SSCP Systems Security Certified Practitioner All-in-One Exam Guide

Using Proxy Servers

A proxy server is used as an intermediary, or proxy, for clients. Instead of clients retrieving web pages directly from the Internet, they instead send the request to the proxy server. The proxy server retrieves the web page on the client’s behalf and returns it to the client.

Chapter 3 briefly introduced proxy servers in the context of Network Address Translation (NAT). Remember that NAT translates private IP addresses to public addresses and public IP addresses back to private. Proxy servers commonly include NAT as an additional service. Additionally, proxy servers provide two primary additional services: caching and filtering. Figure 4-5 shows how caching and filtering works.

Figure 4-5 Proxy used for caching and filtering ...