ipfw(8) on FreeBSD
The text 588cff1589c2, as FreeBSD 11.4-RELEASE shipped it.
User interface for firewall, traffic shaper, packet scheduler, in-kernel NAT.
Flags it lists
-
-D -
-N -
-S -
-T -
-a -
-b -
-c -
-d -
-f -
-i -
-n -
-q -
-s -
-t