Mac OS X: Using a Firewall to Protect Your Computer

(Excerpted from Mac Help)

Mac OS X includes firewall software you can use to block unwanted network communication with your computer. You can use a firewall to protect all of the services available in Mac OS X, such as Personal File Sharing, Windows Sharing, and Remote Login. Using a firewall protects the services on your computer from users on other networks or the Internet. This firewall is disabled by default.

Note: When you select a service in the Services pane of Sharing preferences, it is automatically selected in the Firewall pane. To prevent that service while the firewall is on, turn off the service in the Services pane.

To enable firewall protection on your computer:

1. Open System Preferences.
2. Click Sharing.
3. Select the Firewall pane.
4. Click on the Start button on the top left corner. The status of the firewall will change to Firewall On.

To turn off firewall protection for any service while your firewall software is turned on, turn off the service by deselecting it in the Services pane.

You can not edit the firewall ports used by built-in services. They are enabled and disabled automatically when you turn the corresponding service on or off in the Services pane.

If you use iChat, iTunes Sharing or iPhoto Bonjour Sharing, make sure to allow these services in and out of your firewall. You can do this by turning on their services in the Firewall pane.

I Can't Change Firewall Settings

The firewall built into Mac OS X includes ports for each of the services listed in the Services pane of Sharing preferences.

You can not enable or disable these firewall ports directly. They are enabled and disabled automatically when you turn the corresponding service on or off in the Services pane.

You can control the firewall settings for other ports that you add using the Firewall pane of System Preferences.

To turn the firewall for a built-in service on or off:

1. Open System Preferences.
2. Click Sharing.
3. Now click Services.
4. Enable OR disable the service.

Firewall access for the service is set accordingly.

If you have questions, please contact the ITS Help Desks at helpdesk@psu.edu.