Quick and dirty Ubuntu x11vnc configuration

ubuntu-x11vnc.md

Ubuntu x11vnc setup with start upon interactive user login to the without-monitor box.

Quick intro

After much time wasted with struggling to get VNC working on Ubuntu that stands for without monitor box - I've compiled the below draft notes on how I finally managed to configure the damn VNC. This should be stated, that I've come a long journey from systemd/init.d configuration scripts, through various VNC daemons (tightvnc, tigervnc, xvnc) and experienced lot of issues (VNC starting before X, VNC not having Xauthority, VNC not being able to open display :0, and so on) .

Finally, this below setup got me working with VNC.

Setup

Initial installation and VNC password creation:

$ sudo apt-get install x11vnc
$ sudo x11vnc -storepasswd "vnc-password" /etc/x11vnc.pass
$ sudo chmod a+r /etc/x11vnc.pass

The last command may be arguably very unsafe but it's necessary for launching x11vnc as an ordinary user in rfbauth access mode.

First of all, we have to install xorg dummy video driver like so: sudo apt-get install xserver-xorg-video-dummy

Then inside of /usr/share/X11/xorg.conf.d/ one has to create a file named xorg.conf with the following contents:

Section "Device"
    Identifier  "Configured Video Device"
    Driver      "dummy"
EndSection

Section "Monitor"
    Identifier  "Configured Monitor"
    HorizSync 31.5-48.5
    VertRefresh 50-70
EndSection

Section "Screen"
    Identifier  "Default Screen"
    Monitor     "Configured Monitor"
    Device      "Configured Video Device"
    DefaultDepth 24
    SubSection "Display"
    Depth 24
    Modes "1920x1080"
    EndSubSection
EndSection

Where the Modes directive stands for work resolution.

Then, using a following script $HOME/start-vnc.sh:

#!/bin/bash

pidfile=$HOME/x11vnc.pid
vncpath=/usr/bin/x11vnc
vnclog=/var/log/x11vnc
vncoptions="-display :0 -xrandr -forever -loop -noxdamage -repeat -rfbauth /etc/x11vnc.pass -rfbport 5904 -shared"

action=$1

function start_vpn {
	$vncpath $vncoptions > $vnclog 2>&1 &
	echo $! > $pidfile
	cat $pidfile
	sleep 1

	if netstat -plutan 2>/dev/null | grep LISTEN | grep x11vnc | grep -q 5904 ; then	
		echo "x11vnc started listening on port 5904."
	else
		echo "[!] x11vnc is not listening!"
	fi
}

if [ -f "$pidfile" ]; then
	if [ "$action" == "start" ] || [ "$action" == "" ]; then
		if [ -s "$pidfile" ] && [[ `cat $pidfile` > 0 ]]; then 
			if pgrep $vncpath ; then
				echo "x11vnc: running (pid file)."
			else
				killall $vncpath 2> /dev/null
				echo 0 > $pidfile
				start_vpn
			fi
		elif pgrep $vncpath ; then
			echo "x11vnc: running (pgrep)."
		else 
			start_vpn
		fi
	elif [ "$action" == "stop" ]; then
		killall $vncpath 2> /dev/null
		echo 0 > $pidfile
		cat $pidfile
	fi

else
	echo "[!] PIDFILE: $pidfile does not exists, cannot proceed."
fi

(WARNING: In order to limit access to the x11vnc it is strongly advised to add -localhost switch to the vncoptions variable within above script)

Of course we will have to grant execute permission to this script file:

$ chmod +x $HOME/start-vnc.sh

We will be able to launch VNC on demand easily. Before we use it, this will be necessary to touch a pid file:

$ touch ~/x11vnc.pid

Then launching it from ~/.profile can be arranged like so:

[...]
$HOME/start-vnc.sh start

In order to invoke this script one has to at least ssh into the machine.:

ssh [email protected]
Welcome to Ubuntu 16.04.1 LTS (GNU/Linux 4.4.0-59-generic x86_64)
[...]

You have new mail.
Last login: Thu Jan 19 16:36:32 2017
3241
x11vnc started listening on port 5904.
user@hostname:~$ 

We can observe from the second to the last line that the VNC server has been observed to listening.