I suppose this is useful if you have two systems both behind NAT... I've run into many situations where I'm remote and need to SSH into a NATed machine to fix

I suppose this is useful if you have two systems both behind NAT... I've run into many situations where I'm remote and need to SSH into a NATed machine to fix something, and I typically will SSH reverse tunnel to a VPS. From the NATed machine: ssh -fN -R52222:localhost:22 user@publichost And then from the public machine: ssh user@localhost -p 52222