Control New Display

How to Install and Configure VNC on Ubuntu 22.04 | DigitalOcean

Control Existing Display

• To control the user's session at boot, enable auto login on settings and set up auto locking.

  #Add this to Startup Applications Preferences app
  sh -c "sleep 3 && dbus-send --type=method_call --dest=org.gnome.ScreenSaver /org/gnome/ScreenSaver org.gnome.ScreenSaver.Lock"
  
  #Or
  sudo apt install gnome-screensaver
  sh -c "sleep 3 && gnome-screensaver-command -l"
  

• Uncomment WaylandEnable=false on /etc/gdm3/custom.conf.

  sudo systemctl restart gdm
  

• Put this to ~/.config/systemd/user/x11vnc.service.

  • Add -listen localnetworkaddress to allow only local network to reach it.
  • For vncserver, add -interface localnetworkaddress.

  [Unit]
  Description=x11vnc Service
  
  [Service]
  Type=simple
  ExecStart=/usr/bin/x11vnc -auth guess -forever -noxdamage -repeat -rfbauth %h/.vnc/passwd -rfbport 5900 -shared
  Restart=on-failure
  RestartSec=2
  
  [Install]
  WantedBy=default.target
  

• Install x11vnc, create a password and enable it at login.

  sudo apt install x11vnc
  x11vnc -storepasswd
  systemctl --user enable x11vnc
  systemctl --user start x11vnc
  

For Headless Installations

How to run X server using xserver-xorg-video-dummy driver on Ubuntu - TechOverflow