how to check whether the ssh tunnel is up

[Damien Miller]

On Fri, 26 Apr 2013, Vincent Lin wrote:

> Hi all,
> 
> I use the command below to set up a ssh tunnel. And I run it as a daemon
> process to keep the ssh tunnel work all the time. And I should wait for the
> ssh tunnel to be up and notify the tunnel is OK before sending any command
> to the remote port on the remote server. But the question is I don't know
> how to check the ssh tunnel status. Is there a way to show whether the ssh
> tunnel is up?  Thank you for your help.
> 
> *"ssh -i /root/ah_rsa -oUserKnownHostsFile=/root/hosts
> -oStrictHostKeyChecking=yes -oNumberOfPasswordPrompts=0 -oBatchMode=yes
> -oHostKeyAlgorithms=ssh-rsa -R 20001:localhost:22 user at xxx.xxx.xxx.xxx -p
> 13422 -Nyv"*

ExitOnForwardFailure=yes should provide the checking you need. If you use
it with -f then the fork is delayed until the forwarding is answered by
the server, though note that this doesn't include an end-to-end test that
involves the forward target - that is till up to you to check if you need it.

-d