As stated earlier, internet proxies act as go-betweens for requests from clients seeking resources from other serves. This is meant for the purpose of either keeping the machines anonymous or speeding up access to a resource via caching. The two main proxies we’ll talk about are web proxies and content filtering proxies.
Web proxies are those focusing on www traffic. The most common use for a web proxy is in web caching. Caching keeps local copies of frequently requested resources allowing one to significantly reduce their upstream bandwidth cost and usage while increasing performance. Some web proxies also provide a means to deny access to certain URLs in a blacklist, thus providing for some form of content filtering.
One of the more well-known freeware web proxies is Squid. It functions as a proxy server and a web cache daemon. It serves a variety of uses from speeding up a web server to caching repeated requests. It also caches web, DNS, and other computer network lookups for people sharing network resources. Squid also aids in filtering traffic thus aiding in security. It also has some features that can help anonymize connections such as disabling or changing specific header fields in a client’s HTTP requests. Whether they are set and what they are set to do is up to the person who controls the computer running Squid.
Squid can also function as a reverse proxy – that is, serving an unlimited number of clients for a limited number of webservers. This results in less traffic to the source server, meaning less CPU and memory usage, and less need for bandwidth. All without any action by the clients. Squid works on a variety of platforms, including Windows, Linux, Mac OS X, etc.
Content filtering proxies, also known as censorware or web filtering software, is a term for software designed and optimised for controlling what content is permitted to a reader, especially when used to restrict material delivered over the web. Content-control software determines what content will be available on a particular machine or network. The motive is often to prevent persons from viewing content which may be considered objectionable.