You can use traditional netstat / lsof command to lists open Internet or UNIX domain sockets on FreeBSD. FreeBSD comes with a simple and easy to use command called sockstat.
The -4 option only displays IPv4 sockets.

The -6 option only displays IPv6 sockets.

The -c option only displays connected sockets.

The -l option only displays listening sockets (open port).

For example, display IPv4 related open ports, enter:
# sockstat -4 -l
Output:

USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN ADDRESS
root     sendmail   653   3  tcp4   127.0.0.1:25          *:*
root     sshd       647   3  tcp4   10.20.110.2:22        *:*
root     ntpd       616   4  udp4   *:123                 *:*

Here the equivalent of netstat:
$ netstat -nat | grep LISTEN
For information read sockstat command man page:
$ man sockstat