Proxy Server

Proxy Server
A proxy server, in a general sense of the term proxy, is a stand-in server. In a network, a proxy server is the entity that sits between corporate client machines and the Internet. For example, it may sit between a client application, such as a Web browser and the corporate server. Proxies are used to intercept incoming and outgoing requests to see if it can fulfill the requests itself. If not, it then forwards the request to the real server.

Forward and Reverse Proxies
The most common types of proxy servers are called forward and reverse proxies. A forward proxy is used to forward outgoing requests from a private network or intranet to the Internet, usually through a firewall. The main goal of the forward proxy is to provide a level of security and also to reduce network traffic. For example, if a Web browser is configured to do so, all requests will be made through the proxy, which in turn will apply filtering rules. The proxy will then request the site the user was trying to reach on his or her behalf, or more accurately: "by proxy."

In contrast, a reverse proxy handles requests coming from the Internet to the private network or intranet. This provides a level of security that prevents the Internet clients from having direct access to data on the corporate servers. The reverse proxy sits between your Web server and the world. When an HTTP connection comes in, the reverse proxy will decide what to do, and then make a request to the appropriate backend Web server. Reverse proxies are very important, and they are commonly used to secure and load balance Web servers and also act as a content filter.

Proxy servers can also be chained. This is not a type of proxy server, but rather a method for using reverse and forward proxy servers across your network or across multiple networks in cases where the number of requests to the proxy may exceed its limits causing it to slow down. A proxy server chain lets you assign a specific number of clients to each proxy within the chain.