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rated 0 times [  2] [ 0]  / answers: 1 / hits: 14292  / 2 Years ago, sat, november 12, 2022, 12:31:38

so I was having issues with domain resolution with WSL whenever I use the VPN. I would get this:


ping: google.com: Temporary failure in name resolution

I tried following instructions from these answers Temporary Failure in name resolution on WSL


Specifically from this part:




  1. Inside WSL2, create or append 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


    echo "[network]" | sudo tee /etc/wsl.conf
    
echo "generateResolvConf = false" | sudo tee -a /etc/wsl.conf


  3. In a cmd window, run wsl --shutdown



  4. Start WSL2



  5. Run the following inside WSL2


    sudo rm -rf /etc/resolv.conf
    
sudo cat << EOF > /etc/resolv.conf
    
search [yourbase.domain.local]
    
nameserver 8.8.8.8
    
nameserver 1.1.1.1
    
EOF




However, I cannot seem to be able to edit the file /etc/resolv.conf as I would get zsh: permission denied: /etc/resolv.conf


I also don't know what it means [yourbase.domain.local] or with what I should be replacing it. I already messed up my domain resolution, and now I get the first error every time, even when my laptop is not connected to the VPN. I really need to know how to fix the config files that I modified


Edit: using muru's suggestion from the comments, I was able to fix the domain resolution with the command


sudo tee /etc/resolv.conf <<EOF

However, I'd like to know if there is a solution for this error when I connect to a VPN. Since none of the solutions from the mentioned link didn't work for me.


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 Answers
2

Well, it's a different potential solution than I've seen before, but it's worked for some folks. I'm no longer on Cisco VPN, so I can't test it, but ...


There are two parts to resolving the issue:



  • Fix Internet Connectivity

  • Fix DNS resolution


In the comments, you confirmed that you also can't ping 8.8.8.8, which may mean that you haven't resolved the first part. However, I do see in this Github comment that ping just won't work at all with some AnyConnect settings, so perhaps that's not the best indicator.


Try:


wget https://$(powershell.exe -c "(Resolve-DnsName -type a askubuntu.com)[0] | Select-Object -ExpandProperty IPAddress" | tr -d '

')

That's going to use PowerShell to resolve the IP Address for Ask Ubuntu, then attempt to wget from it. It should fail, but you should get back:


ERROR: cannot verify 151.101.129.69's certificate, issued by ‘CN=R3,O=Let's Encrypt,C=US’:

...

If not, then you probably really haven't resolve the connection issue. And until that is fixed, DNS resolution definitely won't work.


Try the 4th command there:


Get-NetAdapter | Where-Object {$_.InterfaceDescription -Match "Cisco AnyConnect"} | Set-NetIPInterface -InterfaceMetric 6000

Then try the wget above again. Any difference?


If not, then try (in this order):



  • Exit Ubuntu



  • Disconnect AnyConnect



  • wsl --shutdown from POwerShell



  • Start Ubuntu



  • Connect to AnyConnect



  • Run (again):


    In PowerShell:


    Get-NetAdapter | Where-Object {$_.InterfaceDescription -Match "Cisco AnyConnect"} | Set-NetIPInterface -InterfaceMetric 6000

    In Ubuntu:


    wget https://$(powershell.exe -c "(Resolve-DnsName -type a askubuntu.com)[0] | Select-Object -ExpandProperty IPAddress" | tr -d '
    
')



If you do then have Internet connection, then follow the rest of the steps to try to fix the DNS resolution.


But for some users, this continues to be a problem.


Also see this gist for what may be a better guide. It's the same overall information, but slightly different order and implementation.


Possible Alternative - Run Ubuntu in WSL1

If your use-case for WSL supports it, WSL1 will typically run without issues when connect to a VPN. You can convert the instance from PowerShell via:


wsl -l -v

# Confirm distribution name, adjust commands as needed

wsl --export Ubuntu windowspath	osaveubuntu.tar

wsl --set-version Ubuntu 1

Or, if you'd like, you can wsl --import that backup into a new instance WSL1 instance via wsl --import UbuntuWSL1 location orinstance path oubuntu.tar --version 1


[#636] Saturday, November 12, 2022, 2 Years  [reply] [flag answer]
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