Determine the active IP address on a Windows machine with PowerShell. http://uglygizmo.blogspot.com.au/

Get-ActiveIP.ps1

<# 
    .Synopsis
    Returns IPv4 address details for the local machine.
    Information is gathered from the active interface being used by the default route.
#>
[CmdletBinding()]
[OutputType([string])]
Param ()

Write-Verbose -Message ("Begin: " + $MyInvocation.MyCommand.Path)

<#
    .Synopsis
    This function uses regular expressions to return the first IPv4
    dotted decimal notation string in the list of strings passed.
#>
function Get-First
{
    [CmdletBinding()]
    [OutputType([string])]
    Param( $List )
    [Regex]$reg = "\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}"
    $result = ""
    foreach ($ip in $List)
    {
        $match = $reg.Match($ip)
        if ($match.Success)
        {
            $result = $match.Groups[0].Value
            break
        }
    }
    $result
}

Write-Verbose -Message "Getting the interface index being used by the default route."
$NICIndex = Get-CimInstance -ClassName Win32_IP4RouteTable |
    Where-Object { $_.Destination -eq "0.0.0.0"-and $_.Mask -eq "0.0.0.0" } |
    Sort-Object Metric1 |
    Select-Object -First 1 |
    Select-Object -ExpandProperty InterfaceIndex

Write-Verbose -Message "Getting the default route network adapter configuration."
$AdapterConfig = Get-CimInstance -ClassName Win32_NetworkAdapter |
    Where-Object { $_.InterfaceIndex -eq $NICIndex } |
    Get-CimAssociatedInstance -ResultClassName Win32_NetworkAdapterConfiguration

Write-Verbose -Message "Populating a custom PSObject with the desired details."
$ipconfig = [PSCustomObject]@{Description = $AdapterConfig.Description;
                              MACAddress = $AdapterConfig.MACAddress;
                              Address = (Get-First $AdapterConfig.IPAddress);
                              NetMask = (Get-First $AdapterConfig.IPSubnet);
                              Gateway = (Get-First $AdapterConfig.DefaultIPGateway);
                              DHCPServer = $AdapterConfig.DHCPServer;
                              DNSHostName = $AdapterConfig.DNSHostName;
                              DNSDomain = $AdapterConfig.DNSDomain;
                              DNSSearch = $AdapterConfig.DNSDomainSuffixSearchOrder}

# Return the result.
$ipconfig
    
Write-Verbose -Message ("End: " + $MyInvocation.MyCommand.Path)

This is a little easier now. Drop the following into a script:

$defaultRouteNic = Get-NetRoute -DestinationPrefix 0.0.0.0/0 | Sort-Object -Property RouteMetric | Select-Object -ExpandProperty ifIndex
$ipv4 = Get-NetIPAddress -AddressFamily IPv4 -InterfaceIndex $defaultRouteNic | Select-Object -ExpandProperty IPAddress
Return $ipv4

Or even more compact

(Get-NetIPAddress -InterfaceIndex (Get-NetIPInterface -ConnectionState Connected -InterfaceAlias "Ethernet*").ifIndex).IPv4Address

Hi @MichaelWerner,

That's not quite the same mate. You are making an assumption that there is only one ethernet interface in a connected state. As soon as you have multiple ethernet interfaces in a connected state, the order of interfaces is unknown.

This is why my example has the default route component. We need the workout the interface which is being used by the default route with the lowest metric.

You are correct. I assume I have only one connection. This should be correct for most laptops or workstations but not for a server.

…

Sent from my iPhone

On Jan 6, 2021, at 7:26 PM, Grant Carthew ***@***.***> wrote: ***@***.*** commented on this gist. Hi @MichaelWerner, That's not quite the same mate. You are making an assumption that there is only one ethernet interface in a connected state. As soon as you have multiple ethernet interfaces in a connected state, the order of interfaces is unknown. This is why my example has the default route component. We need the workout the interface which is being used by the default route with the lowest metric. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.