Proxy server

From ArticleWorld

A proxy server is a network service that allows its clients to initiate and use indirect connections to other hosts. The typical procedure requires the client to connect to the proxy server first. The client sends its requests to the proxy server, who feeds them to the third host, which the client wants to access, and redirects answers from the host to the client. The hosts may or may not be aware that the client is connecting through a proxy.

Transparency

Proxy servers are often used by network administrators to enforce network policies or to provide various services like caching. Although this is quite controversial, since it violates the basic TCP/IP end-to-end principle, it is commonly used because it is cheap and very efficient.

In general, the proxy servers are not application-transparent, meaning that applications must be specially configured to use proxy servers. Most network-enabled applications support the usage of proxy servers nowadays.

Usage

Proxies are often used because they can provide a high degree of anonymity. Journalists who live under totalitarian regimes, like those in China or Cuba, often use proxy servers to post their articles on the Internet without being easily tracked. However, proxy servers are also used for malicious purposes: spammers often use these so that tracking the actual origin of a message is made more difficult. Forum users who have had their IP banned also use proxies to register again, as anonymous proxies do not let the host know that the client is connecting through a third party (the proxy server). It is also a common crackers' practice to use trojans in order to install proxy servers on users' computers, which will be used by them for their further action.

A special use is that of a reverse proxy, which is a server installed along web servers. Traffic coming from the Internet is going through the server, in order to improve security, SSL acceleration, distribute the load and compress the content so that it takes less to load on the client's computer.