WSL picks up major update in September 2023 with new features

Microsoft releases update for its Windows Subsystem for Linux bringing new experimental features to improve networking, memory, and storage.

WSL September update
WSL September update
  • Windows Subsystem for Linux gets to version 2.0.0.
  • The update brings new experimental features to improve networking, memory, and storage.
  • You have to enable the new features manually after updating to the newest version.

Microsoft updates the Windows Subsystem for Linux (WSL) to version 2.0.0 with new features, changes, and various fixes. According to the official announcement, the features are available as “experimental,” and you have to choose to enable them manually.

In this new release of WSL, the development team is bringing features to shrink the virtual machine memory, automatically shrink the subsystem virtual hard disk (VHD), apply the Windows Firewall rules to the subsystem, and automatically make WSL use the operating system proxy information. In addition, there’s a new mirrored mode and new DNS Tunneling to improve network compatibility.

Windows Subsystem for Linux September update

You can enable and try these new features on WSL with the September 2023 update.

Reclaim memory automatically

The “autoMemoryReclaim” feature shrinks the virtual machine in memory. The feature detects whether the processor is idle for five minutes, and then the system will reclaim cached memory over time using the cgroup memory.reclaim feature. The only caveat is that the feature requires turning off “cgroups v1,” which can cause some issues.

The string of the feature is “autoMemoryReclaim,” and the available options include “gradual” and “dropcache.”

You can customize the idle detection, but Microsoft recommends using a bash script.

Sparse VHD

Since virtual drives for WSL can grow in size over time, the new “Sparse VHD” feature will help shrink the size. When using the new option, it’ll automatically configure a VHD as sparse, allowing the system to reduce the size of the drive.

The string of the feature is “sparseVhd,” and you can set it to “false” or “true.” Microsoft has also added a new wsl --manage DISTRO-NAME --set-sparse TRUE or FALSE command to configure the feature.

Mirrored networking mode

The “mirrored” networking mode aims to mirror the network interfaces from Windows 11 into Linux, adding new features and improving compatibility, including support for IPv6, localhost address (, and multicast, direct connection of WSL to the local network, and better VPN compatibility.

The string of the feature is “networkingMode,” and the default option is “NAT,” but you can choose the “mirrored” option.

DNS Tunneling

The “DNS Tunneling” feature resolved the issue of DNS calls being blocked by Windows 11. When using the tunneling feature, WSL can “resolve the DNS name request without sending a networking packet,” allowing better internet connectivity “even if you have a VPN, specific firewall setup, or other networking configurations.”

The string of the feature is “dnsTunneling,” and you can set it to “false” or “true.”

Firewall configuration

The new “Hyper-V Firewall” feature lets you quickly configure the WSL firewall settings. This means that once the option is enabled, any changes to the Microsoft Defender Firewall will apply to WSL. Alternatively, you can use the New-NetFirewallHyperVRule PowerShell command to create a rule that will only apply to the Windows Subsystem for Linux.

The string of the feature is “firewall,” and you can set it to “false” or “true.”

Proxy configuration

The new “Auto Proxy” option has been designed to apply the same HTTP proxy settings on Windows 11 into WSL without having to update the proxy setting in the subsystem, which can cause unwanted problems.

The string of the feature is “autoProxy,” and you can set it to “false” or “true.”

WSL fixes

As part of the fixes and improvements, in this update the GH 9231 Store WSL isn’t accessible from Session 0, and GUI apps now have Windows snapping with the keyboard support.

Turn on experimental features

The new mirrored networking mode, DNS Tunneling, and Hyper-V Firewall features are currently only available for devices enrolled on any of the channels of the Windows Insider Program. Also, the Auto Proxy is only available for Windows 11 22H2.

On WSL, to enable the new experimental features, you must create a “.wslconfig” file on the root of the profile folder (for example, C:\Users\UserName) and use the [experimental] section with each setting. For example, [experimental] autoMemoryReclaim=gradual.

If you don’t have the Windows Subsystem for Linux on your device, you can use the wsl --install command to install the components and the Ubuntu distro by default. Alternatively, you can run the wsl --update --pre-release command to install the latest review of the platform. You can also follow these instructions to install WSL.

In the case that you’re still using an older version of the platform, you can use the wsl --update to upgrade. These instructions will help update WSL on Windows 11. You can also check this guide to confirm the version of WSL installed on your computer.

About the author

Mauro Huculak is a Windows How-To Expert who started Pureinfotech in 2010 as an independent online publication. He has also been a Windows Central contributor for nearly a decade. Mauro has over 15 years of experience writing comprehensive guides and creating professional videos about Windows and software, including Android and Linux. Before becoming a technology writer, he was an IT administrator for seven years. In total, Mauro has over 21 years of combined experience in technology. Throughout his career, he achieved different professional certifications from Microsoft (MSCA), Cisco (CCNP), VMware (VCP), and CompTIA (A+ and Network+), and he has been recognized as a Microsoft MVP for many years. You can follow him on X (Twitter), YouTube, LinkedIn and Email him at [email protected].