Proxy
Servers
Most
home and small office networks use a dial-up or modem network
connection to an ISP, which in turn connects them to the Internet.
The ISP assigns a single IP address to each network for connecting
to the Internet. In addition, each computer in a network requires an
IP address for Internet connection. Rather than using separate IP
addresses for each computer, it is more cost-effective to use a
single IP address for multiple computers. A
proxy server
is a
firewall component that enables you to connect multiple computers in
a network to the Internet by using a single IP address. Proxy
servers have two main functions: to improve network performance and
filter client requests.
Proxy servers reduce the time it takes to respond to requests made
by groups of users. This is because a proxy server caches, or saves,
the results of all requests made during an interval of time. If a
user wants to redisplay a Web page that was requested earlier, the
proxy server simply returns that page to the user rather than
forwarding the request to the Web server and downloading the page
again.
Proxy servers can also be used to filter client requests for certain
Internet connections. For example, a company can use a proxy server
to prevent its employees from accessing a specific set of Web sites.
How
Does a Proxy Server Work?
When
using a proxy server, the computers on the local network are
configured for private IP addresses. When a computer makes a request
to connect to the Internet, the computer passes its data through the
TCP/IP network to the proxy server. The proxy server modifies the
request, inserts its own name and IP address, which was provided by
the ISP, and sends the data out on the Internet. When a response to
the request is received, the proxy server passes it back through the
local network to the computer that initiated the request.
