[OpenWrt-Devel] sysupgrade + reverse SSH tunnel broken

Bastian Bittorf bittorf at bluebottle.com
Thu Dec 17 04:17:34 EST 2015

when starting sysupgrade on a router with
an interactive reverse SSH session provided
via dropbear/dbclient, the "dbclient" gets
killed during early run of the script, keeping
the box unreachable. maybe this is the same
user other tunnels too.

there are 3 possible ways i can imagine:

warn the user when such a tunnel is detected

keep the tunnel-proider in a whitelist, so
they dont get killed during sysupgrade

nohup the script more early (and keep the process
running when the connection is lost)

internally we are using this for such things:

	# close stdin, and make any read attempt an error
	[ -t 0 ] && exec 0>/dev/null

	# redirect stdout to a file if it's a TTY
	[ -t 1 ] && {
		exec 1>nohup.out || exec 1>nohup.out

	# redirect stderr to stdout if it's a TTY
	[ -t 2 ] && exec 2>&1

	# trap the HUP signal to ignore it
	trap : HUP

# detach script from shell

...further commands

has somebody and idea what is the "best"?

bye, bastian
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