Today I ran into a problem where I wanted to find out what Linux process (PID) was listening on which port. You might
A fellow sysadmin coworker showed me this command:
lsof -i :port
Lsof will list the PID and the owner of the process that is listening or interacting on that port!
lsof -i :22
sshd 1997 root 3u IPv6 5602 TCP *:ssh (LISTEN) sshd 2458 root 3u IPv6 7721 TCP centos-at01.canada003.com:ssh->10.20.0.12:55858 (ESTABLISHED)
Sweet!
Alternatively you can also do this:
netstat -nap |grep port|grep -i LISTEN
Which will list the ports that the server is listening on as well as the associated PID. Below is a sample output of the httpd process that is listening on port 80 with PID 591
tcp 0 0 :::80 :::* LISTEN 591/httpd
For a complete list of PIDs that a port is listening on you may want to use the fuser command. Below is an example for the port 80 httpd process.
fuser -v 80/tcp
USER PID ACCESS COMMAND
80/tcp: apache 591 F.... httpd
apache 8979 F.... httpd
apache 15452 F.... httpd
apache 15453 F.... httpd
apache 15454 F.... httpd
apache 15455 F.... httpd
apache 15456 F.... httpd
apache 15457 F.... httpd
apache 15458 F.... httpd
apache 15459 F.... httpd
apache 15514 F.... httpd
apache 15559 F.... httpd
apache 15654 F.... httpd
apache 15752 F.... httpd
apache 15783 F.... httpd
apache 16506 F.... httpd
apache 17572 F.... httpd
apache 21656 F.... httpd
root 23934 F.... httpd
apache 23963 F.... httpd
apache 32508 F.... httpd
