Stateful Packet Filtering

A Screen, which sits between the client and server, uses stateful packet filtering to examine each data packet as it arrives. Based on information in the packet, state retained from previous events, and a set of the security policy rules, the Screen either passes the data packet or blocks it.

SunScreen uses a set of ordered rules to filter packets. When you configure SunScreen, you translate the security policies for your site into a series of policy rules that specify which services are allowed, what to do with packets for services that are disallowed, and what to do when packets are dropped. You then place these policy rules in sequence to specify which rules override others.