[yz@localhost ~]$ lsof -i 4
COMMAND    PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
node     10444   yz   27u  IPv4 1356954      0t0  TCP localhost:45393->localhost:36542 (ESTABLISHED)
postgres 17442   yz    6u  IPv4  824829      0t0  TCP localhost:7404 (LISTEN)
node     24258   yz   18u  IPv4  848159      0t0  TCP localhost:45393 (LISTEN)
node     24258   yz   21u  IPv4 1353624      0t0  TCP localhost:45393->localhost:36540 (ESTABLISHED)
node     24258   yz   23u  IPv4 1353553      0t0  TCP localhost:45393->localhost:36532 (ESTABLISHED)
node     24352   yz   23u  IPv4 1353556      0t0  TCP localhost:45393->localhost:36534 (ESTABLISHED)