cosmic-ext-rdp-server

Multi-user RDP server for the COSMIC Desktop Environment. Provides concurrent remote desktop access for multiple users with per-session isolation, PAM authentication, and automatic session lifecycle management. Supports standard RDP clients such as Windows Remote Desktop (mstsc.exe), FreeRDP, and Remmina.

Part of the COSMIC Remote Desktop stack - works together with xdg-desktop-portal-cosmic (portal) and cosmic-comp-rdp (compositor) for full remote desktop functionality.

Screenshots

RDP Session (FreeRDP connected to COSMIC Desktop)

COSMIC RDP Server Settings GUI

General	Security

Display	Features

Features

Multi-user multi-session via the session broker — multiple RDP clients connect simultaneously, each user gets their own isolated desktop session
Live screen capture via the ScreenCast XDG portal and PipeWire
H.264 streaming via EGFX/AVC420 Dynamic Virtual Channel (10-50x bandwidth reduction vs raw bitmap, with automatic bitmap fallback for clients without EGFX support)
Keyboard and mouse injection via reis/libei (direct libei protocol)
Clipboard sharing (text) between local and remote sessions via CLIPRDR
Audio forwarding from the desktop to the RDP client via RDPSND + PipeWire
Dynamic display resize when the client window changes size
Cursor shape forwarding (position, RGBA bitmap, hide/show)
Lock key synchronization (Caps Lock, Num Lock, Scroll Lock state sync)
PAM authentication via the session broker, with per-user session isolation
NLA authentication via CredSSP (optional, for single-user mode)
TLS encryption with self-signed certificates or user-provided PEM files
Hardware-accelerated encoding with VAAPI (Intel/AMD) and NVENC (NVIDIA) support, automatic fallback to x264 software encoding
Session lifecycle management with idle timeout, reconnection, and state persistence across broker restarts
COSMIC Settings GUI for configuration management via D-Bus IPC
NixOS module with systemd service, firewall integration, and secrets management
Home Manager module for user-level installation
Graceful shutdown on SIGINT/SIGTERM and D-Bus stop/reload commands
View-only fallback when input injection is unavailable

Architecture

Crate overview

Workspace with 7 crates (v0.3.0):

Crate	Purpose
`cosmic-ext-rdp-server`	Per-user daemon: CLI, config, TLS, D-Bus server, orchestration
`cosmic-ext-rdp-broker`	Multi-user session broker: TCP proxy, PAM auth, session lifecycle
`cosmic-ext-rdp-settings`	COSMIC Settings GUI: config editor, D-Bus status, nav pages
`rdp-dbus`	Shared D-Bus types, config structs, client/server proxy
`rdp-capture`	Screen capture via ScreenCast portal + PipeWire
`rdp-input`	Input injection via reis/libei (direct libei protocol)
`rdp-encode`	Video encoding via GStreamer (H.264) + bitmap fallback

Multi-user architecture

The session broker accepts all RDP connections on port 3389, authenticates users via PAM, and spawns isolated per-user cosmic-ext-rdp-server instances:

RDP Client A ──┐
RDP Client B ──┤  TCP :3389
RDP Client C ──┘
       │
       ▼
cosmic-ext-rdp-broker (system service, root)
       ├── Read X.224 Connection Request → extract cookie username
       ├── PAM authentication
       ├── Spawn per-user server via systemd-run
       └── TCP proxy (bidirectional byte-level forwarding)
            │
            ├── cosmic-ext-rdp-server :3390 (user A's session)
            ├── cosmic-ext-rdp-server :3391 (user B's session)
            └── cosmic-ext-rdp-server :3392 (user C's session)

Each per-user server inherits the user's environment (WAYLAND_DISPLAY, XDG_RUNTIME_DIR, DBUS_SESSION_BUS_ADDRESS) so all portals and PipeWire work transparently.

