I have both a VPS and a server behind a NAT firewall. I want to use the server behind a NAT firewall as a backup for the VPS. The VPS needs to be able to initiate the backup process and send the backups over the internet, past the router doing NAT and to the backup machine. I do not have control over the router, so my backup machine has no public IP address.
Is there a way for me to open a SSH tunnel (or equivalent) from the backup machine to the server such that the server can copy files across this connection?
Topology like so:
________ _______________ ________ | server | -- ( internet ) -- | router w/ NAT | -- | backup | -------- --------------- --------