A proxy server is one that receives requests intended for another server and that acts on the behalf of the client (as the client proxy) to obtain the requested service. A proxy server is often used when the client and the server are incompatible for direct connection. For example, the client may be unable to meet the security authentication requirements of the server but may be required to access some services. It may also be used for screening purposes to enable the administrator to control access to undesirable sites. The proxy server may also be used for caching purposes which enables faster access to frequently used websites. All the computers connected to the LAN access the Internet through a single IP address which results in improved security simply because the number of ports exposed is reduced. Proxy servers work on the seventh layer (the Application Layer) of the OSI model thus tending to be application dependent unlike firewalls that work at lower layers. They are also more difficult to install and maintain than firewalls, as proxy functionality for each application protocol like HTTP, SMTP, or SOCKS must be configured individually. However, a properly configured proxy server improves network security and performance. Since proxy servers function at the OSI Application layer, their filterin   read more »