Per-user data flow

RDP Client
    |
    v
cosmic-ext-rdp-server (per-user daemon)
    |
    |-- ScreenCast portal --> PipeWire --> rdp-capture --> rdp-encode --> EGFX H.264 or bitmap
    |-- RemoteDesktop portal --> EIS socket --> rdp-input --> compositor keyboard/mouse
    |-- CLIPRDR channel <--> arboard --> system clipboard
    |-- RDPSND channel <-- PipeWire audio monitor
    |-- D-Bus IPC <--> cosmic-ext-rdp-settings (GUI)
    v
ironrdp-server (RDP protocol)

H.264 encoding pipeline

PipeWire (BGRx/BGRA) --> R/B swap --> GStreamer appsrc (BGRx, BT.709 full-range)
    --> videoconvert --> capsfilter (I420, BT.709 full-range)
    --> encoder (VAAPI/NVENC/x264) --> h264parse
    --> appsink (byte-stream, AU aligned)
    --> EGFX AVC420 PDU --> ZGFX compression --> DVC channel --> FreeRDP client

The encoder auto-detects hardware acceleration in priority order: VAAPI (Intel/AMD) > NVENC (NVIDIA) > x264 (software fallback).

D-Bus interfaces

Interface	Bus	Purpose
`io.github.olafkfreund.CosmicExtRdpBroker`	System	Session broker: list/terminate sessions, session count
`io.github.olafkfreund.CosmicExtRdpServer`	Session	Per-user daemon: status, reload, stop (settings GUI IPC)
`org.freedesktop.impl.portal.RemoteDesktop`	Session	Portal for input injection (called by rdp-input)
`org.freedesktop.impl.portal.ScreenCast`	Session	Portal for screen capture (called by rdp-capture)

Requirements

COSMIC Desktop (Wayland compositor with XDG portals)
PipeWire (screen capture and audio)
libei (input injection via the libei protocol)
GStreamer 1.x with plugins-base, plugins-good, plugins-bad (video encoding)
Rust 1.85+ (edition 2021)

Full stack requirements

For full remote desktop functionality (capture + input), you also need:

xdg-desktop-portal-cosmic with RemoteDesktop support
cosmic-comp-rdp with EIS receiver

See the Full Remote Desktop Stack section for setup instructions.

Building

Using Nix (recommended)

nix develop              # Enter dev shell with all dependencies
just build-release       # Build release binary
just test                # Run tests

# Or build directly with Nix
nix build                           # Build server
nix build .#cosmic-ext-rdp-settings     # Build settings GUI
nix build .#cosmic-ext-rdp-broker       # Build session broker

Using Cargo (requires system libraries)

Install the required development headers for your distribution:

Fedora/RHEL:

sudo dnf install pipewire-devel libei-devel wayland-devel libxkbcommon-devel \
  gstreamer1-devel gstreamer1-plugins-base-devel openssl-devel \
  fontconfig-devel freetype-devel mesa-libGL-devel mesa-libEGL-devel \
  vulkan-loader-devel dbus-devel clang-devel

Debian/Ubuntu:

sudo apt install libpipewire-0.3-dev libei-dev libwayland-dev libxkbcommon-dev \
  libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev libssl-dev \
  libfontconfig-dev libfreetype-dev libgl-dev libegl-dev \
  libvulkan-dev libdbus-1-dev clang

Arch Linux:

sudo pacman -S pipewire libei wayland libxkbcommon gstreamer gst-plugins-base \
  openssl fontconfig freetype2 mesa vulkan-icd-loader dbus clang

Then build:

cargo build --release

Build commands (justfile)

just                           # Build release (default)
just build-debug               # Debug build
just build-release             # Release build
just build-settings-debug      # Build settings GUI (debug)
just build-settings-release    # Build settings GUI (release)
just build-broker-debug        # Build session broker (debug)
just build-broker-release      # Build session broker (release)
just check                     # Clippy with pedantic warnings
just run                       # Run server with RUST_BACKTRACE=full
just run-settings              # Run settings GUI
just run-broker                # Run session broker
just test                      # Run all workspace tests
just fmt                       # Format code
just clean                     # Clean build artifacts
sudo just install              # Install server to /usr/bin + desktop entry
sudo just install-settings     # Install settings GUI to /usr/bin + desktop entry
sudo just install-broker       # Install session broker to /usr/bin
sudo just install-all          # Install everything

