be treated differently because the default neighbor type
2238 applies for hostnames which do not match domains listed here.
2241 cache_peer cache.foo.org parent 3128 3130
2242 neighbor_type_domain cache.foo.org sibling .com .net
2243 neighbor_type_domain cache.foo.org sibling .au .de
2246 NAME: dead_peer_timeout
2250 LOC: Config.Timeout.deadPeer
2252 This controls how long Squid waits to declare a peer cache
2253 as "dead." If there are no ICP replies received in this
2254 amount of time, Squid will declare the peer dead and not
2255 expect to receive any further ICP replies. However, it
2256 continues to send ICP queries, and will mark the peer as
2257 alive upon receipt of the first subsequent ICP reply.
2259 This timeout also affects when Squid expects to receive ICP
2260 replies from peers. If more than 'dead_peer' seconds have
2261 passed since the last ICP reply was received, Squid will not
2262 expect to receive an ICP reply on the next query. Thus, if
2263 your time between requests is greater than this timeout, you
2264 will see a lot of requests sent DIRECT to origin servers
2265 instead of to your parents.
2268 NAME: forward_max_tries
2271 LOC: Config.forward_max_tries
2273 Controls how many different forward paths Squid will try
2274 before giving up. See also forward_timeout.
2276 NOTE: connect_retries (default: none) can make each of these
2277 possible forwarding paths be tried multiple times.
2280 NAME: hierarchy_stoplist
2283 LOC: Config.hierarchy_stoplist
2285 A list of words which, if found in a URL, cause the object to
2286 be handled directly by this cache. In other words, use this
2287 to not query neighbor caches for certain objects. You may
2288 list this option multiple times.
2289 Note: never_direct overrides this option.
2292 # We recommend you to use at least the following line.
2293 hierarchy_stoplist cgi-bin ?
2298 MEMORY CACHE OPTIONS
2299 -----------------------------------------------------------------------------
2306 LOC: Config.memMaxSize
2308 NOTE: THIS PARAMETER DOES NOT SPECIFY THE MAXIMUM PROCESS SIZE.
2309 IT ONLY PLACES A LIMIT ON HOW MUCH ADDITIONAL MEMORY SQUID WILL
2310 USE AS A MEMORY CACHE OF OBJECTS. SQUID USES MEMORY FOR OTHER
2311 THINGS AS WELL. SEE THE SQUID FAQ SECTION 8 FOR DETAILS.
2313 'cache_mem' specifies the ideal amount of memory to be used
2315 * In-Transit objects
2317 * Negative-Cached objects
2319 Data for these objects are stored in 4 KB blocks. This
2320 parameter specifies the ideal upper limit on the total size of
2321 4 KB blocks allocated. In-Transit objects take the highest
2324 In-transit objects have priority over the others. When
2325 additional space is needed for incoming data, negative-cached
2326 and hot objects will be released. In other words, the
2327 negative-cached and hot objects will fill up any unused space
2328 not needed for in-transit objects.
2330 If circumstances require, this limit will be exceeded.
2331 Specifically, if your incoming request rate requires more than
2332 'cache_mem' of memory to hold in-transit objects, Squid will
2333 exceed this limit to satisfy the new requests. When the load
2334 decreases, blocks will be freed until the high-water mark is
2335 reached. Thereafter, blocks will be used to store hot
2339 NAME: maximum_object_size_in_memory
2343 LOC: Config.Store.maxInMemObjSize
2345 Objects greater than this size will not be attempted to kept in
2346 the memory cache. This should be set high enough to keep objects
2347 accessed frequently in memory to improve performance whilst low
2348 enough to keep larger objects from hoarding cache_mem.
2351 NAME: memory_cache_mode
2356 Controls which objects to keep in the memory cache (cache_mem)
2358 always Keep most recently fetched objects in memory (default)
2360 disk Only disk cache hits are kept in memory, which means
2361 an object must first be cached on disk and then hit
2362 a second time before cached in memory.
2364 network Only objects fetched from network is kept in memory
2367 NAME: memory_replacement_policy
2369 LOC: Config.memPolicy
2372 The memory replacement policy parameter determines which
2373 objects are purged from memory when memory space is needed.
2375 See cache_replacement_policy for details.
2380 -----------------------------------------------------------------------------
2383 NAME: cache_replacement_policy
2385 LOC: Config.replPolicy
2388 The cache replacement policy parameter determines which
2389 objects are evicted (replaced) when disk space is needed.
2391 lru : Squid's original list based LRU policy
2392 heap GDSF : Greedy-Dual Size Frequency
2393 heap LFUDA: Least Frequently Used with Dynamic Aging
2394 heap LRU : LRU policy implemented using a heap
2396 Applies to any cache_dir lines listed below this.
2398 The LRU policies keeps recently referenced objects.
2400 The heap GDSF policy optimizes object hit rate by keeping smaller
2401 popular objects in cache so it has a better chance of getting a
2402 hit. It achieves a lower byte hit rate than LFUDA though since
2403 it evicts larger (possibly popular) objects.
2405 The heap LFUDA policy keeps popular objects in cache regardless of
2406 their size and thus optimizes byte hit rate at the expense of
2407 hit rate since one large, popular object will prevent many
2408 smaller, slightly less popular objects from being cached.
2410 Both policies utilize a dynamic aging mechanism that prevents
2411 cache pollution that can otherwise occur with frequency-based
2412 replacement policies.
2414 NOTE: if using the LFUDA replacement policy you should increase
2415 the value of maximum_object_size above its default of 4096 KB to
2416 to maximize the potential byte hit rate improvement of LFUDA.
2418 For more information about the GDSF and LFUDA cache replacement
2419 policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
2420 and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
2426 LOC: Config.cacheSwap
2430 cache_dir Type Directory-Name Fs-specific-data [options]
2432 You can specify multiple cache_dir lines to spread the
2433 cache among different disk partitions.
2435 Type specifies the kind of storage system to use. Only "ufs"
2436 is built by default. To enable any of the other storage systems
2437 see the --enable-storeio configure option.
2439 'Directory' is a top-level directory where cache swap
2440 files will be stored. If you want to use an entire disk
2441 for caching, this can be the mount-point directory.
2442 The directory must exist and be writable by the Squid
2443 process. Squid will NOT create this directory for you.
2447 "ufs" is the old well-known Squid storage format that has always
2450 cache_dir ufs Directory-Name Mbytes L1 L2 [options]
2452 'Mbytes' is the amount of disk space (MB) to use under this
2453 directory. The default is 100 MB. Change this to suit your
2454 configuration. Do NOT put the size of your disk drive here.
2455 Instead, if you want Squid to use the entire disk drive,
2456 subtract 20% and use that value.
2458 'L1' is the number of first-level subdirectories which
2459 will be created under the 'Directory'. The default is 16.
2461 'L2' is the number of second-level subdirectories which
2462 will be created under each first-level directory. The default
2465 The aufs store type:
2467 "aufs" uses the same storage format as "ufs", utilizing
2468 POSIX-threads to avoid blocking the main Squid process on
2469 disk-I/O. This was formerly known in Squid as async-io.
2471 cache_dir aufs Directory-Name Mbytes L1 L2 [options]
2473 see argument descriptions under ufs above
2475 The diskd store type:
2477 "diskd" uses the same storage format as "ufs", utilizing a
2478 separate process to avoid blocking the main Squid process on
2481 cache_dir diskd Directory-Name Mbytes L1 L2 [options] [Q1=n] [Q2=n]
2483 see argument descriptions under ufs above
2485 Q1 specifies the number of unacknowledged I/O requests when Squid
2486 stops opening new files. If this many messages are in the queues,
2487 Squid won't open new files. Default is 64
2489 Q2 specifies the number of unacknowledged messages when Squid
2490 starts blocking. If this many messages are in the queues,
2491 Squid blocks until it receives some replies. Default is 72
2493 When Q1 < Q2 (the default), the cache directory is optimized
2494 for lower response time at the expense of a decrease in hit
2495 ratio. If Q1 > Q2, the cache directory is optimized for
2496 higher hit ratio at the expense of an increase in response
2499 The coss store type:
2501 NP: COSS filesystem in Squid-3 has been deemed too unstable for
2502 production use and has thus been removed from this release.
2503 We hope that it can be made usable again soon.
2505 block-size=n defines the "block size" for COSS cache_dir's.
2506 Squid uses file numbers as block numbers. Since file numbers
2507 are limited to 24 bits, the block size determines the maximum
2508 size of the COSS partition. The default is 512 bytes, which
2509 leads to a maximum cache_dir size of 512<<24, or 8 GB. Note
2510 you should not change the coss block size after Squid
2511 has written some objects to the cache_dir.
2513 The coss file store has changed from 2.5. Now it uses a file
2514 called 'stripe' in the directory names in the config - and
2515 this will be created by squid -z.
2519 no-store, no new objects should be stored to this cache_dir
2521 max-size=n, refers to the max object size this storedir supports.
2522 It is used to initially choose the storedir to dump the object.
2523 Note: To make optimal use of the max-size limits you should order
2524 the cache_dir lines with the smallest max-size value first and the
2525 ones with no max-size specification last.
2527 Note for coss, max-size must be less than COSS_MEMBUF_SZ,
2528 which can be changed with the --with-coss-membuf-size=N configure
2532 # Uncomment and adjust the following to add a disk cache directory.
2533 #cache_dir ufs @DEFAULT_SWAP_DIR@ 100 16 256
2537 NAME: store_dir_select_algorithm
2539 LOC: Config.store_dir_select_algorithm
2542 Set this to 'round-robin' as an alternative.
2545 NAME: max_open_disk_fds
2547 LOC: Config.max_open_disk_fds
2550 To avoid having disk as the I/O bottleneck Squid can optionally
2551 bypass the on-disk cache if more than this amount of disk file
2552 descriptors are open.
2554 A value of 0 indicates no limit.
2557 NAME: minimum_object_size
2561 LOC: Config.Store.minObjectSize
2563 Objects smaller than this size will NOT be saved on disk. The
2564 value is specified in kilobytes, and the default is 0 KB, which
2565 means there is no minimum.
2568 NAME: maximum_object_size
2572 LOC: Config.Store.maxObjectSize
2574 Objects larger than this size will NOT be saved on disk. The
2575 value is specified in kilobytes, and the default is 4MB. If
2576 you wish to get a high BYTES hit ratio, you should probably
2577 increase this (one 32 MB object hit counts for 3200 10KB
2578 hits). If you wish to increase speed more than your want to
2579 save bandwidth you should leave this low.
2581 NOTE: if using the LFUDA replacement policy you should increase
2582 this value to maximize the byte hit rate improvement of LFUDA!
2583 See replacement_policy below for a discussion of this policy.
2586 NAME: cache_swap_low
2587 COMMENT: (percent, 0-100)
2590 LOC: Config.Swap.lowWaterMark
2593 NAME: cache_swap_high
2594 COMMENT: (percent, 0-100)
2597 LOC: Config.Swap.highWaterMark
2600 The low- and high-water marks for cache object replacement.
2601 Replacement begins when the swap (disk) usage is above the
2602 low-water mark and attempts to maintain utilization near the
2603 low-water mark. As swap utilization gets close to high-water
2604 mark object eviction becomes more aggressive. If utilization is
2605 close to the low-water mark less replacement is done each time.
2607 Defaults are 90% and 95%. If you have a large cache, 5% could be
2608 hundreds of MB. If this is the case you may wish to set these
2609 numbers closer together.
2614 -----------------------------------------------------------------------------
2619 LOC: Config.Log.logformats
2624 logformat <name> <format specification>
2626 Defines an access log format.
2628 The <format specification> is a string with embedded % format codes
2630 % format codes all follow the same basic structure where all but
2631 the formatcode is optional. Output strings are automatically escaped
2632 as required according to their context and the output format
2633 modifiers are usually not needed, but can be specified if an explicit
2634 output format is desired.
2636 % ["|[|'|#] [-] [[0]width] [{argument}] formatcode
2638 " output in quoted string format
2639 [ output in squid text log format as used by log_mime_hdrs
2640 # output in URL quoted format
2644 width field width. If starting with 0 the
2645 output is zero padded
2646 {arg} argument such as header name etc
2650 % a literal % character
2651 >a Client source IP address
2653 >p Client source port
2654 <A Server IP address or peer name
2655 la Local IP address (http_port)
2656 lp Local port number (http_port)
2657 <lp Local port number of the last server or peer connection
2658 sn Unique sequence number per log line entry
2659 ts Seconds since epoch
2660 tu subsecond time (milliseconds)
2661 tl Local time. Optional strftime format argument
2662 default %d/%b/%Y:%H:%M:%S %z
2663 tg GMT time. Optional strftime format argument
2664 default %d/%b/%Y:%H:%M:%S %z
2665 tr Response time (milliseconds)
2666 dt Total time spent making DNS lookups (milliseconds)
2668 HTTP cache related format codes:
2670 [http::]>h Original request header. Optional header name argument
2671 on the format header[:[separator]element]
2672 [http::]>ha The HTTP request headers after adaptation and redirection.
2673 Optional header name argument as for >h
2674 [http::]<h Reply header. Optional header name argument
2676 [http::]un User name
2677 [http::]ul User name from authentication
2678 [http::]ui User name from ident
2679 [http::]us User name from SSL
2680 [http::]ue User name from external acl helper
2681 [http::]>Hs HTTP status code sent to the client
2682 [http::]<Hs HTTP status code received from the next hop
2683 [http::]<bs Number of HTTP-equivalent message body bytes
2684 received from the next hop, excluding chunked
2685 transfer encoding and control messages.
2686 Generated FTP/Gopher listings are treated as
2688 [http::]Ss Squid request status (TCP_MISS etc)
2689 [http::]Sh Squid hierarchy status (DEFAULT_PARENT etc)
2690 [http::]mt MIME content type
2691 [http::]rm Request method (GET/POST etc)
2692 [http::]ru Request URL
2693 [http::]rp Request URL-Path excluding hostname
2694 [http::]rv Request protocol version
2695 [http::]et Tag returned by external acl
2696 [http::]ea Log string returned by external acl
2697 [http::]<st Sent reply size including HTTP headers
2698 [http::]>st Received request size including HTTP headers. In the
2699 case of chunked requests the chunked encoding metadata
2701 [http::]>sh Received HTTP request headers size
2702 [http::]<sh Sent HTTP reply headers size
2703 [http::]st Request+Reply size including HTTP headers
2704 [http::]<sH Reply high offset sent
2705 [http::]<sS Upstream object size
2706 [http::]<pt Peer response time in milliseconds. The timer starts
2707 when the last request byte is sent to the next hop
2708 and stops when the last response byte is received.
2709 [http::]<tt Total server-side time in milliseconds. The timer
2710 starts with the first connect request (or write I/O)
2711 sent to the first selected peer. The timer stops
2712 with the last I/O with the last peer.
2714 If ICAP is enabled, the following two codes become available (as
2715 well as ICAP log codes documented with the icap_log option):
2717 icap::tt Total ICAP processing time for the HTTP
2718 transaction. The timer ticks when ICAP
2719 ACLs are checked and when ICAP
2720 transaction is in progress.
2722 icap::<last_h The header of the last ICAP response
2723 related to the HTTP transaction. Like
2724 <h, accepts an optional header name
2725 argument. Will not change semantics
2726 when multiple ICAP transactions per HTTP
2727 transaction are supported.
2729 If adaptation is enabled the following two codes become available:
2731 adapt::sum_trs Summed adaptation transaction response
2732 times recorded as a comma-separated list in
2733 the order of transaction start time. Each time
2734 value is recorded as an integer number,
2735 representing response time of one or more
2736 adaptation (ICAP or eCAP) transaction in
2737 milliseconds. When a failed transaction is
2738 being retried or repeated, its time is not
2739 logged individually but added to the
2740 replacement (next) transaction. See also:
2743 adapt::all_trs All adaptation transaction response times.
2744 Same as adaptation_strs but response times of
2745 individual transactions are never added
2746 together. Instead, all transaction response
2747 times are recorded individually.
