Network Security Hacks: Firewalling

Overview

When designing a network, it's often desirable to define policies governing how and where certain vital network services can be accessed. The firewall is a key technology that is instrumental in enforcing these policies and can allow network administrators to delineate trust relationships between networks and hosts with a fine grain of detail. By instituting a firewall, one can prevent unauthorized access to services at the network level before an attacker is given the chance to attempt to exploit them. One can use a firewall not only to limit what information flows into a network, but also to prevent the egress of information.