Building an AUR package (Arch Linux)

Create a PKGBUILD:

# Maintainer: Your Name <you@example.com>
pkgname=cosmic-ext-rdp-server
pkgver=0.3.0
pkgrel=1
pkgdesc="RDP server for the COSMIC Desktop Environment"
arch=('x86_64' 'aarch64')
url="https://github.com/olafkfreund/cosmic-ext-rdp-server"
license=('GPL-3.0-only')
depends=('pipewire' 'libei' 'wayland' 'libxkbcommon' 'gstreamer' 'gst-plugins-base'
         'gst-plugins-good' 'gst-plugins-bad' 'gst-plugin-va' 'openssl' 'dbus')
makedepends=('cargo' 'just' 'clang' 'pkg-config')
source=("$pkgname-$pkgver.tar.gz::$url/archive/v$pkgver.tar.gz")
sha256sums=('SKIP')

prepare() {
  cd "$pkgname-$pkgver"
  export RUSTUP_TOOLCHAIN=stable
  cargo fetch --locked --target "$(rustc -vV | sed -n 's/host: //p')"
}

build() {
  cd "$pkgname-$pkgver"
  export RUSTUP_TOOLCHAIN=stable
  just build-release
  just build-settings-release
}

package() {
  cd "$pkgname-$pkgver"
  just rootdir="$pkgdir" install-all
}

Build and install:

makepkg -si

Building a Debian package

Create the debian/ directory structure:

mkdir -p debian/source

debian/control:

Source: cosmic-ext-rdp-server
Section: net
Priority: optional
Maintainer: Your Name <you@example.com>
Build-Depends: debhelper-compat (= 13), cargo, rustc (>= 1.85),
 just, clang, pkg-config, libpipewire-0.3-dev, libei-dev,
 libwayland-dev, libxkbcommon-dev, libgstreamer1.0-dev,
 libgstreamer-plugins-base1.0-dev, libssl-dev, libfontconfig-dev,
 libfreetype-dev, libgl-dev, libvulkan-dev, libdbus-1-dev
Standards-Version: 4.7.0
Homepage: https://github.com/olafkfreund/cosmic-ext-rdp-server

Package: cosmic-ext-rdp-server
Architecture: any
Depends: ${shlibs:Depends}, ${misc:Depends}, pipewire, libei1,
 gstreamer1.0-plugins-base, gstreamer1.0-plugins-good,
 gstreamer1.0-plugins-bad, gstreamer1.0-vaapi
Description: RDP server for the COSMIC Desktop Environment
 Allows remote desktop access to COSMIC sessions using standard
 RDP clients. Supports live screen capture, keyboard/mouse injection,
 clipboard sharing, audio forwarding, and dynamic display resizing.

debian/rules:

#!/usr/bin/make -f
%:
	dh $@

override_dh_auto_build:
	just build-release
	just build-settings-release

override_dh_auto_install:
	just rootdir=debian/cosmic-ext-rdp-server install-all

debian/changelog:

cosmic-ext-rdp-server (0.3.0-1) unstable; urgency=medium

  * Multi-user multi-session broker (PAM auth, per-user isolation).
  * H.264 EGFX streaming with correct colors.
  * Hardware-accelerated encoding (VAAPI/NVENC).
  * COSMIC Settings GUI.
  * NixOS and Home Manager modules.

 -- Your Name <you@example.com>  Tue, 11 Feb 2026 00:00:00 +0000

debian/source/format:

3.0 (quilt)

