Proxy servers

Quite simply, a proxy server is a device that forwards requests from one device to the intended recipient, and does the reverse for any response. Let's talk through Figure 14.7, where we can see this operation:

Figure 14.7: Communicating via a proxy server

1. PC A wants to look at the website www.packtpub.com and sends its request to the proxy server.
2. The proxy server forwards the request on to www.packtpub.com.
3. The web server at www.packtpub.com receives the request and sends the requested web pages to the proxy server.
4. The proxy server forwards the web pages to PC A.

It should be noted that between step 3 and step 4, the proxy server may cache the requested web pages locally for use by other devices. Figure 14.8 continues on the preceding steps to show this:

Figure 14.8: Retrieving web pages from a proxy server cache

5. PC B wants to look at the website www...