I have a server running SSH which is Internet facing (lets call this host A).
I also have a server running which is behind a firewall. It is running sshd, however it cannot SSH out to the Internet, including to host A. Let's call this host 'gibson'.
I have my own box (localhost, host B) which is on a different subnet to host B, however it can SSH to the gibson. The gibson cannot ssh to host B though.
I want to allow people to temporarily ssh to the gibson. Is it possible to make a tunnel through from the gibson to host B, which then terminates through to host A to allow remote access to the gibson for a short amount of time via the Internet?