ARCHIVED: In Mac OS X, how do I enable or disable the firewall?

Mac OS X includes an easy-to-use firewall that can prevent potentially harmful incoming connections from other computers. To turn it on or off:

Mac OS X 10.6 and later

1. From the Apple menu, select System Preferences... . When the System Preferences window appears, from the View menu, select Security & Privacy (10.7 and later) or Security (10.6).
   
   
2. Click the Firewall tab.
   
   
3. If the orange padlock icon in the lower left side of the window is closed, click it, and then authenticate with your Mac's administrator username and password. This will allow you to make changes.
   
   
4. Click Turn On Firewall (10.7 and later) or Start (10.6) to enable the firewall. Click Turn Off Firewall (10.7 and later) or Stop (10.6) to disable the firewall.
   
   
5. To configure the firewall, click Firewall Options... (10.7 and later) or Advanced...  (10.6). In the sheet that appears, choose from the following options:
   
   
   • For the strictest setting, check Block all incoming connections.
   • Check Automatically allow signed software to receive incoming connections to allow digitally signed applications access to your network without prompting.
   • Click Enable stealth mode to have your computer ignore pings and similar software that attempts to discover your computer.
   • Use the plus and minus buttons to add and remove applications from the firewall. When added, you can either allow or block traffic to them.
   
   Click OK to save your settings.

Mac OS X 10.5

1. From the Apple menu, select System Preferences... . When the System Preferences window appears, from the View menu, select Security.
   
   
2. Click the Firewall tab.
   
   
3. If the orange padlock icon in the lower left side of the window is closed, click it, and then authenticate with your Mac's administrator username and password. This will allow you to make changes.
   
   
4. To configure the firewall, at the top of the window, click one of the radio buttons:
   
   
   • Set access for specific services and applications is the best choice for most users; it will block most incoming connections, but allow you to make exceptions for trusted services and applications.
   • Allow only essential services activates the firewall in its strictest mode.
   • Allow all incoming connections deactivates the firewall.