Make dhclient set interface MTU if it was provided.
This version implements MTU setting in dhclient itself before it runs
dhclient-script.
PR: 206721
Submitted by: novel@
Reported by: Jarrod Petz <jlpetz at gmail.com>
Reviewed by: cem, allanjude
Differential Revision: https://reviews.freebsd.org/D5675
Currently it was allowed to send any UDP packets from unprivileged process and
possibly any packets because /dev/bpf was open for writing.
Move sending packets to privileged process. Unprivileged process has no longer
access to not connected UDP socket and has only access to /dev/bpf in read-only
mode.
Reviewed by: brooks
Sponsored by: The FreeBSD Foundation
