WSL 2 - Fix DNS Issues

README.md

Fix DNS Issues in WSL 2

This guide will help overcome the DNS issues present in WSL 2 while still making the Windows host IP autogenerated by WSL available for use. Note: this was tested on Windows 10 Build 2004, running Ubuntu 20.04 LTS in WSL 2.

• Open a WSL terminal

• Copy the contents of configure-wsl-dns.sh to /opt/configure-wsl-dns.sh:

  sudo nano /opt/configure-wsl-dns.sh

• Make it executable:

  sudo chmod +x /opt/configure-wsl-dns.sh

• Add a passwordless sudo entry in the file /etc/sudoers.d/configure-wsl-dns:

  %admin ALL = (root) NOPASSWD: /opt/configure-wsl-dns.sh
  

• Update ~/.zshrc or ~/.bashrc:

  # WSL networking
  sudo /opt/configure-wsl-dns.sh
  
  export $(</etc/wsl-host.env)
  
  # The env var 'WSL_HOST' is now available which
  # contains the IP of the host machine if you need
  # it for XServer setup etc.

• Exit and then go back into WSL terminal

configure-wsl-dns.sh

#! /usr/bin/env bash
set -e

resolvConfPath="/etc/resolv.conf"
resolvConfDirPath="/etc/resolvconf/resolv.conf.d"
resolvHeadConfPath="${resolvConfDirPath}/head"
wslHostEnvPath="/etc/wsl-host.env"

function writeResolvConf() {
  cat > "$1" <<- EOM
## Change the below as you see fit

# cloudflare
nameserver 1.1.1.1

# google
nameserver 8.8.8.8

# local
nameserver 192.168.0.1
EOM
}

function saveWslHostConfig() {
  rm -f "${wslHostEnvPath}"

  local wslHost=$(cat "${resolvConfPath}" | grep -v '#' | cut -d ' ' -f 2)

  printf "WSL_HOST=${wslHost}" > "${wslHostEnvPath}"
}

function main() {
  # exit if resolv.conf has already been patched
  grep 'generated by WSL' /etc/resolv.conf > /dev/null || exit 0

  saveWslHostConfig

  writeResolvConf "${resolvConfPath}"

  # if systemd is enabled - you will need this
  mkdir -p "${resolvConfDirPath}"
  writeResolvConf "${resolvHeadConfPath}"
}

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