Most online port checks assume that you already have an application (such as your game or torrent) listening for the port test on your computer, and then assume that the test was OK simply because they were able to connect to your computer.
Also, web only port checkers are not able to test UDP since UDP is a connectionless protocol and there is no way to know if the packet actually made it to your computer without some sort of program on your computer waiting for that packet.
Our port test uses a local application to listen for the server trying to connect and then positively verifies that your port is forwarded.
After downloading PFPortChecker, you run the installation file to install it on your computer.
Then you run PFPortCheck (located in the Start menu under portforward.com) and type in the port you want to check, and whether you want to check TCP or UDP, and click Check Me.
If it says Your port is OPEN then we are absolutely sure that your port is definitely open. No other port checker can claim that.
If it says Your port is NOT OPEN or not reachable! then we were unable to establish a connection to your computer, which means that most likely either your port is not open or your software firewall is still preventing an inbound connection from being made.
For additional instructions click here.