I'd like to setup x11vnc (or any other vnc server) to start at boot-time. The display manager is kdm, the distribution is Ubuntu 12.04.2 LTS.
When I try to start x11vnc, I'm getting this errors:
$ x11vnc -rfbauth /var/run/xauth/A:0-crWk72  -rfbport 5901
 passing arg to libvncserver: -rfbauth
 passing arg to libvncserver: /var/run/xauth/A:0-crWk72
 passing arg to libvncserver: -rfbport
 passing arg to libvncserver: 5901
 x11vnc version: 0.9.12 lastmod: 2010-09-09  pid: 2828
 XOpenDisplay("") failed.
 Trying again with XAUTHLOCALHOSTNAME=localhost ...
 *** XOpenDisplay failed. No -display or DISPLAY.
 *** Trying ":0" in 4 seconds.  Press Ctrl-C to abort.
 *** 1 2 3 4 
 XOpenDisplay(":0") failed.
 Trying again with XAUTHLOCALHOSTNAME=localhost ...
 XOpenDisplay(":0") failed.
 Trying again with unset XAUTHLOCALHOSTNAME ...
I've tried installing xserver-xorg-video-dummy in order to avoid issues with no screen attached, but so far with no success.