[yz@localhost ~]$ lsof -i 6
COMMAND    PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
postgres 17442   yz    5u  IPv6 824828      0t0  TCP localhost:7404 (LISTEN)
postgres 17442   yz    8u  IPv6 824834      0t0  UDP localhost:37288->localhost:37288
postgres 17444   yz    8u  IPv6 824834      0t0  UDP localhost:37288->localhost:37288
postgres 17445   yz    8u  IPv6 824834      0t0  UDP localhost:37288->localhost:37288