Windows Subsystem for Linux 2

1. Information

See https://superuser.com/questions/198525/how-can-i-execute-a-windows-command-line-in-background.

2. Preparation

Open Programs and Features.
Select Turn Windows Features on or off.
Check Virtual Machine Platform.
Check Windows Subsystem for Linux.
Click OK.
Close Programs and Features.
Restart the computer.

Enter the following commands at a Command Prompt with administrative privileges.

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart
dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart
:: Restart the computer.

where.exe wsl           # C:\Windows\System32\wsl.exe
where.exe wslconfig     # C:\Windows\System32\wslconfig.exe
where.exe wslg          # C:\Windows\System32\wslg.exe
wsl.exe --help
wsl.exe --version       # 2.6.2.0

wsl.exe --update
wsl.exe --set-default-version 2
wsl.exe --status

:: List available distributions.
wsl.exe --list --online

powershell.exe wsl.exe -- ip -o -4 -json addr list eth0

3. Installation

Windows user    WSL instance name       Linux hostname  Linux username  Linux password  Linux IP address
--------------  -----------------       --------------  --------------  --------------  ----------------
Administrator   Admin-Main-Wsl          admin-main-wsl  admin           <level 1>       172.22.88.1
Delta           Delta-Main-Wsl          delta-main-wsl  delta           <level 2>       172.22.88.10
Douwe           Douwe-Main-Wsl          douwe-main-wsl  douwe           <level 3>       172.22.88.100

Enter the following commands at a Command Prompt with standard privileges.

:: Installation of Debian distribution for DELTA-CA-WSL Certificate Authority server.
wsl.exe --list --all --verbose
wsl.exe --install --location C:\WSL\Admin-Main-Wsl --name Admin-Main-Wsl --distribution Debian
wsl.exe --install --location C:\WSL\Delta-Main-Wsl --name Delta-Main-Wsl --distribution Debian
wsl.exe --install --location C:\WSL\Douwe-Main-Wsl --name Douwe-Main-Wsl --distribution Debian
:: Enter new UNIX username: <username>
:: New password: <password>
:: Retype new password: <password>

Optional: Close the Welcome to Windows Subsystem for Linux window.

Enter the following commands at a Command Line.

# Update.
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get autoremove
sudo apt-get autoclean

# Set SSH port number.
sudo apt-get install openssh-server
sudo sed -i "s/#Port 22/Port 222/" /etc/ssh/sshd_config

# Set hostname.
host=<hostname>
cat << EOF | sed -e "s/^  //" | sudo tee --append "/etc/wsl.conf"

  [network]
  hostname=${host}
  generateHosts=false
EOF
cat /etc/wsl.conf

# Fix temporary failure in name resolution.
cat /etc/hosts
sudo sed -i "s/<windows hostname>/<linux hostname>/g" /etc/hosts
cat /etc/hosts

# Shut down WSL instance.
exit

Enter the following commands at a Command Prompt with standard privileges.

:: Wait about 8 seconds.
wsl.exe --list --all --verbose

:: Show IP address.
wsl.exe --distribution DELTA-CA-WSL hostname -I
:: Start specific WSL instance.
wsl.exe --distribution Delta-Main-Wsl

# Shut down all instances.
wsl.exe --shutdown

# Shut down a specific instance.
wsl.exe --terminate Delta-Main-Wsl

4. Uninstallation

Enter the following commands at a Command Prompt with standard privileges.

wsl.exe --list --all --verbose
wsl.exe --unregister Debian
wsl.exe --unregister Delta-Main-Wsl

5. Start

Enter the following commands at a Command Prompt with standard privileges.

:: Start default WSL instance.
wsl.exe

:: Start specific WSL instance.
wsl.exe -- distribution Douwe-Main-Wsl

:: Start specific WSL instance for other Windows user.
ssh.exe -i id_ed25519-auto delta@127.0.0.2
wsl.exe -- distribution Delta-Main-Wsl

:: Start specific WSL instance for other Windows user in background.
Start-BackgroundJob wsl.exe '--distribution $Delta-Main-Wsl'

6. Configuration

Enter the following commands at a Command Line.

sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get autoremove
sudo apt-get autoclean

cat /etc/debian_version
sudo apt-get install openssh-server

7. Networking

Contents of C:\Users\<User>\.wslconfig file.