Build the package:

dpkg-buildpackage -us -uc -b
# Or using debuild:
debuild -us -uc -b

Usage

Quick start

# Start the server with defaults (binds to 0.0.0.0:3389, self-signed TLS)
cosmic-ext-rdp-server

# Specify a custom address and port
cosmic-ext-rdp-server --addr 0.0.0.0 --port 13389

# Use a custom TLS certificate
cosmic-ext-rdp-server --cert /path/to/cert.pem --key /path/to/key.pem

# Use a configuration file
cosmic-ext-rdp-server --config /path/to/config.toml

# Start with a static blue screen (for testing, no portal needed)
cosmic-ext-rdp-server --static-display

CLI options

Flag	Description
`--addr <ADDRESS>`	Bind address (default: `0.0.0.0`)
`--port <PORT>`	Listen port (default: `3389`)
`--cert <PATH>`	TLS certificate file (PEM format)
`--key <PATH>`	TLS private key file (PEM format)
`--config`, `-c <PATH>`	Configuration file (TOML)
`--static-display`	Use a static blue screen instead of live capture
`--swap-colors`	Force R/B channel swap (usually not needed, auto-detected)

Connecting from a client

# FreeRDP with H.264 EGFX (recommended - best quality and bandwidth)
xfreerdp /v:hostname:3389 /cert:ignore /gfx:avc420

# FreeRDP with NLA authentication
xfreerdp /v:hostname:3389 /u:myuser /p:mypassword /sec:nla /cert:ignore /gfx:avc420

# FreeRDP with dynamic resize
xfreerdp /v:hostname:3389 /cert:ignore /dynamic-resolution

# FreeRDP without EGFX (bitmap fallback)
xfreerdp /v:hostname:3389 /cert:ignore /gfx:off

# Remmina (Linux GUI)
# Create a new RDP connection, set Server to hostname:3389

# Windows Remote Desktop (mstsc.exe)
mstsc /v:hostname:3389

Configuration

Configuration is read from TOML. Default location: $XDG_CONFIG_HOME/cosmic-ext-rdp-server/config.toml (~/.config/cosmic-ext-rdp-server/config.toml).

Full example

# Network
bind = "0.0.0.0:3389"

# TLS (omit for self-signed)
# cert_path = "/etc/cosmic-ext-rdp-server/cert.pem"
# key_path = "/etc/cosmic-ext-rdp-server/key.pem"

# Static blue screen mode (for testing)
static_display = false

# NLA Authentication (CredSSP)
[auth]
enable = false
username = ""
password = ""
# domain = "WORKGROUP"

# Screen capture
[capture]
fps = 30
channel_capacity = 4
multi_monitor = false
swap_colors = true    # R/B channel swap for COSMIC portal (default: true)

# Video encoding
[encode]
encoder = "auto"       # "auto", "vaapi", "nvenc", or "software"
preset = "ultrafast"
bitrate = 10000000     # bits per second

# Clipboard sharing
[clipboard]
enable = true

# Audio forwarding (RDPSND)
[audio]
enable = true
sample_rate = 44100
channels = 2

Configuration sections

`[auth]` - NLA Authentication

Key	Type	Default	Description
`enable`	bool	`false`	Enable NLA via CredSSP
`username`	string	`""`	Username for authentication
`password`	string	`""`	Password for authentication
`domain`	string	`null`	Windows domain (optional)

`[capture]` - Screen Capture

Key	Type	Default	Description
`fps`	int	`30`	Target frames per second
`channel_capacity`	int	`4`	PipeWire frame buffer depth
`multi_monitor`	bool	`false`	Merge all monitors into a single virtual desktop
`swap_colors`	bool	`true`	Swap R/B channels (needed for COSMIC portal pixel format)

`[encode]` - Video Encoding

Key	Type	Default	Description
`encoder`	string	`"auto"`	Encoder backend: `auto`, `vaapi`, `nvenc`, `software`
`preset`	string	`"ultrafast"`	H.264 encoding preset
`bitrate`	int	`10000000`	Target bitrate in bits/second

`[clipboard]` - Clipboard Sharing

Key	Type	Default	Description
`enable`	bool	`true`	Enable text clipboard sharing via CLIPRDR

`[audio]` - Audio Forwarding

Key	Type	Default	Description
`enable`	bool	`true`	Enable RDPSND audio forwarding
`sample_rate`	int	`44100`	Sample rate in Hz
`channels`	int	`2`	Number of audio channels (1=mono, 2=stereo)

