What is a Firewall?

A firewall is a device or software designed to block certain types of network traffic. Firewalls can be very effective at blocking a type of virus called a worm that rapidly spreads over networks such as the Internet. Windows XP and Macinosh OS 10.2 and later have built-in firewall software.

If a firewall is not configured correctly it can prevent a successful network connection or prevent access to certain network resources. Due to this, it is very important to configure your firewall correctly.

How to configure the firewall in Windows XP

How to configure the firewall in Macintosh OS 10.2 and later