What is meant by 'proxy'?

Question

When I have gone through networking texts, I have seen the term 'proxy' address.

Can anybody provide details of what a proxy is and why we are using it?

Can you list some better software's(mostly used) which acts as proxy after its installation and also how can i configure it in a simple network?

Answer 1

Basically, when you have a proxy server set up, all your internet connections (or just HTTP, depending) go through the proxy first before going to either end of the line. This is useful when the direct connections are blocked or you want to do something like tracking your history for research or something.

A proxy can do anything it wants with the data that goes through it, which is both good (Prioxy) or bad (Man in the Middle Attacks/this Hak5 episode).

Answer 2

A proxy is a server that you connect to, that then connects to the internet. If you use a proxy, your computer doesn't communicate directly with the website servers you are looking at, but communicates through the proxy.

Some people use it for privacy so the web server can't see who you are, but only sees the proxy.

The Wikipedia page, has a good descriptions of what a proxy is and what it does.

Answer 3

Wikipedia

In computer networks, a proxy server is a server (a computer system or an application program) that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. The proxy server evaluates the request according to its filtering rules. For example, it may filter traffic by IP address or protocol. If the request is validated by the filter, the proxy provides the resource by connecting to the relevant server and requesting the service on behalf of the client. A proxy server may optionally alter the client's request or the server's response, and sometimes it may serve the request without contacting the specified server. In this case, it 'caches' responses from the remote server, and returns subsequent requests for the same content directly.

A proxy server has a large variety of potential purposes, including:

• To keep machines behind it anonymous (mainly for security).
• To speed up access to resources (using caching). Web proxies are commonly used to cache web pages from a web server.
• To apply access policy to network services or content, e.g. to block undesired sites.
• To log / audit usage, i.e. to provide company employee Internet usage reporting.
• To bypass security/ parental controls.
• To scan transmitted content for malware before delivery.
• To scan outbound content, e.g., for data leak protection.
• To circumvent regional restrictions.

A proxy server that passes requests and replies unmodified is usually called a gateway or sometimes tunneling proxy.

A proxy server can be placed in the user's local computer or at various points between the user and the destination servers on the Internet.

A reverse proxy is (usually) an Internet-facing proxy used as a front-end to control and protect access to a server on a private network, commonly also performing tasks such as load-balancing, authentication, decryption or caching.

Answer 4

Simply put, a proxy server is a device that acts as an indirection between the client and other network locations.

So, instead of directly connecting to a website or service the proxy will connect on behalf of the client.

This means a client will ask the proxy server for a particular network resource (a file, website, etc), and the proxy server would connect to, download, and then return the resource back to the client - the client never connects to the other server holding the resource.