Bug in ARP requests

[Andre Oppermann]

Hello,

There is a nasty bug in the ARP request code in 4.8-STABLE regarding
the target hardware address field which is left unset.

tmm fixed this in rev 1.97 in -CURRENT 3 month ago but forgot to MFC
it back to -STABLE since (despite his MFC in two weeks comment).

I got hit by this pretty hard when I connected a FreeBSD/Zebra box
to AMSIX. Appearently the Cisco and Juniper boxes don't answer to
broken ARP requests if the target hardware address field is not set
to NULL but filled with random memory junk. While debugging this we
got really confused by the tcpdumps... Ethereal saved the day because
it has a much nicer display than tcpdump.

Anyway, please MFC to fix -STABLE.

-- 
Andre