Re^5: Proving a UDP port is closed

[Anonymous Monk]

Is it possible for a listener to black-hole the port, and soak up messages (possibly acting on them) with no replies or indication that it has happened to the outside world?

Such a case would require checking for listener processes rather than just shouting at the computer and waiting for echoes.

[davis]

Another good point. I suppose I could have "nc -lu 111" or similar running, and that might appear to be the same as "unreachable".

I think this is nudging me down the netstat/lsof route...