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1. About Squid, this FAQ, and other Squid information resources

1.1 What is Squid?

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.

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.

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.

Squid consists of a main server program squid, a Domain Name System lookup program dnsserver, a program for retrieving FTP data ftpget, and some management and client tools. When squid starts up, it spawns a configurable number of dnsserver 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.

Squid is derived from the ARPA-funded Harvest project.

1.2 What is Internet object caching?

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.

1.3 Why is it called Squid?

Harris' Lament says, ``All the good ones are taken."

We needed to distinguish this new version from the Harvest cache software. Squid was the code name for initial development, and it stuck.

1.4 What is the latest version of Squid?

Squid is updated often; please see the Squid home page for the most recent versions.

1.5 Who is responsible for Squid?

Squid is the result of efforts by numerous individuals from the Internet community. Duane Wessels of the National Laboratory for Applied Network Research (funded by the National Science Foundation) leads code development. Please see the CONTRIBUTORS file for a list of our excellent contributors.

1.6 Where can I get Squid?

You can download Squid via FTP from the primary FTP site or one of the many worldwide mirror sites.

Many sushi bars also have Squid.

1.7 What Squid mailing lists are available?

Archives of the various public mailing lists are available for browsing.

1.8 What Squid web pages are available?

Several Squid and Squid-related web pages are available. Go to the Squid home page for information on the Squid software, and the NLANR Cache Project page for much more information on web caching in general.

1.9 Does Squid support SSL?

Squid can proxy SSL requests. By default, Squid will forward all SSL requests directly to their origin servers. In firewall configurations, Squid will forward all SSL requests to one other proxy, defined with the ssl_proxy directive.

1.10 What's the legal status of Squid?

From the Squid distribution, README file:

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

1.11 Squid FAQ contributors

The following people have made contributions to this document:

Please send corrections, updates, and comments to:

1.12 About This Doument

This document was written in SGML and converted with the SGML-Tools package. This document is available in both HTML and compressed Postscript.

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