[wsl2]
#vmSwitch="WSL (Hyper-V firewall)"
#networkingMode=bridged
#networkingMode=nat
networkingMode=mirrored

# Explicitly enable DNS tunneling behavior to improve name resolution under complex host networking.
dnsTunneling=true

# Tell WSL to adopt Windows' HTTP proxy settings automatically.
autoProxy=true

# Ensure WSL traffic is subject to the Hyper‑V firewall integration (recommended unless you have a specific reason to disable it).
firewall=true

8. Configuration

See https://linux-training.be/security/ch06.html.
See https://linux-training.be/security/ch07.html.
See https://linux-training.be/security/ch08.html.

Enter the following commands at a Command Line.

sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get autoremove
sudo apt-get autoclean

cat /etc/debian_version

sudo useradd --comment "Delta"         --create-home --shell /bin/bash delta
sudo useradd --comment "Douwe"         --create-home --shell /bin/bash douwe
sudo useradd --comment "Douwe Kiestra" --create-home --shell /bin/bash douwe
sudo passwd delta
sudo passwd douwe

# See https://unix.stackexchange.com/questions/507571/how-to-allow-folder-permission-for-another-user-in-linux
# Create a group shared and add users delta and douwe to it.
sudo groupadd shared
sudo usermod --append --groups shared delta
sudo usermod --append --groups shared douwe
sudo usermod --append --groups shared www-data

sudo mkdir --parents          /home/data
sudo chmod 2770               /home/data
sudo chgrp --recursive shared /home/data

sudo mkdir --parents           /var/www/html/docs
sudo chmod 2770                /var/www/html/docs
sudo chgrp ---recursive shared /var/www/html/docs

scp -p delta@10.10.1.2:/media/Windows/Software/_Delta/delta-linux-tools-1.9.1-1-all.deb .
sudo dpkg -i delta-linux-tools-1.9.1-1-all.deb

sudo delta config bash                          # Configure bash shell for each user.
sudo delta config cron                          # Configure cron jobs.
sudo delta config editor                        # Set default editor to vim.tiny for each user.
sudo delta config locale                        # Configure locale settings.

sudo delta setup openssh                        # Install and configure openssh server.

sudo passwd                                     # Set root password.
sudo delta setup sudo                           # Install and configure sudo for each user.

sudo delta setup ntp                            # Install and configure network time.
sudo delta setup rsyslog                        # Install and configure rsyslog logging daemon.
sudo delta setup timezone                       # Install and configure time zone.

sudo delta setup basic-tools                    # Install basic commands like curl and wget.
sudo delta setup ufw                            # Install and configure uncomplicated firewall.
sudo delta setup vim                            # Install and configure vim editor for each user.

Restart the computer.

9. Documentation

Enter the following commands at a Command Line.

sudo apt-get --yes install devscripts           # Needed for checkbashisms.
sudo apt-get --yes install gawk                 # Needed for ansi2html.
sudo apt-get --yes install make
sudo apt-get --yes install python3
sudo apt-get --yes install shellcheck           # Needed for shellcheck.
sudo apt-get --yes install colorized-logs       # Needed for ansi2html, used by search.
sudo apt-get --yes install fonts-thai-tlwg      # Thai fonts.


sudo delta setup apache                         # Install and configure apache http server.
sudo apt-get --yes install libharfbuzz0b        # Needed  for jre-headless.

sudo delta setup jre-headless                   # Needed for diagrams support.
sudo delta setup php                            # Needed for search.
sudo delta setup ruby                           # Needed for asciidoctor.


