I configured Real VNC server on Red Hat Enterprise Linux 7.2 with a monitor plugged in, now with the monitor unplugged I cannot connect using vnc client, I get "connection refused". Does VNC need a monitor physically plugged into the server? Is there a way to configure Xorg to allow VNC connection with no monitor plugged directly into the server?
The latest version of Xorg, and by extension Xvnc have -nolisten as a default option.
When I need a graphical display on a headless node I have an init script (RHEL 6, old I know) with the following command:
exec /usr/bin/Xvnc -geometry 1024x768 -listen tcp +iglx -AlwaysShared -DisconnectClients=0 -SecurityTypes=None :<displaynum>
Note, this starts another X display.
I use start xvnc-headless when I need to start it, stop xvnc-headless when I'm done.
You can also use -rfbport to change the port, and may also wish to setup and define SecurityTypes to something other than none.