netstat -lnp
The meaning of this command is listed inside the system listening port number of the network connection and the corresponding process PID.
Parameters:
-t: flag to list the TCP connection (you can also add -u parameter indicates also lists the UDP network connections)
the -l: indicates that the service is listed network monitoring
key parameters are the following two:
-n: expressed as port number to show
-p: PID represents the process list
reference: