I read about Shields Up! last year in a magazine article and tried it. I was disappointed to find that I had several shields not functioning properly. When I probed my Ports, I had one of the most important ports OPEN! I downloaded Zone Alarm (see my review of ZoneAlarm for more information) and it closed my ports to stealth mode! I would never had known that people could sneak into my computer without Shields Up. I have a cable modem and my computers are networked to it. One day I noticed that two other people were accessing my files even though I had a password on it. When I downloaded Zone Alarm, they were no longer there. It was because my NetBios Port was open, which I found out from Probe My Ports (a division of Shields Up!). I am very grateful for Shields Up! It is a free service that tests you computer to see if it is just asking hackers to hack.
You can run it at http://www.grc.com

Recommended: Yes