2749 You can prefix adapt::*_trs format codes with adaptation
2750 service name in curly braces to record response time(s) specific
2751 to that service. For example: %{my_service}adapt::sum_trs
2753 The default formats available (which do not need re-defining) are:
2755 logformat squid %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %un %Sh/%<A %mt
2756 logformat squidmime %ts.%03tu %6tr %>a %Ss/%03>Hs %<st %rm %ru %un %Sh/%<A %mt [%>h] [%<h]
2757 logformat common %>a %ui %un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st %Ss:%Sh
2758 logformat combined %>a %ui %un [%tl] "%rm %ru HTTP/%rv" %>Hs %<st "%{Referer}>h" "%{User-Agent}>h" %Ss:%Sh
2761 NAME: access_log cache_access_log
2763 LOC: Config.Log.accesslogs
2765 DEFAULT_IF_NONE: daemon:@DEFAULT_ACCESS_LOG@ squid
2767 These files log client request activities. Has a line every HTTP or
2768 ICP request. The format is:
2769 access_log <module>:<place> [<logformat name> [acl acl ...]]
2770 access_log none [acl acl ...]]
2772 Will log to the specified module:place using the specified format (which
2773 must be defined in a logformat directive) those entries which match
2774 ALL the acl's specified (which must be defined in acl clauses).
2775 If no acl is specified, all requests will be logged to this destination.
2777 ===== Modules Currently available =====
2779 none Do not log any requests matchign these ACL.
2780 Do not specify Place or logformat name.
2782 stdio Write each log line to disk immediately at the completion of
2784 Place: the filename and path to be written.
2786 daemon Very similar to stdio. But instead of writing to disk the log
2787 line is passed to a daemon helper for asychronous handling instead.
2788 Place: varies depending on the daemon.
2790 log_file_daemon Place: the file name and path to be written.
2792 syslog To log each request via syslog facility.
2793 Place: The syslog facility and priority level for these entries.
2794 Place Format: facility.priority
2796 where facility could be any of:
2797 authpriv, daemon, local0 ... local7 or user.
2799 And priority could be any of:
2800 err, warning, notice, info, debug.
2802 udp To send each log line as text data to a UDP receiver.
2803 Place: The destination host name or IP and port.
2804 Place Format: \\host:port
2806 tcp To send each log line as text data to a TCP receiver.
2807 Place: The destination host name or IP and port.
2808 Place Format: \\host:port
2811 access_log daemon:@DEFAULT_ACCESS_LOG@ squid
2817 LOC: Config.Log.icaplogs
2820 ICAP log files record ICAP transaction summaries, one line per
2823 The icap_log option format is:
2824 icap_log <filepath> [<logformat name> [acl acl ...]]
2825 icap_log none [acl acl ...]]
2827 Please see access_log option documentation for details. The two
2828 kinds of logs share the overall configuration approach and many
2831 ICAP processing of a single HTTP message or transaction may
2832 require multiple ICAP transactions. In such cases, multiple
2833 ICAP transaction log lines will correspond to a single access
2836 ICAP log uses logformat codes that make sense for an ICAP
2837 transaction. Header-related codes are applied to the HTTP header
2838 embedded in an ICAP server response, with the following caveats:
2839 For REQMOD, there is no HTTP response header unless the ICAP
2840 server performed request satisfaction. For RESPMOD, the HTTP
2841 request header is the header sent to the ICAP server. For
2842 OPTIONS, there are no HTTP headers.
2844 The following format codes are also available for ICAP logs:
2846 icap::<A ICAP server IP address. Similar to <A.
2848 icap::<service_name ICAP service name from the icap_service
2849 option in Squid configuration file.
2851 icap::ru ICAP Request-URI. Similar to ru.
2853 icap::rm ICAP request method (REQMOD, RESPMOD, or
2854 OPTIONS). Similar to existing rm.
2856 icap::>st Bytes sent to the ICAP server (TCP payload
2857 only; i.e., what Squid writes to the socket).
2859 icap::<st Bytes received from the ICAP server (TCP
2860 payload only; i.e., what Squid reads from
2863 icap::<bs Number of message body bytes received from the
2864 ICAP server. ICAP message body, if any, usually
2865 includes encapsulated HTTP message headers and
2866 possibly encapsulated HTTP message body. The
2867 HTTP body part is dechunked before its size is
2870 icap::tr Transaction response time (in
2871 milliseconds). The timer starts when
2872 the ICAP transaction is created and
2873 stops when the transaction is completed.
2876 icap::tio Transaction I/O time (in milliseconds). The
2877 timer starts when the first ICAP request
2878 byte is scheduled for sending. The timers
2879 stops when the last byte of the ICAP response
2882 icap::to Transaction outcome: ICAP_ERR* for all
2883 transaction errors, ICAP_OPT for OPTION
2884 transactions, ICAP_ECHO for 204
2885 responses, ICAP_MOD for message
2886 modification, and ICAP_SAT for request
2887 satisfaction. Similar to Ss.
2889 icap::Hs ICAP response status code. Similar to Hs.
2891 icap::>h ICAP request header(s). Similar to >h.
2893 icap::<h ICAP response header(s). Similar to <h.
2895 The default ICAP log format, which can be used without an explicit
2896 definition, is called icap_squid:
2898 logformat icap_squid %ts.%03tu %6icap::tr %>a %icap::to/%03icap::Hs %icap::<size %icap::rm %icap::ru% %un -/%icap::<A -
2900 See also: logformat, log_icap, and %icap::<last_h
2903 NAME: logfile_daemon
2905 DEFAULT: @DEFAULT_LOGFILED@
2906 LOC: Log::TheConfig.logfile_daemon
2908 Specify the path to the logfile-writing daemon. This daemon is
2909 used to write the access and store logs, if configured.
2911 Squid sends a number of commands to the log daemon:
2912 L<data>\n - logfile data
2917 r<n>\n - set rotate count to <n>
2918 b<n>\n - 1 = buffer output, 0 = don't buffer output
2920 No responses is expected.
2925 LOC: Config.accessList.log
2927 COMMENT: allow|deny acl acl...
2929 This options allows you to control which requests gets logged
2930 to access.log (see access_log directive). Requests denied for
2931 logging will also not be accounted for in performance counters.
2933 This clause only supports fast acl types.
2934 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
2940 LOC: Config.accessList.icap
2943 This options allows you to control which requests get logged
2944 to icap.log. See the icap_log directive for ICAP log details.
2947 NAME: cache_store_log
2950 LOC: Config.Log.store
2952 Logs the activities of the storage manager. Shows which
2953 objects are ejected from the cache, and which objects are
2954 saved and for how long. To disable, enter "none" or remove the line.
2955 There are not really utilities to analyze this data, so you can safely
2959 cache_store_log @DEFAULT_STORE_LOG@
2962 NAME: cache_swap_state cache_swap_log
2964 LOC: Config.Log.swap
2967 Location for the cache "swap.state" file. This index file holds
2968 the metadata of objects saved on disk. It is used to rebuild
2969 the cache during startup. Normally this file resides in each
2970 'cache_dir' directory, but you may specify an alternate
2971 pathname here. Note you must give a full filename, not just
2972 a directory. Since this is the index for the whole object
2973 list you CANNOT periodically rotate it!
2975 If %s can be used in the file name it will be replaced with a
2976 a representation of the cache_dir name where each / is replaced
2977 with '.'. This is needed to allow adding/removing cache_dir
2978 lines when cache_swap_log is being used.
2980 If have more than one 'cache_dir', and %s is not used in the name
2981 these swap logs will have names such as:
2987 The numbered extension (which is added automatically)
2988 corresponds to the order of the 'cache_dir' lines in this
2989 configuration file. If you change the order of the 'cache_dir'
2990 lines in this file, these index files will NOT correspond to
2991 the correct 'cache_dir' entry (unless you manually rename
2992 them). We recommend you do NOT use this option. It is
2993 better to keep these index files in each 'cache_dir' directory.
2996 NAME: logfile_rotate
2999 LOC: Config.Log.rotateNumber
3001 Specifies the number of logfile rotations to make when you
3002 type 'squid -k rotate'. The default is 10, which will rotate
3003 with extensions 0 through 9. Setting logfile_rotate to 0 will
3004 disable the file name rotation, but the logfiles are still closed
3005 and re-opened. This will enable you to rename the logfiles
3006 yourself just before sending the rotate signal.
3008 Note, the 'squid -k rotate' command normally sends a USR1
3009 signal to the running squid process. In certain situations
3010 (e.g. on Linux with Async I/O), USR1 is used for other
3011 purposes, so -k rotate uses another signal. It is best to get
3012 in the habit of using 'squid -k rotate' instead of 'kill -USR1
3015 Note, from Squid-3.1 this option has no effect on the cache.log,
3016 that log can be rotated separately by using debug_options
3019 NAME: emulate_httpd_log
3023 LOC: Config.onoff.common_log
3025 The Cache can emulate the log file format which many 'httpd'
3026 programs use. To disable/enable this emulation, set
3027 emulate_httpd_log to 'off' or 'on'. The default
3028 is to use the native log format since it includes useful
3029 information Squid-specific log analyzers use.
3032 NAME: log_ip_on_direct
3036 LOC: Config.onoff.log_ip_on_direct
3038 Log the destination IP address in the hierarchy log tag when going
3039 direct. Earlier Squid versions logged the hostname here. If you
3040 prefer the old way set this to off.
3045 DEFAULT: @DEFAULT_MIME_TABLE@
3046 LOC: Config.mimeTablePathname
3048 Pathname to Squid's MIME table. You shouldn't need to change
3049 this, but the default file contains examples and formatting
3050 information if you do.
3056 LOC: Config.onoff.log_mime_hdrs
3059 The Cache can record both the request and the response MIME
3060 headers for each HTTP transaction. The headers are encoded
3061 safely and will appear as two bracketed fields at the end of
3062 the access log (for either the native or httpd-emulated log
3063 formats). To enable this logging set log_mime_hdrs to 'on'.
3068 LOC: Config.Log.useragent
3070 IFDEF: USE_USERAGENT_LOG
3072 Squid will write the User-Agent field from HTTP requests
3073 to the filename specified here. By default useragent_log
3077 NAME: referer_log referrer_log
3079 LOC: Config.Log.referer
3081 IFDEF: USE_REFERER_LOG
3083 Squid will write the Referer field from HTTP requests to the
3084 filename specified here. By default referer_log is disabled.
3085 Note that "referer" is actually a misspelling of "referrer"
3086 however the misspelt version has been accepted into the HTTP RFCs
3092 DEFAULT: @DEFAULT_PID_FILE@
3093 LOC: Config.pidFilename
3095 A filename to write the process-id to. To disable, enter "none".
3102 LOC: Config.onoff.log_fqdn
3104 Turn this on if you wish to log fully qualified domain names
3105 in the access.log. To do this Squid does a DNS lookup of all
3106 IP's connecting to it. This can (in some situations) increase
3107 latency, which makes your cache seem slower for interactive
3111 NAME: client_netmask
3113 LOC: Config.Addrs.client_netmask
3116 A netmask for client addresses in logfiles and cachemgr output.
3117 Change this to protect the privacy of your cache clients.
3118 A netmask of 255.255.255.0 will log all IP's in that range with
3119 the last digit set to '0'.
3126 LOC: Config.Log.forward
3128 Logs the server-side requests.
3130 This is currently work in progress.
3133 NAME: strip_query_terms
3135 LOC: Config.onoff.strip_query_terms
3138 By default, Squid strips query terms from requested URLs before
3139 logging. This protects your user's privacy.
3146 LOC: Config.onoff.buffered_logs
3148 cache.log log file is written with stdio functions, and as such
3149 it can be buffered or unbuffered. By default it will be unbuffered.
3150 Buffering it can speed up the writing slightly (though you are
3151 unlikely to need to worry unless you run with tons of debugging
3152 enabled in which case performance will suffer badly anyway..).
3155 NAME: netdb_filename
3157 DEFAULT: @DEFAULT_NETDB_FILE@
3158 LOC: Config.netdbFilename
3161 A filename where Squid stores it's netdb state between restarts.
3162 To disable, enter "none".
3166 OPTIONS FOR TROUBLESHOOTING
3167 -----------------------------------------------------------------------------
3173 DEFAULT_IF_NONE: @DEFAULT_CACHE_LOG@
3174 LOC: Debug::cache_log
3176 Cache logging file. This is where general information about
3177 your cache's behavior goes. You can increase the amount of data
3178 logged to this file and how often its rotated with "debug_options"
3184 LOC: Debug::debugOptions
3186 Logging options are set as section,level where each source file
3187 is assigned a unique section. Lower levels result in less
3188 output, Full debugging (level 9) can result in a very large
3189 log file, so be careful.
3191 The magic word "ALL" sets debugging levels for all sections.
3192 We recommend normally running with "ALL,1".
3194 The rotate=N option can be used to keep more or less of these logs
3195 than would otherwise be kept by logfile_rotate.
3196 For most uses a single log should be enough to monitor current
3197 events affecting Squid.
3202 LOC: Config.coredump_dir
3204 DEFAULT_IF_NONE: none
3206 By default Squid leaves core files in the directory from where
3207 it was started. If you set 'coredump_dir' to a directory
3208 that exists, Squid will chdir() to that directory at startup
3209 and coredump files will be left there.
3213 # Leave coredumps in the first cache dir
3214 coredump_dir @DEFAULT_SWAP_DIR@
3220 OPTIONS FOR FTP GATEWAYING
3221 -----------------------------------------------------------------------------
3227 LOC: Config.Ftp.anon_user
3229 If you want the anonymous login password to be more informative
3230 (and enable the use of picky ftp servers), set this to something
3231 reasonable for your domain, like wwwuser@somewhere.net
3233 The reason why this is domainless by default is the
3234 request can be made on the behalf of a user in any domain,
3235 depending on how the cache is used.
3236 Some ftp server also validate the email address is valid
3237 (for example perl.com).
3243 LOC: Config.Ftp.passive
3245 If your firewall does not allow Squid to use passive
3246 connections, turn off this option.
3248 Use of ftp_epsv_all option requires this to be ON.
3254 LOC: Config.Ftp.epsv_all
3256 FTP Protocol extensions permit the use of a special "EPSV ALL" command.
3258 NATs may be able to put the connection on a "fast path" through the
3259 translator, as the EPRT command will never be used and therefore,
3260 translation of the data portion of the segments will never be needed.
3262 When a client only expects to do two-way FTP transfers this may be
3264 If squid finds that it must do a three-way FTP transfer after issuing
3265 an EPSV ALL command, the FTP session will fail.
3267 If you have any doubts about this option do not use it.
3268 Squid will nicely attempt all other connection methods.
3270 Requires ftp_passive to be ON (default) for any effect.
3276 LOC: Config.Ftp.epsv
3278 FTP Protocol extensions permit the use of a special "EPSV" command.
3280 NATs may be able to put the connection on a "fast path" through the
3281 translator using EPSV, as the EPRT command will never be used
3282 and therefore, translation of the data portion of the segments
3283 will never be needed.
3285 Turning this OFF will prevent EPSV being attempted.
3286 WARNING: Doing so will convert Squid back to the old behavior with all
3287 the related problems with external NAT devices/layers.
3289 Requires ftp_passive to be ON (default) for any effect.
3292 NAME: ftp_sanitycheck
3295 LOC: Config.Ftp.sanitycheck
3297 For security and data integrity reasons Squid by default performs
3298 sanity checks of the addresses of FTP data connections ensure the
3299 data connection is to the requested server. If you need to allow
3300 FTP connections to servers using another IP address for the data
3301 connection turn this off.
3304 NAME: ftp_telnet_protocol
3307 LOC: Config.Ftp.telnet
3309 The FTP protocol is officially defined to use the telnet protocol
3310 as transport channel for the control connection. However, many
3311 implementations are broken and does not respect this aspect of
3314 If you have trouble accessing files with ASCII code 255 in the
3315 path or similar problems involving this ASCII code you can
3316 try setting this directive to off. If that helps, report to the
3317 operator of the FTP server in question that their FTP server
3318 is broken and does not follow the FTP standard.
3322 OPTIONS FOR EXTERNAL SUPPORT PROGRAMS
3323 -----------------------------------------------------------------------------
3328 DEFAULT: @DEFAULT_DISKD@
3329 LOC: Config.Program.diskd
3331 Specify the location of the diskd executable.
3332 Note this is only useful if you have compiled in
3333 diskd as one of the store io modules.
3336 NAME: unlinkd_program
3339 DEFAULT: @DEFAULT_UNLINKD@
3340 LOC: Config.Program.unlinkd
3342 Specify the location of the executable for file deletion process.
3345 NAME: pinger_program
3347 DEFAULT: @DEFAULT_PINGER@
3348 LOC: Config.pinger.program
3351 Specify the location of the executable for the pinger process.
3357 LOC: Config.pinger.enable
3360 Control whether the pinger is active at run-time.
3361 Enables turning ICMP pinger on and off with a simple
3362 squid -k reconfigure.
