Application Filtering

There are known security weaknesses in several Internet applications. The application level gateway examines the application data inside every packet that it receives. Any packets that contain attempts to exploit security weaknesses in an application are dropped.

This is to prevent application based attacks. The gateway firewall is using its intimate knowledge of applications to look for these type of attacks.

For example. e-mail can be used to cause disruption to a network. The gateway firewall examines all e-mail packets to make sure they do not exhibit behavior that can cause disruption.