Brent Kearney

I was a little disappointed to see that Apple removed the GUI for ipfw, the firewall software from FreeBSD that I’ve been using for many years, from the latest version of their operating system, 10.5. Ipfw is still included, but there is no built-in graphical interface for it. They’ve replaced the default firewall with what they call an application firewall, and I’m still not sure exactly what it does. I’ve been unable to locate any technical documentation on it. If you know of any, please let me know!

From what I’ve read, Apple’s application firewall is similar to Little Snitch, except that it involves digital signatures built into software packages, and it doesn’t give you any feedback as to what your applications are doing on the network. Apple’s application firewall gives software developers the ability to add a digital signature to their software that automatically grants permission for their applications to open ports on your computer’s firewall. Apple also explicitly states that their application firewall does not prevent outgoing traffic, so it can’t prevent software from “calling home”. They say that "you might be able to block" outgoing traffic for an application — not exactly reassuring.

If you want real control over what applications are allowed to access the network, and you want to be informed about what your computer is doing, get Little Snitch. Or, if you want a free but less sophisticated way to control who can access your computer over the network, and how, you should configure the other firewall that comes with Leopard.