# Manual.
sudo apt-get install --yes default-jre-headless
sudo apt-get install --yes php php-curl php-gd php-mbstring php-mysql php-pgsql php-xml
sudo apt-get install --yes ruby

# Save file with list of pre-installed gems.
file="/root/rubygems.org"
if [ ! -f "${file}" ]; then
  gem list > "${file}"
fi



sudo delta setup vim                            # Install and configure vim editor for each user.
sudo    delta config vim powershell             # Add powershell syntax highlighting.

sudo    delta setup asciidoctor
sudo    delta update asciidoctor


# Manual.
gem install asciidoctor
gem install asciidoctor-diagram
gem install asciidoctor-diagram-ditaamini
gem install --prerelease asciidoctor-pdf
gem install --prerelease asciidoctor-tabs
gem install gem-path
gem install pygments.rb

gem update asciidoctor
gem update asciidoctor-diagram
gem update asciidoctor-diagram-ditaamini
gem update --prerelease asciidoctor-pdf
gem update --prerelease asciidoctor-tabs
gem update gem-path
gem update pygments.rb


which asciidoctor asciidoctor-pdf
asciidoctor --version                           # 2.0.26
asciidoctor-pdf --version                       # 2.3.24

sudo mkdir -p /var/www/html/docs
ls -ald /var/www/html/docs                              # drwxr-xr-x 2 root root 4096 2026-04-06 19:46:35 /var/www/html/docs
curl --silent http://localhost | grep -i "it works!"    # It works!
sudo make clean
sudo make                                               # make: check-adoc-links: No such file or directory
                                                        # make: check-adoc-syntax: No such file or directory
# Temp fix for missing check-adoc-links and check-adoc-syntax commands.
sudo touch    /usr/local/bin/check-adoc-links
sudo touch    /usr/local/bin/check-adoc-syntax
sudo chmod +x /usr/local/bin/check-adoc-links
sudo chmod +x /usr/local/bin/check-adoc-syntax




sudo ufw allow http
sudo ufw status verbose
# Browse to http://185.62.58.28
# Browse to http://185.62.58.28/docs
# Browse to http://deltasoftware.frl
# Browse to http://deltasoftware.frl/docs




sudo delta setup git
mkdir -p ~delta/github/git/delta-software-labs
cd ~delta/github/git/delta-software-labs
mkdir -p /home/data/github/git/delta-software-labs
cd /home/data/github/git/delta-software-labs
git clone https://delta-software-labs@github.com/delta-software-labs/Documentation.git
# Type the GitHub - PAT (Personal Access Token) stored in KeePass Password Manager.

cd ~delta/github/git/delta-software-labs/Documentation
make clean; make
make check

Browse to http://localhost/docs to view the documentation.

10. Proton Mail

See https://ndo.dev/posts/headless_protonbridge.
See https://github.com/ProtonMail/proton-bridge.
See https://github.com/emersion/hydroxide.

11. Change User Name

Enter the following commands at a Command Prompt with standard privileges.

wsl.exe -d Debian -u root usermod -l delta smru
wsl.exe -d Debian -u root groupmod -n delta smru
wsl.exe -d Debian -u root usermod -d /home/delta -m delta

12. Problems

See *https://support.atlassian.com/bitbucket-cloud/kb/git-command-returns-fatal-error-detected-dubious-ownership[^].

# Log in as douwe.
cd /home/data/github/git/delta-software-labs/Documentation
ls -ald
# Notice that directory is owned by user delta.
git status
# Notice the fatal error.

drwxrwsr-x 35 delta shared 4096 2026-02-10 11:45:30 .

fatal: detected dubious ownership in repository at '/home/data/github/git/delta-software-labs/Documentation'
To add an exception for this directory, call:

        git config --global --add safe.directory /home/data/github/git/delta-software-labs/Documentation

13. Cosmic DE

Enter the following commands at a Command Prompt with administrative privileges.
```
wsl.exe --update
```

