What is a Proxy Server?

Proxy is a term which we come across often, in a network. In general, a proxy is referred to as a person authorized to act for other. A proxy server is nothing but a mediator which acts between the requests sent from a client asking for the resources from the server. Whenever a request is made from the client in a network, the proxy server evaluates the request and allows it to access the resource if it’s a valid one. There are also caches in proxy server (i.e.,) the proxy server receives response from the remote server and returns it to the client.

There are different types of proxy servers. Some of them are as follows,

• Web Proxy


• Content filtering Proxy


• Caching Proxy


• Open Proxy


• Tunneling Proxy


• Reverse Proxy

There are a wide number of proxy servers available for use. Each has their own characteristics and features. Various Open Source proxy servers too available for use and we can customize it as needed.

Some of the proxy servers available are,

• Squid Proxy


• Privoxy


• TinyProxy


• Ziproxy


• Apache HTTP Server

Let me give an overview of Squid Proxy server (Open Source)which is used commonly in many organizations.

It’s primarily designed to run on Unix Systems. Consider that your Squid Proxy runs on your server with ip address 165.165.100.2 and the default port number for Squid is 3128. The port number is customizable one, consider the default one here. Let the client connected bear the ip address 165.165.1.1

The client interacts with the proxy server as follows,

You can configure your ip address either static or can be set dynamic at the client but there are a few more configurations to be done in your web browsers to access to the external resource (internet).I ‘ll just explain using ie here.Choose Options from Tools menu and navigate to connections tab and then LAN Settings.Check use proxy server option and fill out the necessary ip address and port number . It must look something as follows.

What it means is that , all the requests made from client is passed to server with ip address 165.165.100.2 and port 3128 , where the squid proxy is running already. Then the requests are processed and results are returned.

You can also find out the type of proxy used in the network whenever the error page , something like Access denied ! is displayed ! The proxy server name is specified in the last line of the error page.