3367 OPTIONS FOR URL REWRITING
3368 -----------------------------------------------------------------------------
3371 NAME: url_rewrite_program redirect_program
3373 LOC: Config.Program.redirect
3376 Specify the location of the executable for the URL rewriter.
3377 Since they can perform almost any function there isn't one included.
3379 For each requested URL rewriter will receive on line with the format
3381 URL <SP> client_ip "/" fqdn <SP> user <SP> method [<SP> kvpairs]<NL>
3383 In the future, the rewriter interface will be extended with
3384 key=value pairs ("kvpairs" shown above). Rewriter programs
3385 should be prepared to receive and possibly ignore additional
3386 whitespace-separated tokens on each input line.
3388 And the rewriter may return a rewritten URL. The other components of
3389 the request line does not need to be returned (ignored if they are).
3391 The rewriter can also indicate that a client-side redirect should
3392 be performed to the new URL. This is done by prefixing the returned
3393 URL with "301:" (moved permanently) or 302: (moved temporarily).
3395 By default, a URL rewriter is not used.
3398 NAME: url_rewrite_children redirect_children
3399 TYPE: HelperChildConfig
3400 DEFAULT: 20 startup=0 idle=1 concurrency=0
3401 LOC: Config.redirectChildren
3403 The maximum number of redirector processes to spawn. If you limit
3404 it too few Squid will have to wait for them to process a backlog of
3405 URLs, slowing it down. If you allow too many they will use RAM
3406 and other system resources noticably.
3408 The startup= and idle= options allow some measure of skew in your
3413 Sets a minimum of how many processes are to be spawned when Squid
3414 starts or reconfigures. When set to zero the first request will
3415 cause spawning of the first child process to handle it.
3417 Starting too few will cause an initial slowdown in traffic as Squid
3418 attempts to simultaneously spawn enough processes to cope.
3422 Sets a minimum of how many processes Squid is to try and keep available
3423 at all times. When traffic begins to rise above what the existing
3424 processes can handle this many more will be spawned up to the maximum
3425 configured. A minimum setting of 1 is required.
3429 The number of requests each redirector helper can handle in
3430 parallel. Defaults to 0 which indicates the redirector
3431 is a old-style single threaded redirector.
3433 When this directive is set to a value >= 1 then the protocol
3434 used to communicate with the helper is modified to include
3435 a request ID in front of the request/response. The request
3436 ID from the request must be echoed back with the response
3440 NAME: url_rewrite_host_header redirect_rewrites_host_header
3443 LOC: Config.onoff.redir_rewrites_host
3445 By default Squid rewrites any Host: header in redirected
3446 requests. If you are running an accelerator this may
3447 not be a wanted effect of a redirector.
3449 WARNING: Entries are cached on the result of the URL rewriting
3450 process, so be careful if you have domain-virtual hosts.
3453 NAME: url_rewrite_access redirector_access
3456 LOC: Config.accessList.redirector
3458 If defined, this access list specifies which requests are
3459 sent to the redirector processes. By default all requests
3462 This clause supports both fast and slow acl types.
3463 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3466 NAME: url_rewrite_bypass redirector_bypass
3468 LOC: Config.onoff.redirector_bypass
3471 When this is 'on', a request will not go through the
3472 redirector if all redirectors are busy. If this is 'off'
3473 and the redirector queue grows too large, Squid will exit
3474 with a FATAL error and ask you to increase the number of
3475 redirectors. You should only enable this if the redirectors
3476 are not critical to your caching system. If you use
3477 redirectors for access control, and you enable this option,
3478 users may have access to pages they should not
3479 be allowed to request.
3483 OPTIONS FOR TUNING THE CACHE
3484 -----------------------------------------------------------------------------
3487 NAME: cache no_cache
3490 LOC: Config.accessList.noCache
3492 A list of ACL elements which, if matched and denied, cause the request to
3493 not be satisfied from the cache and the reply to not be cached.
3494 In other words, use this to force certain objects to never be cached.
3496 You must use the words 'allow' or 'deny' to indicate whether items
3497 matching the ACL should be allowed or denied into the cache.
3499 Default is to allow all to be cached.
3501 This clause supports both fast and slow acl types.
3502 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3505 NAME: refresh_pattern
3506 TYPE: refreshpattern
3510 usage: refresh_pattern [-i] regex min percent max [options]
3512 By default, regular expressions are CASE-SENSITIVE. To make
3513 them case-insensitive, use the -i option.
3515 'Min' is the time (in minutes) an object without an explicit
3516 expiry time should be considered fresh. The recommended
3517 value is 0, any higher values may cause dynamic applications
3518 to be erroneously cached unless the application designer
3519 has taken the appropriate actions.
3521 'Percent' is a percentage of the objects age (time since last
3522 modification age) an object without explicit expiry time
3523 will be considered fresh.
3525 'Max' is an upper limit on how long objects without an explicit
3526 expiry time will be considered fresh.
3528 options: override-expire
3534 ignore-must-revalidate
3540 override-expire enforces min age even if the server
3541 sent an explicit expiry time (e.g., with the
3542 Expires: header or Cache-Control: max-age). Doing this
3543 VIOLATES the HTTP standard. Enabling this feature
3544 could make you liable for problems which it causes.
3546 Note: override-expire does not enforce staleness - it only extends
3547 freshness / min. If the server returns a Expires time which
3548 is longer than your max time, Squid will still consider
3549 the object fresh for that period of time.
3551 override-lastmod enforces min age even on objects
3552 that were modified recently.
3554 reload-into-ims changes client no-cache or ``reload''
3555 to If-Modified-Since requests. Doing this VIOLATES the
3556 HTTP standard. Enabling this feature could make you
3557 liable for problems which it causes.
3559 ignore-reload ignores a client no-cache or ``reload''
3560 header. Doing this VIOLATES the HTTP standard. Enabling
3561 this feature could make you liable for problems which
3564 ignore-no-cache ignores any ``Pragma: no-cache'' and
3565 ``Cache-control: no-cache'' headers received from a server.
3566 The HTTP RFC never allows the use of this (Pragma) header
3567 from a server, only a client, though plenty of servers
3570 ignore-no-store ignores any ``Cache-control: no-store''
3571 headers received from a server. Doing this VIOLATES
3572 the HTTP standard. Enabling this feature could make you
3573 liable for problems which it causes.
3575 ignore-must-revalidate ignores any ``Cache-Control: must-revalidate``
3576 headers received from a server. Doing this VIOLATES
3577 the HTTP standard. Enabling this feature could make you
3578 liable for problems which it causes.
3580 ignore-private ignores any ``Cache-control: private''
3581 headers received from a server. Doing this VIOLATES
3582 the HTTP standard. Enabling this feature could make you
3583 liable for problems which it causes.
3585 ignore-auth caches responses to requests with authorization,
3586 as if the originserver had sent ``Cache-control: public''
3587 in the response header. Doing this VIOLATES the HTTP standard.
3588 Enabling this feature could make you liable for problems which
3591 refresh-ims causes squid to contact the origin server
3592 when a client issues an If-Modified-Since request. This
3593 ensures that the client will receive an updated version
3594 if one is available.
3596 store-stale stores responses even if they don't have explicit
3597 freshness or a validator (i.e., Last-Modified or an ETag)
3598 present, or if they're already stale. By default, Squid will
3599 not cache such responses because they usually can't be
3600 reused. Note that such responses will be stale by default.
3602 Basically a cached object is:
3604 FRESH if expires < now, else STALE
3606 FRESH if lm-factor < percent, else STALE
3610 The refresh_pattern lines are checked in the order listed here.
3611 The first entry which matches is used. If none of the entries
3612 match the default will be used.
3614 Note, you must uncomment all the default lines if you want
3615 to change one. The default setting is only active if none is
3620 # Add any of your own refresh_pattern entries above these.
3621 refresh_pattern ^ftp: 1440 20% 10080
3622 refresh_pattern ^gopher: 1440 0% 1440
3623 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
3624 refresh_pattern . 0 20% 4320
3628 NAME: quick_abort_min
3632 LOC: Config.quickAbort.min
3635 NAME: quick_abort_max
3639 LOC: Config.quickAbort.max
3642 NAME: quick_abort_pct
3646 LOC: Config.quickAbort.pct
3648 The cache by default continues downloading aborted requests
3649 which are almost completed (less than 16 KB remaining). This
3650 may be undesirable on slow (e.g. SLIP) links and/or very busy
3651 caches. Impatient users may tie up file descriptors and
3652 bandwidth by repeatedly requesting and immediately aborting
3655 When the user aborts a request, Squid will check the
3656 quick_abort values to the amount of data transfered until
3659 If the transfer has less than 'quick_abort_min' KB remaining,
3660 it will finish the retrieval.
3662 If the transfer has more than 'quick_abort_max' KB remaining,
3663 it will abort the retrieval.
3665 If more than 'quick_abort_pct' of the transfer has completed,
3666 it will finish the retrieval.
3668 If you do not want any retrieval to continue after the client
3669 has aborted, set both 'quick_abort_min' and 'quick_abort_max'
3672 If you want retrievals to always continue if they are being
3673 cached set 'quick_abort_min' to '-1 KB'.
3676 NAME: read_ahead_gap
3677 COMMENT: buffer-size
3679 LOC: Config.readAheadGap
3682 The amount of data the cache will buffer ahead of what has been
3683 sent to the client when retrieving an object from another server.
3687 IFDEF: USE_HTTP_VIOLATIONS
3690 LOC: Config.negativeTtl
3693 Set the Default Time-to-Live (TTL) for failed requests.
3694 Certain types of failures (such as "connection refused" and
3695 "404 Not Found") are able to be negatively-cached for a short time.
3696 Modern web servers should provide Expires: header, however if they
3697 do not this can provide a minimum TTL.
3698 The default is not to cache errors with unknown expiry details.
3700 Note that this is different from negative caching of DNS lookups.
3702 WARNING: Doing this VIOLATES the HTTP standard. Enabling
3703 this feature could make you liable for problems which it
3707 NAME: positive_dns_ttl
3710 LOC: Config.positiveDnsTtl
3713 Upper limit on how long Squid will cache positive DNS responses.
3714 Default is 6 hours (360 minutes). This directive must be set
3715 larger than negative_dns_ttl.
3718 NAME: negative_dns_ttl
3721 LOC: Config.negativeDnsTtl
3724 Time-to-Live (TTL) for negative caching of failed DNS lookups.
3725 This also sets the lower cache limit on positive lookups.
3726 Minimum value is 1 second, and it is not recommendable to go
3727 much below 10 seconds.
3730 NAME: range_offset_limit
3731 COMMENT: size [acl acl...]
3733 LOC: Config.rangeOffsetLimit
3736 usage: (size) [units] [[!]aclname]
3738 Sets an upper limit on how far (number of bytes) into the file
3739 a Range request may be to cause Squid to prefetch the whole file.
3740 If beyond this limit, Squid forwards the Range request as it is and
3741 the result is NOT cached.
3743 This is to stop a far ahead range request (lets say start at 17MB)
3744 from making Squid fetch the whole object up to that point before
3745 sending anything to the client.
3747 Multiple range_offset_limit lines may be specified, and they will
3748 be searched from top to bottom on each request until a match is found.
3749 The first match found will be used. If no line matches a request, the
3750 default limit of 0 bytes will be used.
3752 'size' is the limit specified as a number of units.
3754 'units' specifies whether to use bytes, KB, MB, etc.
3755 If no units are specified bytes are assumed.
3757 A size of 0 causes Squid to never fetch more than the
3758 client requested. (default)
3760 A size of 'none' causes Squid to always fetch the object from the
3761 beginning so it may cache the result. (2.0 style)
3763 'aclname' is the name of a defined ACL.
3765 NP: Using 'none' as the byte value here will override any quick_abort settings
3766 that may otherwise apply to the range request. The range request will
3767 be fully fetched from start to finish regardless of the client
3768 actions. This affects bandwidth usage.
3771 NAME: minimum_expiry_time
3774 LOC: Config.minimum_expiry_time
3777 The minimum caching time according to (Expires - Date)
3778 Headers Squid honors if the object can't be revalidated
3779 defaults to 60 seconds. In reverse proxy environments it
3780 might be desirable to honor shorter object lifetimes. It
3781 is most likely better to make your server return a
3782 meaningful Last-Modified header however. In ESI environments
3783 where page fragments often have short lifetimes, this will
3784 often be best set to 0.
3787 NAME: store_avg_object_size
3791 LOC: Config.Store.avgObjectSize
3793 Average object size, used to estimate number of objects your
3794 cache can hold. The default is 13 KB.
3797 NAME: store_objects_per_bucket
3800 LOC: Config.Store.objectsPerBucket
3802 Target number of objects per bucket in the store hash table.
3803 Lowering this value increases the total number of buckets and
3804 also the storage maintenance rate. The default is 20.
3809 -----------------------------------------------------------------------------
3812 NAME: request_header_max_size
3816 LOC: Config.maxRequestHeaderSize
3818 This specifies the maximum size for HTTP headers in a request.
3819 Request headers are usually relatively small (about 512 bytes).
3820 Placing a limit on the request header size will catch certain
3821 bugs (for example with persistent connections) and possibly
3822 buffer-overflow or denial-of-service attacks.
3825 NAME: reply_header_max_size
3829 LOC: Config.maxReplyHeaderSize
3831 This specifies the maximum size for HTTP headers in a reply.
3832 Reply headers are usually relatively small (about 512 bytes).
3833 Placing a limit on the reply header size will catch certain
3834 bugs (for example with persistent connections) and possibly
3835 buffer-overflow or denial-of-service attacks.
3838 NAME: request_body_max_size
3842 LOC: Config.maxRequestBodySize
3844 This specifies the maximum size for an HTTP request body.
3845 In other words, the maximum size of a PUT/POST request.
3846 A user who attempts to send a request with a body larger
3847 than this limit receives an "Invalid Request" error message.
3848 If you set this parameter to a zero (the default), there will
3849 be no limit imposed.
3852 NAME: chunked_request_body_max_size
3856 LOC: Config.maxChunkedRequestBodySize
3858 A broken or confused HTTP/1.1 client may send a chunked HTTP
3859 request to Squid. Squid does not have full support for that
3860 feature yet. To cope with such requests, Squid buffers the
3861 entire request and then dechunks request body to create a
3862 plain HTTP/1.0 request with a known content length. The plain
3863 request is then used by the rest of Squid code as usual.
3865 The option value specifies the maximum size of the buffer used
3866 to hold the request before the conversion. If the chunked
3867 request size exceeds the specified limit, the conversion
3868 fails, and the client receives an "unsupported request" error,
3869 as if dechunking was disabled.
3871 Dechunking is enabled by default. To disable conversion of
3872 chunked requests, set the maximum to zero.
3874 Request dechunking feature and this option in particular are a
3875 temporary hack. When chunking requests and responses are fully
3876 supported, there will be no need to buffer a chunked request.
3880 IFDEF: USE_HTTP_VIOLATIONS
3883 LOC: Config.accessList.brokenPosts
3885 A list of ACL elements which, if matched, causes Squid to send
3886 an extra CRLF pair after the body of a PUT/POST request.
3888 Some HTTP servers has broken implementations of PUT/POST,
3889 and rely on an extra CRLF pair sent by some WWW clients.
3891 Quote from RFC2616 section 4.1 on this matter:
3893 Note: certain buggy HTTP/1.0 client implementations generate an
3894 extra CRLF's after a POST request. To restate what is explicitly
3895 forbidden by the BNF, an HTTP/1.1 client must not preface or follow
3896 a request with an extra CRLF.
3898 This clause only supports fast acl types.
3899 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
3902 acl buggy_server url_regex ^http://....
3903 broken_posts allow buggy_server
3906 NAME: icap_uses_indirect_client
3909 IFDEF: FOLLOW_X_FORWARDED_FOR&&ICAP_CLIENT
3911 LOC: Adaptation::Icap::TheConfig.icap_uses_indirect_client
3913 Controls whether the indirect client address
3914 (see follow_x_forwarded_for) instead of the
3915 direct client address is passed to an ICAP
3916 server as "X-Client-IP".
3920 IFDEF: USE_HTTP_VIOLATIONS
3924 LOC: Config.onoff.via
3926 If set (default), Squid will include a Via header in requests and
3927 replies as required by RFC2616.
