Remote login in SDDM (RustDesk, X11?)

Help
1

I am aware, that X11 is obsolete and will fade out eventually. However I still have a specific use case for it:

I use RustDesk to access my Linux box at home when needed. First it will be started using wake-on-lan and then I can access it using RustDesk which is installed as service and uses my own relay server.

RustDesk also works fine with Wayland - but only in the Desktop session after logging in. For SDDM RustDesk only supports X11.

Kubuntu 25.10 still used X11 for SDDM and I could use RustDesk to login remotely as well and then access the desktop in Wayland without any issues. However with Kubuntu 26.04 X11 is no longer installed by default and SDDM now also uses Wayland. And this is not supported by RustDesk yet (it may be in the future, but so far I have to live with it).

So my plan was to install X11 as well and configure SDDM to use X11 instead of Wayland. But I am not sure, if this would work and where to start.

My current workaround is using auto-login in SDDM. Since the system is in a private environment that’s not too bad - but I’d prefer being able to access the login screen remotely as well.

Are there any other known remote access solutions or is it possible to trigger a login in SDDM via SSH?

2

I raised a similar question on the GNOME side, and the discussion there also seemed to point to the same underlying issue: this is not really about whether one specific desktop environment or display manager supports this feature today.

The core problem seems to be that there is no commonly agreed Wayland protocol or standardized interface for third-party remote desktop software to access and control the pre-login / login-screen environment in a generic, compositor-independent way.

Because of that, each desktop environment or display manager naturally has to build its own solution. GNOME has its GDM/gnome-remote-desktop/RDP path. KDE seems to be moving toward its own Plasma/KRdp/Plasma Login Manager direction. But third-party software such as RustDesk, AnyDesk, or similar tools still has no common Wayland-native target for unattended access before a user session has started.

I think this is unfortunate for the Linux desktop ecosystem as a whole. Linux has traditionally been valued for giving users choice and flexibility, but in this particular area the practical options seem to be narrowing. As distributions phase out X11 components, the old fallback path for unattended remote access is disappearing, while the generic Wayland-native replacement that third-party software would need does not appear to exist yet.

The end result is that users who need unattended remote access are increasingly pushed toward RDP-based or desktop-specific stacks, even if they would prefer to use other remote desktop software. That feels like a loss of flexibility for the Linux ecosystem, not because any single project is doing something wrong, but because the shared protocol layer needed by third-party tools has not materialized.

So my question is: is there any ongoing discussion, roadmap, or interest in defining such a common Wayland-native interface for pre-login / login-screen remote access, or is the expectation that every desktop environment and display manager will continue to solve this independently?

3

There is a way to use RDP in SDDM with Wayland? That would be ok for me as well. Or did I misunderstand this?

4

At least possible, but not smooth, the smooth here doesn’t mean streaming, I mean the procedures.

5

Mission impossible: Choose remote desktop software I want on Linux.

6

I don’t care which software it is - it just has to work. But at the moment I have no solution at all to access SDDM running in Wayland via a remote connection. I would happily use VNC, RDP or whatever is required, if it just works.

7

VNC and RDP are not for general purposes, because it needs direct IP connection for the destination computers, and it is impossible for the computers that behind a firewall.

Only able to use only VNC or RDP are unacceptable.

8

No issue for me. I have VPN and my own server for that.

9

Not the case for most people

10

Yes, but I did not ask for a solution for most people but just for using VNC or RDP in SDDM. Is this possible?

Also Rustdesk is also not a good solution for Wayland at the moment since it has a number of bugs when it comes to different display scaling between client and remote system and keyboard input when the client uses a different layout than the remote sytem - because Rustdesk does not send character input but translated keycodes.

11

If x11 continuing sunseting, and Wayland still lacks critical features, people will get around it, in dangerous way, this is lose-lose situation.

github. com/rustdesk/rustdesk/pull/15420

12

Hmmm… bypassing xdg-desktop-portal and access the framebuffer using the DRM/KMS kernel interface, so you can also access the login screen.

