We will show you how to use fuser to find out which process is running a given port.
E.g. if we want to find out which process is running on the UDP port 829 on current system, we can run,
$ sudo fuser 829/udp 829/udp: 15070 $ ps -ef | grep 15070 root 15070 1 0 Jan28 ? 00:00:25 /sbin/rpcbind -w