I trying to run x11vnc to connect to running Xclient. There no one is
logged into Xsession on server, I just what to x11vnc show me login screen
into X session. Is this possible?
Maybe there is other VNC server which i should try to start?

The error which I get is:
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified

XOpenDisplay failed (:0)

Pawel Rutkowski