in reply to Re^3: Proving a UDP port is closed
in thread Proving a UDP port is closed

Sorry, I realised the stupidity of what I'd said (the implied magic) fairly quickly! Yeah, grokking the "netstat -af inet" output would almost certainly work for me for both TCP and UDP listeners, but there's still something somehow... cleaner about the attempted connection method, at least in my head.


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Re^5: Proving a UDP port is closed
by Anonymous Monk on Feb 01, 2011 at 15:29 UTC

    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.

      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...