Fix DNS resolution in WSL2

fix-wsl2-dns-resolution

More recent resolution:

1. cd ~/../../etc (go to etc folder in WSL).
2. echo "[network]" | sudo tee wsl.conf (Create wsl.conf file and add the first line).
3. echo "generateResolvConf = false" | sudo tee -a wsl.conf (Append wsl.conf the next line).
4. wsl --terminate Debian (Terminate WSL in Windows cmd, in case is Ubuntu not Debian).
5. cd ~/../../etc (go to etc folder in WSL).
6. sudo rm -Rf resolv.conf (Delete the resolv.conf file).
7. In windows cmd, ps or terminal with the vpn connected do: Get-NetIPInterface or ipconfig /all for get the dns primary and
secondary.
8. With the dns primary and secondary getted replace the numbers in the next step in the X.X.X.X
9. echo "nameserver X.X.X.X" | sudo tee resolv.conf (Create resolv.conf and append the line.)
10. echo "nameserver X.X.X.X" | sudo tee -a resolv.conf (Append the line in resolv.conf)
11. wsl --terminate Debian (Terminate WSL in Windows cmd, in case is Ubuntu not Debian).
12. sudo chattr +i resolv.conf
13. And finally in windows cmd, ps or terminal:
Get-NetAdapter | Where-Object {$_.InterfaceDescription -Match "Cisco AnyConnect"} | Set-NetIPInterface -InterfaceMetric 6000

Credit: @MartinCaccia, @yukosgiti, @machuu and @AlbesK:
https://github.com/microsoft/WSL/issues/4277
https://github.com/microsoft/WSL/issues/4246

---

Original resoltuion:

1. Create a file: /etc/wsl.conf.
2. Put the following lines in the file in order to ensure the your DNS changes do not get blown away

[network]
generateResolvConf = false

3. In a cmd window, run wsl --shutdown
4. Restart WSL2
5. Create a file: /etc/resolv.conf. If it exists, replace existing one with this new file.
6. Put the following line in the file

nameserver 8.8.8.8 # Or use your DNS server instead of 8.8.8.8 which is a Google DNS server

7. Repeat step 3 and 4. You will see git working fine now.

Credit: https://github.com/microsoft/WSL/issues/4285#issuecomment-522201021

In the wsl2 docs I noticed a comment on using Mirrored Networking mode being that it offers better compatibility with VPNs Maybe that's worth looking into for the complaints around the random subnets issue. Or not. Unsure. https://learn.microsoft.com/en-us/windows/wsl/networking#mirrored-mode-networking But either case had no issues with dns resolv.cof on wsl2 ubuntu lts 2024-04

Thanks so much! Please note that step 13 must be executed in an admin PowerShell.

Created an issue for
DNS resolution for internal sites doesn't work from inside WSL2 distros when using Global Secure Access Client as VPN.

microsoft/WSL#11745

@ThePlenkov solution worked best, specifying just one DNS of my VPN software resulted in slow queries, but with your command,
it dumped all valid nameservers into WSL and now curl: time_namelookup: 0.001621s

ThePlenkov

Thank you for the simplest solution. It worked like a charm.

I have found that with dnsTunneling=true in .wslconfig in windows and generateResolvConf=true in /etc/wsl.conf in wsl (both of which are now the defaults), DNS is working well for me. I had generateResolvConf=false from previous efforts to fix this, which was preventing dnsTunneling from working

dnsTunneling

The entire fix:

1. Create .wslconfig under %USERPROFILE%
2. Add:

[wsl2]
dnsTunneling=true

That's it. According to the documentation, it should be the default. Apparently it is not.

I have found that with dnsTunneling=true in .wslconfig in windows and generateResolvConf=true in /etc/wsl.conf in wsl (both of which are now the defaults), DNS is working well for me. I had generateResolvConf=false from previous efforts to fix this, which was preventing dnsTunneling from working

dnsTunneling

The entire fix:

1. Create .wslconfig under %USERPROFILE%
2. Add:

[wsl2]
dnsTunneling=true

That's it. According to the documentation, it should be the default. Apparently it is not.

I can confirm those posts. Enabling generateResolvConf=true again and putting dnsTunneling=true to .wslconfig works on Windows 11.

I use WSL2 2.4.10.0.
By using the proposed solution (default setup with the .wslconfig file), I see strange behaviour:
ping google.com works fine, however, after several minutes this command gives ping: connect: Network is unreachable in the output.

The wsl—- shutdown fixes the problem, but I have to do it repeatedly.

I have no VPN, just WiFi at home.

If anyone wants to propose changes to the gist, please provide a codebox with the desired state of the gist. (Perhaps we could do it in markdown) and I will gladly credit you for helping.

For Windows novices like me, you can cut-paste this to Powershell and press enter (thanks AI):

@"
[wsl2]
dnsTunneling=true
"@ | Set-Content -Path "$env:USERPROFILE\.wslconfig"

And remember to re-enable autogeneration of resolv.conf (within WSL), and restart WSL (again).