PowerShell Azure – Get First Available IP From IP Range

If you build virtual machines in Azure you may find this script useful.

Currently it’s not the fastest it could likely be if you have a large subnet but it works for my needs.

It mixes two resources to make what I needed.

Resources:
1. List IP addresses in a range (Microsoft – https://gallery.technet.microsoft.com/scriptcenter/List-the-IP-addresses-in-a-60c5bb6b)
2. Check IP Addresses Available in Azure Virtual Network (IT Pro Windows – http://windowsitpro.com/azure/check-ip-addresses-available-azure-virtual-network)

function Get-IPrange
    {
        <# 
            .SYNOPSIS  
                Get the IP addresses in a range 
            .EXAMPLE 
                Get-IPrange -start 192.168.8.2 -end 192.168.8.20 
            .EXAMPLE 
                Get-IPrange -ip 192.168.8.2 -mask 255.255.255.0 
            .EXAMPLE 
                Get-IPrange -ip 192.168.8.3 -cidr 24 
        #> 
 
        param 
        ( 
          [string]$start, 
          [string]$end, 
          [string]$ip, 
          [string]$mask, 
          [int]$cidr 
        ) 
 
        function IP-toINT64 () { 
          param ($ip) 
 
          $octets = $ip.split(".") 
          return [int64]([int64]$octets[0]*16777216 +[int64]$octets[1]*65536 +[int64]$octets[2]*256 +[int64]$octets[3]) 
        } 
 
        function INT64-toIP() { 
          param ([int64]$int) 

          return (([math]::truncate($int/16777216)).tostring()+"."+([math]::truncate(($int%16777216)/65536)).tostring()+"."+([math]::truncate(($int%65536)/256)).tostring()+"."+([math]::truncate($int%256)).tostring() )
        } 
 
        if ($ip) {$ipaddr = [Net.IPAddress]::Parse($ip)} 
        if ($cidr) {$maskaddr = [Net.IPAddress]::Parse((INT64-toIP -int ([convert]::ToInt64(("1"*$cidr+"0"*(32-$cidr)),2)))) } 
        if ($mask) {$maskaddr = [Net.IPAddress]::Parse($mask)} 
        if ($ip) {$networkaddr = new-object net.ipaddress ($maskaddr.address -band $ipaddr.address)} 
        if ($ip) {$broadcastaddr = new-object net.ipaddress (([system.net.ipaddress]::parse("255.255.255.255").address -bxor $maskaddr.address -bor $networkaddr.address))} 
 
        if ($ip) { 
          $startaddr = IP-toINT64 -ip $networkaddr.ipaddresstostring 
          $endaddr = IP-toINT64 -ip $broadcastaddr.ipaddresstostring 
        } else { 
          $startaddr = IP-toINT64 -ip $start 
          $endaddr = IP-toINT64 -ip $end 
        } 
 
        for ($i = $startaddr; $i -le $endaddr; $i++) 
        { 
          INT64-toIP -int $i 
        }
    }

function Get-FirstAvailableIP
    {
        <# 
            .SYNOPSIS  
                Get the first available IP address in a range 
            .EXAMPLE 
                Get-FirstAvailableIP vNetworkName 10.60.0.128 26
        #> 
 
        param 
        ( 
          [string]$networkName,
          [string]$networkIP,
          [int]$networkCIDR 
        ) 
        $setIP=0

        foreach ($ip in $(Get-IPrange -ip $networkIP -cidr $networkCIDR))
        {
            $Address = Test-AzureStaticVNetIP -VNetName $networkName -IPAddress $ip
            If ($Address.IsAvailable –eq $False)
                {
                    #Write-Host "$ip is not available" -ForegroundColor Red
                }
            else
                {
                    #Write-Host "$ip is available" -ForegroundColor Green
                    $setIP=$ip
                    break
                }
        }

        Write-Output $setIP
    }