See https://software.opensuse.org/download/package?package=cosmic-osd&project=home%3Anomispaz%3Adebian%3Acosmic-desktop

apt-get install curl gpg

echo 'deb http://download.opensuse.org/repositories/home:/nomispaz:/debian:/cosmic-desktop/Debian_13/ /' |
  sudo tee /etc/apt/sources.list.d/home:nomispaz:debian:cosmic-desktop.list
curl -fsSL https://download.opensuse.org/repositories/home:nomispaz:debian:cosmic-desktop/Debian_13/Release.key |
  gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/home_nomispaz_debian_cosmic-desktop.gpg > /dev/null
sudo apt update
sudo apt install cosmic-session

Install VirtualBox Guest Additions.

mkdir -p /mnt/cdrom
mount -t iso9660 -o ro /dev/sr0 /mnt/cdrom
cp -a /mnt/cdrom/VBoxLinuxAdditions.run /opt
umount /mnt/cdrom
apt-get install gcc make perl
apt-get install linux-headers-$(uname -r)

Restart the computer.

See https://github.com/olafkfreund/cosmic-ext-rdp-server.

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

sudo apt install libpipewire-0.3-dev libei-dev libwayland-dev libxkbcommon-dev \
  libglib2.0-dev libfontconfig-dev libfreetype-dev libgl-dev libegl-dev \
  libvulkan-dev libdbus-1-dev libgbm-dev clang

sudo apt install libwayland-dev libxkbcommon-dev libinput-dev libegl-dev \
  libgl-dev libseat-dev libei-dev libsystemd-dev libfontconfig-dev \
  libpixman-1-dev libdisplay-info-dev clang

sudo apt-get install just
just  --version                 # just 1.40.0

# The cosmic-ext-rdp-server repo needs rustc => 1.89
# The cosmic-ext-comp-rdp repo needs rustc => 1.90

# See https://linuxcapable.com/how-to-install-rust-on-debian-linux
sudo apt install curl ca-certificates build-essential
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
# Type 1 or press Enter to accept the default stable toolchain.
# Type 2 if you want to customize the installation profile or default toolchain.
# Type 3 to cancel without changing the system.
source ~/.cargo/env

cargo --version                 # cargo 1.94.0 (85eff7c80 2026-01-15)
rustc --version                 # rustc 1.94.0 (4a4ef493e 2026-03-02)

mkdir -p ~/debian/source
cd ~/debian/source
git clone https://github.com/olafkfreund/cosmic-ext-rdp-server.git
git clone https://github.com/olafkfreund/xdg-desktop-portal-cosmic.git
git clone https://github.com/olafkfreund/cosmic-ext-comp-rdp.git

cd ~/debian/source/cosmic-ext-rdp-server
cargo build --release
ls -al target/release
sudo just install-all

cd ~/debian/source/xdg-desktop-portal-cosmic
cargo build --release
ls -al target/release
sudo make install

cd ~/debian/source/cosmic-ext-comp-rdp
cargo build --release
ls -al target/release
sudo install -Dm0755 target/release/cosmic-comp /usr/bin/cosmic-comp

# Create folder for configuration.
mkdir -p .config/cosmic-ext-rdp-server

Contents of the ~/.config/cosmic-ext-rdp-server/config.toml file.

# 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 = ""
enable = true
username = "delta"
password = "<level 2>"
# 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

Quick start.

