Firewalls

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A firewall is a program or hardware device that keeps hostile attackers from accessing a computer's data. Firewalls can help prevent virus transmission, and overall, they are good to have. Unfortunately, configuration of some firewalls can be painstaking. Without proper configuration, certain firewalls can block all Internet access.

Certain products come with firewalls. For example, Linksys routers act as firewalls, but the router firmware also makes available a trial version of a software-based firewall. Trend Micro's PC-Cillin antivirus program comes with a firewall that, at least in recent versions, won't deactivate even when the program settings indicate that it is disabled. (To disable it in 2000 or XP, go into Services and disable the Trend Micro personal firewall service there.) As mentioned earlier, Windows XP comes with the ICF.

Here are some basic recommendations about use of firewalls:

• Use of more than one firewall on a system will probably stop most or all Internet traffic. Stick with one.

• If you are using Internet Connection Sharing in 2000/XP, enable the ICF or use another firewall product.

• If you use a proxy server to connect to the Internet, don't use a firewall, except on the proxy server. (It is not necessary to know what a proxy server is for our purposes.)

See XP's Help and Support for more information about the ICF.

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