PowerShell Boolean

Question

    $e = $ErrorActionPreference
    $ErrorActionPreference="stop"
    $E_Subnet_1 = '10.0.1'
    $E_Subnet_2 = '10.0.2'
    $O_Subnet_1 = '10.11.1'
    $O_Subnet_2 = '10.11.2'
    $D_Subnet_1 = '10.12.1'
    $D_Subnet_2 = '10.12.2'
    $Ethernet0 = 'Ethernet0'
    $All_Subnets = @("$E_Subnet_1", "$E_Subnet_2", "$O_Subnet_1",
                     "$O_Subnet_2", "$D_Subnet_1", "$D_Subnet_2")

    $result = (Get-NetAdapter |
                    ? status -eq 'up' |
                    Get-NetIPAddress -ErrorAction 0 |
                    ? PrefixOrigin -eq 'Manual' |
                    ? IPAddress -match $All_Subnets |
                   foreach { $Ethernet0 -eq $_.InterfaceAlias})

    Write-Host "interface_alias=$result"

If you will please consider the PowerShell snippet above which queries the network interfaces and based on the matching subnet it then checks if the interface name equals "Ethernet0" producing a boolean value.

The IPAddress of the server I am currently working matches the first three octets of $D_Subnet_1 and produces a value of interface_alias=True if I target $D_Subnet_1 like this:

    $result = (Get-NetAdapter |
                    ? status -eq 'up' |
                    Get-NetIPAddress -ErrorAction 0 |
                    ? PrefixOrigin -eq 'Manual' |
                    ? IPAddress -match $D_Subnet_1 |
                    foreach { $Ethernet0 -eq $_.InterfaceAlias})

    Write-Host "interface_alias=$result"

But if I try to run the command using the $All_Subnets array:

    $result = (Get-NetAdapter |
                    ? status -eq 'up' |
                    Get-NetIPAddress -ErrorAction 0 |
                    ? PrefixOrigin -eq 'Manual' |
                    ? IPAddress -match $All_Subnets |
                    foreach { $Ethernet0 -eq $_.InterfaceAlias})

    Write-Host "interface_alias=$result"

It just produces interface_alias= with no value at all.

I have tried swapping -match for -contain and like with no luck. How can I fix this?

Answer 1

You're using the wrong comparisons here:

Where-Object -Property 'IPAddress' -Match @('10.30.2','10.40.2')

You need to grab the first 3 octets to do this comparison properly:

Where-Object -FilterScript { $_.IPAddress.Substring(0, $_.IPAddress.LastIndexOf('.')) -in $All_Subnets }

And if you're not on version 3+, just swap the comparison's sides and change the operator to -contains