Session Broker Configuration

The multi-user session broker (cosmic-ext-rdp-broker) has its own TOML configuration. Default: /etc/cosmic-ext-rdp-broker/config.toml

bind = "0.0.0.0:3389"
server_binary = "/usr/bin/cosmic-ext-rdp-server"
port_range_start = 3390
port_range_end = 3489
pam_service = "cosmic-ext-rdp"
idle_timeout_secs = 3600
max_sessions = 100
session_policy = "OnePerUser"   # or "ReplaceExisting"
state_file = "/var/lib/cosmic-ext-rdp-broker/sessions.json"

Key	Type	Default	Description
`bind`	string	`"0.0.0.0:3389"`	Address and port for the broker to listen on
`server_binary`	string	auto	Path to the `cosmic-ext-rdp-server` binary
`port_range_start`	int	`3390`	Start of the port range for per-user sessions
`port_range_end`	int	`3489`	End of the port range (supports up to 100 concurrent users)
`pam_service`	string	`"cosmic-ext-rdp"`	PAM service name for authentication
`idle_timeout_secs`	int	`3600`	Seconds of idle time before a session is terminated
`max_sessions`	int	`100`	Maximum number of concurrent user sessions
`session_policy`	string	`"OnePerUser"`	`OnePerUser` reconnects to existing sessions; `ReplaceExisting` terminates old sessions
`state_file`	string	see above	Path to the JSON session persistence file

Installation

NixOS Module

The flake provides a NixOS module for declarative configuration.

Basic setup

{
  inputs.cosmic-ext-rdp-server.url = "github:olafkfreund/cosmic-ext-rdp-server";

  outputs = { self, nixpkgs, cosmic-ext-rdp-server, ... }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
      modules = [
        cosmic-ext-rdp-server.nixosModules.default
        {
          nixpkgs.overlays = [ cosmic-ext-rdp-server.overlays.default ];

          services.cosmic-ext-rdp-server = {
            enable = true;
            openFirewall = true;

            settings = {
              bind = "0.0.0.0:3389";
              capture.fps = 30;
              audio.enable = true;
              clipboard.enable = true;
            };
          };
        }
      ];
    };
  };
}

With NLA authentication

services.cosmic-ext-rdp-server = {
  enable = true;
  openFirewall = true;

  auth = {
    enable = true;
    username = "rdpuser";
    # Password is loaded via systemd LoadCredential (never in Nix store).
    # Compatible with agenix, sops-nix, or any file-based secrets manager.
    passwordFile = "/run/agenix/cosmic-ext-rdp-password";
  };

  settings = {
    bind = "0.0.0.0:3389";
  };
};

NixOS module options

Option	Type	Default	Description
`enable`	bool	`false`	Enable the COSMIC RDP Server service
`package`	package	`pkgs.cosmic-ext-rdp-server`	Server package to use
`installSettings`	bool	`true`	Install the COSMIC Settings GUI
`settingsPackage`	package	`pkgs.cosmic-ext-rdp-settings`	Settings GUI package
`openFirewall`	bool	`false`	Open the RDP port in the firewall
`auth.enable`	bool	`false`	Enable NLA authentication
`auth.username`	string	`""`	NLA username
`auth.domain`	string	`null`	NLA domain (optional)
`auth.passwordFile`	path	`null`	Path to password file (loaded via `LoadCredential`)
`settings`	attrs	`{}`	TOML configuration (see Configuration section)

The systemd service runs as a user service (graphical-session.target) with security hardening (no new privileges, read-only home, private tmp, restricted syscalls).

Multi-user broker setup (NixOS)

For multi-user remote desktop access, enable the session broker alongside the per-user server:

services.cosmic-ext-rdp-broker = {
  enable = true;
  openFirewall = true;

  settings = {
    bind = "0.0.0.0:3389";
    port_range_start = 3390;
    port_range_end = 3489;
    max_sessions = 100;
    idle_timeout_secs = 3600;
  };
};

The broker runs as a system service (root) to perform PAM authentication and spawn per-user sessions via systemd-run. It automatically configures PAM and creates a systemd slice (cosmic-ext-rdp-sessions.slice) with resource limits (8 GB memory, 4096 tasks) for all RDP sessions combined.

