Have you ever wanted to SSH to an host that sits behind a firewall doing NAT ?
That possible with some trickery via a reverse SSH tunnel.
First, let say to our nated-host’s administrator to SSH our public-host relay server like this:
ssh -R 2222:localhost:22 user@<public-host>
This command open the port
2222 on the public-host and redirect it to the nated-host port
Then we simply connect to the public-host as usual :
and then access to the SSH tunnel:
ssh localhost -p 2222