Macintosh Firewall

Firewalls limit network traffic arriving to and leaving from your computer.

To enable the Mac OS X built-in firewall follow these steps:

1. Open the Apple menu in the upper left corner of the screen.
2. Select System Preferences....
3. In the Internet & Wireless section, click Sharing.
4. Click the Firewall tab.
5. Click the Start button if the firewall is off.