Home Manager Module

For user-level installation without system-wide NixOS changes.

Basic setup

{
  inputs.cosmic-ext-rdp-server.url = "github:olafkfreund/cosmic-ext-rdp-server";

  outputs = { self, nixpkgs, home-manager, cosmic-ext-rdp-server, ... }: {
    homeConfigurations."user" = home-manager.lib.homeManagerConfiguration {
      modules = [
        cosmic-ext-rdp-server.homeManagerModules.default
        {
          nixpkgs.overlays = [ cosmic-ext-rdp-server.overlays.default ];

          services.cosmic-ext-rdp-server = {
            enable = true;
            autoStart = true;

            settings = {
              bind = "0.0.0.0:3389";
              capture.fps = 30;
              audio.enable = true;
            };
          };
        }
      ];
    };
  };
}

With NLA authentication (Home Manager)

services.cosmic-ext-rdp-server = {
  enable = true;
  autoStart = true;

  auth = {
    enable = true;
    username = "rdpuser";
    passwordFile = "/run/agenix/cosmic-ext-rdp-password";
  };

  settings.bind = "0.0.0.0:3389";
};

Home Manager options

Option	Type	Default	Description
`enable`	bool	`false`	Enable the COSMIC RDP Server
`package`	package	`pkgs.cosmic-ext-rdp-server`	Server package to use
`installSettings`	bool	`true`	Install the COSMIC Settings GUI
`settingsPackage`	package	`pkgs.cosmic-ext-rdp-settings`	Settings GUI package
`autoStart`	bool	`false`	Start with the graphical session
`auth.enable`	bool	`false`	Enable NLA authentication
`auth.username`	string	`""`	NLA username
`auth.domain`	string	`null`	NLA domain (optional)
`auth.passwordFile`	path	`null`	Path to password file (loaded via `LoadCredential`)
`settings`	attrs	`{}`	TOML configuration (see Configuration section)

The Home Manager service includes the same systemd security hardening as the NixOS module.

Manual installation

After building with just build-release and just build-settings-release:

sudo just install          # Install server to /usr/bin + desktop entry
sudo just install-settings # Install settings GUI to /usr/bin + desktop entry

To uninstall:

sudo just uninstall-all

Full Remote Desktop Stack

For a complete remote desktop setup on COSMIC, you need three components working together:

                                    +-----------------------+
                                    |  cosmic-comp-rdp      |
                                    |  (compositor + EIS)   |
                                    +-----------^-----------+
                                                |
                                    AcceptEisSocket(fd)
                                                |
+------------+     +-------------------+     +--+--------------------------+
| RDP Client | --> | cosmic-ext-rdp-server | --> | xdg-desktop-portal-cosmic   |
| (mstsc,    |     | (this repo)       |     | (RemoteDesktop + ScreenCast)|
| FreeRDP,   | <-- | RDP protocol,     | <-- | EIS socket pairs,          |
| Remmina)   |     | TLS, auth         |     | PipeWire streams            |
+------------+     +-------------------+     +-----------------------------+

Component	Repository	Purpose
cosmic-ext-rdp-server	This repo	RDP protocol server, capture + input orchestration
xdg-desktop-portal-cosmic	Portal fork	RemoteDesktop + ScreenCast portal interfaces
cosmic-comp-rdp	Compositor fork	EIS receiver for input injection

How the components interact

cosmic-ext-rdp-server starts and calls the RemoteDesktop portal to request input injection and the ScreenCast portal to request screen capture
xdg-desktop-portal-cosmic shows a consent dialog, creates a UNIX socket pair for EIS, and sends the server-side fd to the compositor
cosmic-comp-rdp receives the EIS socket via D-Bus (AcceptEisSocket) and creates a seat with keyboard, pointer, and touch capabilities
The RDP server receives the client-side EIS socket via ConnectToEIS and sends input events through it
PipeWire streams carry screen frames from the compositor to the RDP server for encoding and delivery

NixOS example (all three components)