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

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

cosmic-ext-rdp-server --addr 0.0.0.0 --port 3389

2026-03-18T13:14:41.869459Z  INFO rdp_dbus::config: Configuration loaded path="/home/delta/.config/cosmic-ext-rdp-server/config.toml"
2026-03-18T13:14:41.877720Z  INFO cosmic_ext_rdp_server::dbus: D-Bus server started service="io.github.olafkfreund.CosmicExtRdpServer"
2026-03-18T13:14:41.878060Z  INFO cosmic_ext_rdp_server::tls: Generating self-signed TLS certificate
2026-03-18T13:14:41.887884Z  INFO cosmic_ext_rdp_server: NLA authentication enabled username=delta
2026-03-18T13:14:41.887920Z  INFO cosmic_ext_rdp_server: Starting cosmic-ext-rdp-server bind=0.0.0.0:3389
2026-03-18T13:14:42.336180Z  WARN cosmic_ext_rdp_server: Failed to start screen capture: ScreenCast portal session failed
2026-03-18T13:14:42.336223Z  INFO cosmic_ext_rdp_server: Falling back to static blue screen display
2026-03-18T13:14:42.336229Z  INFO cosmic_ext_rdp_server: Clipboard sharing enabled
2026-03-18T13:14:42.336231Z  INFO cosmic_ext_rdp_server: Audio forwarding enabled (RDPSND) channels=2 sample_rate=44100
2026-03-18T13:14:42.337011Z  INFO cosmic_ext_rdp_server::egfx: EGFX: event sender configured
2026-03-18T13:14:42.337036Z  INFO cosmic_ext_rdp_server::server: NLA credentials configured username=delta
2026-03-18T13:14:56.996262Z  WARN rustls::msgs::handshake: Illegal SNI extension: ignoring IP address presented as hostname (3137322e32322e38382e313030)
2026-03-18T13:14:57.157629Z  INFO ironrdp_cliprdr: CLIPRDR(clipboard) virtual channel has been initialized
2026-03-18T13:14:57.157702Z  INFO cosmic_ext_rdp_server::clipboard: CLIPRDR channel ready
2026-03-18T13:14:57.163897Z  INFO cosmic_ext_rdp_server::sound: Starting audio capture for RDPSND channels=2 sample_rate=44100
2026-03-18T13:14:57.168373Z  INFO rdp_capture::audio_stream: PipeWire audio stream connected channels=2 sample_rate=44100
2026-03-18T13:14:57.171839Z  WARN cosmic_ext_rdp_server::clipboard: Failed to write to local clipboard: Unknown error while interacting with the clipboard: X11 server connection timed out because it was unreachable
2026-03-18T13:14:57.561716Z  INFO cosmic_ext_rdp_server::egfx: EGFX: channel ready negotiated=V10 { flags: CapabilitiesV10Flags(0x0) }

sudo systemctl --type=service ● cosmic-greeter.service loaded failed failed COSMIC Greeter * Comment out the Restart lines in the /usr/lib/systemd/system/cosmic-greeter.service file.

14. Nix

See https://nixos.org/download.

sh <(curl --proto '=https' --tlsv1.2 -L https://nixos.org/nix/install) --daemon

Restart the computer.

nix --version                   # nix (Nix) 2.34.1
nix-env --version               # nix-env (Nix) 2.34.1
nix-channel --version           # nix-channel (Nix) 2.34.1

nix-channel --help
nix-channel --list
nix-channel --add https://nixos.org/channels/nixpkgs-unstable
nix-channel --list

mkdir -p ~/.config/nix

Contents of the ~/.config/nix/nix.conf file.

extra-experimental-features = flakes
extra-experimental-features = nix-command

cd ~/debian/source/cosmic-ext-rdp-server
nix develop             # Enter dev shell with all dependencies.
just build-release      # Build release binary.
just test               # Run tests.
ls -al target/release
sudo just install-all

cd ~/debian/source/xdg-desktop-portal-cosmic
nix develop             # Enter dev shell with all dependencies.
make                    # Build release binary.
ls -al target/release
sudo make install

cd ~/debian/source/cosmic-ext-comp-rdp
nix develop             # Enter dev shell with all dependencies.
cargo build --release   # Build release binary.
ls -al target/release

# See https://nix-community.github.io/home-manager/index.xhtml#sec-install-standalone
cat config1
cat config2
cat config3
???

sudo install -Dm0755 target/release/cosmic-comp /usr/bin/cosmic-comp

Windows Subsystem for Linux 2

Home

1. Information

2. Preparation

3. Installation

4. Uninstallation

5. Start

6. Configuration

7. Networking

8. Configuration

9. Documentation

10. Proton Mail

11. Change User Name

12. Problems

13. Cosmic DE

14. Nix