ipmon(8) on FreeBSD
The text 88d108b13bc4, as FreeBSD 12.1-RELEASE shipped it.
monitors /dev/ipl for logged packets
Flags it lists
-
-B -
-C -
-D -
-F -
-L -
-N -
-O -
-P -
-S -
-X -
-a -
-b -
-f -
-n -
-o -
-p -
-s -
-t -
-v -
-x