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Alex G
Asked: 2012-09-06 16:00:34 +0800 CST

How to determine which TCP/UDP ports are being opened by a given process (linux)?

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I know how to do the opposite (find out what process has a given port open) using lsof or netstat, but extensive research on Google hasn't helped me solve the reverse problem.

I know I could use "netstat -np" combined with some grep and sed, but it seems hacky. Is there a reversed version of "lsof -i tcp:80" that will show me all the local ports opened by a given process?

tcp

2 Answers

  1. Best Answer

    Take a look at the man page, you'll find that you can use the -p option to specify a process id, and the -i option to limit the display to internet domain sockets (-i4 for just ipv4 and -i6 for just ipv6). So if you string them together...

    lsof -p <pid> -i

    ...you get not quite what you want, because by default lsof will or together your requests. So add the -a (and) flag...

    lsof -p <pid> -a -i

    ...and you'll get a list of the IPv4 sockets open by the specified process id.

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  2. I know I could use netstat -np combined with some grep and sed, but it seems hacky.

    How about this:

    # netstat --inet -nlp | grep <processname>

    Is there a reversed version of lsof -i tcp:80 that will show me all the local ports opened by a given process?

    # lsof -c <processname> | grep LISTEN
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