Understanding Firewall protection

In buildings, a firewall is a barrier that prevents a fire from spreading. In computers, the concept is similar. There are a variety of "fires" out there on the Internet—hacker activity, viruses, worms, and so forth. A firewall is a system that stops these attempts to damage your computer.

The ZoneAlarm security software firewall guards the "doors" to your computer—that is, the ports through which Internet traffic comes in and goes out. ZoneAlarm security software examines all the network traffic arriving at your computer, and asks these questions:

• What Zone did the traffic come from and what port is it addressed to?
• Do the rules for that Zone allow traffic through that port?
• Does the traffic violate any global rules?
• Is the traffic authorized by a program on your computer (Application Control settings)?

The answers to these questions determine whether the traffic is allowed or blocked.

• Choosing security levels
• Setting advanced security options
• Managing traffic sources
• Blocking and unblocking ports
• Understanding expert firewall rules