3933 LOC: Config.onoff.ie_refresh
3936 Microsoft Internet Explorer up until version 5.5 Service
3937 Pack 1 has an issue with transparent proxies, wherein it
3938 is impossible to force a refresh. Turning this on provides
3939 a partial fix to the problem, by causing all IMS-REFRESH
3940 requests from older IE versions to check the origin server
3941 for fresh content. This reduces hit ratio by some amount
3942 (~10% in my experience), but allows users to actually get
3943 fresh content when they want it. Note because Squid
3944 cannot tell if the user is using 5.5 or 5.5SP1, the behavior
3945 of 5.5 is unchanged from old versions of Squid (i.e. a
3946 forced refresh is impossible). Newer versions of IE will,
3947 hopefully, continue to have the new behavior and will be
3948 handled based on that assumption. This option defaults to
3949 the old Squid behavior, which is better for hit ratios but
3950 worse for clients using IE, if they need to be able to
3951 force fresh content.
3954 NAME: vary_ignore_expire
3957 LOC: Config.onoff.vary_ignore_expire
3960 Many HTTP servers supporting Vary gives such objects
3961 immediate expiry time with no cache-control header
3962 when requested by a HTTP/1.0 client. This option
3963 enables Squid to ignore such expiry times until
3964 HTTP/1.1 is fully implemented.
3966 WARNING: If turned on this may eventually cause some
3967 varying objects not intended for caching to get cached.
3970 NAME: request_entities
3972 LOC: Config.onoff.request_entities
3975 Squid defaults to deny GET and HEAD requests with request entities,
3976 as the meaning of such requests are undefined in the HTTP standard
3977 even if not explicitly forbidden.
3979 Set this directive to on if you have clients which insists
3980 on sending request entities in GET or HEAD requests. But be warned
3981 that there is server software (both proxies and web servers) which
3982 can fail to properly process this kind of request which may make you
3983 vulnerable to cache pollution attacks if enabled.
3986 NAME: request_header_access
3987 IFDEF: USE_HTTP_VIOLATIONS
3988 TYPE: http_header_access[]
3989 LOC: Config.request_header_access
3992 Usage: request_header_access header_name allow|deny [!]aclname ...
3994 WARNING: Doing this VIOLATES the HTTP standard. Enabling
3995 this feature could make you liable for problems which it
3998 This option replaces the old 'anonymize_headers' and the
3999 older 'http_anonymizer' option with something that is much
4000 more configurable. This new method creates a list of ACLs
4001 for each header, allowing you very fine-tuned header
4004 This option only applies to request headers, i.e., from the
4005 client to the server.
4007 You can only specify known headers for the header name.
4008 Other headers are reclassified as 'Other'. You can also
4009 refer to all the headers with 'All'.
4011 For example, to achieve the same behavior as the old
4012 'http_anonymizer standard' option, you should use:
4014 request_header_access From deny all
4015 request_header_access Referer deny all
4016 request_header_access Server deny all
4017 request_header_access User-Agent deny all
4018 request_header_access WWW-Authenticate deny all
4019 request_header_access Link deny all
4021 Or, to reproduce the old 'http_anonymizer paranoid' feature
4024 request_header_access Allow allow all
4025 request_header_access Authorization allow all
4026 request_header_access WWW-Authenticate allow all
4027 request_header_access Proxy-Authorization allow all
4028 request_header_access Proxy-Authenticate allow all
4029 request_header_access Cache-Control allow all
4030 request_header_access Content-Encoding allow all
4031 request_header_access Content-Length allow all
4032 request_header_access Content-Type allow all
4033 request_header_access Date allow all
4034 request_header_access Expires allow all
4035 request_header_access Host allow all
4036 request_header_access If-Modified-Since allow all
4037 request_header_access Last-Modified allow all
4038 request_header_access Location allow all
4039 request_header_access Pragma allow all
4040 request_header_access Accept allow all
4041 request_header_access Accept-Charset allow all
4042 request_header_access Accept-Encoding allow all
4043 request_header_access Accept-Language allow all
4044 request_header_access Content-Language allow all
4045 request_header_access Mime-Version allow all
4046 request_header_access Retry-After allow all
4047 request_header_access Title allow all
4048 request_header_access Connection allow all
4049 request_header_access All deny all
4051 although many of those are HTTP reply headers, and so should be
4052 controlled with the reply_header_access directive.
4054 By default, all headers are allowed (no anonymizing is
4058 NAME: reply_header_access
4059 IFDEF: USE_HTTP_VIOLATIONS
4060 TYPE: http_header_access[]
4061 LOC: Config.reply_header_access
4064 Usage: reply_header_access header_name allow|deny [!]aclname ...
4066 WARNING: Doing this VIOLATES the HTTP standard. Enabling
4067 this feature could make you liable for problems which it
4070 This option only applies to reply headers, i.e., from the
4071 server to the client.
4073 This is the same as request_header_access, but in the other
4076 This option replaces the old 'anonymize_headers' and the
4077 older 'http_anonymizer' option with something that is much
4078 more configurable. This new method creates a list of ACLs
4079 for each header, allowing you very fine-tuned header
4082 You can only specify known headers for the header name.
4083 Other headers are reclassified as 'Other'. You can also
4084 refer to all the headers with 'All'.
4086 For example, to achieve the same behavior as the old
4087 'http_anonymizer standard' option, you should use:
4089 reply_header_access From deny all
4090 reply_header_access Referer deny all
4091 reply_header_access Server deny all
4092 reply_header_access User-Agent deny all
4093 reply_header_access WWW-Authenticate deny all
4094 reply_header_access Link deny all
4096 Or, to reproduce the old 'http_anonymizer paranoid' feature
4099 reply_header_access Allow allow all
4100 reply_header_access Authorization allow all
4101 reply_header_access WWW-Authenticate allow all
4102 reply_header_access Proxy-Authorization allow all
4103 reply_header_access Proxy-Authenticate allow all
4104 reply_header_access Cache-Control allow all
4105 reply_header_access Content-Encoding allow all
4106 reply_header_access Content-Length allow all
4107 reply_header_access Content-Type allow all
4108 reply_header_access Date allow all
4109 reply_header_access Expires allow all
4110 reply_header_access Host allow all
4111 reply_header_access If-Modified-Since allow all
4112 reply_header_access Last-Modified allow all
4113 reply_header_access Location allow all
4114 reply_header_access Pragma allow all
4115 reply_header_access Accept allow all
4116 reply_header_access Accept-Charset allow all
4117 reply_header_access Accept-Encoding allow all
4118 reply_header_access Accept-Language allow all
4119 reply_header_access Content-Language allow all
4120 reply_header_access Mime-Version allow all
4121 reply_header_access Retry-After allow all
4122 reply_header_access Title allow all
4123 reply_header_access Connection allow all
4124 reply_header_access All deny all
4126 although the HTTP request headers won't be usefully controlled
4127 by this directive -- see request_header_access for details.
4129 By default, all headers are allowed (no anonymizing is
4133 NAME: header_replace
4134 IFDEF: USE_HTTP_VIOLATIONS
4135 TYPE: http_header_replace[]
4136 LOC: Config.request_header_access
4139 Usage: header_replace header_name message
4140 Example: header_replace User-Agent Nutscrape/1.0 (CP/M; 8-bit)
4142 This option allows you to change the contents of headers
4143 denied with header_access above, by replacing them with
4144 some fixed string. This replaces the old fake_user_agent
4147 This only applies to request headers, not reply headers.
4149 By default, headers are removed if denied.
4152 NAME: relaxed_header_parser
4153 COMMENT: on|off|warn
4155 LOC: Config.onoff.relaxed_header_parser
4158 In the default "on" setting Squid accepts certain forms
4159 of non-compliant HTTP messages where it is unambiguous
4160 what the sending application intended even if the message
4161 is not correctly formatted. The messages is then normalized
4162 to the correct form when forwarded by Squid.
4164 If set to "warn" then a warning will be emitted in cache.log
4165 each time such HTTP error is encountered.
4167 If set to "off" then such HTTP errors will cause the request
4168 or response to be rejected.
4171 NAME: ignore_expect_100
4173 IFDEF: USE_HTTP_VIOLATIONS
4175 LOC: Config.onoff.ignore_expect_100
4178 This option makes Squid ignore any Expect: 100-continue header present
4179 in the request. RFC 2616 requires that Squid being unable to satisfy
4180 the response expectation MUST return a 417 error.
4182 Note: Enabling this is a HTTP protocol violation, but some clients may
4183 not handle it well..
4188 -----------------------------------------------------------------------------
4191 NAME: forward_timeout
4194 LOC: Config.Timeout.forward
4197 This parameter specifies how long Squid should at most attempt in
4198 finding a forwarding path for the request before giving up.
4201 NAME: connect_timeout
4204 LOC: Config.Timeout.connect
4207 This parameter specifies how long to wait for the TCP connect to
4208 the requested server or peer to complete before Squid should
4209 attempt to find another path where to forward the request.
4212 NAME: peer_connect_timeout
4215 LOC: Config.Timeout.peer_connect
4218 This parameter specifies how long to wait for a pending TCP
4219 connection to a peer cache. The default is 30 seconds. You
4220 may also set different timeout values for individual neighbors
4221 with the 'connect-timeout' option on a 'cache_peer' line.
4227 LOC: Config.Timeout.read
4230 The read_timeout is applied on server-side connections. After
4231 each successful read(), the timeout will be extended by this
4232 amount. If no data is read again after this amount of time,
4233 the request is aborted and logged with ERR_READ_TIMEOUT. The
4234 default is 15 minutes.
4240 LOC: Config.Timeout.write
4243 This timeout is tracked for all connections that have data
4244 available for writing and are waiting for the socket to become
4245 ready. After each successful write, the timeout is extended by
4246 the configured amount. If Squid has data to write but the
4247 connection is not ready for the configured duration, the
4248 transaction associated with the connection is terminated. The
4249 default is 15 minutes.
4252 NAME: request_timeout
4254 LOC: Config.Timeout.request
4257 How long to wait for an HTTP request after initial
4258 connection establishment.
4261 NAME: persistent_request_timeout
4263 LOC: Config.Timeout.persistent_request
4266 How long to wait for the next HTTP request on a persistent
4267 connection after the previous request completes.
4270 NAME: client_lifetime
4273 LOC: Config.Timeout.lifetime
4276 The maximum amount of time a client (browser) is allowed to
4277 remain connected to the cache process. This protects the Cache
4278 from having a lot of sockets (and hence file descriptors) tied up
4279 in a CLOSE_WAIT state from remote clients that go away without
4280 properly shutting down (either because of a network failure or
4281 because of a poor client implementation). The default is one
4284 NOTE: The default value is intended to be much larger than any
4285 client would ever need to be connected to your cache. You
4286 should probably change client_lifetime only as a last resort.
4287 If you seem to have many client connections tying up
4288 filedescriptors, we recommend first tuning the read_timeout,
4289 request_timeout, persistent_request_timeout and quick_abort values.
4292 NAME: half_closed_clients
4294 LOC: Config.onoff.half_closed_clients
4297 Some clients may shutdown the sending side of their TCP
4298 connections, while leaving their receiving sides open. Sometimes,
4299 Squid can not tell the difference between a half-closed and a
4300 fully-closed TCP connection.
4302 By default, Squid will immediately close client connections when
4303 read(2) returns "no more data to read."
4305 Change this option to 'on' and Squid will keep open connections
4306 until a read(2) or write(2) on the socket returns an error.
4307 This may show some benefits for reverse proxies. But if not
4308 it is recommended to leave OFF.
4313 LOC: Config.Timeout.pconn
4316 Timeout for idle persistent connections to servers and other
4323 LOC: Ident::TheConfig.timeout
4326 Maximum time to wait for IDENT lookups to complete.
4328 If this is too high, and you enabled IDENT lookups from untrusted
4329 users, you might be susceptible to denial-of-service by having
4330 many ident requests going at once.
4333 NAME: shutdown_lifetime
4336 LOC: Config.shutdownLifetime
4339 When SIGTERM or SIGHUP is received, the cache is put into
4340 "shutdown pending" mode until all active sockets are closed.
4341 This value is the lifetime to set for all open descriptors
4342 during shutdown mode. Any active clients after this many
4343 seconds will receive a 'timeout' message.
4347 ADMINISTRATIVE PARAMETERS
4348 -----------------------------------------------------------------------------
4354 LOC: Config.adminEmail
4356 Email-address of local cache manager who will receive
4357 mail if the cache dies. The default is "webmaster."
4363 LOC: Config.EmailFrom
4365 From: email-address for mail sent when the cache dies.
4366 The default is to use 'appname@unique_hostname'.
4367 Default appname value is "squid", can be changed into
4368 src/globals.h before building squid.
4374 LOC: Config.EmailProgram
4376 Email program used to send mail if the cache dies.
4377 The default is "mail". The specified program must comply
4378 with the standard Unix mail syntax:
4379 mail-program recipient < mailfile
4381 Optional command line options can be specified.
4384 NAME: cache_effective_user
4386 DEFAULT: @DEFAULT_CACHE_EFFECTIVE_USER@
4387 LOC: Config.effectiveUser
4389 If you start Squid as root, it will change its effective/real
4390 UID/GID to the user specified below. The default is to change
4391 to UID of @DEFAULT_CACHE_EFFECTIVE_USER@.
4392 see also; cache_effective_group
4395 NAME: cache_effective_group
4398 LOC: Config.effectiveGroup
4400 Squid sets the GID to the effective user's default group ID
4401 (taken from the password file) and supplementary group list
4402 from the groups membership.
4404 If you want Squid to run with a specific GID regardless of
4405 the group memberships of the effective user then set this
4406 to the group (or GID) you want Squid to run as. When set
4407 all other group privileges of the effective user are ignored
4408 and only this GID is effective. If Squid is not started as
4409 root the user starting Squid MUST be member of the specified
4412 This option is not recommended by the Squid Team.
4413 Our preference is for administrators to configure a secure
4414 user account for squid with UID/GID matching system policies.
4417 NAME: httpd_suppress_version_string
4421 LOC: Config.onoff.httpd_suppress_version_string
4423 Suppress Squid version string info in HTTP headers and HTML error pages.
4426 NAME: visible_hostname
4428 LOC: Config.visibleHostname
4431 If you want to present a special hostname in error messages, etc,
4432 define this. Otherwise, the return value of gethostname()
4433 will be used. If you have multiple caches in a cluster and
4434 get errors about IP-forwarding you must set them to have individual
4435 names with this setting.
4438 NAME: unique_hostname
4440 LOC: Config.uniqueHostname
4443 If you want to have multiple machines with the same
4444 'visible_hostname' you must give each machine a different
4445 'unique_hostname' so forwarding loops can be detected.
4448 NAME: hostname_aliases
4450 LOC: Config.hostnameAliases
4453 A list of other DNS names your cache has.
4461 Minimum umask which should be enforced while the proxy
4462 is running, in addition to the umask set at startup.
4464 For a traditional octal representation of umasks, start
4469 OPTIONS FOR THE CACHE REGISTRATION SERVICE
4470 -----------------------------------------------------------------------------
4472 This section contains parameters for the (optional) cache
4473 announcement service. This service is provided to help
4474 cache administrators locate one another in order to join or
4475 create cache hierarchies.
4477 An 'announcement' message is sent (via UDP) to the registration
4478 service by Squid. By default, the announcement message is NOT
4479 SENT unless you enable it with 'announce_period' below.
4481 The announcement message includes your hostname, plus the
4482 following information from this configuration file:
4488 All current information is processed regularly and made
4489 available on the Web at http://www.ircache.net/Cache/Tracker/.
4492 NAME: announce_period
4494 LOC: Config.Announce.period
4497 This is how frequently to send cache announcements. The
4498 default is `0' which disables sending the announcement
4501 To enable announcing your cache, just set an announce period.
4504 announce_period 1 day
4509 DEFAULT: tracker.ircache.net
4510 LOC: Config.Announce.host
4516 LOC: Config.Announce.file
4522 LOC: Config.Announce.port
4524 announce_host and announce_port set the hostname and port
4525 number where the registration message will be sent.
4527 Hostname will default to 'tracker.ircache.net' and port will
4528 default default to 3131. If the 'filename' argument is given,
4529 the contents of that file will be included in the announce
4534 HTTPD-ACCELERATOR OPTIONS
4535 -----------------------------------------------------------------------------
4538 NAME: httpd_accel_surrogate_id
4541 LOC: Config.Accel.surrogate_id
4543 Surrogates (http://www.esi.org/architecture_spec_1.0.html)
4544 need an identification token to allow control targeting. Because
4545 a farm of surrogates may all perform the same tasks, they may share
4546 an identification token.
