A simple and easy way to test the effectiveness of your firewall is to do a port scan on it. This is what attackers would do on your system to see if there is a way in. A great (and free) online tool to do this is called “Shields Up!” and is available at GRC’s website here: www.grc.com.

You will find the Shields Up option about halfway down the page. Give your firewall a scan and make sure you are as secure as you think you are.