configures then activates gnome-remote-desktop from the command line

launch-GRD.sh

#!/usr/bin/env bash

# run this on the remote terminal machine, as auser with sudo powers, probably through a remote ssh shell

# this will overwrite all the settings it touches

# the name of the user to run these commands as
TARGET_USER=jane

# we need an inlocked desktop session. we can either start a new autologin one or unlock an existing one
echo -e "[daemon]\nAutomaticLogin=${TARGET_USER}\nAutomaticLoginEnable=true\n" | sudo tee /run/gdm/custom.conf
sudo systemctl restart gdm
#sudo loginctl unlock-sessions  # unlocks all existing sessions

# print the session type
busctl get-property org.freedesktop.Accounts /org/freedesktop/Accounts/User$(id -u) org.freedesktop.Accounts.User Session

# the password for that target user (needed to unlock their keyring)
TUP="target user password"

# password to use for VNC server
VNC_PASS="welcome to narnia"

# TODO: unlock the keyring (probably by first killing it and then re-launching it like PAM would)
#killall gnome-keyring-daemon
#echo -n ${TUP} | gnome-keyring-daemon --daemonize --login

# write vnc password to the keychain
sudo -i -u ${TARGET_USER} VNC_PASS="${VNC_PASS}" DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'echo -n ${VNC_PASS} | secret-tool store --label "GRD VNC pass" xdg:schema org.gnome.RemoteDesktop.VncPassword'
# or if you want you can print the existing password with
# secret-tool lookup xdg:schema org.gnome.RemoteDesktop.VncPassword

# allow screen control
sudo -i -u ${TARGET_USER} DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'gsettings set org.gnome.desktop.remote-desktop.vnc view-only false'

# use password authentication
sudo -i -u ${TARGET_USER} DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'gsettings set org.gnome.desktop.remote-desktop.vnc auth-method password'

# let's also setup RDP creds just for fun
RDP_USER="john"
RDP_PASS="welcome to narnia"
RDP_CREDS="{\"password\": \"${RDP_PASS}\", \"username\": \"${RDP_USER}\"}"

TLS_STORE=/var/tmp/rdptls
mkdir -p ${TLS_STORE}
# generate the TLS things for the RDP server
winpr-makecert -rdp -path ${TLS_STORE} > /dev/null

# write RDP credentials to the keychain
sudo -i -u ${TARGET_USER} RDP_CREDS="${RDP_CREDS}" DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'echo -n ${RDP_CREDS} | secret-tool store --label "GRD RDP creds" xdg:schema org.gnome.RemoteDesktop.RdpCredentials'

# set RDP tls certificate path
sudo -i -u ${TARGET_USER} TLS_CRT="${TLS_STORE}/$(hostname --fqdn).crt" DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'gsettings set org.gnome.desktop.remote-desktop.rdp tls-cert "${TLS_CRT}"'

# set RDP tls private key path
sudo -i -u ${TARGET_USER} TLS_KEY="${TLS_STORE}/$(hostname --fqdn).key" DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'gsettings set org.gnome.desktop.remote-desktop.rdp tls-key "${TLS_KEY}"'

# allow RDP remote control
sudo -i -u ${TARGET_USER} DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u ${TARGET_USER})/bus" bash -c 'gsettings set org.gnome.desktop.remote-desktop.rdp view-only false'

# now launch the server (needs to be run as the ${TARGET_USER}, haven't figured out how to fool pipewire yet)
/usr/lib/gnome-remote-desktop-daemon

What are the security implications of auto-login/unlocking like this?

VNC setup not working on Ubuntu24.04, only RDP yes
In order to use the script above we need to enable the Desktop Sharing from the GUI first I think in Ubuntu 24.04
It is not working if not enable the Desktop sharing.

But I am facing some issue on another Ubuntu 24.04, I am getting the error below:
(secret-tool:3538): GLib-GIO-CRITICAL **: 15:15:30.324: g_task_return_error: assertion 'error != NULL' failed

(secret-tool:3538): GLib-GIO-CRITICAL **: 15:15:30.324: GTask secret_service_real_prompt_async (source object: 0x5de4c2f20ba0, source tag: 0x7b25d58adc40) finalized without ever returning (using g_task_return_*()). This potentially indicates a bug in the program.