4548 The default ID is the visible_hostname
4551 NAME: http_accel_surrogate_remote
4555 LOC: Config.onoff.surrogate_is_remote
4557 Remote surrogates (such as those in a CDN) honour Surrogate-Control: no-store-remote.
4558 Set this to on to have squid behave as a remote surrogate.
4562 IFDEF: USE_SQUID_ESI
4563 COMMENT: libxml2|expat|custom
4565 LOC: ESIParser::Type
4568 ESI markup is not strictly XML compatible. The custom ESI parser
4569 will give higher performance, but cannot handle non ASCII character
4574 DELAY POOL PARAMETERS
4575 -----------------------------------------------------------------------------
4579 TYPE: delay_pool_count
4584 This represents the number of delay pools to be used. For example,
4585 if you have one class 2 delay pool and one class 3 delays pool, you
4586 have a total of 2 delay pools.
4590 TYPE: delay_pool_class
4595 This defines the class of each delay pool. There must be exactly one
4596 delay_class line for each delay pool. For example, to define two
4597 delay pools, one of class 2 and one of class 3, the settings above
4601 delay_pools 4 # 4 delay pools
4602 delay_class 1 2 # pool 1 is a class 2 pool
4603 delay_class 2 3 # pool 2 is a class 3 pool
4604 delay_class 3 4 # pool 3 is a class 4 pool
4605 delay_class 4 5 # pool 4 is a class 5 pool
4607 The delay pool classes are:
4609 class 1 Everything is limited by a single aggregate
4612 class 2 Everything is limited by a single aggregate
4613 bucket as well as an "individual" bucket chosen
4614 from bits 25 through 32 of the IPv4 address.
4616 class 3 Everything is limited by a single aggregate
4617 bucket as well as a "network" bucket chosen
4618 from bits 17 through 24 of the IP address and a
4619 "individual" bucket chosen from bits 17 through
4620 32 of the IPv4 address.
4622 class 4 Everything in a class 3 delay pool, with an
4623 additional limit on a per user basis. This
4624 only takes effect if the username is established
4625 in advance - by forcing authentication in your
4628 class 5 Requests are grouped according their tag (see
4629 external_acl's tag= reply).
4631 NOTE: If an IP address is a.b.c.d
4632 -> bits 25 through 32 are "d"
4633 -> bits 17 through 24 are "c"
4634 -> bits 17 through 32 are "c * 256 + d"
4636 NOTE-2: Due to the use of bitmasks in class 2,3,4 pools they only apply to
4637 IPv4 traffic. Class 1 and 5 pools may be used with IPv6 traffic.
4641 TYPE: delay_pool_access
4646 This is used to determine which delay pool a request falls into.
4648 delay_access is sorted per pool and the matching starts with pool 1,
4649 then pool 2, ..., and finally pool N. The first delay pool where the
4650 request is allowed is selected for the request. If it does not allow
4651 the request to any pool then the request is not delayed (default).
4653 For example, if you want some_big_clients in delay
4654 pool 1 and lotsa_little_clients in delay pool 2:
4657 delay_access 1 allow some_big_clients
4658 delay_access 1 deny all
4659 delay_access 2 allow lotsa_little_clients
4660 delay_access 2 deny all
4661 delay_access 3 allow authenticated_clients
4664 NAME: delay_parameters
4665 TYPE: delay_pool_rates
4670 This defines the parameters for a delay pool. Each delay pool has
4671 a number of "buckets" associated with it, as explained in the
4672 description of delay_class. For a class 1 delay pool, the syntax is:
4674 delay_parameters pool aggregate
4676 For a class 2 delay pool:
4678 delay_parameters pool aggregate individual
4680 For a class 3 delay pool:
4682 delay_parameters pool aggregate network individual
4684 For a class 4 delay pool:
4686 delay_parameters pool aggregate network individual user
4688 For a class 5 delay pool:
4690 delay_parameters pool tag
4692 The variables here are:
4694 pool a pool number - ie, a number between 1 and the
4695 number specified in delay_pools as used in
4698 aggregate the "delay parameters" for the aggregate bucket
4701 individual the "delay parameters" for the individual
4702 buckets (class 2, 3).
4704 network the "delay parameters" for the network buckets
4707 user the delay parameters for the user buckets
4710 tag the delay parameters for the tag buckets
4713 A pair of delay parameters is written restore/maximum, where restore is
4714 the number of bytes (not bits - modem and network speeds are usually
4715 quoted in bits) per second placed into the bucket, and maximum is the
4716 maximum number of bytes which can be in the bucket at any time.
4718 For example, if delay pool number 1 is a class 2 delay pool as in the
4719 above example, and is being used to strictly limit each host to 64kbps
4720 (plus overheads), with no overall limit, the line is:
4722 delay_parameters 1 -1/-1 8000/8000
4724 Note that the figure -1 is used to represent "unlimited".
4726 And, if delay pool number 2 is a class 3 delay pool as in the above
4727 example, and you want to limit it to a total of 256kbps (strict limit)
4728 with each 8-bit network permitted 64kbps (strict limit) and each
4729 individual host permitted 4800bps with a bucket maximum size of 64kb
4730 to permit a decent web page to be downloaded at a decent speed
4731 (if the network is not being limited due to overuse) but slow down
4732 large downloads more significantly:
4734 delay_parameters 2 32000/32000 8000/8000 600/8000
4736 There must be one delay_parameters line for each delay pool.
4738 Finally, for a class 4 delay pool as in the example - each user will
4739 be limited to 128Kb no matter how many workstations they are logged into.:
4741 delay_parameters 4 32000/32000 8000/8000 600/64000 16000/16000
4744 NAME: delay_initial_bucket_level
4745 COMMENT: (percent, 0-100)
4749 LOC: Config.Delay.initial
4751 The initial bucket percentage is used to determine how much is put
4752 in each bucket when squid starts, is reconfigured, or first notices
4753 a host accessing it (in class 2 and class 3, individual hosts and
4754 networks only have buckets associated with them once they have been
4759 WCCPv1 AND WCCPv2 CONFIGURATION OPTIONS
4760 -----------------------------------------------------------------------------
4765 LOC: Config.Wccp.router
4769 Use this option to define your WCCP ``home'' router for
4772 wccp_router supports a single WCCP(v1) router
4774 wccp2_router supports multiple WCCPv2 routers
4776 only one of the two may be used at the same time and defines
4777 which version of WCCP to use.
4781 TYPE: IpAddress_list
4782 LOC: Config.Wccp2.router
4786 Use this option to define your WCCP ``home'' router for
4789 wccp_router supports a single WCCP(v1) router
4791 wccp2_router supports multiple WCCPv2 routers
4793 only one of the two may be used at the same time and defines
4794 which version of WCCP to use.
4799 LOC: Config.Wccp.version
4803 This directive is only relevant if you need to set up WCCP(v1)
4804 to some very old and end-of-life Cisco routers. In all other
4805 setups it must be left unset or at the default setting.
4806 It defines an internal version in the WCCP(v1) protocol,
4807 with version 4 being the officially documented protocol.
4809 According to some users, Cisco IOS 11.2 and earlier only
4810 support WCCP version 3. If you're using that or an earlier
4811 version of IOS, you may need to change this value to 3, otherwise
4812 do not specify this parameter.
4815 NAME: wccp2_rebuild_wait
4817 LOC: Config.Wccp2.rebuildwait
4821 If this is enabled Squid will wait for the cache dir rebuild to finish
4822 before sending the first wccp2 HereIAm packet
4825 NAME: wccp2_forwarding_method
4827 LOC: Config.Wccp2.forwarding_method
4831 WCCP2 allows the setting of forwarding methods between the
4832 router/switch and the cache. Valid values are as follows:
4834 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
4835 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
4837 Currently (as of IOS 12.4) cisco routers only support GRE.
4838 Cisco switches only support the L2 redirect assignment method.
4841 NAME: wccp2_return_method
4843 LOC: Config.Wccp2.return_method
4847 WCCP2 allows the setting of return methods between the
4848 router/switch and the cache for packets that the cache
4849 decides not to handle. Valid values are as follows:
4851 gre - GRE encapsulation (forward the packet in a GRE/WCCP tunnel)
4852 l2 - L2 redirect (forward the packet using Layer 2/MAC rewriting)
4854 Currently (as of IOS 12.4) cisco routers only support GRE.
4855 Cisco switches only support the L2 redirect assignment.
4857 If the "ip wccp redirect exclude in" command has been
4858 enabled on the cache interface, then it is still safe for
4859 the proxy server to use a l2 redirect method even if this
4860 option is set to GRE.
4863 NAME: wccp2_assignment_method
4865 LOC: Config.Wccp2.assignment_method
4869 WCCP2 allows the setting of methods to assign the WCCP hash
4870 Valid values are as follows:
4872 hash - Hash assignment
4873 mask - Mask assignment
4875 As a general rule, cisco routers support the hash assignment method
4876 and cisco switches support the mask assignment method.
4881 LOC: Config.Wccp2.info
4883 DEFAULT_IF_NONE: standard 0
4886 WCCP2 allows for multiple traffic services. There are two
4887 types: "standard" and "dynamic". The standard type defines
4888 one service id - http (id 0). The dynamic service ids can be from
4889 51 to 255 inclusive. In order to use a dynamic service id
4890 one must define the type of traffic to be redirected; this is done
4891 using the wccp2_service_info option.
4893 The "standard" type does not require a wccp2_service_info option,
4894 just specifying the service id will suffice.
4896 MD5 service authentication can be enabled by adding
4897 "password=<password>" to the end of this service declaration.
4901 wccp2_service standard 0 # for the 'web-cache' standard service
4902 wccp2_service dynamic 80 # a dynamic service type which will be
4903 # fleshed out with subsequent options.
4904 wccp2_service standard 0 password=foo
4907 NAME: wccp2_service_info
4908 TYPE: wccp2_service_info
4909 LOC: Config.Wccp2.info
4913 Dynamic WCCPv2 services require further information to define the
4914 traffic you wish to have diverted.
4918 wccp2_service_info <id> protocol=<protocol> flags=<flag>,<flag>..
4919 priority=<priority> ports=<port>,<port>..
4921 The relevant WCCPv2 flags:
4922 + src_ip_hash, dst_ip_hash
4923 + source_port_hash, dst_port_hash
4924 + src_ip_alt_hash, dst_ip_alt_hash
4925 + src_port_alt_hash, dst_port_alt_hash
4928 The port list can be one to eight entries.
4932 wccp2_service_info 80 protocol=tcp flags=src_ip_hash,ports_source
4933 priority=240 ports=80
4935 Note: the service id must have been defined by a previous
4936 'wccp2_service dynamic <id>' entry.
4941 LOC: Config.Wccp2.weight
4945 Each cache server gets assigned a set of the destination
4946 hash proportional to their weight.
4951 LOC: Config.Wccp.address
4958 LOC: Config.Wccp2.address
4962 Use this option if you require WCCP to use a specific
4965 The default behavior is to not bind to any specific address.
4969 PERSISTENT CONNECTION HANDLING
4970 -----------------------------------------------------------------------------
4972 Also see "pconn_timeout" in the TIMEOUTS section
4975 NAME: client_persistent_connections
4977 LOC: Config.onoff.client_pconns
4981 NAME: server_persistent_connections
4983 LOC: Config.onoff.server_pconns
4986 Persistent connection support for clients and servers. By
4987 default, Squid uses persistent connections (when allowed)
4988 with its clients and servers. You can use these options to
4989 disable persistent connections with clients and/or servers.
4992 NAME: persistent_connection_after_error
4994 LOC: Config.onoff.error_pconns
4997 With this directive the use of persistent connections after
4998 HTTP errors can be disabled. Useful if you have clients
4999 who fail to handle errors on persistent connections proper.
5002 NAME: detect_broken_pconn
5004 LOC: Config.onoff.detect_broken_server_pconns
5007 Some servers have been found to incorrectly signal the use
5008 of HTTP/1.0 persistent connections even on replies not
5009 compatible, causing significant delays. This server problem
5010 has mostly been seen on redirects.
5012 By enabling this directive Squid attempts to detect such
5013 broken replies and automatically assume the reply is finished
5014 after 10 seconds timeout.
5018 CACHE DIGEST OPTIONS
5019 -----------------------------------------------------------------------------
5022 NAME: digest_generation
5023 IFDEF: USE_CACHE_DIGESTS
5025 LOC: Config.onoff.digest_generation
5028 This controls whether the server will generate a Cache Digest
5029 of its contents. By default, Cache Digest generation is
5030 enabled if Squid is compiled with --enable-cache-digests defined.
5033 NAME: digest_bits_per_entry
5034 IFDEF: USE_CACHE_DIGESTS
5036 LOC: Config.digest.bits_per_entry
5039 This is the number of bits of the server's Cache Digest which
5040 will be associated with the Digest entry for a given HTTP
5041 Method and URL (public key) combination. The default is 5.
5044 NAME: digest_rebuild_period
5045 IFDEF: USE_CACHE_DIGESTS
5048 LOC: Config.digest.rebuild_period
5051 This is the wait time between Cache Digest rebuilds.
5054 NAME: digest_rewrite_period
5056 IFDEF: USE_CACHE_DIGESTS
5058 LOC: Config.digest.rewrite_period
5061 This is the wait time between Cache Digest writes to
5065 NAME: digest_swapout_chunk_size
5068 IFDEF: USE_CACHE_DIGESTS
5069 LOC: Config.digest.swapout_chunk_size
5072 This is the number of bytes of the Cache Digest to write to
5073 disk at a time. It defaults to 4096 bytes (4KB), the Squid
5077 NAME: digest_rebuild_chunk_percentage
5078 COMMENT: (percent, 0-100)
5079 IFDEF: USE_CACHE_DIGESTS
5081 LOC: Config.digest.rebuild_chunk_percentage
5084 This is the percentage of the Cache Digest to be scanned at a
5085 time. By default it is set to 10% of the Cache Digest.
5090 -----------------------------------------------------------------------------
5095 LOC: Config.Port.snmp
5099 The port number where Squid listens for SNMP requests. To enable
5100 SNMP support set this to a suitable port number. Port number
5101 3401 is often used for the Squid SNMP agent. By default it's
5102 set to "0" (disabled)
5110 LOC: Config.accessList.snmp
5112 DEFAULT_IF_NONE: deny all
5115 Allowing or denying access to the SNMP port.
5117 All access to the agent is denied by default.
5120 snmp_access allow|deny [!]aclname ...
5122 This clause only supports fast acl types.
5123 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5125 snmp_access allow snmppublic localhost
5126 snmp_access deny all
5129 NAME: snmp_incoming_address
5131 LOC: Config.Addrs.snmp_incoming
5136 NAME: snmp_outgoing_address
5138 LOC: Config.Addrs.snmp_outgoing
5142 Just like 'udp_incoming_address', but for the SNMP port.
5144 snmp_incoming_address is used for the SNMP socket receiving
5145 messages from SNMP agents.
5146 snmp_outgoing_address is used for SNMP packets returned to SNMP
5149 The default snmp_incoming_address is to listen on all
5150 available network interfaces.
5152 If snmp_outgoing_address is not set it will use the same socket
5153 as snmp_incoming_address. Only change this if you want to have
5154 SNMP replies sent using another address than where this Squid
5155 listens for SNMP queries.
5157 NOTE, snmp_incoming_address and snmp_outgoing_address can not have
5158 the same value since they both use port 3401.
5163 -----------------------------------------------------------------------------
5166 NAME: icp_port udp_port
5169 LOC: Config.Port.icp
5171 The port number where Squid sends and receives ICP queries to
5172 and from neighbor caches. The standard UDP port for ICP is 3130.
5173 Default is disabled (0).
5176 icp_port @DEFAULT_ICP_PORT@
5183 LOC: Config.Port.htcp
5185 The port number where Squid sends and receives HTCP queries to
5186 and from neighbor caches. To turn it on you want to set it to
5187 4827. By default it is set to "0" (disabled).
5193 NAME: log_icp_queries
5197 LOC: Config.onoff.log_udp
5199 If set, ICP queries are logged to access.log. You may wish
5200 do disable this if your ICP load is VERY high to speed things
5201 up or to simplify log analysis.
5204 NAME: udp_incoming_address
5206 LOC:Config.Addrs.udp_incoming
5209 udp_incoming_address is used for UDP packets received from other
5212 The default behavior is to not bind to any specific address.
5214 Only change this if you want to have all UDP queries received on
5215 a specific interface/address.
