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<H2><A NAME="s1">1.</A> <A HREF="FAQ.html#toc1">About Squid, this FAQ, and other Squid information resources</A></H2>
<H2><A NAME="ss1.1">1.1</A> <A HREF="FAQ.html#toc1.1">What is Squid?</A>
</H2>
<P>Squid is a high-performance proxy caching server for web clients,
supporting FTP, gopher, and HTTP data objects. Unlike traditional
caching software, Squid handles all requests in a single,
non-blocking, I/O-driven process.</P>
<P>Squid keeps
meta data and especially hot objects cached in RAM, caches
DNS lookups, supports non-blocking DNS lookups, and implements
negative caching of failed requests.</P>
<P>Squid supports SSL, extensive
access controls, and full request logging. By using the
lightweight Internet Cache Protocol, Squid caches can be arranged
in a hierarchy or mesh for additional bandwidth savings.</P>
<P>Squid consists of a main server program <EM>squid</EM>, a Domain Name System
lookup program <EM>dnsserver</EM>, some optional programs for rewriting
requests and performing authentication, and some management and client
tools. When <EM>squid</EM> starts up, it spawns a configurable number of
<EM>dnsserver</EM> processes, each of which can perform a single, blocking
Domain Name System (DNS) lookup. This reduces the amount of time the
cache waits for DNS lookups.</P>
<P>Squid is derived from the ARPA-funded
<A HREF="http://harvest.cs.colorado.edu/">Harvest project</A>.</P>
<H2><A NAME="ss1.2">1.2</A> <A HREF="FAQ.html#toc1.2">What is Internet object caching?</A>
</H2>
<P>Internet object caching is a way to store requested Internet objects
(i.e., data available via the HTTP, FTP, and gopher protocols) on a
system closer to the requesting site than to the source. Web browsers
can then use the local Squid cache as a proxy HTTP server, reducing
access time as well as bandwidth consumption.</P>
<H2><A NAME="ss1.3">1.3</A> <A HREF="FAQ.html#toc1.3">Why is it called Squid?</A>
</H2>
<P>Harris' Lament says, ``All the good ones are taken."</P>
<P>We needed to distinguish this new version from the Harvest
cache software. Squid was the code name for initial
development, and it stuck.</P>
<H2><A NAME="ss1.4">1.4</A> <A HREF="FAQ.html#toc1.4">What is the latest version of Squid?</A>
</H2>
<P>Squid is updated often; please see
<A HREF="http://www.squid-cache.org/">the Squid home page</A>
for the most recent versions.</P>
<H2><A NAME="ss1.5">1.5</A> <A HREF="FAQ.html#toc1.5">Who is responsible for Squid?</A>
</H2>
<P>Squid is the result of efforts by numerous individuals from
the Internet community.
<A HREF="mailto:wessels@squid-cache.org">Duane Wessels</A>
of the National Laboratory for Applied Network Research (funded by
the National Science Foundation) leads code development.
Please see
<A HREF="http://www.squid-cache.org/CONTRIBUTORS">the CONTRIBUTORS file</A>
for a list of our excellent contributors.</P>
<H2><A NAME="ss1.6">1.6</A> <A HREF="FAQ.html#toc1.6">Where can I get Squid?</A>
</H2>
<P>You can download Squid via FTP from
<A HREF="ftp://ftp.squid-cache.org/pub/">the primary FTP site</A>
or one of the many worldwide
<A HREF="http://www.squid-cache.org/mirrors.html">mirror sites</A>.</P>
<P>Many sushi bars also have Squid.</P>
<H2><A NAME="ss1.7">1.7</A> <A HREF="FAQ.html#toc1.7">What Operating Systems does Squid support?</A>
</H2>
<P>The software is designed to operate on any modern Unix system, and
is known to work on at least the following platforms:
<UL>
<LI> Linux</LI>
<LI> FreeBSD</LI>
<LI> NetBSD</LI>
<LI> BSDI</LI>
<LI> Mac OS/X</LI>
<LI> OSF and Digital Unix</LI>
<LI> IRIX</LI>
<LI> SunOS/Solaris</LI>
<LI> NeXTStep</LI>
<LI> SCO Unix</LI>
<LI> AIX</LI>
<LI> HP-UX</LI>
<LI>
<A HREF="FAQ-2.html#building-os2">OS/2</A></LI>
</UL>
</P>
<P>For more specific information, please see
<A HREF="http://www.squid-cache.org/platforms.html">platforms.html</A>.
