I've moved our server box into the DMZ and now my ssh tunnels doesn't work anymore. When it was on the same subnet, all was fine. The scenario now:
box private ip -> 172.111.111.x
gateway ip ->172.111.111.1
box public ip -> 196.111.111.y
The firewall is set up to allow acces from the internal network to the DMZ only on port 22. I've set up a few tunnels but the following one is the most important:: L 8080 -> localhost:8080. As i said, it was working fine before, but alas, no more tunnels. I can putty in (to 172.111.111.x), no problem.

Any hints please??

Jack

Can you explain a little more about the tunnel? Are you tunneling from the internal machine to the DMZ machine? If you are tunneling the other way around, I would say your firewall is blocking it. Are you able to get firewall logs? how about ssh and sshd logs?