X11VNC SystemD Service XUbuntu 18.04 (LightDM)

Have you always wanted to remote into your Linux both with VNC on the same XServer as the desktop is current running on? It's a common issue that most VNC software start new XSessions when all you want to see is what is currently displaying on the screen.

That's where X11VNC comes in.

X11VNC allows you to VNC into an existing XSession so that you can see what is currently being displayed on your Linux box's output. The only issue is that if you want the VNC server running all the time you'll have implement your own script to start it up on boot.

Looking around I found a few guides here and there for setting X11VNC up correctly for Ubuntu 18.04 as a SystemD service however most were outdated or had annoying issues such as the SystemD unit hanging.

Note: if you have not done so already you'll need a password for your VNC server: x11vnc -storepasswd

Using an amalgamation of knowledge from a lot of different places I came up with my own Unit script.

Use your favourite editor and create a new file: sudo nano /etc/systemd/system/x11vnc-h.service (I called my service x11vnc-h just to be different from the existing script)

[Unit]
Description=x11vnc VNC Server for X11
Requires=lightdm.service
After=lightdm.service

[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -auth /var/run/lightdm/root/:0 -display WAIT:0 -forever -shared -rfbauth /home/user/.vnc/passwd -rfbport 5900
ExecStop=/usr/bin/killall x11vnc
Restart=on-failure
RestartSec=2
SuccessExitStatus=3

[Install]
WantedBy=graphical.target

Now the magic here is Type=simple. This little type switch will stop the unit hanging when you go to start it using the normal forking mode. Another useful part of the unit are the restart switches which make sure that the VNC server is always up and restarts if it crashes.

Note: -rfbauth is the path to the VNC password file that you generated earlier.

Note: If you're an Arch user running LightDM you might not have anything inside the /var/run/lightdm/ folder to which I have not found a fix for just yet.

Update 22/Dec/2018: On further testing the path may not exist on Manjaro / Arch based systems correctly but the same path still seems to work.

After you've saved your unit script reload SystemD with systemctl daemon-reload and fire it up with systemctl start x11vnc-h.

If all went well you should have an output like this: systemctl status x11vnc-h

● x11vnc-h.service - x11vnc VNC Server for X11
   Loaded: loaded (/etc/systemd/system/x11vnc-h.service; disabled; vendor preset: enabled)
   Active: active (running) since Fri 2018-12-21 21:12:29 GMT; 3s ago
  Process: 23528 ExecStop=/usr/bin/killall x11vnc (code=exited, status=0/SUCCESS)
 Main PID: 23530 (x11vnc)
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/x11vnc-h.service
           └─23530 /usr/bin/x11vnc -auth /var/run/lightdm/root/:0 -display WAIT:0 -forever -shared -rfbauth /home/user/.vnc/passwd -rfbport 5900

Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29 initialize_screen: fb_depth/fb_bpp/fb_Bpl 24/32/2560
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29 Listening for VNC connections on TCP port 5900
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29 Listening for VNC connections on TCP6 port 5900
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29 listen6: bind: Address already in use
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29 Not listening on IPv6 interface.
Dec 21 21:12:29 xee x11vnc[23530]: 21/12/2018 21:12:29
Dec 21 21:12:29 xee x11vnc[23530]: The VNC desktop is:      xee:0
Dec 21 21:12:29 xee x11vnc[23530]: PORT=5900

X11VNC SystemD Service XUbuntu 18.04 (LightDM)

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