Click the Firewall link near the left hand side of the page.
Click the Expert link near the top of the page.
We will list a series of lines here that will show you exactly how to setup Zone Alarm's firewall for Battlefield 2. Go ahead and enter the settings shown below into the Add Rule menu.
You should see another page of settings below that need to be added to Zone Alarm. Open up a new Add Protocol page and enter those settings.
When you are finished, click the Apply button at the bottom of your screen. And that is it! You are done!