In Linux, how does one know what a port is running?

When we use netstat-an, we sometimes see similar output:

Udp 0 0 0.0.0.0: 32768 0.0.0.0 :*

However, what should I do if I find that/etc/services does not have this port? Is this a hacker program? Is there a way to check which program listens on this port?

Use lsof-I: 32768 to see:

COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME

Rpc. statd 603 root 4u IPv4 953 UDP *: 32768

Rpc. statd 603 root 6u IPv4 956 TCP *: 32768 (LISTEN)

It was originally an rpc program.

Use lsof-I: port to view the program running on the specified port and the current connection.