A web proxy cache is a centralized place to store files downloaded from the internet via HTTP, FTP and other protocols. Proxy caches are simple to set up and provide a number of benefits:
Making access to web and FTP sites seem faster. By keeping files downloaded from the internet in a central cache, users subsequently accessing those files can fetch them directly from the cache, which is faster to access than the outside world.
To ensure that web clients don't get stale information from their cache, web server operators provide expiry information for the files they serve.
Lowing cost of the internet connections by downloading less data though them (as the same oinformation isn't downloaded multiple times).
Providing a central place to control access to the outside world. Many organizations only provide access to the internet through their proxy cache, and then filter undesired content, pop ups, and advertisements using their proxy software (or plugins for their proxy software). Fedora provides the Squidguard program for this purpose.
Reduces load on external sites. By downloading data from the origin site less, proxy servers reduce load on these machines, helping other users get faster access.
The web proxy cache used by Fedora is Squid. Squid is the most popular web proxy cache on the internet. Its features include an excellent access control mechanism that can filter access by a variety of criteria, support for peering with other cachies, and excellent support from a variety of add-on applications and ang plugins.
Squid also supports transparent caching, allowing all web/FTP access to use the cache without having to configure the web browser on each machine.
Asides from this tutorial, additional documentation for Squid is available in /usr/share/doc/squid-2.5.STABLE3/, particularly the Squid FAQ.
| Task | Web and FTP proxy serving |
|---|---|
| Implementation | Squid |
| Function | Stored files downloaded by HTTP and FTP in a central location |
| Packages | squid |
| Config Tool | None yet |
| Config Files | /etc/squid/squid.conf |
| Packages | squid |
| Service | squid |
| Service Type | Permanently Running |
| Directory Served | The cache is served from /var/spool/squid/ |
| Network Port(s) | 3128 (squid). |
| Logging | Does not use syslog by default, but will use the daemon facility if configured to do so (add "-s" to /etc/sysconfig/squid to do this) |
| Default Log File | /var/log/squid |
| Diagnostics | squid -k parse |
Table 1. Secure FTP service profile