I have forwarded ports 80, 443, and 4125 to my home server, and want to test if my ISP (or my modem) is blocking any ports. When I ran ShieldsUp!, I expected to find ports 80, 443 and 4125 open (if they were not blocked, as stated by my ISP), but ShieldsUp! said they were all in "stealth mode".
I don't understand this. Could someone please explain? How can I confirm whether or not these ports are, in fact, open, or blocked?
Thanks