A router that performs packet filtering as a firewall. In many cases, a single screening router is the entire firewall solution. See firewall
, firewall methods
, packet filter
Protected and More Protected
In the top diagram, the internal network is protected by only one screening router (a router with packet filtering). If servers on the internal network provide services to Internet users, this offers minimal protection against an attack. The use of two screening routers in the bottom diagram offers two points of protection from the outside world to the internal LAN.