sudo netstat -anp | grep 631
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      4876/cupsd
tcp6       0      0 ::1:631                 :::*                    LISTEN      4876/cupsd
tcp6       1      0 ::1:35936               ::1:631                 CLOSE_WAIT  1449/cups-browsed
udp        0      0 0.0.0.0:631             0.0.0.0:*                           1449/cups-browsed