How did that signal get past your firewall? Well, to put it simply, the firewall 'knows' that you asked for the information in the first place. For example, let's say you use your browser to navigate to Your computer sends out a signal to MacFixIt's server, saying, 'I'd like to see your front page, please.' And MacFixIt's server obligingly sends a signal to your computer, providing the data for the MacFixIt front page that you see in your browser.

On the other hand, the whole idea of a firewall is that it assumes that network traffic from inside your computer is good. (A good recent discussion is this TidBITS article.) The firewall prevents this sort of intrusion from the outside. The idea is that if your computer is connected to the Internet, then other computers elsewhere on the Internet can potentially see your computer and can do things to it. And you probably know that this has something to do with security. What does it do? Well, you probably know that Mac OS X comes with a software firewall, and if you're using a router as part of the network that connects you to the Internet, you're probably also behind a hardware firewall.

Little Snitch is an absolutely essential utility that we here at MacFixIt wouldn't be without. Objective Development has released version 2 of its Little Snitch utility.

What is little snitch software