Pourquoi J'ai no internet connexion on Ubuntu WSL while on a VPN?

[ForumBot]

J'ai un Ubuntu 20.04 Version 2 WSL running on my Windows 10 Laptop. Everything works fine, J'ai internet connection. But only as long as I am not connected to a VPN network.

If I connect to my the network of my university using Cisco AnyConnect, I can no longer connect to the internet on WSL, while everything works fine using e.g. Firefox in the Windows system. I get:

```
ping: google.de: Temporary failure in name resolution

```

I already tried the following:

Open Windows command in admin mode and type these commands:
`netsh winsock reset
netsh int ip reset all
netsh winhttp reset proxy
ipconfig /flushdns
reboot

```

That worked once, I had access to the internet. But dès que I disconnected the VPN connection and connected again, I had the same problem all over again. J'ai essayé de just execute the commands again and rebooted, but now that's not working anymore.

So I really do not know what else to do. I really need to use WSL while being connected via VPN.

[ForumBot]

There is an issue with DNS Forwarding in WSL2 when using VPN ([see github Issue](https://github.com/microsoft/WSL/issues/1350)). Plus there is a issue with the *Cisco AnyConnect*. So here is a workaround for these problems. Should work for Ubuntu and Debian.

## Solution de contournement (new - automatic)

This solution is automatic and was created by **EdwardCooke** (see [https://www.frakkingsweet.com/automatic-dns-configuration-with-wsl-and-anyconnect-client/](
12)). This is just the first part of his solution **updating resolv.conf when starting WSL.**

-

**Re-enable auto generation of resolv.conf** (if disabled)

by commented the disable with `#`

```
sudo nano /etc/wsl.conf

```

`#[network]
#generateResolvConf = false

```

-

**Create the script**
`sudo nano /bin/vpn-dns.sh

```

`#!/bin/bash

echo "Getting current DNS servers, this takes a couple of seconds"

/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe -Command '
$ErrorActionPreference="SilentlyContinue"
Get-NetAdapter -InterfaceDescription "Cisco AnyConnect*" | Get-DnsClientServerAddress | Select -ExpandProperty ServerAddresses
Get-NetAdapter | ?{-not ($_.InterfaceDescription -like "Cisco AnyConnect*") } | Get-DnsClientServerAddress | Select -ExpandProperty ServerAddresses
' | \
awk 'BEGIN { print "# Generated by vpn fix func on", strftime("%c"); print } { print "nameserver", $1 }' | \
tr -d '\r' > /etc/resolv.conf
clear

```

-

**Make it executable/run as sudo**
`sudo chmod +x /bin/vpn-dns.sh
echo "$(whoami) ALL=(ALL) NOPASSWD: /bin/vpn-dns.sh" | sudo tee /etc/sudoers.d/010-$(whoami)-vpn-dns

```

-

Make it **run** on **wsl startup**
`echo "sudo /bin/vpn-dns.sh" | sudo tee /etc/profile.d/vpn-dns.sh

```

You can also run it manually:
`sudo /bin/vpn-dns.sh`

## Workaround (old manual)

-

Find out nameserver with **Windows PowerShell** (during VPN Session)
`nslookup

```

You'll get the IPv4 address of your corporate nameserver
Copy this address.

-

Disable *resolv.conf* generation **in wsl:**
`sudo nano /etc/wsl.conf

```

copy this text to the file (to disable resolve.conf generation, when wsl starts up)
`[network]
generateResolvConf = false

```

-

**In wsl** Add your corporate nameserver to `resolv.conf`
`sudo nano /etc/resolv.conf

```

Remove other entries and add your corporate nameserver IP (if you have a secondary nameserver, add it in a separate line)

- `nameserver X.X.X.X` (where X.X.X.X is your address obtained in step 1)

-

Set your VPN adapter (if you have *Cisco AnyConnect*) **open a admin powershell**

- Find out your VPN adapter name: `Get-NetIPInterface` (in my case: `"Cisco AnyConnect"`)

- Set adapter metric (Replace -Match with your name), **in my case I have to run this after ever reboot or VPN reconnect**:

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

```

([Qu'est-ce que interface metric](https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/automatic-metric-for-ipv4-routes): Used to determine route, windows use interface with lowest metric)

-

Restart wsl **in PowerShell**: `wsl.exe --shutdown`

-

Test it **in wsl** run: `wget google.com` - if this command works, you are done.

In my case I get DNS issues when try to connect to internal stuff via browser (on Windows 10, f.e.: intranet), caused by the high metric value set in step 4 (basically kind of disabling VPN Route). So here is the workaround for the workaround:

- Check your default metric (of VPNs Interface) **in PowerShell** (replace -Match with your interface name)

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

```

- When running into problems on Windows 10 restore this default value with **admin powershell** (replace value at the end with your default value):

`Get-NetAdapter | Where-Object {$_.InterfaceDescription -Match "Cisco AnyConnect"} | Set-NetIPInterface -InterfaceMetric 1

```