How to enable the Firewall in Mac OS X
If you want to beef up the security on your Mac, you can try enabling the built-in firewall.
Enabling the Firewall in Mac OS X 10.6 Snow Leopard
* Open “System Preferences” from the Apple menu
* Click on the ‘Security’ icon
* Click on the ‘Firewall’ tab
* In the corner of this window, you’ll see a lock icon, click on that and enter the administrator password
* Now click on the ‘Start’ button to activate the firewall
Yes, it’s that simple.
If you want to allow certain ports, applications, or network connections, you can enter the ‘Advanced’ tab and adjust the settings as necessary. The Mac OS X firewall is quite secure by default and will block nearly all incoming connections (again, unless specified otherwise). It’s my opinion that if you’re behind a router with it’s own firewall, and on a trusted network, you probably don’t need to use the Mac firewall at all. For small home and school networks you should be fine, but for larger, untrusted, or exposed networks, using the firewall may be a prudent idea, even if the likelihood of an attack on your Mac is extremely low in comparison to a Windows machine.
It’s worth mentioning that since Mac OS X 10.6, the Firewall service has been placed under the “Security” systems preference as opposed to ‘Sharing’ as it was in prior versions of Mac OS X.



If you Option-Click the Airport Menu you can get extended information about the wireless network you are connected to (and the ones you’re not as well), including Channel information, MAC address of the access point, signal strength, and the transmission rate. This is Snow Leopard only, if you haven’t upgraded to Snow Leopard yet and your Mac is compatible, it’s highly recommended.
This works in many versions of Mac OS X
You can get detailed wireless information from the Airport menu by holding down the “Option” key when clicking the menu icon. The ability to pull the Security type and Channel directly out of the menu is a big plus for me, but the other information should certainly be useful when troubleshooting a WiFi problem too.