Get-Ipv4SubnetInfo

This function will take an IP address and either a subnet mask, or a mask length, and return a custom object with information about that subnet. The information you get is basic stuff like network address, the first and the last usable addresses, the broadcast address etc. But it will also tell you the class of the address, as well as if it’s a private address or not. If run without any parameters it will try to get the needed information from the host you are running it on.

As always, if you discover any bugs, or have any ideas for future improvement, drop me a line in the comments section below!

function Get-Ipv4SubnetInfo {
<#
.SYNOPSIS
Get subnet information.
.DESCRIPTION
This function will return basic subnet information if given an IP address as well as either
a subnet mask, or a mask length.
.EXAMPLE
Get-Ipv4SubnetInfo -IPAddress '10.10.10.1' -SubnetMask '255.255.0.0'
.EXAMPLE
Get-Ipv4SubnetInfo -IPAddress '192.168.0.4' -MaskLength 16
.NOTES
Author: Øyvind Kallstad
Date: 28.04.2015
Version: 1.0
#>
[CmdletBinding(DefaultParameterSetName = 'SubnetMask')]
param (
[Parameter()]
[IPAddress] $IPAddress = ([System.Net.NetworkInformation.NetworkInterface]::GetAllNetworkInterfaces() | Where-Object {$_.OperationalStatus -eq 'Up' -and $_.NetworkInterfaceType -ne [System.Net.NetworkInformation.NetworkInterfaceType]::Loopback}).GetIPProperties().UnicastAddresses.Address.ToString(),
[Parameter(ParameterSetName = 'SubnetMask')]
[IPAddress] $SubnetMask = ([System.Net.NetworkInformation.NetworkInterface]::GetAllNetworkInterfaces() | Where-Object {$_.OperationalStatus -eq 'Up' -and $_.NetworkInterfaceType -ne [System.Net.NetworkInformation.NetworkInterfaceType]::Loopback}).GetIPProperties().UnicastAddresses.IPv4Mask,
[Parameter(ParameterSetName = 'MaskLength')]
[ValidateRange(0,32)]
[int] $MaskLength
)
function ConvertTo-IPAddressUInt32 {
param (
[Parameter()]
[ValidateNotNullOrEmpty()]
[string] $IPAddress
)
try {
$ip = [IPAddress]::Parse($IPAddress)
$ipBytes = $ip.GetAddressBytes()
[System.Array]::Reverse($ipBytes)
$output = [BitConverter]::ToUInt32($ipBytes,0)
}
catch {
Write-Warning $_.Exception.Message
}
Write-Output $output
}
function ConvertTo-IPAddress {
param (
[Parameter()]
[ValidateRange([System.UInt32]::MinValue, [System.UInt32]::MaxValue)]
[uint32] $IPAddress
)
try {
$ipBytes = [BitConverter]::GetBytes($IPAddress)
[System.Array]::Reverse($ipBytes)
}
catch {
Write-Warning $_.Exception.Message
}
Write-Output ([IPAddress]$ipBytes)
}
function Get-IPv4AddressClass {
[CmdletBinding()]
param (
[Parameter(Position = 0)]
[IPAddress] $IPAddress
)
$ipBinary = ($IPAddress.GetAddressBytes() | ForEach-Object {[Convert]::ToString($_,2).PadLeft(8, '0') }) -join ''
switch Regex ($ipBinary) {
'^1111' {$class = 'E';break}
'^1110' {$class = 'D';break}
'^110' {$class = 'C';break}
'^10' {$class = 'B';break}
'^0' {$class = 'A';break}
}
Write-Output $class
}
function Test-Ipv4IsPrivate {
[CmdletBinding()]
param (
[Parameter(Position = 0)]
[IPAddress] $IPAddress
)
$private = $false
$ipBinary = ($IPAddress.GetAddressBytes() | ForEach-Object {[Convert]::ToString($_,2).PadLeft(8, '0') }) -join ''
if (($ipBinary -match '^1100000010101000') -or ($ipBinary -match '^101011000001') -or ($ipBinary -match '^0000101')) {
$private = $true
}
Write-Output $private
}
if ($PSCmdlet.ParameterSetName -eq 'SubnetMask') {
# convert the subnetmask to uint32
$smUint32 = ConvertTo-IPAddressUInt32 IPAddress $SubnetMask
# calculate mask length (CIDR) by converting the subnetmask to binary and counting the 1s
$SubnetMask.GetAddressBytes() | ForEach-Object {$cidr += [Convert]::ToString($_,2)}
$MaskLength = $cidr.TrimEnd('0').Length
}
else {
# create the subnetmask from the mask length, and convert to uint32
$smUint32 = [Convert]::ToUInt32($(('1' * $MaskLength).PadRight(32, '0')), 2)
$SubnetMask = ConvertTo-IPAddress IPAddress $smUint32
}
# convert the IP address
$ipUint32 = ConvertTo-IPAddressUInt32 IPAddress $IPAddress
# calculate the network and broadcast addresses of the subnet
$networkAddress = $ipUint32 -band $smUint32
$broadcastAddress = $ipUint32 -bor ((-bnot $smUint32) -band [UInt32]::MaxValue)
# calculate the first and the last address in the subnet
$firstIP = $networkAddress + 1
$lastIP = $broadcastAddress 1
$usableAddresses = $lastIP $networkAddress
Write-Output ([PSCustomObject] [Ordered] @{
NetworkAddress = (ConvertTo-IPAddress IPAddress $networkAddress)
SubnetMask = $SubnetMask
FirstAddress = (ConvertTo-IPAddress IPAddress $firstIP)
LastAddress = (ConvertTo-IPAddress IPAddress $lastIP)
BroadcastAddress = (ConvertTo-IPAddress IPAddress $broadcastAddress)
UsableAddresses = $usableAddresses
MaskLength = $MaskLength
AddressClass = (Get-IPv4AddressClass IPAddress $IPAddress)
IsPrivate = (Test-Ipv4IsPrivate IPAddress $IPAddress)
})
}

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