I need a remote assistance tool (i.e. tool that makes it possible to control another persons screen) that:
- works between two machines that are both NAT'ed behind different NAT-walls
- does not require modification of NAT-wall (i.e. port forwarding is no-go)
- works as both client and server on both Windows 7+XP and GNU/Linux
- is free (as in freedom - not price) software
It should preferably survive if any of the machines change its internal IP address (e.g. as part of a DHCP change).
TeamViewer delivers 1, 2, and 3, but fails 4 because of its license.
Google Chrome Remote Desktop delivers 1, 2, and 3, but fails 4 because of its license.
The different VNC tools deliver 3 and 4, but fails for either 1 or 2.