My property management company provides free internet access. All the apartments in many buildings are behind some common NAT, so none of us have our own public IP addresses. Thus, services like dyndns.org don't work, at least not that I could figure out. All I want to do is to be able to ssh into a machine on my home LAN (which is behind 2 levels of NAT, one at the ISP which I don't control and one at my router which I do control). I can set up port forwarding and so forth on my router no problem. My suspicion is that some machine on my LAN (machine 1) has to poke out to an external machine (machine 2) with a public IP to establish an SSH tunnel, then I can tunnel from machines elsewhere (machine 3) through machine 2 to machine 1.
My questions are:
- Is my suspicion true, or is there some other approach?
- If I have to tunnel out to some other box, are there public ssh proxies or similar available, or do I need to bug someone with a public IP to let me tunnel through their machine?