Setting Up Your Mac’s Firewall

If your Mac is constantly connected to the Internet, conceivably someone could hack into your computer and get into all sorts of mischief. While unlikely, it’s always best to protect yourself from such events so your Mac comes with a built-in Firewall* to protect your computer from attack, which is turned off by default. Most modern routers come with a Firewall built-in so for many folks, the Mac firewall is not a necessity. However, if your computer is connected through a DSL box or cable modem, then its important that you set up some sort of Firewall.

You can turn on your Mac’s firewall from the Security & Privacy pane of System Preferences. You will need administrator access to activate the Firewall.

Once you have turned on the Firewall, you can set some additional Firewall options:

Block all incoming connections – This blocks most network connections including iTunes sharing, most Web sites during surfing, screen sharing and many applications. Most of the time, this setting is more a pain than its worth.
List of applications that are allowed to accept incoming connections window – To add programs to the list, click the + symbol and choose the desired application. To block incoming connections for the application, click the drop-down list and choose Block incoming connections from the list.
Automatically allow signed software to receive incoming connections – this allows connections for any applications recognized by Apple.
Enable Stealth Mode – Allows your Mac to become “invisible” to others (it will not respond to any pings).