Proxy Servers

Proxy Servers

Proxying represents the opposite extreme in firewall design. Rather
than using a general-purpose mechanism to allow many different kinds
of traffic to flow (as in packet filters), special-purpose code can be used
for each desired application. A proxy server provides Internet access to
a single or a very small number of hosts, while appearing to provide
access to all the internal network’s hosts, see Figure 52. One can see this
as another example where security is enhanced by the implementation
of an intermediate level of control: the user’s client program on the
internal network talks to a proxy server instead of talking directly to the
’real’ server on the Internet.