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I have a server running on a local server. Every once in a while it will freeze up, and I'll need to use a Ctrl+Z to cancel out of it. The issue is that the port it uses is still open to it after I force close it, and it can't reclaim that port when I restart the program. So then I need to restart the entire server.

Is there a way I could force that port closed, so the service could open it when it starts back up, or maybe refresh all the ports?


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Did you write this program? This is a program bug, most likely failing to set SO_REUSEPORT. – David Schwartz Oct 15 '11 at 3:06
up vote 1 down vote accepted

ctrl-z is a suspend.

You probably want ctrl-c.

You can also send a signal to the individual PID. For example, if I wanted to close port 80, I could first query open files with lsof:

lsof -i tcp:80

httpd 24579 root 3u IPv6 142712111 TCP *:http (LISTEN)

Then send a kill signal:

kill -9   24579 
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That's what I was looking for, thanks! – Ben Oct 15 '11 at 3:13

Ctrl+Z is only suspend your job, place it in the backgroud, so the port is still open. Just use Ctrl+C instead.

In your case, find out the process which is listening on this port with:

# netstat --protocol=ip -nlp | grep :port

and kill the PID. No need to reboot the server.

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