Custom Linux OS Template

DaDesktop carries several well-known Linux distros, but there might be times when you need a specific one not currently offered. For most mainstream distributions, we’re happy to assist here in Germany. Just let us know where to find the ISO file and which server should host your custom OS template.

Important:

About Disk Partitioning
1. Your custom template should have just one partition, or two at most: a dedicated EFI/Boot partition and another for the system and data.
2. LVM is not supported—please avoid using it.
3. An incorrect partition layout will prevent auto-resizing and other features from working properly.

Linux Template

Once we’ve downloaded the ISO file to the server, you’ll find it listed in your account under Admin Menu->OS IMAGES->ISO FILES.

Next, prepare the template by going to Admin Menu->OS IMAGES->CUSTOM OS TEMPLATES

Please follow this guide carefully, and complete all the steps as otherwise full DaDesktop operation is likely not to work.

Install the operating system.
Set the default username to "student" and the password also to "student".
Configure the "student" account for automatic login.
Use the DaDesktop or your own brand wallpaper
Many newer distributions now come with Wayland as the default display manager. While it does work with DaDesktop, we currently recommend switching back to X11.

Here’s how to disable Wayland:

Edit the file /etc/gdm/custom.conf, for example:
```
# Uncomment the line below to force the login screen to use Xorg
        WaylandEnable=false
        
```
Log out and log in again afterwards.
Install spice-vdagent—your package manager is the simplest way. (Note: it might already be present, depending on your distribution.)
- After installing correctly, reboot the machine, and verify that both spice-vdagent and spice-vdagentd are running.
Install the qemu-guest-agent, again via your package manager—that's the easiest route.
Install X11VNC. Keep in mind that some distributions—for instance, Red Hat–based ones like Oracle Linux or Rocky Linux—might require you to add extra repositories such as 'epel'.

Configure X11VNC

Ensure X11VNC is installed.
Open a root shell by running sudo -i

Run the following to enable X11VNC to start automatically after a reboot:

cat > /etc/xdg/autostart/x11vnc.desktop <<EOF
                [Desktop Entry]
                Type=Application
                Exec=/usr/bin/x11vnc -N -no6 -rfbportv6 -1 -allow 10.0.3.1 -nopw -shared -alwaysshared -forever -repeat -nowireframe -noscr -nocursorshape -skip_lockkeys -cursor_drag -grab_buster -deferupdate 10 -speeds 6000,5000,20 -afteraccept announce-vnc-users.sh -gone announce-vnc-users.sh
                Hidden=false
                X-MATE-Autostart-enabled=true
                X-MATE-AutoRestart=true
                Name[en_US]=X11VNC
                Name=X11VNC
                Comment[en_US]=Share desktop over VNC
                Comment=Share desktop over VNC
                EOF

Set up the desktop notification script by running these commands:

cat > /usr/local/bin/announce-vnc-users.sh <<EOF
        notify-send -a x11vnc "VNC users connected: $RFB_CLIENT_COUNT"
        EOF
        chmod +x /usr/local/bin/announce-vnc-users.sh

Restart the system.
Check the firewall configuration to make sure TCP port 5900 is accessible, for instance by running:

ss -pntl
It’s recommended to disable the sudo password requirement.
Test that everything works.

When you connect, if the URL changes to include a token query parameter, you’re all set. This indicates X11VNC is functioning correctly, and the text box at the bottom left—used for clipboard sharing between your local and virtual desktop—should also be operational.

Please Note

To enable additional optional features like:

DDWebdav lets you sync the trainer’s content folders to each participant’s machine,
DDUpload makes it simple to upload files into a DaDesktop environment;

Please contact DaDesktop Tech Support.