Have x11vnc automatically start in Ubuntu 16.04 server without someone first logging in at the server physically

Question

What I would like to do is automatically start x11vnc as a service. Then lets say when the server restarts for some reason, I would remotely login to the remote ubuntu 16.04 server, without anybody logging in physically to the computer at first. Any clues how this can be done?

The page at https://help.ubuntu.com/community/VNC/Servers#x11vnc says that x11vnc can be started while your computer is still showing a login screen. I think this is exactly my requirement.

When I run "x11vnc -findauth" I get the result XAUTHORITY=/run/user/1000/gdm/Xauthority.

FYI: I made it as a system service with this content

[Unit]
Description=Start x11vnc at startup. 
After=multi-user.target

[Service]
Type=simple 
ExecStart=/usr/bin/x11vnc -auth /run/user/1000/gdm/Xauthority -display :1 -forever -loop -noxdamage -repeat -rfbauth /home/mms2/.vnc/passwd -rfbport 5900 -shared

[Install] 
WantedBy=multi-user.target

It works fine when any user has first logged into the system. But if no user has logged in first, I see this error in the log file:

Oct 16 19:45:19 ubuntu x11vnc[1486]: Starting with x11vnc 0.9.9 you can have it try to guess by using:
Oct 16 19:45:19 ubuntu x11vnc[1486]: -auth guess
Oct 16 19:45:19 ubuntu x11vnc[1486]:    (see also the x11vnc -findauth option.)
Oct 16 19:45:19 ubuntu x11vnc[1486]:    Only root will have read permission for the file, and so x11vnc must be run
Oct 16 19:45:19 ubuntu x11vnc[1486]:    as root (or copy it).  The random characters in the filenames will of course
Oct 16 19:45:19 ubuntu x11vnc[1486]:    change and the directory the cookie file resides in is system dependent.
Oct 16 19:45:19 ubuntu x11vnc[1486]:    See also: http://www.karlrunge.com/x11vnc/faq.html
Oct 16 19:45:19 ubuntu x11vnc[1486]:  --- x11vnc loop: sleeping 2000 ms ---

Answer 1

Try adding the -create option to x11vnc. The command over ssh I use is:

ssh -t -L 5900:localhost:5900 192.168.1.131 "sudo x11vnc -localhost -create -auth guess  -display :0"

so I don't even need to have a service x11vnc running.

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The ssh command maps the remote 5900 to the local port 5900, so the x11 server and viewer both think they are running locally on port 5900. A viewer command I use when invoking the above ssh command, explicitly uses localhost:5900 (the other options are just for performance).

xtightvncviewer -encodings RRE -bgr233 localhost::5900  

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Assuming no password on the vnc server, the above will use the current username for the server, and ask for its password. If you have a different user on the server, include it in front of the IP with an @ sign. e.g. user@192...