frauxm,
Goto to Shields UP website https://grc.com/x/ne.dll?bh0bkyd2 to test your firewall at full Stealth, when you are at the Shields UP website click on Proceed then click on Common Ports.
What Sheilds UP do is to test all your port numbers to make sure your firewall is working, all you have to see and to make sure all your port numbers is reading STEALTH it mean you have pass the test mean your firewall is working.
If any of your port numbers are not reading stealth mean your port number is open, someone can get inside your computer without your permission unless you fix the port number to Stealth.
Do you understand?