Firewalls

A firewall is a type of network filter which is usually placed between a private and public network. They can also be used within a private network in order to enhance network security through segmentation. Their main goal is to keep unwanted users out.

Firewalls got their name from the construction industry. In the past builders would put up a heavy duty wall between different parts of the construction project. The purpose was to prevent a fire from spreading from one side of the project to another. Hence the term "firewall."

Today firewalls are basically a packet filter which can restrict TCP and UDP packets to a set of rules configured by the user. The "rule base" is a bit like a traffic cop letting certain traffic go here, and preventing other traffic from going there.

There are many companies out there with their own firewall products. On this site we will constantly review the latest products while scrutinizing established solutions such as those from CheckPoint, Cisco, and Netscreen.