First, the proxy server acts as an intermediary, helping users on a private network get information from the Internet when they need it, while ensuring that network security is maintained. Second, a proxy server may store frequently requested information in a . . .
First, the proxy server acts as an intermediary, helping users on a private network get information from the Internet when they need it, while ensuring that network security is maintained. Second, a proxy server may store frequently requested information in a local disk cache, rapidly delivering it to multiple users without having to go back to the Internet to get it.

A proxy server is usually just one component of software that provides a variety of other services, such as a gateway to connect the local network to the Internet or a firewall to provide protection from outside intrusion.

Because proxy servers and firewalls are so often bundled together, people often confuse the two. However, a packet-filtering firewall operates at the Network layer of the OSI model, while proxy servers work at the Application layer. Packet filters use routers to filter information coming to and from a network. Because routers check each packet against some sort of access-control table (listing, for example, the IP addresses of trusted servers), they make it easy to block traffic that's not trusted. Firewalls can also screen packets based upon TCP and UDP port numbers; therefore, you can permit certain types of connections (Telnet or FTP, for example) to only certain trusted servers.

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