Finding out if a port is closed
I need to open a few ports for our new IT security software. Ports 17472, 17486, 636.
But my question is, how do I know if I even need to open these ports on WatchGuard?
I understand If I can't login to a website on a specific port, I can assume that port is blocked, but is there like a list of closed and open ports that I can look at?