5217 NOTE: udp_incoming_address is used by the ICP, HTCP, and DNS
5218 modules. Altering it will affect all of them in the same manner.
5220 see also; udp_outgoing_address
5222 NOTE, udp_incoming_address and udp_outgoing_address can not
5223 have the same value since they both use the same port.
5226 NAME: udp_outgoing_address
5228 LOC: Config.Addrs.udp_outgoing
5231 udp_outgoing_address is used for UDP packets sent out to other
5234 The default behavior is to not bind to any specific address.
5236 Instead it will use the same socket as udp_incoming_address.
5237 Only change this if you want to have UDP queries sent using another
5238 address than where this Squid listens for UDP queries from other
5241 NOTE: udp_outgoing_address is used by the ICP, HTCP, and DNS
5242 modules. Altering it will affect all of them in the same manner.
5244 see also; udp_incoming_address
5246 NOTE, udp_incoming_address and udp_outgoing_address can not
5247 have the same value since they both use the same port.
5254 LOC: Config.onoff.icp_hit_stale
5256 If you want to return ICP_HIT for stale cache objects, set this
5257 option to 'on'. If you have sibling relationships with caches
5258 in other administrative domains, this should be 'off'. If you only
5259 have sibling relationships with caches under your control,
5260 it is probably okay to set this to 'on'.
5261 If set to 'on', your siblings should use the option "allow-miss"
5262 on their cache_peer lines for connecting to you.
5265 NAME: minimum_direct_hops
5268 LOC: Config.minDirectHops
5270 If using the ICMP pinging stuff, do direct fetches for sites
5271 which are no more than this many hops away.
5274 NAME: minimum_direct_rtt
5277 LOC: Config.minDirectRtt
5279 If using the ICMP pinging stuff, do direct fetches for sites
5280 which are no more than this many rtt milliseconds away.
5286 LOC: Config.Netdb.low
5292 LOC: Config.Netdb.high
5294 The low and high water marks for the ICMP measurement
5295 database. These are counts, not percents. The defaults are
5296 900 and 1000. When the high water mark is reached, database
5297 entries will be deleted until the low mark is reached.
5300 NAME: netdb_ping_period
5302 LOC: Config.Netdb.period
5305 The minimum period for measuring a site. There will be at
5306 least this much delay between successive pings to the same
5307 network. The default is five minutes.
5314 LOC: Config.onoff.query_icmp
5316 If you want to ask your peers to include ICMP data in their ICP
5317 replies, enable this option.
5319 If your peer has configured Squid (during compilation) with
5320 '--enable-icmp' that peer will send ICMP pings to origin server
5321 sites of the URLs it receives. If you enable this option the
5322 ICP replies from that peer will include the ICMP data (if available).
5323 Then, when choosing a parent cache, Squid will choose the parent with
5324 the minimal RTT to the origin server. When this happens, the
5325 hierarchy field of the access.log will be
5326 "CLOSEST_PARENT_MISS". This option is off by default.
5329 NAME: test_reachability
5333 LOC: Config.onoff.test_reachability
5335 When this is 'on', ICP MISS replies will be ICP_MISS_NOFETCH
5336 instead of ICP_MISS if the target host is NOT in the ICMP
5337 database, or has a zero RTT.
5340 NAME: icp_query_timeout
5344 LOC: Config.Timeout.icp_query
5346 Normally Squid will automatically determine an optimal ICP
5347 query timeout value based on the round-trip-time of recent ICP
5348 queries. If you want to override the value determined by
5349 Squid, set this 'icp_query_timeout' to a non-zero value. This
5350 value is specified in MILLISECONDS, so, to use a 2-second
5351 timeout (the old default), you would write:
5353 icp_query_timeout 2000
5356 NAME: maximum_icp_query_timeout
5360 LOC: Config.Timeout.icp_query_max
5362 Normally the ICP query timeout is determined dynamically. But
5363 sometimes it can lead to very large values (say 5 seconds).
5364 Use this option to put an upper limit on the dynamic timeout
5365 value. Do NOT use this option to always use a fixed (instead
5366 of a dynamic) timeout value. To set a fixed timeout see the
5367 'icp_query_timeout' directive.
5370 NAME: minimum_icp_query_timeout
5374 LOC: Config.Timeout.icp_query_min
5376 Normally the ICP query timeout is determined dynamically. But
5377 sometimes it can lead to very small timeouts, even lower than
5378 the normal latency variance on your link due to traffic.
5379 Use this option to put an lower limit on the dynamic timeout
5380 value. Do NOT use this option to always use a fixed (instead
5381 of a dynamic) timeout value. To set a fixed timeout see the
5382 'icp_query_timeout' directive.
5385 NAME: background_ping_rate
5389 LOC: Config.backgroundPingRate
5391 Controls how often the ICP pings are sent to siblings that
5392 have background-ping set.
5396 MULTICAST ICP OPTIONS
5397 -----------------------------------------------------------------------------
5402 LOC: Config.mcast_group_list
5405 This tag specifies a list of multicast groups which your server
5406 should join to receive multicasted ICP queries.
5408 NOTE! Be very careful what you put here! Be sure you
5409 understand the difference between an ICP _query_ and an ICP
5410 _reply_. This option is to be set only if you want to RECEIVE
5411 multicast queries. Do NOT set this option to SEND multicast
5412 ICP (use cache_peer for that). ICP replies are always sent via
5413 unicast, so this option does not affect whether or not you will
5414 receive replies from multicast group members.
5416 You must be very careful to NOT use a multicast address which
5417 is already in use by another group of caches.
5419 If you are unsure about multicast, please read the Multicast
5420 chapter in the Squid FAQ (http://www.squid-cache.org/FAQ/).
5422 Usage: mcast_groups 239.128.16.128 224.0.1.20
5424 By default, Squid doesn't listen on any multicast groups.
5427 NAME: mcast_miss_addr
5428 IFDEF: MULTICAST_MISS_STREAM
5430 LOC: Config.mcast_miss.addr
5433 If you enable this option, every "cache miss" URL will
5434 be sent out on the specified multicast address.
5436 Do not enable this option unless you are are absolutely
5437 certain you understand what you are doing.
5440 NAME: mcast_miss_ttl
5441 IFDEF: MULTICAST_MISS_STREAM
5443 LOC: Config.mcast_miss.ttl
5446 This is the time-to-live value for packets multicasted
5447 when multicasting off cache miss URLs is enabled. By
5448 default this is set to 'site scope', i.e. 16.
5451 NAME: mcast_miss_port
5452 IFDEF: MULTICAST_MISS_STREAM
5454 LOC: Config.mcast_miss.port
5457 This is the port number to be used in conjunction with
5461 NAME: mcast_miss_encode_key
5462 IFDEF: MULTICAST_MISS_STREAM
5464 LOC: Config.mcast_miss.encode_key
5465 DEFAULT: XXXXXXXXXXXXXXXX
5467 The URLs that are sent in the multicast miss stream are
5468 encrypted. This is the encryption key.
5471 NAME: mcast_icp_query_timeout
5475 LOC: Config.Timeout.mcast_icp_query
5477 For multicast peers, Squid regularly sends out ICP "probes" to
5478 count how many other peers are listening on the given multicast
5479 address. This value specifies how long Squid should wait to
5480 count all the replies. The default is 2000 msec, or 2
5485 INTERNAL ICON OPTIONS
5486 -----------------------------------------------------------------------------
5489 NAME: icon_directory
5491 LOC: Config.icons.directory
5492 DEFAULT: @DEFAULT_ICON_DIR@
5494 Where the icons are stored. These are normally kept in
5498 NAME: global_internal_static
5500 LOC: Config.onoff.global_internal_static
5503 This directive controls is Squid should intercept all requests for
5504 /squid-internal-static/ no matter which host the URL is requesting
5505 (default on setting), or if nothing special should be done for
5506 such URLs (off setting). The purpose of this directive is to make
5507 icons etc work better in complex cache hierarchies where it may
5508 not always be possible for all corners in the cache mesh to reach
5509 the server generating a directory listing.
5512 NAME: short_icon_urls
5514 LOC: Config.icons.use_short_names
5517 If this is enabled Squid will use short URLs for icons.
5518 If disabled it will revert to the old behavior of including
5519 it's own name and port in the URL.
5521 If you run a complex cache hierarchy with a mix of Squid and
5522 other proxies you may need to disable this directive.
5527 -----------------------------------------------------------------------------
5530 NAME: error_directory
5532 LOC: Config.errorDirectory
5535 If you wish to create your own versions of the default
5536 error files to customize them to suit your company copy
5537 the error/template files to another directory and point
5540 WARNING: This option will disable multi-language support
5541 on error pages if used.
5543 The squid developers are interested in making squid available in
5544 a wide variety of languages. If you are making translations for a
5545 language that Squid does not currently provide please consider
5546 contributing your translation back to the project.
5547 http://wiki.squid-cache.org/Translations
5549 The squid developers working on translations are happy to supply drop-in
5550 translated error files in exchange for any new language contributions.
5553 NAME: error_default_language
5554 IFDEF: USE_ERR_LOCALES
5556 LOC: Config.errorDefaultLanguage
5559 Set the default language which squid will send error pages in
5560 if no existing translation matches the clients language
5563 If unset (default) generic English will be used.
5565 The squid developers are interested in making squid available in
5566 a wide variety of languages. If you are interested in making
5567 translations for any language see the squid wiki for details.
5568 http://wiki.squid-cache.org/Translations
5571 NAME: error_log_languages
5572 IFDEF: USE_ERR_LOCALES
5574 LOC: Config.errorLogMissingLanguages
5577 Log to cache.log what languages users are attempting to
5578 auto-negotiate for translations.
5580 Successful negotiations are not logged. Only failures
5581 have meaning to indicate that Squid may need an upgrade
5582 of its error page translations.
5585 NAME: err_page_stylesheet
5587 LOC: Config.errorStylesheet
5588 DEFAULT: @DEFAULT_CONFIG_DIR@/errorpage.css
5590 CSS Stylesheet to pattern the display of Squid default error pages.
5592 For information on CSS see http://www.w3.org/Style/CSS/
5597 LOC: Config.errHtmlText
5600 HTML text to include in error messages. Make this a "mailto"
5601 URL to your admin address, or maybe just a link to your
5602 organizations Web page.
5604 To include this in your error messages, you must rewrite
5605 the error template files (found in the "errors" directory).
5606 Wherever you want the 'err_html_text' line to appear,
5607 insert a %L tag in the error template file.
5610 NAME: email_err_data
5613 LOC: Config.onoff.emailErrData
5616 If enabled, information about the occurred error will be
5617 included in the mailto links of the ERR pages (if %W is set)
5618 so that the email body contains the data.
5619 Syntax is <A HREF="mailto:%w%W">%w</A>
5624 LOC: Config.denyInfoList
5627 Usage: deny_info err_page_name acl
5628 or deny_info http://... acl
5629 or deny_info TCP_RESET acl
5631 This can be used to return a ERR_ page for requests which
5632 do not pass the 'http_access' rules. Squid remembers the last
5633 acl it evaluated in http_access, and if a 'deny_info' line exists
5634 for that ACL Squid returns a corresponding error page.
5636 The acl is typically the last acl on the http_access deny line which
5637 denied access. The exceptions to this rule are:
5638 - When Squid needs to request authentication credentials. It's then
5639 the first authentication related acl encountered
5640 - When none of the http_access lines matches. It's then the last
5641 acl processed on the last http_access line.
5643 NP: If providing your own custom error pages with error_directory
5644 you may also specify them by your custom file name:
5645 Example: deny_info ERR_CUSTOM_ACCESS_DENIED bad_guys
5647 Alternatively you can tell Squid to reset the TCP connection
5648 by specifying TCP_RESET.
5650 Or you can specify an error URL or URL pattern. The browsers will
5651 get redirected (302) to the specified URL after formattgin tags have
5655 %a - username (if available. Password NOT included)
5658 %E - Error description
5660 %H - Request domain name
5661 %i - Client IP Address
5663 %o - Message result from external ACL helper
5664 %p - Request Port number
5665 %P - Request Protocol name
5666 %R - Request URL path
5667 %T - Timestamp in RFC 1123 format
5668 %U - Full canonical URL from client
5669 (HTTPS URLs terminate with *)
5670 %u - Full canonical URL from client
5671 %w - Admin email from squid.conf
5672 %% - Literal percent (%) code
5677 OPTIONS INFLUENCING REQUEST FORWARDING
5678 -----------------------------------------------------------------------------
5681 NAME: nonhierarchical_direct
5683 LOC: Config.onoff.nonhierarchical_direct
5686 By default, Squid will send any non-hierarchical requests
5687 (matching hierarchy_stoplist or not cacheable request type) direct
5690 If you set this to off, Squid will prefer to send these
5691 requests to parents.
5693 Note that in most configurations, by turning this off you will only
5694 add latency to these request without any improvement in global hit
5697 If you are inside an firewall see never_direct instead of
5703 LOC: Config.onoff.prefer_direct
5706 Normally Squid tries to use parents for most requests. If you for some
5707 reason like it to first try going direct and only use a parent if
5708 going direct fails set this to on.
5710 By combining nonhierarchical_direct off and prefer_direct on you
5711 can set up Squid to use a parent as a backup path if going direct
5714 Note: If you want Squid to use parents for all requests see
5715 the never_direct directive. prefer_direct only modifies how Squid
5716 acts on cacheable requests.
5721 LOC: Config.accessList.AlwaysDirect
5724 Usage: always_direct allow|deny [!]aclname ...
5726 Here you can use ACL elements to specify requests which should
5727 ALWAYS be forwarded by Squid to the origin servers without using
5728 any peers. For example, to always directly forward requests for
5729 local servers ignoring any parents or siblings you may have use
5732 acl local-servers dstdomain my.domain.net
5733 always_direct allow local-servers
5735 To always forward FTP requests directly, use
5738 always_direct allow FTP
5740 NOTE: There is a similar, but opposite option named
5741 'never_direct'. You need to be aware that "always_direct deny
5742 foo" is NOT the same thing as "never_direct allow foo". You
5743 may need to use a deny rule to exclude a more-specific case of
5744 some other rule. Example:
5746 acl local-external dstdomain external.foo.net
5747 acl local-servers dstdomain .foo.net
5748 always_direct deny local-external
5749 always_direct allow local-servers
5751 NOTE: If your goal is to make the client forward the request
5752 directly to the origin server bypassing Squid then this needs
5753 to be done in the client configuration. Squid configuration
5754 can only tell Squid how Squid should fetch the object.
5756 NOTE: This directive is not related to caching. The replies
5757 is cached as usual even if you use always_direct. To not cache
5758 the replies see the 'cache' directive.
5760 This clause supports both fast and slow acl types.
5761 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5766 LOC: Config.accessList.NeverDirect
5769 Usage: never_direct allow|deny [!]aclname ...
5771 never_direct is the opposite of always_direct. Please read
5772 the description for always_direct if you have not already.
5774 With 'never_direct' you can use ACL elements to specify
5775 requests which should NEVER be forwarded directly to origin
5776 servers. For example, to force the use of a proxy for all
5777 requests, except those in your local domain use something like:
5779 acl local-servers dstdomain .foo.net
5780 never_direct deny local-servers
5781 never_direct allow all
5783 or if Squid is inside a firewall and there are local intranet
5784 servers inside the firewall use something like:
5786 acl local-intranet dstdomain .foo.net
5787 acl local-external dstdomain external.foo.net
5788 always_direct deny local-external
5789 always_direct allow local-intranet
5790 never_direct allow all
5792 This clause supports both fast and slow acl types.
5793 See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.
5797 ADVANCED NETWORKING OPTIONS
5798 -----------------------------------------------------------------------------
5801 NAME: incoming_icp_average
5804 LOC: Config.comm_incoming.icp_average
5807 NAME: incoming_http_average
5810 LOC: Config.comm_incoming.http_average
5813 NAME: incoming_dns_average
5816 LOC: Config.comm_incoming.dns_average
5819 NAME: min_icp_poll_cnt
5822 LOC: Config.comm_incoming.icp_min_poll
5825 NAME: min_dns_poll_cnt
5828 LOC: Config.comm_incoming.dns_min_poll
5831 NAME: min_http_poll_cnt
5834 LOC: Config.comm_incoming.http_min_poll
5836 Heavy voodoo here. I can't even believe you are reading this.
5837 Are you crazy? Don't even think about adjusting these unless
5838 you understand the algorithms in comm_select.c first!
