pull Windows DNS from WSL

readme.md

content

there is two scripts:

• powershell dns.ps1
• bash dns.sh

how it works

the bash script dns.sh (ran from WSL) calls the powershell script dns.ps1 wich retrieves the DNS informations

you can write directly its output to resolv.conf (as root):

./dns.sh > /etc/resolv.conf

requirements

• configure in dns.sh line 5 the absolute path to the powershell script
• JQ is required : apt install jq

dns.ps1

# Discover things and create an $Entries object.
$NetworkInterfaces  = Get-NetIPInterface -AddressFamily IPv4 | Where-Object ConnectionState -EQ 'Connected' | Where-Object NlMtu -LT 9001
$DNSServerAddresses = Get-DnsClientServerAddress -AddressFamily IPv4
$DNSClients = Get-DnsClient

$Entries = $NetworkInterfaces | ForEach-Object {
  [PSCustomObject]@{
    'InterfaceAlias'      = $_.InterfaceAlias
    'InterfaceIndex'      = $_.InterfaceIndex
    'InterfaceMetric'     = $_.InterfaceMetric
    'DNSServerAddresses'  = ($DNSServerAddresses | Where-Object InterfaceIndex -EQ $_.InterfaceIndex | Where-Object AddressFamily -EQ 2).ServerAddresses
    'DNSSuffixes'  =  @(($DNSClients | Where-Object InterfaceIndex -EQ $_.InterfaceIndex).ConnectionSpecificSuffix) + @(($DNSClients).ConnectionSpecificSuffixSearchList | Out-Null)
  }
} | Sort-Object InterfaceMetric -Unique



$array_suffixes = (Get-DnsClientGlobalSetting).SuffixSearchList
$array_servers = $Entries.DNSServerAddresses | select -Unique

$jsonBase = @{}
$jsonBase.Add("servers",$array_servers)
$jsonBase.Add("suffixes",$array_suffixes)
$jsonBase | ConvertTo-Json -Compress

dns.sh

#!/bin/bash

POWERSHELL=/mnt/c/WINDOWS/System32/WindowsPowerShell/v1.0/powershell.exe

JSON=$($POWERSHELL 'C:\Users\change-me!!\Documents\dns.ps1')

SUFFIXES=$(jq -r '.suffixes | join(",")' <<< "$JSON")

for server in $(jq -r '.servers[]' <<< "$JSON"); do
        echo "nameserver $server"
done
echo "search $SUFFIXES"