Last updated on November 24, 2020 by Dan Nanni
You can detect which process is bound to what port number by using
lsof command. Simply specify the port number you are interested in with
For example, to find out which processes are opening a port number
631, run the following command.
$ sudo lsof -i:631 -n -P
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME cupsd 776 root 10u IPv6 9353 0t0 TCP [::1]:631 (LISTEN) cupsd 776 root 11u IPv4 9354 0t0 TCP 127.0.0.1:631 (LISTEN) cups-brow 953 root 8u IPv4 9930 0t0 UDP *:631
In the above,
-n option prevents automatic conversion of host IP address to host name, and
-P option prohibits conversion of port number to port name. In this example,
cups-brow processes are using TCP and UDP port number
To see a list of all open TCP ports, along with their associated programs/processes, you can run the command below.
$ sudo lsof -i -n -P | grep TCP