A computer that can act on the behalf of other computers to request content from the Internet or an intranet. Proxy Server is placed between a user's machine and the Internet. It can act as a firewall to provide protection and as a cache area to speed up Web page display. A firewall mechanism that replaces the IP address of a host on the internal (protected) network with its own IP address for all traffic passing through it. A software agent that acts on behalf of a user, typical proxies accept a connection from a user, make a decision as to whether or not the user or client IP address is permitted to use the proxy, perhaps does additional authentication, and then completes a connection on behalf of the user to a remote destination.

Proxy servers have two main purposes:

  • Improve Performance: Proxy servers can dramatically improve performance for groups of users. This is because it saves the results of all requests for a certain amount of time. proxy server is often on the same network as the user, this is a much faster Real proxy servers support hundreds or thousands of users.
  • Filter Requests: Proxy servers can also be used to filter requests.

Types of Proxy:

1. Forward Proxy:

Forward proxies are proxies where the client server names the target server to connect to. Forward proxies are able to retrieve from a wide range of sources (in most cases anywhere on the Internet).The terms "forward proxy" and "forwarding proxy" are a general description of behavior (forwarding traffic) and thus ambiguous. Except for Reverse proxy


                  Fig: A forward proxy taking requests from an internal network and forwarding

                                                             them to the Internet

2. Open Proxy:

An open proxy is a forward proxy server that is accessible by any Internet user. Gordon Lyon estimates there are "hundreds of thousands" of open proxies on the Internet.[4] An anonymous open proxy allows users to conceal their IP address while browsing the Web or using other Internet services.


                                Fig: An open proxy forwarding requests from and to anywhere on

                                                                the Internet.

3. Reverse Proxy:

A reverse proxy is a proxy server that appears to clients to be an ordinary server. Requests are forwarded to one or more origin servers that handle the request. The response is returned as if it came directly from the proxy server


 Fig: A reverse proxy taking requests from the Internet and forwarding them to servers in an internal network. Those making requests connect to the proxy and may not be aware of the internal network.