We're going to deploy info screens in various places. They have a browser running and pull the info via HTTP. To reconfigure them, it would be useful if they connected to a central host from where we could open SSH or VNC sessions. They are not reachable from outside and we wouldn't know their address anyway. And before you ask, yes we have permission to place the screens and this botnet is totally legit.
I found autossh
which addresses the main problem of getting the machines connected. Ideally though I would prefer a tool where the machines do not need login authorization on the central host. It would also be nice to have a list of running screens too.