When you are connected to the internet, the internet is also connected to you: Malicious people can use that internet connection to look for ways to access your computer's files, programs, and devices such as printers. Although problems of this kind are relatively rare, several software developers now offer firewalls - programs that restrict the kind of information that can be exchanged over the internet connection. Firewalls are not foolproof, but they can make a computer much less susceptible to unauthorized access. There are several popular firewalls, including ZoneAlarm and Norton Internet Security. Windows XP comes with its own protection against unwelcome intruders: the Internet Connection Firewall.
However, the Internet Connection Firewall is available only for Windows XP and does not protect against some security risks. If you don't use Windows XP or want a more fully featured firewall, you might be interested in the ZoneAlarm Firewall. ZoneAlarm is available in free and in pay versions from Zone Labs. To download the free version of this software visit http://www.zonealarm.com