What is a Proxy Server

Before knowing what is a proxy server, let's have a brief idea of what is a server. A server is a device with a specific set of programs or protocols that provide different types of services, which other machines or clients request to perform certain tasks. For example, a file server is a machine that maintains files and allows clients to upload and download files from it. Similarly a web server serves the websites and allows the Internet users to access these websites.

Proxy Server
When a client connects to the proxy server, it requests for a connection, file or some other resource which is available on a different server. The proxy server either by linking to the particular server or by serving it from a cache gives the resource. The proxy server appears to be invisible for its users, i.e. its IP address has to be assigned as a configuration alternative to the browser or other protocol program. Hence, all requests and responses seem to be directly with the addressed Internet server. Sometimes, it may even alter the client's request or the server's response for various reasons.

When the server receives a request for an Internet service like a web page request from a client, the server passes filtering requirements, acts as a cache server and searches in its local cache of earlier downloaded web pages. If the page is not found, the server acts as a client on behalf of the user and employs its own IP addresses to provide the page out on the Internet. When the page is returned, it associates the page to the original requests and sends to the actual client. In an enterprise that utilizes the Internet, a proxy server serves as a mediator between a workstation user and the Internet. It insures the enterprise with security, administrative control and caching service. Along with the gateway server, it distinguishes the enterprise network from the exterior network and protects from outside intrusion.

Proxy servers acts as a firewall and content filter by disabling access or filtering content requests to some websites which are regarded as offensive or harmful for the network and the users. Whenever a user requests a web page which is accessed by some other hosts, the proxy server instead of retrieving the page from the content provider, employs the cached (stored) information. This leads to faster access of the web pages and improves performance.

Types of Proxy Servers
The different types of proxy servers are:

• Transparent Proxy Server: This type of proxy server makes the original IP address accessible through the http headers, and has an ability to cache websites without effecting the anonymity of those who use them.
• Anonymous Proxy: This type of proxy server is perceptible but does not make the original IP address available, hence maintains reasonable anonymity for most of the users.
• Distorting Proxy: This type of proxy server creates a wrong original IP address which is accessible through the http headers.
• High Anonymity Proxy: This type of proxy server does not distinguish itself as a proxy server and does not makes the original IP address accessible through the http header.

One of the biggest advantage of a proxy server is that its cache can serve all users at the same time. It can do logging and can also be placed in the user's local computer. Hence, I hope now you must have got some idea of what is a proxy server and how it actually works.