It's been surprisingly difficult to set up a remote display between two CentOS boxes, one headless running v.5.9 and the other a new laptop running v.7.2. Since the one machine is headless, it should be obvious which is to display the desktop of the other. The two machines are on the same local network, yet there is iptables running on both of them. But it's not a big deal for me to add rules for them. There's already a solid ssh connection from the laptop to the headless machine. I recently set up remote display of applications from a Raspian (Debian running on a Raspberry Pi) to my Android phone-- that took only about an hour-- and (quite a while ago) an X server displaying apps from another Linux box-- was also trivial to do-- which is why it's been a mystery why using gdm is so difficult. Since I've tried a lot of different settings over the past several days, it would take too long to describe them all. If perhaps someone could describe the steps from the beginning, that would be much simpler and would give others seeking the same on the internet a doc to work from. So does anyone know how this is done?