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

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).