5844 LOC: Config.accept_filter
5848 The name of an accept(2) filter to install on Squid's
5849 listen socket(s). This feature is perhaps specific to
5850 FreeBSD and requires support in the kernel.
5852 The 'httpready' filter delays delivering new connections
5853 to Squid until a full HTTP request has been received.
5854 See the accf_http(9) man page for details.
5856 The 'dataready' filter delays delivering new connections
5857 to Squid until there is some data to process.
5858 See the accf_dataready(9) man page for details.
5862 The 'data' filter delays delivering of new connections
5863 to Squid until there is some data to process by TCP_ACCEPT_DEFER.
5864 You may optionally specify a number of seconds to wait by
5865 'data=N' where N is the number of seconds. Defaults to 30
5866 if not specified. See the tcp(7) man page for details.
5869 accept_filter httpready
5874 NAME: client_ip_max_connections
5876 LOC: Config.client_ip_max_connections
5879 Set an absolute limit on the number of connections a single
5880 client IP can use. Any more than this and Squid will begin to drop
5881 new connections from the client until it closes some links.
5883 Note that this is a global limit. It affects all HTTP, HTCP, Gopher and FTP
5884 connections from the client. For finer control use the ACL access controls.
5886 Requires client_db to be enabled (the default).
5888 WARNING: This may noticably slow down traffic received via external proxies
5889 or NAT devices and cause them to rebound error messages back to their clients.
5892 NAME: tcp_recv_bufsize
5896 LOC: Config.tcpRcvBufsz
5898 Size of receive buffer to set for TCP sockets. Probably just
5899 as easy to change your kernel's default. Set to zero to use
5900 the default buffer size.
5905 -----------------------------------------------------------------------------
5912 LOC: Adaptation::Icap::TheConfig.onoff
5915 If you want to enable the ICAP module support, set this to on.
5918 NAME: icap_connect_timeout
5921 LOC: Adaptation::Icap::TheConfig.connect_timeout_raw
5924 This parameter specifies how long to wait for the TCP connect to
5925 the requested ICAP server to complete before giving up and either
5926 terminating the HTTP transaction or bypassing the failure.
5928 The default for optional services is peer_connect_timeout.
5929 The default for essential services is connect_timeout.
5930 If this option is explicitly set, its value applies to all services.
5933 NAME: icap_io_timeout
5937 LOC: Adaptation::Icap::TheConfig.io_timeout_raw
5940 This parameter specifies how long to wait for an I/O activity on
5941 an established, active ICAP connection before giving up and
5942 either terminating the HTTP transaction or bypassing the
5945 The default is read_timeout.
5948 NAME: icap_service_failure_limit
5949 COMMENT: limit [in memory-depth time-units]
5950 TYPE: icap_service_failure_limit
5952 LOC: Adaptation::Icap::TheConfig
5955 The limit specifies the number of failures that Squid tolerates
5956 when establishing a new TCP connection with an ICAP service. If
5957 the number of failures exceeds the limit, the ICAP service is
5958 not used for new ICAP requests until it is time to refresh its
5961 A negative value disables the limit. Without the limit, an ICAP
5962 service will not be considered down due to connectivity failures
5963 between ICAP OPTIONS requests.
5965 Squid forgets ICAP service failures older than the specified
5966 value of memory-depth. The memory fading algorithm
5967 is approximate because Squid does not remember individual
5968 errors but groups them instead, splitting the option
5969 value into ten time slots of equal length.
5971 When memory-depth is 0 and by default this option has no
5972 effect on service failure expiration.
5974 Squid always forgets failures when updating service settings
5975 using an ICAP OPTIONS transaction, regardless of this option
5979 # suspend service usage after 10 failures in 5 seconds:
5980 icap_service_failure_limit 10 in 5 seconds
5983 NAME: icap_service_revival_delay
5986 LOC: Adaptation::Icap::TheConfig.service_revival_delay
5989 The delay specifies the number of seconds to wait after an ICAP
5990 OPTIONS request failure before requesting the options again. The
5991 failed ICAP service is considered "down" until fresh OPTIONS are
5994 The actual delay cannot be smaller than the hardcoded minimum
5995 delay of 30 seconds.
5998 NAME: icap_preview_enable
6002 LOC: Adaptation::Icap::TheConfig.preview_enable
6005 The ICAP Preview feature allows the ICAP server to handle the
6006 HTTP message by looking only at the beginning of the message body
6007 or even without receiving the body at all. In some environments,
6008 previews greatly speedup ICAP processing.
6010 During an ICAP OPTIONS transaction, the server may tell Squid what
6011 HTTP messages should be previewed and how big the preview should be.
6012 Squid will not use Preview if the server did not request one.
6014 To disable ICAP Preview for all ICAP services, regardless of
6015 individual ICAP server OPTIONS responses, set this option to "off".
6017 icap_preview_enable off
6020 NAME: icap_preview_size
6023 LOC: Adaptation::Icap::TheConfig.preview_size
6026 The default size of preview data to be sent to the ICAP server.
6027 -1 means no preview. This value might be overwritten on a per server
6028 basis by OPTIONS requests.
6031 NAME: icap_206_enable
6035 LOC: Adaptation::Icap::TheConfig.allow206_enable
6038 206 (Partial Content) responses is an ICAP extension that allows the
6039 ICAP agents to optionally combine adapted and original HTTP message
6040 content. The decision to combine is postponed until the end of the
6041 ICAP response. Squid supports Partial Content extension by default.
6043 Activation of the Partial Content extension is negotiated with each
6044 ICAP service during OPTIONS exchange. Most ICAP servers should handle
6045 negotation correctly even if they do not support the extension, but
6046 some might fail. To disable Partial Content support for all ICAP
6047 services and to avoid any negotiation, set this option to "off".
6053 NAME: icap_default_options_ttl
6056 LOC: Adaptation::Icap::TheConfig.default_options_ttl
6059 The default TTL value for ICAP OPTIONS responses that don't have
6060 an Options-TTL header.
6063 NAME: icap_persistent_connections
6067 LOC: Adaptation::Icap::TheConfig.reuse_connections
6070 Whether or not Squid should use persistent connections to
6074 NAME: icap_send_client_ip
6078 LOC: Adaptation::Icap::TheConfig.send_client_ip
6081 This adds the header "X-Client-IP" to ICAP requests.
6084 NAME: icap_send_client_username
6088 LOC: Adaptation::Icap::TheConfig.send_client_username
6091 This sends authenticated HTTP client username (if available) to
6092 the ICAP service. The username value is encoded based on the
6093 icap_client_username_encode option and is sent using the header
6094 specified by the icap_client_username_header option.
6097 NAME: icap_client_username_header
6100 LOC: Adaptation::Icap::TheConfig.client_username_header
6101 DEFAULT: X-Client-Username
6103 ICAP request header name to use for send_client_username.
6106 NAME: icap_client_username_encode
6110 LOC: Adaptation::Icap::TheConfig.client_username_encode
6113 Whether to base64 encode the authenticated client username.
6117 TYPE: icap_service_type
6119 LOC: Adaptation::Icap::TheConfig
6122 Defines a single ICAP service using the following format:
6124 icap_service service_name vectoring_point [options] service_url
6127 an opaque identifier which must be unique in squid.conf
6129 vectoring_point: reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
6130 This specifies at which point of transaction processing the
6131 ICAP service should be activated. *_postcache vectoring points
6132 are not yet supported.
6134 service_url: icap://servername:port/servicepath
6135 ICAP server and service location.
6137 ICAP does not allow a single service to handle both REQMOD and RESPMOD
6138 transactions. Squid does not enforce that requirement. You can specify
6139 services with the same service_url and different vectoring_points. You
6140 can even specify multiple identical services as long as their
6141 service_names differ.
6144 Service options are separated by white space. ICAP services support
6145 the following name=value options:
6148 If set to 'on' or '1', the ICAP service is treated as
6149 optional. If the service cannot be reached or malfunctions,
6150 Squid will try to ignore any errors and process the message as
6151 if the service was not enabled. No all ICAP errors can be
6152 bypassed. If set to 0, the ICAP service is treated as
6153 essential and all ICAP errors will result in an error page
6154 returned to the HTTP client.
6156 Bypass is off by default: services are treated as essential.
6159 If set to 'on' or '1', the ICAP service is allowed to
6160 dynamically change the current message adaptation plan by
6161 returning a chain of services to be used next. The services
6162 are specified using the X-Next-Services ICAP response header
6163 value, formatted as a comma-separated list of service names.
6164 Each named service should be configured in squid.conf and
6165 should have the same method and vectoring point as the current
6166 ICAP transaction. Services violating these rules are ignored.
6167 An empty X-Next-Services value results in an empty plan which
6168 ends the current adaptation.
6170 Routing is not allowed by default: the ICAP X-Next-Services
6171 response header is ignored.
6174 Only has effect on split-stack systems. The default on those systems
6175 is to use IPv4-only connections. When set to 'on' this option will
6176 make Squid use IPv6-only connections to contact this ICAP service.
6178 Older icap_service format without optional named parameters is
6179 deprecated but supported for backward compatibility.
6182 icap_service svcBlocker reqmod_precache bypass=0 icap://icap1.mydomain.net:1344/reqmod
6183 icap_service svcLogger reqmod_precache routing=on icap://icap2.mydomain.net:1344/respmod
6187 TYPE: icap_class_type
6192 This deprecated option was documented to define an ICAP service
6193 chain, even though it actually defined a set of similar, redundant
6194 services, and the chains were not supported.
6196 To define a set of redundant services, please use the
6197 adaptation_service_set directive. For service chains, use
6198 adaptation_service_chain.
6202 TYPE: icap_access_type
6207 This option is deprecated. Please use adaptation_access, which
6208 has the same ICAP functionality, but comes with better
6209 documentation, and eCAP support.
6214 -----------------------------------------------------------------------------
6221 LOC: Adaptation::Ecap::TheConfig.onoff
6224 Controls whether eCAP support is enabled.
6228 TYPE: ecap_service_type
6230 LOC: Adaptation::Ecap::TheConfig
6233 Defines a single eCAP service
6235 ecap_service servicename vectoring_point bypass service_url
6237 vectoring_point = reqmod_precache|reqmod_postcache|respmod_precache|respmod_postcache
6238 This specifies at which point of transaction processing the
6239 eCAP service should be activated. *_postcache vectoring points
6240 are not yet supported.
6242 If set to 1, the eCAP service is treated as optional. If the
6243 service cannot be reached or malfunctions, Squid will try to
6244 ignore any errors and process the message as if the service
6245 was not enabled. No all eCAP errors can be bypassed.
6246 If set to 0, the eCAP service is treated as essential and all
6247 eCAP errors will result in an error page returned to the
6249 service_url = ecap://vendor/service_name?custom&cgi=style¶meters=optional
6252 ecap_service service_1 reqmod_precache 0 ecap://filters-R-us/leakDetector?on_error=block
6253 ecap_service service_2 respmod_precache 1 icap://filters-R-us/virusFilter?config=/etc/vf.cfg
6256 NAME: loadable_modules
6258 IFDEF: USE_LOADABLE_MODULES
6259 LOC: Config.loadable_module_names
6262 Instructs Squid to load the specified dynamic module(s) or activate
6263 preloaded module(s).
6265 loadable_modules @DEFAULT_PREFIX@/lib/MinimalAdapter.so
6269 MESSAGE ADAPTATION OPTIONS
6270 -----------------------------------------------------------------------------
6273 NAME: adaptation_service_set
6274 TYPE: adaptation_service_set_type
6275 IFDEF: USE_ADAPTATION
6280 Configures an ordered set of similar, redundant services. This is
6281 useful when hot standby or backup adaptation servers are available.
6283 adaptation_service_set set_name service_name1 service_name2 ...
6285 The named services are used in the set declaration order. The first
6286 applicable adaptation service from the set is used first. The next
6287 applicable service is tried if and only if the transaction with the
6288 previous service fails and the message waiting to be adapted is still
6291 When adaptation starts, broken services are ignored as if they were
6292 not a part of the set. A broken service is a down optional service.
6294 The services in a set must be attached to the same vectoring point
6295 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
6297 If all services in a set are optional then adaptation failures are
6298 bypassable. If all services in the set are essential, then a
6299 transaction failure with one service may still be retried using
6300 another service from the set, but when all services fail, the master
6301 transaction fails as well.
6303 A set may contain a mix of optional and essential services, but that
6304 is likely to lead to surprising results because broken services become
6305 ignored (see above), making previously bypassable failures fatal.
6306 Technically, it is the bypassability of the last failed service that
6309 See also: adaptation_access adaptation_service_chain
6312 adaptation_service_set svcBlocker urlFilterPrimary urlFilterBackup
6313 adaptation service_set svcLogger loggerLocal loggerRemote
6316 NAME: adaptation_service_chain
6317 TYPE: adaptation_service_chain_type
6318 IFDEF: USE_ADAPTATION
6323 Configures a list of complementary services that will be applied
6324 one-by-one, forming an adaptation chain or pipeline. This is useful
6325 when Squid must perform different adaptations on the same message.
6327 adaptation_service_chain chain_name service_name1 svc_name2 ...
6329 The named services are used in the chain declaration order. The first
6330 applicable adaptation service from the chain is used first. The next
6331 applicable service is applied to the successful adaptation results of
6332 the previous service in the chain.
6334 When adaptation starts, broken services are ignored as if they were
6335 not a part of the chain. A broken service is a down optional service.
6337 Request satisfaction terminates the adaptation chain because Squid
6338 does not currently allow declaration of RESPMOD services at the
6339 "reqmod_precache" vectoring point (see icap_service or ecap_service).
6341 The services in a chain must be attached to the same vectoring point
6342 (e.g., pre-cache) and use the same adaptation method (e.g., REQMOD).
6344 A chain may contain a mix of optional and essential services. If an
6345 essential adaptation fails (or the failure cannot be bypassed for
6346 other reasons), the master transaction fails. Otherwise, the failure
6347 is bypassed as if the failed adaptation service was not in the chain.
6349 See also: adaptation_access adaptation_service_set
6352 adaptation_service_chain svcRequest requestLogger urlFilter leakDetector
6355 NAME: adaptation_access
6356 TYPE: adaptation_access_type
6357 IFDEF: USE_ADAPTATION
6361 Sends an HTTP transaction to an ICAP or eCAP adaptation service.
6363 adaptation_access service_name allow|deny [!]aclname...
6364 adaptation_access set_name allow|deny [!]aclname...
6366 At each supported vectoring point, the adaptation_access
6367 statements are processed in the order they appear in this
6368 configuration file. Statements pointing to the following services
6369 are ignored (i.e., skipped without checking their ACL):
6371 - services serving different vectoring points
6372 - "broken-but-bypassable" services
6373 - "up" services configured to ignore such transactions
6374 (e.g., based on the ICAP Transfer-Ignore header).
6376 When a set_name is used, all services in the set are checked
6377 using the same rules, to find the first applicable one. See
6378 adaptation_service_set for details.
6380 If an access list is checked and there is a match, the
6381 processing stops: For an "allow" rule, the corresponding
6382 adaptation service is used for the transaction. For a "deny"
6383 rule, no adaptation service is activated.
6385 It is currently not possible to apply more than one adaptation
6386 service at the same vectoring point to the same HTTP transaction.
6388 See also: icap_service and ecap_service
6391 adaptation_access service_1 allow all
6394 NAME: adaptation_service_iteration_limit
6396 IFDEF: USE_ADAPTATION
6397 LOC: Adaptation::Config::service_iteration_limit
6400 Limits the number of iterations allowed when applying adaptation
6401 services to a message. If your longest adaptation set or chain
6402 may have more than 16 services, increase the limit beyond its
6403 default value of 16. If detecting infinite iteration loops sooner
6404 is critical, make the iteration limit match the actual number
6405 of services in your longest adaptation set or chain.
6407 Infinite adaptation loops are most likely with routing services.
6409 See also: icap_service routing=1
6412 NAME: adaptation_masterx_shared_names
6414 IFDEF: USE_ADAPTATION
6415 LOC: Adaptation::Config::masterx_shared_name
6418 For each master transaction (i.e., the HTTP request and response
6419 sequence, including all related ICAP and eCAP exchanges), Squid
6420 maintains a table of metadata. The table entries are (name, value)
6421 pairs shared among eCAP and ICAP exchanges. The table is destroyed
6422 with the master transaction.
6424 This option specifies the table entry names that Squid must accept
6425 from and forward to the adaptation transactions.
