Run systemd on WSL2 Distro

  • Ensure target WSL distro has latest updates applied
PS C:\> wsl -d kali-linux bash -c "sudo apt update && sudo apt upgrade"
  • Check current version of WSL
PS C:\> wsl --version
WSL version: 0.66.2.0
  • If running version is <0.67.6, download the latest *.msixbundle update for WSL from official git repo releases section
  • Install the .msixbundle
  • After installation is complete, check to ensure WSL has been updated
C:\>wsl --version
WSL version: 0.67.6.0
  • Add the following to /etc/wsl.conf WSL distro
└─$ cat /etc/wsl.conf
[boot]
systemd=true
  • shutdown the distro
PS C:\> wsl --terminate kali-linuxThe operation completed successfully.
  • Check systemd is running
PS C:\> wsl -d kali-linux$ ps 1PID TTY      STAT   TIME COMMAND
1 ? Ss 0:00 /lib/systemd/systemd --unit=graphical.target

Procedure Enabling systemd for WSL version <0.67.6

Objectives

  • Enable systemd on WSL2 Kali Linux distro using the one-script variant of the systemd hack for WSL2, sourced from git repo : https://github.com/diddledani/one-script-wsl2-systemd
  • Although the steps outlined in this article were tested against Kali, the hack should work with other WSL2 distributions
  • Refer to the documentation within git repo for further details on supported distributions

Assumptions

  • The script was tested on Windows 11 Pro, version 21H2 using Kali Linux, downloaded from Microsoft Store
[~]-> cat /etc/os-release
PRETTY_NAME="Kali GNU/Linux Rolling"
NAME="Kali GNU/Linux"
ID=kali
VERSION="2022.3"
VERSION_ID="2022.3"
VERSION_CODENAME="kali-rolling"
ID_LIKE=debian
ANSI_COLOR="1;31"
HOME_URL="https://www.kali.org/"
SUPPORT_URL="https://forums.kali.org/"
BUG_REPORT_URL="https://bugs.kali.org/"

Preparing WSL2 Distro

To simplify script deployment, passwordless sudo access for the target distribution username will be enabled.

Enable Passwordless sudo for WSL distro

  • To enable passwordless sudo, edit /etc/sudoers
sudo visudo
  • Append the following line, replacing kali with the default username associated with target WSL distro:
#includedir /etc/sudoers.d
...
kali ALL=(ALL:ALL) NOPASSWD:ALL
  • Save changes with Ctrl+S and exit using Ctrl+X.
  • Apply system updates
[~]-> sudo apt update \
&& sudo apt upgrade -y

Running the systemd Hack Script

  • From a Windows terminal, launch a PowerShell Administrator session
  • Note that Desktop edition of Powershell is used, i.e. PSEdition: Desktop
    ▪ Refer to the documentation on alternatives
  • Once within the session, change to an appropriate directory for saving the required script (to be downloaded in subsequent steps)
  • Run the following to install the wsl PowerShell module
PS C:\apps> Install-Module -Scope CurrentUser Wsl
PS C:\apps> Invoke-WebRequest -Uri 'https://raw.githubusercontent.com/diddledani/one-script-wsl2-systemd/main/install.ps1' -OutFile 'install.ps1'
  • Confirm the name of the target WSL distro, where systemd is to be enabled
PS C:\apps> wsl --list
Windows Subsystem for Linux Distributions:
....
kali-linux
  • Confirm the default username for the target distro
PS C:\apps> wsl -d kali-linux  "whoami"
kali
  • Run the systemd hack script, substituting the values of distro name and default username as obtained from the previous steps
    ▪ For the below example, distro name: kali-linux and default username: kali) are used
    ▪ Also, note that debug option has been enabled to allow for isolation and debugging of each process/command triggered by the installation script
PS C:\apps> powershell.exe -NoProfile -ExecutionPolicy Bypass -File install.ps1 -distro kali-linux -NoGPG -NoKernel -user kali --debug
  • Respond with Y for subsequent prompts
  • If there are no errors, the script should complete with the following message
Done.
You may now close this window...
  • Reboot WSL2
PS C:\apps> wsl --terminate kali-linux

