A firewall is software that prevents the flow of Internet traffic. Businesses and large network administrators use firewalls to contain traffic and maintain security. Firewalls keep traffic out, or they keep it in. A simple firewall configuration for most home users would block all outside traffic not generated at the users' request.. . .
A firewall is software that prevents the flow of Internet traffic. Businesses and large network administrators use firewalls to contain traffic and maintain security. Firewalls keep traffic out, or they keep it in. A simple firewall configuration for most home users would block all outside traffic not generated at the users' request. So, trading e-mail with someone on your contact list would be fine, but allowing an unknown, outside user to download music from your computer would not. Unless you're hosting a Web site or running your own Internet Service Provider, this type of configuration works well.

Linux provides a mechanism for firewalling traffic within its core, or kernel, called "iptables." This mechanism can be used as the basis for a very flexible and powerful firewall. In fact, many commercial firewall solutions base their products on iptables (or their older cousin, "ipchains").

The link for this article located at ChicagoTribune is no longer available.