#!/usr/bin/ksh93

#

# Ethernet/tap forwarding via ssh

#

set -o xtrace

set -o errexit

set -o nounset

# list of commands our ssh session should execute

typeset -a sshcmds=(

	#

	# cleanup:

	#

	# we need to clean up the bridge interface ourselves, if

	# we do not do that we risk getting that any subsequent

	# ifconfig/ip/etc command hangs

	#

	'(( trap_once=0 )) ;'

	"netcleanup() { "

		"set +o errexit ;"

		'(( trap_once++ > 0 )) && return 0 ;'

		"brctl delif br19 tap19 ;"

		"brctl delif br19 eno1 ;"

		"ifconfig tap19 down ;"

		"ifconfig br19 down ;"

		"brctl delbr br19 ;"

		"exit 0 ;"

	"} ;"

	'trap netcleanup EXIT ;'

	'trap netcleanup HUP ;'

	"set -o xtrace ;"

	"set -o errexit ;"

	"brctl addbr br19 ;"

	"brctl addif br19 tap19 ;"

	"brctl addif br19 eno1 ;"

	"brctl show ;"

	"ifconfig tap19 promisc ;"

	"ifconfig tap19 up ;"

	"ifconfig br19 up ;"

	"read dummy ;" # wait

	# this is tricky (and nasty):

	# we have to tell our session sshd instance to quit, and then

	# busy-wait until we get SIGHUP from gthat sshd process back

	# so our HUP trap handler function gets called

	'kill -s INT ${PPID} ;'

	'while true ; do sleep 0.1 ; done ;'

)

ssh \

	-o ExitOnForwardFailure=yes \

	-o PermitLocalCommand=yes \

	-o LocalCommand="ifconfig tap19 up" \

	-o Tunnel=ethernet -w 19:19 \

	root@10.49.20.202 \

	"${sshcmds[*]}"

# cleanup

# ...

# EOF.