Windows Subsystem for Linux: error fetching identities: communication with agent failed with keys from KeepassXC

Question

My ssh keys are stored in KeepassXC (version 2.7.1). I've enabled the SSH Agent integration in KeepassXC and have it use OpenSSH. I tried using Pageant and with "Use both agents" but it doesn't work as it fails to connect to the ssh agent. The KeepassXC is installed on my Windows 10.

I have OpenSSH Authentication Agent running, started and on automatic. With all of this setup, I can see that the keys are loaded by doing ssh-add -l in my powershell.

Following the README guide from this repo https://github.com/rupor-github/wsl-ssh-agent, I have:

• Installed socat in WSL2
• Installed wsl-ssh-agent.exe and running in Windows 10.
• Stored npiperelay.exe in Windows 10 partition (currently in Documents folder).
• And added to the bottom of my .zshrc file:

export SSH_AUTH_SOCK=$HOME/.ssh/agent.sock

ss -a | grep -q $SSH_AUTH_SOCK
if [ $? -ne 0 ]; then
        rm -f $SSH_AUTH_SOCK
        (setsid socat UNIX-LISTEN:$SSH_AUTH_SOCK,fork EXEC:"/mnt/c/Users/myusername/Documents/wsl-ssh-agent/npiperelay.exe -ei -s //./pipe/openssh-ssh-agent",nofork &) >/dev/null 2>&1
fi

• Ran and restarted my shell with exec zsh or closed and reopened my terminal and tested with ssh-add -l but I get this error message:

error fetching identities: communication with agent failed

I have also tried restarting my KeepassXC and OpenSSH agent service, same error. But I can confirm that the keys are still loaded via my powershell with ssh-add -l.

What am I doing wrong?

Update: My WSL2 is a Debian.

> cat /etc/debian_version
11.3
> ssh -V
OpenSSH_8.4p1 Debian-5, OpenSSL 1.1.1n  15 Mar 2022

My Windows 10

PS C:\WINDOWS\system32> ssh -V
OpenSSH_for_Windows_8.1p1, LibreSSL 3.0.2

Could it be because of the OpenSSH version difference causing the problem?

Update2:

I was able to update my OpenSSH in Windows 10 to the latest version thanks to an answer at a separate question here: https://superuser.com/a/1609071/830668

PS C:\WINDOWS\system32> ssh -V
OpenSSH_for_Windows_8.9p1, LibreSSL 3.0.2

Restarted and tested, the error persists.

Answer 1

This may be an issue with WSL2 interoperability if you have enabled systemd support in WSL.

Check whether /etc/wsl.conf specifies systemd=true in the [boot] section.

If systemd is enabled, you can refer to Microsoft/WSL - Issue 8843 which suggests a mitigation to restore interoperability:

sudo sh -c 'echo :WSLInterop:M::MZ::/init:PF > /usr/lib/binfmt.d/WSLInterop.conf'