Once the ipfw0 interface has been created, ifconfig(8) create will throw a warning: "ifconfig: create: bad value" when trying to create it again. PR: 241013 Submitted by: Jose Luis Duran Approved by: kp Differential Revision: https://reviews.freebsd.org/D30083 (cherry picked from commit 5c4fe2ac81a5e05062266d684fb53b9faefd0d38)