in reply to Re^4: Proving a UDP port is closed
in thread Proving a UDP port is closed

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.

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Re^6: Proving a UDP port is closed
by davis (Vicar) on Feb 01, 2011 at 15:52 UTC

    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...

    davis