Re: Hung Port

Lawrence MacIntyre
2007-01-17T17:39:15Z

If that was the case, would the port not show up in TIME_WAIT state?
Also, the kernel should only hold a closed socket in TIME_WAIT state for
2 minutes or so. These hung ports stay around until the machine is
rebooted.

This one time, at band camp, Jan Engelhardt wrote:
>> Last week I had a port (TCP:52557) that was mysteriously unavailable on
>> my ubuntu machine (running kernel 2.6.15-27-k7 #1 SMP PREEMPT). If you
>> tried to bind to it, it was unavailable. However, nmap (both to
>> localhost and from an external host) reported the port closed. fuser,
>> lsof, and netstat had no record of the port being used.
>
> Did your application forgot to set SO_REUSEADDR?
>
>> Our firewall
>> logs didn't show any unusual traffic to the machine. Nor did they show
>> any traffic at all to/from that port on the machine. After checking
>> everything I could think of, I rebooted it, and there were no ports that
>> were unavailable in this way when it came back up. This morning another
>> hung port has appeared (TCP:43355). My best guess is that this is an
>> ephemeral port that has somehow gotten hung in the kernel somewhere.
>> Has anyone seen anything like this and/or is there anything else I could
>> look at to figure it out?
>
> -`J'

--
Lawrence MacIntyre 865.574.8696 macintyrelp@ornl.gov
Oak Ridge National Laboratory
Cyber Security and Information Infrastructure Research Group

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