4.3 Hardware firewall

A firewall is a filter that blocks certain kinds of network traffic. It is safe to say that a firewall can block 99%, if not all, worm attacks. This is because worm attacks originate from the Internet, and most firewalls (aka residential gateway, router) by default blocks all connections initiated from the Internet.

However, a hardware firewall cannot stop trojans because the downloading and triggering of trojans are both beyond the understanding and control of a hardware firewall.

Despite the limited capabilities of a hardware firewall (in the context of security), it does enable multiple computers in a household to share the same internet connection. This feature enables the use of a dedicated ``lightning rod'' machine for potentially dangerous online activities.