I understand, why this is done and technically it is a viable solution when you ignore, that you bypass Wayland itself this way. But I also agree, that this is an “ugly” solution nevertheless which should not be needed.

13

And the original question is still unanswered:

How to make SDDM run in X11 again in Kubuntu 26.04 and still use Wayland for KDE? I installed X11 and configured SDDM to use it. But after logging in, I just get a black screen. So I reverted this and still use SDDM in Wayland, which needs autologin as well if I want to be able to access the desktop via Rustdesk unattended.

14

I think x11 packages haven’t removed in Ubuntu 26, but not installed by default if it is fresh install

After installed it, you should able to force SDDM to running in X11 mode, and won’t get black screen.

15

It is unfortunate Wayland still not providing such a protocol to let softwares capture the login screen, in standard and safe way.

16

SDDM itself works with X11 - it is KDE which then does not show up using Wayland after the login.

I don’t know where to search. Kubuntu 25.10 did it exaclty this way: SDDM with X11 and then KDE with Wayland. But it seems this is no longer possible with Kubuntu 26.04 when installing X11 manually and changing SDDM to use X11 instead of Wayland.

17

I finally solved it. This is my solution to have unattended remote login using Rustdesk.

First the installation of Rustdesk:

Download Rustdesk deb-package from https://github.com/rustdesk/rustdesk/releases and install it using sudo dpkg -i rustdesk-1.4.9-x86_64.deb (which is currently the latest version).

Configure the network connections (also see RustDesk – the alternative to TeamViewer and AnyDesk | Arno Welzel on how to host your own relay-server with encryption):

Screenshot_20260822_140331
Screenshot_20260822_1403311600Ă—1200 75.3 KB

Start Rustdesk and start the service by clicking “Start service” in the main window:

image
image1600Ă—1200 131 KB

Connect from a client - Rustdesk will now ask you to choose, which parts of the screen to share. Since it is running as service, this will be stored persistent, so you only have to do this once.

Now to make it work in the login screen with SDDM as well:

Install X11 with sudo apt install xorg.

Configure SDDM with two files in /etc/sddm.conf.d/ - in my case I use UHD (4K) and also need scaling of 200%, adjust this as needed.

/etc/sddm.conf.d/10-default.conf:

# This is the default configuration to make sure, SDDM starts properly
#
# KDE itself will write the login related settings in kde_settings.conf

[General]
# DisplayServer=wayland
DisplayServer=x11

# Note: when using X11 the cursor size in kde_ettings.conf must then also be 48 and not 24!
GreeterEnvironment=QT_SCREEN_SCALE_FACTORS=2, QT_FONT_DPI=192

[Wayland]
CompositorCommand=kwin_wayland --drm --no-lockscreen --no-global-shortcuts --locale1

[X11]
EnableHiDPI=true
ServerArguments=-nolisten tcp -dpi 192

/etc/sddm.conf.d/kde_settings.conf:

Note: this file was auto generated by KDE, but you need to change the cursor size from 24 to 48 if you want to use a cursor with a size of 24 since X11 behaves different in this case.

[General]
HaltCommand=
RebootCommand=

[Theme]
Current=breeze
CursorSize=48
CursorTheme=Bibata-Modern-Classic
Font=Noto Sans,10,-1,5,400,0,0,0,0,0,0,0,0,0,0,1

[Users]
MaximumUid=60000
MinimumUid=1000

[X11]
ServerArguments=-dpi 192

Now Rustdesk can also be used to log in in SDDM, since this uses X11. When the desktop session starts, the connection will be closed and automatically opened again to get access to the Wayland desktop session.

Why it works now and did not in the past - I don’t know. Maybe some updates over the last weeks fixed some bugs here as well. Also Rustdesk itself works better now.

I did not have time yet, to check, if this would also work with the Plasma login manager. Does anyone know, if the Plasma login manager already dropped support for X11 or will do so in the future?