how to check whether the ssh tunnel is up

[Vincent Lin]

Hi damien,

Thanks for your reply. ExitOnForwardFailure=yes will exit the process if
SSH tunnel failed to create. But what if it's OK?  Is there a way to know
when it will be OK? I mean maybe it will cost some time, and when the
tunnel is up, I can know it, or I can get the status all the time on the
SSH client side, if it's possible. And what's the difference with or
without -f, since I already create a  SSH daemon. Do I have to fork another
process again?

Best Regard
Vincent