{
  inputs = {
    cosmic-ext-rdp-server.url = "github:olafkfreund/cosmic-ext-rdp-server";
    xdg-desktop-portal-cosmic.url = "github:olafkfreund/xdg-desktop-portal-cosmic";
    cosmic-comp.url = "github:olafkfreund/cosmic-comp-rdp";
  };

  outputs = { self, nixpkgs, cosmic-ext-rdp-server, xdg-desktop-portal-cosmic, cosmic-comp, ... }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
      modules = [
        cosmic-ext-rdp-server.nixosModules.default
        xdg-desktop-portal-cosmic.nixosModules.default
        cosmic-comp.nixosModules.default
        {
          nixpkgs.overlays = [
            cosmic-ext-rdp-server.overlays.default
            xdg-desktop-portal-cosmic.overlays.default
            cosmic-comp.overlays.default
          ];

          # Compositor with EIS support
          services.cosmic-comp.enable = true;

          # Portal with RemoteDesktop interface
          services.xdg-desktop-portal-cosmic.enable = true;

          # RDP server
          services.cosmic-ext-rdp-server = {
            enable = true;
            openFirewall = true;
            settings.bind = "0.0.0.0:3389";
          };
        }
      ];
    };
  };
}

Home Manager example (all three components)

{
  inputs = {
    cosmic-ext-rdp-server.url = "github:olafkfreund/cosmic-ext-rdp-server";
    xdg-desktop-portal-cosmic.url = "github:olafkfreund/xdg-desktop-portal-cosmic";
    cosmic-comp.url = "github:olafkfreund/cosmic-comp-rdp";
  };

  outputs = { self, nixpkgs, home-manager, cosmic-ext-rdp-server, xdg-desktop-portal-cosmic, cosmic-comp, ... }: {
    homeConfigurations."user" = home-manager.lib.homeManagerConfiguration {
      modules = [
        cosmic-ext-rdp-server.homeManagerModules.default
        xdg-desktop-portal-cosmic.homeManagerModules.default
        cosmic-comp.homeManagerModules.default
        {
          nixpkgs.overlays = [
            cosmic-ext-rdp-server.overlays.default
            xdg-desktop-portal-cosmic.overlays.default
            cosmic-comp.overlays.default
          ];

          services.cosmic-ext-rdp-server = {
            enable = true;
            autoStart = true;
            settings.bind = "0.0.0.0:3389";
          };

          services.xdg-desktop-portal-cosmic.enable = true;

          wayland.compositor.cosmic-comp.enable = true;
        }
      ];
    };
  };
}

Component compatibility

All three repositories are tested together and use compatible dependency versions:

Dependency	cosmic-ext-rdp-server	xdg-desktop-portal-cosmic	cosmic-comp-rdp
reis (libei)	0.5	0.5	0.5
zbus (D-Bus)	5.x	5.x	5.x
ashpd (portals)	0.12	0.12	-
pipewire	0.8	git (freedesktop)	-

D-Bus interface chain (verified compatible):

Portal exposes org.freedesktop.impl.portal.RemoteDesktop with ConnectToEIS
Portal calls com.system76.CosmicComp.RemoteDesktop.AcceptEisSocket(fd) on the compositor
RDP server exposes io.github.olafkfreund.CosmicExtRdpServer for settings GUI IPC

D-Bus Interface

Per-user daemon (io.github.olafkfreund.CosmicExtRdpServer on the session bus):

Properties: Status (Running/Stopped/Error), BindAddress
Methods: Reload, Stop
Signals: Status change notifications

The settings GUI (cosmic-ext-rdp-settings) communicates with the daemon over this interface to display server status and trigger configuration reloads.

Session broker (io.github.olafkfreund.CosmicExtRdpBroker on the system bus):

Methods: ListSessions (returns all active sessions), TerminateSession(username), ActiveSessionCount

The broker's D-Bus interface can be used for monitoring and administration of multi-user sessions.