If you encounter any platform-specific problems, please
let us know by registering a entry in our
<A HREF="http://www.squid-cache.org/bugs/">bug database</A>.</P>
<H2><A NAME="squid-NT"></A> <A NAME="ss1.8">1.8</A> <A HREF="FAQ.html#toc1.8">Does Squid run on Windows NT?</A>
</H2>
<P>Recent versions of Squid will <EM>compile and run</EM> on Windows/NT
with the
<A HREF="http://www.cygnus.com/misc/gnu-win32/">GNU-Win32 package</A>.</P>
<P>
<A HREF="http://serassio.interfree.it/SquidNT.htm">Guido Serassio</A>
have Squid NT pages and is actively working on having the needed changes integrated into the standard Squid distribution. Partially based on earlier NT port by
<A HREF="http://www.phys-iasi.ro/users/romeo/squidnt.htm">Romeo Anghelache</A>.</P>
<P>
<A HREF="http://www.logisense.com/">LogiSense</A>
has ported Squid to Windows NT and sells a supported
version. You can also download the source from
<A HREF="ftp://ftp.logisense.com/pub/cachexpress/">their FTP site</A>.
Thanks to LogiSense for making the code available as required by the GPL terms.</P>
<H2><A NAME="ss1.9">1.9</A> <A HREF="FAQ.html#toc1.9">What Squid mailing lists are available?</A>
</H2>
<P>
<UL>
<LI> squid-users@squid-cache.org: general discussions about the
Squid cache software. Subscribe via
<I>squid-users-subscribe@squid-cache.org</I>.
Previous messages are available for browsing at
<A HREF="http://www.squid-cache.org/mail-archive/squid-users/">the Squid Users Archive</A>,
and also at
<A HREF="http://marc.theaimsgroup.com/?l=squid-users&r=1&w=2">theaimsgroup.com</A>.
</LI>
<LI>squid-users-digest: digested (daily) version of
above. Subscribe via
<I>squid-users-digest-subscribe@squid-cache.org</I>.
</LI>
<LI>squid-announce@squid-cache.org: A receive-only list for
announcements of new versions.
Subscribe via
<I>squid-announce-subscribe@squid-cache.org</I>.
</LI>
<LI><I>squid-bugs@squid-cache.org</I>:
A closed list for sending us bug reports.
Bug reports received here are given priority over
those mentioned on squid-users.
</LI>
<LI><I>squid@squid-cache.org</I>:
A closed list for sending us feed-back and ideas.
</LI>
<LI><I>squid-faq@squid-cache.org</I>:
A closed list for sending us feed-back, updates, and additions to
the Squid FAQ.</LI>
</UL>
</P>
<P>We also have a few other mailing lists which are not strictly
Squid-related.</P>
<P>
<UL>
<LI><I>cache-snmp@ircache.net</I>:
A public list for discussion of Web Caching and SNMP issues and developments.
Eventually we hope to put forth a standard Web Caching MIB.
</LI>
<LI><I>icp-wg@ircache.net</I>:
Mostly-idle mailing list for the nonexistent ICP Working Group within
the IETF. It may be resurrected some day, you never know!
</LI>
</UL>
</P>
<H2><A NAME="ss1.10">1.10</A> <A HREF="FAQ.html#toc1.10">I can't figure out how to unsubscribe from your mailing list.</A>
</H2>
<P>All of our mailing lists have ``-subscribe'' and ``-unsubscribe''
addresses that you must
use for subscribe and unsubscribe requests. To unsubscribe from
the squid-users list, you send a message to <EM>squid-users-unsubscribe@squid-cache.org</EM>.</P>
<H2><A NAME="ss1.11">1.11</A> <A HREF="FAQ.html#toc1.11">What Squid web pages are available?</A>
</H2>
<P>Several Squid and Caching-related web pages are available:
<UL>
<LI>
<A HREF="http://www.squid-cache.org/">The Squid home page</A>
for information on the Squid software
</LI>
<LI>
<A HREF="http://www.ircache.net/Cache/">The IRCache Mesh</A>
gives information on our operational mesh of caches.