Dealing with Errors during Script Execution

  • For any failures encountered, identify the cause and rerun the install script
  • For example, the following shows output of a failed run
DEBUG: --- Enabling custom systemd services in kali-linuxConfirm
Continue with this operation?
[Y] Yes [A] Yes to All [H] Halt Command [S] Suspend [?] Help (default is "Y"): Y
ln: failed to create symbolic link '/etc/systemd/system/sockets.target.wants/': No such file or directory
Wsl.exe returned exit code 1 from distro: kali-linux
  • After some troubleshooting, the cause is found to be a result of an attempt to create a symlink at a non-existent path, i.e.
[~]-> ls  /etc/systemd/system/sockets.target.wants/
ls: cannot access '/etc/systemd/system/sockets.target.wants/':
No such file or directory
  • To resolve the issue, logon to the WSL distro, and manually create the path
Windows PowerShell
Copyright (C) Microsoft Corporation. All rights reserved.
PS C:\apps> wsl -d kali-linux bash[/mnt/c/apps]-> sudo mkdir -p /etc/systemd/system/sockets.target.wants/[/mnt/c/apps]-> exit
exit
  • Attempt to rerun the installation script once again:
PS C:\apps> powershell.exe -NoProfile -ExecutionPolicy Bypass -File install.ps1 -distro kali-linux -NoGPG -NoKernel -user kali --debug
  • Continue responding Y to prompts, and if all goes well, the script should complete with the following message
Done.
You may now close this window...
  • Reboot WSL2
PS C:\apps> wsl --terminate kali-linux

Confirming systemd is Running

  • Logon to the distro and check systemd is running
PS C:\apps> wsl -d kali-linux bashWaiting for systemd to finish booting
.
Systemd is ready. Logging in.
[~]-> ps 1
PID TTY STAT TIME COMMAND
1 ? Ss 0:00 /usr/lib/systemd/systemd --unit=multi-user.target

Troubleshooting systemd Services

  • Check if any systemd services have failed to launch and examine logs to detemine best approach for resolving
[~]-> sudo systemctl list-units --failed
  • Returns that service systemd-sysusers.service failed to load
UNIT                     LOAD   ACTIVE SUB    DESCRIPTION
systemd-sysusers.service loaded failed failed Create System Users
LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB = The low-level unit activation state, values depend on unit type.
1 loaded units listed.
  • Display the service status by running
[~]-> sudo systemctl status systemd-sysusers.service
  • The following shows the error related to the service
× systemd-sysusers.service - Create System Users
Loaded: loaded (/lib/systemd/system/systemd-sysusers.service; static)
Active: failed (Result: exit-code)
Docs: man:sysusers.d(5)
man:systemd-sysusers.service(8)
Process: 30 ExecStart=systemd-sysusers (code=exited, status=243/CREDENTIALS)
Main PID: 30 (code=exited, status=243/CREDENTIALS)
Notice: journal has been rotated since unit was started, output may be incomplete.
  • Quick web search returns the following link, which discusses a workaround: https://github.com/arkane-systems/genie/issues/190
  • The workaround involves adding a “drop in”/override for the service systemd-sysusers.service
  • To include the override, run edit for the service definition
[~]-> sudo systemctl edit systemd-sysusers.service
  • and add the following
[Service]
LoadCredential=
GNU nano 6.4 /etc/systemd/system/systemd-sysusers.service.d/.#override.conf88db274d3ba96c11 *         ### Editing /etc/systemd/system/systemd-sysusers.service.d/override.conf
### Anything between here and the comment below will become the new contents of the file
[Service]
LoadCredential=
### Lines below this comment will be discarded### /lib/systemd/system/systemd-sysusers.service
  • Save changes and exit (ctrl+s followed by ctrl+x)
  • The override file should now have been created at /etc/systemd/system/systemd-sysusers.service.d/override.conf with the following contents:
[~]-> cat /etc/systemd/system/systemd-sysusers.service.d/override.conf
[Service]
LoadCredential=
  • Restart the systemd-sysusers.service service
[~]-> sudo systemctl restart systemd-sysusers.service
  • Check its status for errors
[~]-> sudo systemctl status systemd-sysusers.service
  • This shows the service is now running successfully
● systemd-sysusers.service - Create System Users
Loaded: loaded (/lib/systemd/system/systemd-sysusers.service; static)
Drop-In: /etc/systemd/system/systemd-sysusers.service.d
└─override.conf
Active: active (exited) since Sun 2022-09-25 16:56:04 AEST; 7s ago
Docs: man:sysusers.d(5)
man:systemd-sysusers.service(8)
Process: 676 ExecStart=systemd-sysusers (code=exited, status=0/SUCCESS)
Main PID: 676 (code=exited, status=0/SUCCESS)
  • Check for failed units
[~]-> sudo systemctl list-units --failed
UNIT LOAD ACTIVE SUB DESCRIPTION
0 loaded units listed.

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Tony Tannous

Tony Tannous

62 Followers

Learner. Interests include Cloud and Devops technologies.