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modified post 506718daeb by Anonymous on Thu 14th Apr 2022 14:05
original post b462550ed3 by Anonymous on Thu 14th Apr 2022 13:48
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#!/usr/bin/ksh93

1	1		#!/usr/bin/ksh93
2	2
3	3		#
4	4		# Ethernet/tap forwarding via ssh
5	5		#
6	6
7	7		set -o xtrace
8	8		set -o errexit
9	9		set -o nounset
10	10
11	11		# list of commands our ssh session should execute
12	12		typeset -a sshcmds=(
13	13		#
14	14		# cleanup:
15	15		#
16	16		# we need to clean up the bridge interface ourselves, if
17	17		# we do not do that we risk getting that any subsequent
18	18		# ifconfig/ip/etc command hangs
19	19		#
20	20		'(( trap_once=0 )) ;'
21	21		"netcleanup() { "
22	22		'(( trap_once++ > 0 )) && return 0 ;'
23	23		"set +o errexit ;"
24	24		"brctl delif br19 tap19 ;"
25	25		"brctl delif br19 eno1 ;"
26	26		"ifconfig tap19 down ;"
27	27		"ifconfig br19 down ;"
28	28		"brctl delbr br19 ;"
29	29		"exit 0 ;"
30	30		"} ;"
31	31		'trap netcleanup EXIT ;'
32	32		'trap netcleanup HUP ;'
33	33
34	34		"set -o xtrace ;"
35	35		"set -o errexit ;"
36	36		"brctl addbr br19 ;"
37	37		"brctl addif br19 tap19 ;"
38	38		"brctl addif br19 eno1 ;"
39	39		"brctl show ;"
40	40		"ifconfig tap19 promisc ;"
41	41		"ifconfig tap19 up ;"
42	42		"ifconfig br19 up ;"
43	43
44	44		"read dummy ;" # wait
45	45
46		-	# this is nasty:
	46	+	# this is tricky (and nasty):
47		-	# we have to tell sshd to quit, and then busy-wait
	47	+	# we have to tell our session sshd instance to quit, and then
48		-	# until we get SIGHUP so our HUP trap handler
	48	+	# busy-wait until we get SIGHUP from gthat sshd process back
49		-	# function gets called
	49	+	# so our HUP trap handler function gets called
50	50		'kill -s INT ${PPID} ;'
51		-	'while true ; do sleep 1 ; done ;'
	51	+	'while true ; do sleep 0.1 ; done ;'
52	52		)
53	53
54	54		ssh \
55	55		-o ExitOnForwardFailure=yes \
56	56		-o PermitLocalCommand=yes \
57	57		-o LocalCommand="ifconfig tap19 up" \
58	58		-o Tunnel=ethernet -w 19:19 \
59	59		root@10.49.20.202 \
60	60		"${sshcmds[*]}"
61	61
62	62		# cleanup
63	63		# ...
64	64
65	65		# EOF.
66	66