</LI>
<LI>
<A HREF="http://www.squid-cache.org/Doc/FAQ/">The Squid FAQ</A> (uh, you're reading it).
</LI>
<LI>
<A HREF="http://squid-docs.sourceforge.net/latest/html/book1.htm">Oskar's Squid Users Guide</A>.
</LI>
<LI>
<A HREF="http://www.ircache.net/Cache/FAQ/">The Information Resource Caching FAQ</A>
</LI>
<LI>
<A HREF="http://www.squid-cache.org/Doc/Prog-Guide/prog-guide.html">Squid Programmers Guide</A>.
Yeah, its extremely incomplete. I assure you this is the most recent version.
</LI>
<LI>
<A HREF="http://www.ircache.net/Cache/reading.html">Web Caching Reading list</A>
</LI>
<LI>
<A HREF="/Versions/1.0/Release-Notes-1.0.txt">Squid-1.0 Release Notes</A></LI>
<LI>
<A HREF="/Versions/1.1/Release-Notes-1.1.txt">Squid-1.1 Release Notes</A></LI>
<LI>
<A HREF="http://www.squid-cache.org/Doc/Hierarchy-Tutorial/">Tutorial on Configuring Hierarchical Squid Caches</A></LI>
<LI>
<A HREF="http://info.internet.isi.edu/in-notes/rfc/files/rfc2186.txt">RFC 2186</A> ICPv2 -- Protocol</LI>
<LI>
<A HREF="http://info.internet.isi.edu/in-notes/rfc/files/rfc2187.txt">RFC 2187</A> ICPv2 -- Application</LI>
<LI>
<A HREF="http://info.internet.isi.edu/in-notes/rfc/files/rfc1016.txt">RFC 1016</A></LI>
</UL>
</P>
<H2><A NAME="ss1.12">1.12</A> <A HREF="FAQ.html#toc1.12">Does Squid support SSL/HTTPS/TLS?</A>
</H2>
<P>As of version 2.5, Squid can terminate SSL connections. This is perhaps
only useful in a surrogate (http accelerator) configuration. You must
run configure with <EM>--enable-ssl</EM>. See <EM>https_port</EM> in
squid.conf for more information.</P>
<P>Squid also supports these encrypted protocols by ``tunelling''
traffic between clients and servers. In this case, Squid can relay
the encrypted bits between a client and a server.</P>
<P>Normally, when your browser comes across an <EM>https</EM> URL, it
does one of two things:</P>
<P>
<OL>
<LI>The browser opens an SSL connection directly to the origin
server.</LI>
<LI>The browser tunnels the request through Squid with the
<EM>CONNECT</EM> request method.</LI>
</OL>
</P>
<P>The <EM>CONNECT</EM> method is a way to tunnel any kind of
connection through an HTTP proxy. The proxy doesn't
understand or interpret the contents. It just passes
bytes back and forth between the client and server.
For the gory details on tunnelling and the CONNECT
method, please see
<A HREF="ftp://ftp.isi.edu/in-notes/rfc2817.txt">RFC 2817</A>
and
<A HREF="http://www.web-cache.com/Writings/Internet-Drafts/draft-luotonen-web-proxy-tunneling-01.txt">Tunneling TCP based protocols through Web proxy servers</A> (expired).</P>
<H2><A NAME="ss1.13">1.13</A> <A HREF="FAQ.html#toc1.13">What's the legal status of Squid?</A>
</H2>
<P>Squid is
<A HREF="squid-copyright.txt">copyrighted</A>
by the University of California San Diego.
Squid uses some
<A HREF="squid-credits.txt">code developed by others</A>.</P>
<P>Squid is
<A HREF="http://www.gnu.org/philosophy/free-sw.html">Free Software</A>.</P>
<P>Squid is licensed under the terms of the
<A HREF="http://www.gnu.org/copyleft/gpl.html">GNU General Public License</A>.</P>
<H2><A NAME="ss1.14">1.14</A> <A HREF="FAQ.html#toc1.14">Is Squid year-2000 compliant?</A>
</H2>
<P>We think so. Squid uses the Unix time format for all internal time
representations. Potential problem areas are in printing and
parsing other time representations. We have made the following
fixes in to address the year 2000:
<UL>
<LI><EM>cache.log</EM> timestamps use 4-digit years instead of just 2 digits.</LI>
<LI><EM>parse_rfc1123()</EM> assumes years less than "70" are after 2000.</LI>
<LI><EM>parse_iso3307_time()</EM> checks all four year digits.
