Mac OS X Firewall

OS X’s built-in firewall is enough for most users
By Jeffery Battersby
SUMMARY
Pros: Free with OS X; provides Stealth Mode and logging tools; can block UDP traffic.
Cons: Advanced configuration requires Terminal; logs might confuse network newbies.
Processor Compatibility: Universal
OS Compatibility: 10.4 (Tiger)
Price as rated: Free
Company: Apple, www.apple.com
You don’t have to travel far or pay a fee to start protecting your Mac from break-ins. Take a quick trip to the Sharing pane in your Mac’s System Preferences, and there, with the click of a mouse button, you can turn on the built-in OS X firewall—and put a wall between you and the rest of the world.

OS X’s built-in firewall lacks the flash and sizzle of other firewall applications. It has no multi-colored gauges breaking down network traffic by type, and no alerts, beeps, or buzzes to warn of impending danger. But it’s there if you want it, running silently in the background and monitoring incoming traffic for potential danger.

http://www.macworld.com/2006/05/reviews/osxfirewall/index.php