Sockstat command

On FreeBSD, we can employ sockstat command to list both open Internet and UNIXdomain sockets:

# sockstat
USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN ADDRESS
root     sshd       45768 3  tcp4   192.168.80.129:22     192.168.80.1:60803
root     sshd       22144 3  tcp4   192.168.80.129:22     192.168.80.1:54834
root     sshd       19097 3  tcp4   192.168.80.129:22     192.168.80.1:58174
smmsp    sendmail   662   3  dgram  -> /var/run/log
root     sendmail   659   3  tcp4   127.0.0.1:25          *:*
root     sendmail   659   4  dgram  -> /var/run/logpriv
root     sshd       656   3  tcp6   *:22                  *:*
root     sshd       656   4  tcp4   *:22                  *:*
......

We can see the output of sockstat lists which process owns the socket, the file descriptor number of the socket, etc. So it is a really awesome tool to diagnose network related issues.

Reference:
SOCKSTAT(1).