After port forwarded in the router, does it mean that the port is opened even I didn't use it? From my current situation, the port is closed while I am not using it. But what can trigger the port to be open?
Shutdown my port forwarded PC will turn off the port too?
My actual problem now: I port forwarded a port, and the port is closed when I did not open any application that uses the port. I want to know why.