Technical

Client computer has a setting (specific program or operating system), according to which all network connections on a single protocol are performed not by IP-address of the server (a resource), extracted from DNS-name of a resource, or directly specified, and the ip-address ( and other ports) proxy.
If necessary, refer to any resource on this protocol, the client opens a network connection to the proxy server (on the right port) and provides regular query, as if he was referring directly to the resource.
Recognize the data request by checking its accuracy and resolution of the client computer, the proxy server, without breaking the connection, he opens up a new network connection directly to the resource and makes the same request. After receiving the data (or error), the proxy server sends it to the client computer.
Thus a proxy server is a full-featured client and server for each supported protocol, and has full control over all the details of the implementation of this protocol has the ability to use administrator-defined access policies for each stage of the protocol.
Proxy servers are the most popular way of accessing the Internet from a network of enterprises and organizations. This is facilitated by the following facts:
- The main protocol used on the Internet - HTTP, a standard which describes the support of a proxy;
- Proxy support all major browsers and / or operating systems;
- Access control and traffic by users;
- Traffic filtering (integration with antivirus proxy);
- Proxy server - can work with minimal rights on any OS with network support (stack TCP / IP);
- Many applications that use their own custom protocols can use HTTP as an alternative transport or SOCKS-proxy as a generic proxy, suitable for almost any protocol;
- Lack of access to the Internet on the other (non-standard) protocols can increase security in corporate networks.
At present, despite the growing role of other network protocols, the transition to charging Internet service access speed, as well as the advent of cheap hardware router with NAT, proxies are still widely used in enterprises, as NAT can not provide a sufficient level of control over the Internet (user authentication, content filtering).