Filtering the Web with Proxy Servers

By Faithe Wempen

Many companies and schools that provide Internet access to their employees or students use web filtering software. Their rationale is that if they are providing you with a free Internet connection, they have the right to decide what kind of sites you can visit. For example, a public library might block adult-oriented sites to keep people from using library computers to view pornography, and a workplace might block Facebook to keep employees from wasting their time there.

Most of these filtering programs use a content-filtering proxy server to do what they do. A proxy server is a server that sits between you and the Internet. It runs every request through a filter, looking up each address in its database of allowed or disallowed sites, and it allows or blocks each request based on its internal database. A system administrator can configure the proxy server to allow or block certain sites, so if there is a site that’s being blocked and you don’t think it should be, you might be able to petition the IT department to unblock that site on the proxy server.

Web filtering isn’t the only use for a proxy server. A caching proxy server can also improve web performance by caching frequently used pages so the user request doesn’t have to go all the way out to the Internet at large to get some of the data it needs to display a particular page. For example, satellite Internet services may use proxy servers to help compensate for some of the latency (delay) that’s inherent in satellite technology.

A proxy server can also be used to beef up security for a business. A proxy server can provide network address translation, which makes the individual users and computers on the network anonymous when they are using the Internet. This makes it much harder for hackers to access individual computers on the network.