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

In Linux, how does one know what program a port is running? When we use netstat-an, we sometimes see similar output: www.2cto.com udp 0 0 0.0.0.0: 32768 0.0.0.0: * What should I do if I find that/etc/services does not have the port description? 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) is originally an rpc program. Use lsof-I: port at www.2cto.com to view the program running on the specified port and the current connection.