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I'm trying to establish the following chained ssh tunnel:

ssh -A -t gatewayuser@gatewayserver 'ssh -N -A -t -R 55520:127.0.0.1:55520 user@dbserver' &

This is part of a shell script, I want the tunnel to be established in the background so the shell script can continue what it is doing. The shell script also uses:

trap 'kill $(jobs -p)' EXIT

To kill all child procs on exit.

When the above ssh runs, a process is established but it seems the chained reverse tunnel is immediately dropped (i.e. there is nothing listening to 55520 on the dbserver). How can I do this within the requirements above?

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ssh seems to detect missing user input due to being started in the background and then suspends itself, the -t does not help.

You can have it read from stdin instead, e.g. via ssh [...] < /dev/null & or possibly /dev/zero.

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  • Do you mean on the chained ssh or the outer one, can you give an example? Sorry if its a dumb question i'm fairly new to all this. – James Apr 14 '14 at 15:10
  • The outer ssh call, ssh [..] 'ssh -R [..]' < /dev/null & – finite graygreen Apr 14 '14 at 16:05

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