I've been using VNC over SSH for a while so that I can be a friend's
help desk - set his cable modem router to forward 22 and away we go.

I'd like to be able to do the same to connect to my home machine while
traveling, but it's behind two (NAT) cable modem routers, with 22
going to a machine behind the first router, and my personal computer
behind another router which is downstream of the first router.

Here's an ASCII masterpiece - hope you're monospaced:

WAN -> NAT1 -> Public_Server
            |
            -> NAT2 -> Home_1
                    |
                    -> Home_2

NAT2 is not sending any RIP info upstream, FWIW.

If I set the second router (NAT2) to forward 22 to Home_1, I could
then SSH to Public_Server, and from there, SSH to NAT2 which would
forward to Home_1. (I specifically do not want to forward all 22
traffic from the net straight thru to the internal private network.)

I'm stumped as to how to do a 'VNC two-step' to get to Home_1 from the
outside using this setup. Any help appreciated.

Thanks in advance,

Max