screening router

A router that performs packet filtering and is used as a firewall. In many cases, a single screening router is used as the entire firewall solution. See firewall, packet filter and router.

Protected and More Protected

In the diagram on top, the internal network is protected by only one screening router. If there were any servers on the internal network providing services to Internet users, this would offer minimal protection against an attack. The use of two screening routers in the firewall configuration at the bottom offers two points of protection from the outside world to the internal LAN.