</LI>
</UL>
</P>
<P>Year-2000 fixes were applied to the following Squid versions:
<UL>
<LI>
<A HREF="/Versions/v2/2.1/">squid-2.1</A>:
Year parsing bug fixed for dates in the "Wed Jun 9 01:29:59 1993 GMT"
format (Richard Kettlewell).</LI>
<LI>squid-1.1.22:
Fixed likely year-2000 bug in ftpget's timestamp parsing (Henrik Nordstrom).</LI>
<LI>squid-1.1.20:
Misc fixes (Arjan de Vet).</LI>
</UL>
</P>
<P>Patches:
<UL>
<LI>
<A HREF="../Y2K/patch3">Richard's lib/rfc1123.c patch</A>.
If you are still running 1.1.X, then you should apply this patch to
your source and recompile.</LI>
<LI>
<A HREF="../Y2K/patch2">Henrik's src/ftpget.c patch</A>.</LI>
<LI>
<A HREF="../Y2K/patch1">Arjan's lib/rfc1123.c patch</A>.</LI>
</UL>
</P>
<P>Squid-2.2 and earlier versions have a
<A HREF="http://www.squid-cache.org/Versions/v2/2.2/bugs/index.html#squid-2.2.stable5-mkhttpdlogtime-end-of-year">New Year bug</A>. This is not strictly a Year-2000 bug; it would happen on the first day of any year.</P>
<H2><A NAME="ss1.15">1.15</A> <A HREF="FAQ.html#toc1.15">Can I pay someone for Squid support?</A>
</H2>
<P>Yep. Please see the
<A HREF="/Support/services.html">commercial support page</A>.</P>
<H2><A NAME="ss1.16">1.16</A> <A HREF="FAQ.html#toc1.16">Squid FAQ contributors</A>
</H2>
<P>The following people have made contributions to this document:
<UL>
<LI>
<A HREF="mailto:JLarmour@origin-at.co.uk">Jonathan Larmour</A></LI>
<LI>
<A HREF="mailto:cord@Wunder-Nett.org">Cord Beermann</A></LI>
<LI>
<A HREF="mailto:tony@nlanr.net">Tony Sterrett</A></LI>
<LI>
<A HREF="mailto:ghynes@compusult.nf.ca">Gerard Hynes</A></LI>
<LI>
<A HREF="mailto:tkatayam@pi.titech.ac.jp">Katayama, Takeo</A></LI>
<LI>
<A HREF="mailto:wessels@ircache.net">Duane Wessels</A></LI>
<LI>
<A HREF="mailto:kc@caida.org">K Claffy</A></LI>
<LI>
<A HREF="mailto:pauls@etext.org">Paul Southworth</A></LI>
<LI>
<A HREF="mailto:oskar@is.co.za">Oskar Pearson</A></LI>
<LI>
<A HREF="mailto:ongbh@zpoprp.zpo.dec.com">Ong Beng Hui</A></LI>
<LI>
<A HREF="mailto:torsten.sturm@axis.de">Torsten Sturm</A></LI>
<LI>
<A HREF="mailto:jrg@blodwen.demon.co.uk">James R Grinter</A></LI>
<LI>
<A HREF="mailto:roever@nse.simac.nl">Rodney van den Oever</A></LI>
<LI>
<A HREF="mailto:bertold@tohotom.vein.hu">Kolics Bertold</A></LI>
<LI>
<A HREF="mailto:carson@cugc.org">Carson Gaspar</A></LI>
<LI>
<A HREF="mailto:michael@metal.iinet.net.au">Michael O'Reilly</A></LI>
<LI>
<A HREF="mailto:hclsmith@tallships.istar.ca">Hume Smith</A></LI>
<LI>
<A HREF="mailto:RichardA@noho.co.uk">Richard Ayres</A></LI>
<LI>
<A HREF="mailto:John.Saunders@scitec.com.au">John Saunders</A></LI>
<LI>
<A HREF="mailto:miquels@cistron.nl">Miquel van Smoorenburg</A></LI>
<LI>
<A HREF="mailto:david@avarice.nepean.uws.edu.au">David J N Begley</A></LI>
<LI>
<A HREF="mailto:SarKev@topnz.ac.nz">Kevin Sartorelli</A></LI>
