Function to calculate the start and end addresses

PowerShell Script

Use this function to calculate the start (host min) and end (host max) addresses from the provided Gateway and Subnet Mask.

#Mask
function Get-IPRange {
    param (
        [string]$gateway,
        [string]$subnetMask
    )

    # Check if the gateway and subnet mask are valid
    try {
        $ipAddress = [System.Net.IPAddress]::Parse($gateway)
        $ipMask = [System.Net.IPAddress]::Parse($subnetMask)
    } catch {
        Write-Warning "Invalid IP Address or Subnet Mask: Gateway = $gateway, MASK_KS = $subnetMask"
        return $null, $null
    }

    # Convert IP addresses and mask to bytes and reverse for conversion to UInt32
    $ipBytes = $ipAddress.GetAddressBytes()
    $maskBytes = $ipMask.GetAddressBytes()

    # Reverse the bytes to match the little-endian order expected by BitConverter
    [Array]::Reverse($ipBytes)
    [Array]::Reverse($maskBytes)

    # Convert the byte arrays to integers
    $ipAddressInt = [BitConverter]::ToUInt32($ipBytes, 0)
    $maskInt = [BitConverter]::ToUInt32($maskBytes, 0)

    # Calculate the network address and broadcast address
    $networkInt = $ipAddressInt -band $maskInt
    $broadcastInt = $networkInt -bor (-bnot $maskInt)

    # Calculate the start address (first host) and end address (last host)
    $startAddressInt = $networkInt + 1
    $endAddressInt = $broadcastInt - 1

    # Convert integers back to IP address format
    $startAddressBytes = [BitConverter]::GetBytes($startAddressInt)
    $endAddressBytes = [BitConverter]::GetBytes($endAddressInt)

    # Reverse the bytes again to match the expected IP address format
    [Array]::Reverse($startAddressBytes)
    [Array]::Reverse($endAddressBytes)

    # Convert byte arrays to IP address strings
    $startAddress = [System.Net.IPAddress]::Parse(($startAddressBytes -join '.'))
    $endAddress = [System.Net.IPAddress]::Parse(($endAddressBytes -join '.'))

    return $startAddress, $endAddress
}

Usage

# Example values for Gateway and Subnet Mask
$gateway = "192.168.1.1"       # Example Gateway address
$subnetMask = "255.255.255.0"  # Example Subnet Mask

# Call the Get-IPRange function with the example values
$startAddress, $endAddress = Get-IPRange -gateway $gateway -subnetMask $subnetMask

# Output the results to the console
Write-Host "Start Address (Host Min): $($startAddress.ToString())"
Write-Host "End Address (Host Max): $($endAddress.ToString())"

PowerShell Script on GitHub