Turning On Your Firewall

Then, select "Sharing" to verify or change your network access settings.

The first section that appears is the "Services" settings. Unless you have a reason to enable a particular service, they should all be off (unchecked), as they are by default).

Next, click on the "Firewall" tab. If it says "Firewall Off," click the Start button. Unless you have a reason to turn allow a particular service, all should be off (unchecked). Possible exceptions include "Network Time" (keeps your clock accurate by synchronizing it with an Internet time source) and "iTunes Music Sharing" (if you choose to share your iTunes music on the network).