I have a desktop running Linux Mint 18.3 and am learning how to use rsync for backing up. I have it working, mirroring data directories on my hard drive to another drive in a knockabout machine on my LAN. My next step is to get it to backup using SSH over the internet to a dedicated hard drive connected to a dedicated Raspberry Pi wired to a friend's router. I am trying to work out how to handle the IP address resolution as my friend (hosting the server) does not have a fixed IP, whereas I (hosting the client) DO have a fixed IP address from my ISP. It seems to me that a nifty way to avoid DNS issues is for the remote server to establish the SSH connection to my desktop which my client then uses for rsync. Is this feasible? Am I right to view the SSH connection as an armoured bi-directional pipe which can be used in this way, obviously dropping the ssh option from the rsync command? Are there issues or pitfalls I cannot spot in my inexperience?