Firewalls
Most computers now have some form of software-based firewall, it is included for example in Windows XP and higher. For those who really want to be on the safe side, however, a hardware-based firewall is recommended. A hardware firewall is connected between your Internet connection and network. The computer's own resources to stop unauthorized network traffic will not be used, and it's easier to maintain once it's installed and configured. Cisco, Linksys, Netgear and Linksys are known manufacturers.