6427 An ICAP REQMOD or RESPMOD transaction may set an entry in the
6428 shared table by returning an ICAP header field with a name
6429 specified in adaptation_masterx_shared_names. Squid will store
6430 and forward that ICAP header field to subsequent ICAP
6431 transactions within the same master transaction scope.
6433 Only one shared entry name is supported at this time.
6436 # share authentication information among ICAP services
6437 adaptation_masterx_shared_names X-Subscriber-ID
6443 LOC: Adaptation::Icap::TheConfig.repeat
6445 DEFAULT_IF_NONE: deny all
6447 This ACL determines which retriable ICAP transactions are
6448 retried. Transactions that received a complete ICAP response
6449 and did not have to consume or produce HTTP bodies to receive
6450 that response are usually retriable.
6452 icap_retry allow|deny [!]aclname ...
6454 Squid automatically retries some ICAP I/O timeouts and errors
6455 due to persistent connection race conditions.
6457 See also: icap_retry_limit
6460 NAME: icap_retry_limit
6463 LOC: Adaptation::Icap::TheConfig.repeat_limit
6466 Limits the number of retries allowed. When set to zero (default),
6467 no retries are allowed.
6469 Communication errors due to persistent connection race
6470 conditions are unavoidable, automatically retried, and do not
6471 count against this limit.
6473 See also: icap_retry
6479 -----------------------------------------------------------------------------
6482 NAME: check_hostnames
6485 LOC: Config.onoff.check_hostnames
6487 For security and stability reasons Squid can check
6488 hostnames for Internet standard RFC compliance. If you want
6489 Squid to perform these checks turn this directive on.
6492 NAME: allow_underscore
6495 LOC: Config.onoff.allow_underscore
6497 Underscore characters is not strictly allowed in Internet hostnames
6498 but nevertheless used by many sites. Set this to off if you want
6499 Squid to be strict about the standard.
6500 This check is performed only when check_hostnames is set to on.
6503 NAME: cache_dns_program
6505 IFDEF: USE_DNSSERVERS
6506 DEFAULT: @DEFAULT_DNSSERVER@
6507 LOC: Config.Program.dnsserver
6509 Specify the location of the executable for dnslookup process.
6513 TYPE: HelperChildConfig
6514 IFDEF: USE_DNSSERVERS
6515 DEFAULT: 32 startup=1 idle=1
6516 LOC: Config.dnsChildren
6518 The maximum number of processes spawn to service DNS name lookups.
6519 If you limit it too few Squid will have to wait for them to process
6520 a backlog of requests, slowing it down. If you allow too many they
6521 will use RAM and other system resources noticably.
6522 The maximum this may be safely set to is 32.
6524 The startup= and idle= options allow some measure of skew in your
6529 Sets a minimum of how many processes are to be spawned when Squid
6530 starts or reconfigures. When set to zero the first request will
6531 cause spawning of the first child process to handle it.
6533 Starting too few will cause an initial slowdown in traffic as Squid
6534 attempts to simultaneously spawn enough processes to cope.
6538 Sets a minimum of how many processes Squid is to try and keep available
6539 at all times. When traffic begins to rise above what the existing
6540 processes can handle this many more will be spawned up to the maximum
6541 configured. A minimum setting of 1 is required.
6544 NAME: dns_retransmit_interval
6547 LOC: Config.Timeout.idns_retransmit
6548 IFDEF: !USE_DNSSERVERS
6550 Initial retransmit interval for DNS queries. The interval is
6551 doubled each time all configured DNS servers have been tried.
6557 LOC: Config.Timeout.idns_query
6558 IFDEF: !USE_DNSSERVERS
6560 DNS Query timeout. If no response is received to a DNS query
6561 within this time all DNS servers for the queried domain
6562 are assumed to be unavailable.
6569 LOC: Config.onoff.res_defnames
6571 Normally the RES_DEFNAMES resolver option is disabled
6572 (see res_init(3)). This prevents caches in a hierarchy
6573 from interpreting single-component hostnames locally. To allow
6574 Squid to handle single-component names, enable this option.
6577 NAME: dns_nameservers
6580 LOC: Config.dns_nameservers
6582 Use this if you want to specify a list of DNS name servers
6583 (IP addresses) to use instead of those given in your
6584 /etc/resolv.conf file.
6585 On Windows platforms, if no value is specified here or in
6586 the /etc/resolv.conf file, the list of DNS name servers are
6587 taken from the Windows registry, both static and dynamic DHCP
6588 configurations are supported.
6590 Example: dns_nameservers 10.0.0.1 192.172.0.4
6595 DEFAULT: @DEFAULT_HOSTS@
6596 LOC: Config.etcHostsPath
6598 Location of the host-local IP name-address associations
6599 database. Most Operating Systems have such a file on different
6601 - Un*X & Linux: /etc/hosts
6602 - Windows NT/2000: %SystemRoot%\system32\drivers\etc\hosts
6603 (%SystemRoot% value install default is c:\winnt)
6604 - Windows XP/2003: %SystemRoot%\system32\drivers\etc\hosts
6605 (%SystemRoot% value install default is c:\windows)
6606 - Windows 9x/Me: %windir%\hosts
6607 (%windir% value is usually c:\windows)
6608 - Cygwin: /etc/hosts
6610 The file contains newline-separated definitions, in the
6611 form ip_address_in_dotted_form name [name ...] names are
6612 whitespace-separated. Lines beginning with an hash (#)
6613 character are comments.
6615 The file is checked at startup and upon configuration.
6616 If set to 'none', it won't be checked.
6617 If append_domain is used, that domain will be added to
6618 domain-local (i.e. not containing any dot character) host
6624 LOC: Config.appendDomain
6627 Appends local domain name to hostnames without any dots in
6628 them. append_domain must begin with a period.
6630 Be warned there are now Internet names with no dots in
6631 them using only top-domain names, so setting this may
6632 cause some Internet sites to become unavailable.
6635 append_domain .yourdomain.com
6638 NAME: ignore_unknown_nameservers
6640 LOC: Config.onoff.ignore_unknown_nameservers
6643 By default Squid checks that DNS responses are received
6644 from the same IP addresses they are sent to. If they
6645 don't match, Squid ignores the response and writes a warning
6646 message to cache.log. You can allow responses from unknown
6647 nameservers by setting this option to 'off'.
6650 NAME: dns_v4_fallback
6653 LOC: Config.onoff.dns_require_A
6655 Standard practice with DNS is to lookup either A or AAAA records
6656 and use the results if it succeeds. Only looking up the other if
6657 the first attempt fails or otherwise produces no results.
6659 That policy however will cause squid to produce error pages for some
6660 servers that advertise AAAA but are unreachable over IPv6.
6662 If this is ON squid will always lookup both AAAA and A, using both.
6663 If this is OFF squid will lookup AAAA and only try A if none found.
6665 WARNING: There are some possibly unwanted side-effects with this on:
6666 *) Doubles the load placed by squid on the DNS network.
6667 *) May negatively impact connection delay times.
6671 COMMENT: (number of entries)
6674 LOC: Config.ipcache.size
6681 LOC: Config.ipcache.low
6688 LOC: Config.ipcache.high
6690 The size, low-, and high-water marks for the IP cache.
6693 NAME: fqdncache_size
6694 COMMENT: (number of entries)
6697 LOC: Config.fqdncache.size
6699 Maximum number of FQDN cache entries.
6704 -----------------------------------------------------------------------------
6711 LOC: Config.onoff.mem_pools
6713 If set, Squid will keep pools of allocated (but unused) memory
6714 available for future use. If memory is a premium on your
6715 system and you believe your malloc library outperforms Squid
6716 routines, disable this.
6719 NAME: memory_pools_limit
6723 LOC: Config.MemPools.limit
6725 Used only with memory_pools on:
6726 memory_pools_limit 50 MB
6728 If set to a non-zero value, Squid will keep at most the specified
6729 limit of allocated (but unused) memory in memory pools. All free()
6730 requests that exceed this limit will be handled by your malloc
6731 library. Squid does not pre-allocate any memory, just safe-keeps
6732 objects that otherwise would be free()d. Thus, it is safe to set
6733 memory_pools_limit to a reasonably high value even if your
6734 configuration will use less memory.
6736 If set to none, Squid will keep all memory it can. That is, there
6737 will be no limit on the total amount of memory used for safe-keeping.
6739 To disable memory allocation optimization, do not set
6740 memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
6742 An overhead for maintaining memory pools is not taken into account
6743 when the limit is checked. This overhead is close to four bytes per
6744 object kept. However, pools may actually _save_ memory because of
6745 reduced memory thrashing in your malloc library.
6749 COMMENT: on|off|transparent|truncate|delete
6752 LOC: opt_forwarded_for
6754 If set to "on", Squid will append your client's IP address
6755 in the HTTP requests it forwards. By default it looks like:
6757 X-Forwarded-For: 192.1.2.3
6759 If set to "off", it will appear as
6761 X-Forwarded-For: unknown
6763 If set to "transparent", Squid will not alter the
6764 X-Forwarded-For header in any way.
6766 If set to "delete", Squid will delete the entire
6767 X-Forwarded-For header.
6769 If set to "truncate", Squid will remove all existing
6770 X-Forwarded-For entries, and place itself as the sole entry.
6773 NAME: cachemgr_passwd
6774 TYPE: cachemgrpasswd
6776 LOC: Config.passwd_list
6778 Specify passwords for cachemgr operations.
6780 Usage: cachemgr_passwd password action action ...
6782 Some valid actions are (see cache manager menu for a full list):
6822 * Indicates actions which will not be performed without a
6823 valid password, others can be performed if not listed here.
6825 To disable an action, set the password to "disable".
6826 To allow performing an action without a password, set the
6829 Use the keyword "all" to set the same password for all actions.
6832 cachemgr_passwd secret shutdown
6833 cachemgr_passwd lesssssssecret info stats/objects
6834 cachemgr_passwd disable all
6841 LOC: Config.onoff.client_db
6843 If you want to disable collecting per-client statistics,
6844 turn off client_db here.
6847 NAME: refresh_all_ims
6851 LOC: Config.onoff.refresh_all_ims
6853 When you enable this option, squid will always check
6854 the origin server for an update when a client sends an
6855 If-Modified-Since request. Many browsers use IMS
6856 requests when the user requests a reload, and this
6857 ensures those clients receive the latest version.
6859 By default (off), squid may return a Not Modified response
6860 based on the age of the cached version.
6863 NAME: reload_into_ims
6864 IFDEF: USE_HTTP_VIOLATIONS
6868 LOC: Config.onoff.reload_into_ims
6870 When you enable this option, client no-cache or ``reload''
6871 requests will be changed to If-Modified-Since requests.
6872 Doing this VIOLATES the HTTP standard. Enabling this
6873 feature could make you liable for problems which it
6876 see also refresh_pattern for a more selective approach.
6879 NAME: connect_retries
6881 LOC: Config.connect_retries
6884 This sets the maximum number of connection attempts made for each
6885 TCP connection. The connect_retries attempts must all still
6886 complete within the connection timeout period.
6888 The default is not to re-try if the first connection attempt fails.
6889 The (not recommended) maximum is 10 tries.
6891 A warning message will be generated if it is set to a too-high
6892 value and the configured value will be over-ridden.
6894 Note: These re-tries are in addition to forward_max_tries
6895 which limit how many different addresses may be tried to find
6899 NAME: retry_on_error
6901 LOC: Config.retry.onerror
6904 If set to on Squid will automatically retry requests when
6905 receiving an error response. This is mainly useful if you
6906 are in a complex cache hierarchy to work around access
6910 NAME: as_whois_server
6912 LOC: Config.as_whois_server
6913 DEFAULT: whois.ra.net
6914 DEFAULT_IF_NONE: whois.ra.net
6916 WHOIS server to query for AS numbers. NOTE: AS numbers are
6917 queried only when Squid starts up, not for every request.
6922 LOC: Config.onoff.offline
6925 Enable this option and Squid will never try to validate cached
6929 NAME: uri_whitespace
6930 TYPE: uri_whitespace
6931 LOC: Config.uri_whitespace
6934 What to do with requests that have whitespace characters in the
6937 strip: The whitespace characters are stripped out of the URL.
6938 This is the behavior recommended by RFC2396.
6939 deny: The request is denied. The user receives an "Invalid
6941 allow: The request is allowed and the URI is not changed. The
6942 whitespace characters remain in the URI. Note the
6943 whitespace is passed to redirector processes if they
6945 encode: The request is allowed and the whitespace characters are
6946 encoded according to RFC1738. This could be considered
6947 a violation of the HTTP/1.1
6948 RFC because proxies are not allowed to rewrite URI's.
6949 chop: The request is allowed and the URI is chopped at the
6950 first whitespace. This might also be considered a
6956 LOC: Config.chroot_dir
6959 Specifies a directory where Squid should do a chroot() while
6960 initializing. This also causes Squid to fully drop root
6961 privileges after initializing. This means, for example, if you
6962 use a HTTP port less than 1024 and try to reconfigure, you may
6963 get an error saying that Squid can not open the port.
6966 NAME: balance_on_multiple_ip
6968 LOC: Config.onoff.balance_on_multiple_ip
6971 Modern IP resolvers in squid sort lookup results by preferred access.
6972 By default squid will use these IP in order and only rotates to
6973 the next listed when the most preffered fails.
6975 Some load balancing servers based on round robin DNS have been
6976 found not to preserve user session state across requests
6977 to different IP addresses.
6979 Enabling this directive Squid rotates IP's per request.
6982 NAME: pipeline_prefetch
6984 LOC: Config.onoff.pipeline_prefetch
6987 To boost the performance of pipelined requests to closer
6988 match that of a non-proxied environment Squid can try to fetch
6989 up to two requests in parallel from a pipeline.
6991 Defaults to off for bandwidth management and access logging
6995 NAME: high_response_time_warning
6998 LOC: Config.warnings.high_rptm
7001 If the one-minute median response time exceeds this value,
7002 Squid prints a WARNING with debug level 0 to get the
7003 administrators attention. The value is in milliseconds.
7006 NAME: high_page_fault_warning
7008 LOC: Config.warnings.high_pf
7011 If the one-minute average page fault rate exceeds this
7012 value, Squid prints a WARNING with debug level 0 to get
7013 the administrators attention. The value is in page faults
7017 NAME: high_memory_warning
7019 LOC: Config.warnings.high_memory
7022 If the memory usage (as determined by mallinfo) exceeds
7023 this amount, Squid prints a WARNING with debug level 0 to get
7024 the administrators attention.
7027 NAME: sleep_after_fork
7028 COMMENT: (microseconds)
7030 LOC: Config.sleep_after_fork
7033 When this is set to a non-zero value, the main Squid process
7034 sleeps the specified number of microseconds after a fork()
7035 system call. This sleep may help the situation where your
7036 system reports fork() failures due to lack of (virtual)
7037 memory. Note, however, if you have a lot of child
7038 processes, these sleep delays will add up and your
7039 Squid will not service requests for some amount of time
7040 until all the child processes have been started.
7041 On Windows value less then 1000 (1 milliseconds) are
7045 NAME: windows_ipaddrchangemonitor
7046 IFDEF: _SQUID_MSWIN_
7050 LOC: Config.onoff.WIN32_IpAddrChangeMonitor
7052 On Windows Squid by default will monitor IP address changes and will
7053 reconfigure itself after any detected event. This is very useful for
7054 proxies connected to internet with dial-up interfaces.
7055 In some cases (a Proxy server acting as VPN gateway is one) it could be
7056 desiderable to disable this behaviour setting this to 'off'.
7057 Note: after changing this, Squid service must be restarted.
7062 IFDEF: USE_SQUID_EUI
7064 LOC: Eui::TheConfig.euiLookup
7066 Whether to lookup the EUI or MAC address of a connected client.
7069 NAME: max_filedescriptors max_filedesc
7072 LOC: Config.max_filedescriptors
7074 The maximum number of filedescriptors supported.
7076 The default "0" means Squid inherits the current ulimit setting.
7078 Note: Changing this requires a restart of Squid. Also
7079 not all comm loops supports large values.
7087 Number of main Squid processes or "workers" to fork and maintain.
7088 0: "no daemon" mode, like running "squid -N ..."
7089 1: "no SMP" mode, start one main Squid process daemon (default)
7090 N: start N main Squid process daemons (i.e., SMP mode)
7092 In SMP mode, each worker does nearly all what a single Squid daemon
7093 does (e.g., listen on http_port and forward HTTP requests).