~# nc -v -l 127.0.0.1 900
listening on 0.0.0.0:36915 ...
^C

~# nc -v -l 127.0.0.1 -p 900
listening on 0.0.0.0:900 ...
^C

~# ss -tlnp | grep nc
LISTEN     0      1            *:43395   *:*      (("nc",pid=2210,fd=3))