How to know what listener is running on a port?

Article Title: How to know what listener is running on a port. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
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.