Do you want to make your Mac more secure? Here’s a fast and easy way to secure your Mac against unwanted and unauthorized intrusions — there’s nothing to install — you’ve got a Mac, so it just works.

Mac OS X’s Firewall is part of the default operating system install and it’s super easy to turn and use. In fact, using it is almost 100 percent transparent to the user — you might get the occasional notification to allow a specific app, such as iTunes for internet radio, wants to accept incoming connections.

Here’s what you need to do:
1. Choose System Preferences from the Apple menu
2. Click Security
3. Click the Firewall tab
4. Unlock the pane by clicking the lock in the lower-left corner — enter your username and password
5. Click Start to enable the firewall

Now, if you need to give specific applications access to your Mac, click Advanced to customize the firewall configuration. The low hanging fruit here is activating Stealth Mode, which can help prevent bots and hackers from using Ping and other network services, discovering your Mac and how it’s configured.

Just because you should and it’s one of the steps on the Fairer Platform’s Top 10 free ways to secure your Mac.

via Mac OS X v10.5, 10.6: About the Application Firewall