<LI>
<A HREF="mailto:doering@usf.uni-kassel.de">Andreas Doering</A></LI>
<LI>
<A HREF="mailto:mark@cal026031.student.utwente.nl">Mark Visser</A></LI>
<LI>
<A HREF="mailto:tom@interact.net.au">tom minchin</A></LI>
<LI>
<A HREF="mailto:voeckler@rvs.uni-hannover.de">Jens-S. Vöckler</A></LI>
<LI>
<A HREF="mailto:andre.albsmeier@mchp.siemens.de">Andre Albsmeier</A></LI>
<LI>
<A HREF="mailto:nazard@man-assoc.on.ca">Doug Nazar</A></LI>
<LI>
<A HREF="mailto:hno@squid-cache.org">Henrik Nordstrom</A></LI>
<LI>
<A HREF="mailto:mark@rts.com.au">Mark Reynolds</A></LI>
<LI>
<A HREF="mailto:Arjan.deVet@adv.IAEhv.nl">Arjan de Vet</A></LI>
<LI>
<A HREF="mailto:peter@spinner.dialix.com.au">Peter Wemm</A></LI>
<LI>
<A HREF="mailto:webadm@info.cam.ac.uk">John Line</A></LI>
<LI>
<A HREF="mailto:ARMISTEJ@oeca.otis.com">Jason Armistead</A></LI>
<LI>
<A HREF="mailto:cudch@csv.warwick.ac.uk">Chris Tilbury</A></LI>
<LI>
<A HREF="mailto:jeff@sisna.com">Jeff Madison</A></LI>
<LI>
<A HREF="mailto:mbatchelor@citysearch.com">Mike Batchelor</A></LI>
<LI>
<A HREF="mailto:bogstad@pobox.com">Bill Bogstad</A></LI>
<LI>
<A HREF="mailto:radu at netsoft dot ro">Radu Greab</A></LI>
<LI>
<A HREF="mailto:f.j.bosscha@nhl.nl">F.J. Bosscha</A></LI>
<LI>
<A HREF="mailto:signal@shreve.net">Brian Feeny</A></LI>
<LI>
<A HREF="mailto:Support@dnet.co.uk">Martin Lyons</A></LI>
<LI>
<A HREF="mailto:david@luyer.net">David Luyer</A></LI>
<LI>
<A HREF="mailto:chris@senet.com.au">Chris Foote</A></LI>
<LI>
<A HREF="mailto:elkner@wotan.cs.Uni-Magdeburg.DE">Jens Elkner</A></LI>
<LI>
<A HREF="mailto:simon@mtds.com">Simon White</A></LI>
<LI>
<A HREF="mailto: jmurdoc at itraktech dot com">Jerry Murdock</A></LI>
</UL>
</P>
<P>Please send corrections, updates, and comments to:
<A HREF="mailto:squid-faq@squid-cache.org">squid-faq@squid-cache.org</A>.</P>
<H2><A NAME="ss1.17">1.17</A> <A HREF="FAQ.html#toc1.17">About This Document</A>
</H2>
<P>This document is copyrighted (2000) by Duane Wessels.</P>
<P>This document was written in SGML and converted with the
<A HREF="http://www.sgmltools.org/">SGML-Tools package</A>.</P>
<H3>Want to contribute? Please write in SGML...</H3>
<P>It is easier for us if you send us text which is close to "correct" SGML.
The SQUID FAQ currently uses the LINUXDOC DTD. Its probably easiest
to follow examples in the this file.
Here are the basics:</P>
<P>Use the <url> tag for links, instead of HTML <A HREF ...>
<PRE>
<url url="http://www.squid-cache.org" name="Squid Home Page">
</PRE>
</P>
<P>Use <em> for emphasis, config options, and pathnames:
<PRE>
<em>usr/local/squid/etc/squid.conf</em>
<em/cache_peer/
</PRE>
</P>
<P>Here is how you do lists:
<PRE>
<itemize>
<item>foo
<item>bar
</itemize>
</PRE>
</P>
<P>Use <verb>, just like HTML's <PRE> to show
unformatted text.</P>
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