Squid cache (referred to as Squid) is a popular free software (GNU General Public License) proxy server and Web cache server. Squid has a wide range of uses, from the front-end cache server as a web server cache related requests to improve the speed of the Web server, to a group of people to share network resources and cache the World Wide Web, domain name system and other network search, to filter traffic through the help network Security, to the local area network through the proxy. Squid is primarily designed to run on Unix systems.
Squid’s development history is quite long, the function is quite perfect. In addition to HTTP, FTP and HTTPS support are also very good, in the 3.0 beta also supports IPv6.