Logging

The server uses tracing with RUST_LOG environment variable support:

# Default (info level)
cosmic-ext-rdp-server

# Debug logging
RUST_LOG=debug cosmic-ext-rdp-server

# Trace logging for specific crates
RUST_LOG=rdp_capture=trace,rdp_input=debug cosmic-ext-rdp-server

Troubleshooting

No screen capture (black screen)

Ensure PipeWire is running: systemctl --user status pipewire
Ensure the ScreenCast portal is available: busctl --user list | grep portal
Check that xdg-desktop-portal-cosmic is installed and running
Try --static-display flag to verify the RDP connection itself works

No input (keyboard/mouse not working)

Ensure xdg-desktop-portal-cosmic with RemoteDesktop support is installed
Ensure cosmic-comp-rdp with EIS receiver is running as the compositor
Check the consent dialog was accepted (the portal shows a dialog on first connection)
Check logs: RUST_LOG=rdp_input=debug cosmic-ext-rdp-server

Connection refused

Check the server is running: systemctl --user status cosmic-ext-rdp-server
Check firewall rules: port 3389 (or custom port) must be open
For NixOS: set openFirewall = true in the module configuration

Wrong colors (red/blue swapped)

The swap_colors option defaults to true for COSMIC Desktop
If colors appear inverted, try setting swap_colors = false in [capture]
This is needed because COSMIC's portal reports BGRx format but delivers RGBx byte order

Audio not working

Ensure PipeWire is running with audio support
Check [audio] enable = true in the configuration
Ensure the RDP client supports RDPSND (FreeRDP does by default)

Known Limitations

Dynamic resize: Resize during an active EGFX session may trigger a reconnection loop; bitmap-mode resize works correctly
Cursor shapes: SPA cursor metadata extraction requires unsafe FFI not yet implemented; cursor position is forwarded but custom cursor bitmaps from PipeWire are stubbed
Unicode input: Full IME/compose input is not yet supported (#23); common control characters (Backspace, Tab, Enter, Escape, Delete) sent as Unicode events are handled

License

GPL-3.0-only

Name		Name	Last commit message	Last commit date
crates		crates
data		data
docs		docs
nix		nix
.gitignore		.gitignore
CLAUDE.md		CLAUDE.md
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
GEMINI.md		GEMINI.md
LICENSE		LICENSE
README.md		README.md
catalog-info.yaml		catalog-info.yaml
flake.lock		flake.lock
flake.nix		flake.nix
justfile		justfile
mkdocs.yml		mkdocs.yml
rust-toolchain.toml		rust-toolchain.toml
test-rdp.sh		test-rdp.sh

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cosmic-ext-rdp-server

Screenshots

RDP Session (FreeRDP connected to COSMIC Desktop)

COSMIC RDP Server Settings GUI

Features

Architecture

Crate overview

Multi-user architecture

Per-user data flow

H.264 encoding pipeline

D-Bus interfaces

Requirements

Full stack requirements

Building

Using Nix (recommended)

Using Cargo (requires system libraries)

Build commands (justfile)

Building an AUR package (Arch Linux)

Building a Debian package

Usage

Quick start

CLI options

Connecting from a client

Configuration

Full example

Configuration sections

[auth] - NLA Authentication

[capture] - Screen Capture

[encode] - Video Encoding

[clipboard] - Clipboard Sharing

[audio] - Audio Forwarding

Session Broker Configuration

Installation

NixOS Module

Basic setup

With NLA authentication

NixOS module options

Multi-user broker setup (NixOS)

Home Manager Module

Basic setup

With NLA authentication (Home Manager)

Home Manager options

Manual installation

Full Remote Desktop Stack

How the components interact

NixOS example (all three components)

Home Manager example (all three components)

Component compatibility

D-Bus Interface

Logging

Troubleshooting

No screen capture (black screen)

No input (keyboard/mouse not working)

Connection refused

Wrong colors (red/blue swapped)

Audio not working

Known Limitations

License

About

Resources

Stars

Watchers

Forks

Releases

Packages

Contributors

Languages

`[auth]` - NLA Authentication

`[capture]` - Screen Capture

`[encode]` - Video Encoding

`[clipboard]` - Clipboard Sharing

`[audio]` - Audio Forwarding