A firewall is a barrier to keep viruses, worms, and spyware away from your computer. With the use of filters, the firewall examines the information coming through your Internet connection. If any of the information is flagged by the filters as being dangerous to the computer, it is not allowed through. Firewalls are excellent for a first line of defense in protecting your computer from future infections.

Your computer also has a built in firewall that just needs to be activated. To activate your firewall, you need to:

  • Open System Preferences and click on Security.
  • Select the service you want to share. Firewall protection will be automatically turned on for that service. Click on Firewall to make sure.

Note: In older versions of Mac OS X, the Firewall options are under Sharing rather than Security.