Port 50000 not listening still the system thinks it is in use

devUnix · 10-17-2013, 07:42 AM

Please consider the following output:

Code:

[root@ny ~]# nc -v -l 192.168.1.5 50000
nc: Address already in use


# netstat -an | grep 50000
<No output>

I have restarted nscd and /etc/init.d/dnsmasq services on this system.

The client is reporting that they have an application which tries to listen on this port: 50000 on the server mentioned but it is not working.

How do I resolve the above problem?

kbp · 10-17-2013, 08:58 AM

Port 50000 is high up in the ephemeral range so I wouldn't expect it to be used for a client connection unless the ephemeral range had been fiddled with or the host is extremely busy, would you please provide output from the following:

Code:

netstat -tunlp
netstat -an

zhjim · 10-17-2013, 09:26 AM

Depending on how fast you try to open a new socket an the same port it might still be seen as occupied by the kernel. Also I doubt that nc is that badly programmed but maybe a nother program used the port before. Not sure but i think the so_lingering socket options goes with this.

devUnix · 10-18-2013, 04:05 AM

Quote:

Originally Posted by kbp

Port 50000 is high up in the ephemeral range so I wouldn't expect it to be used for a client connection unless the ephemeral range had been fiddled with or the host is extremely busy, would you please provide output from the following:

Code:

netstat -tunlp
netstat -an

The output of those commands does not contain the port number 50000. I can't comment on the "ephemeral range" part in your feedback.

This ticket has been assigned to me and I have got to resolve it.

devUnix · 10-18-2013, 04:08 AM

Can a system restart resolve the issue?

anon237 · 10-18-2013, 05:00 AM

Not sure if the following will show more then netstat, but it cannot hurt to try:

Code:

lsof -i :50000

Quote:

Can a system restart resolve the issue?

Maybe, but if something is listening on port 50000 and is started at boot you'll end up with the same situation. Another thing that might be frustrating: If it does work after a reboot, what was "wrong" in the first place....

devUnix · 10-21-2013, 03:02 AM

Code:

lsof -i :50000

Does not show anything. I have got approval from the Dev Team for the reboot of the system. It would be bad on my part if that does not resolve the issue because they would put up questions... blah... blah!