XRDP Server on KDE Plasma

Install and Configure XRDP

# Install xRDP server
sudo apt update && sudo apt install -y xrdp dbus-x11
# Add self-signed certificate
sudo rm /etc/xrdp/cert.pem /etc/xrdp/key.pem
sudo openssl req -new -newkey rsa:4096 -x509 -sha256 -days 3650 -nodes -out /etc/xrdp/cert.pem -keyout /etc/xrdp/key.pem
sudo chown root:xrdp /etc/xrdp/key.pem
sudo chmod 440 /etc/xrdp/key.pem
# Enable the RDP daemon
sudo systemctl enable xrdp

Allow Multiple Logon Sessions

You may want to enable this if running a VM where you may have multiple desktop sessions for the same user.

sudo mv /etc/xrdp/startwm.sh /etc/xrdp/startwm.sh.orig
sudo nano /etc/xrdp/startwm.sh

Add this content to the startup script:

dbus-launch --exit-with-session startplasma-x11

Restart the XRDP service

sudo chmod 755 /etc/xrdp/startwm.sh
sudo systemctl restart xrdp display-manager

Define Login Parameters

If we look at /etc/xrdp/sesman.ini, we can see that two groups are required to authenticate to the RDP server:

TerminalServerUsers=tsusers
TerminalServerAdmins=tsadmins

You can choose one of the following things to allow login to this server:

1. Create the required groups and add your user(s)
2. Or, disable checks for these groups

1) Add the Groups

Using the example commands below, we add two groups, tsusers and tsadmins and add the user, user.name to the groups

groupadd tsusers
groupadd tsadmins
usermod -G tsusers,tsadmins user.name

2) Or... Disable Group Checks

Edit the session manager configuration file.

nano /etc/xrdp/sesman.ini

And, comment out the lines that define the login groups. This will allow anyone to login to the RDP server as long as they have valid credentials.

; TerminalServerUsers=tsusers
; TerminalServerAdmins=tsadmins

Allow Login as Non-Root User

echo 'allowed_users=anybody' | sudo tee -a /etc/X11/Xwrapper.config
echo 'needs_root_rights=no' | sudo tee -a /etc/X11/Xwrapper.config
sudo systemctl restart xrdp display-manager

Enable Audio Playback

Per OffSec's documentation on troubleshooting sound issues, they note:

...for those who use Kali’s KDE desktop: PulseAudio is still in charge...

Make sure the requisite PulseAudio packages are installed:

sudo apt install -y pulseaudio pulseaudio-module-xrdp

Also, noting that Proxmox is my hypervisor and I needed to add an audio device to my Kali VM. The driver pictured below worked for me:

Troubleshooting

Good reference here: https://wiki.archlinux.org/title/xrdp

References

https://linux.die.net/man/5/sesman.ini
https://wiki.archlinux.org/title/xrdp
https://www.kali.org/docs/troubleshooting/no-sound/