Packet Filter

A packet filtering firewall, or packet filter for short, is the simplest type of firewall. It performs its services based on the addressing information found in individual packets.

After comparing the addressing information with its programmed security policy, the packet filter simply passes the packet along if it is approved, or drops the packet if it is not approved.

It makes this decision by performing a simple binary comparison of the addressing information with the information found in its security policy.