<# .SYNOPSIS Checks the given subnet mask for validity .DESCRIPTION check-subnet-mask.ps1 [

] .EXAMPLE PS> ./check-subnet-mask 255.255.255.0 ✔️ subnet mask 255.255.255.0 is valid .LINK https://github.com/fleschutz/PowerShell .NOTES Author: Markus Fleschutz · License: CC0 #> param([string]$address = "") function IsSubNetMaskValid { param([string]$IP) $RegEx = "^(254|252|248|240|224|192|128).0.0.0$|^255.(254|252|248|240|224|192|128|0).0.0$|^255.255.(254|252|248|240|224|192|128|0).0$|^255.255.255.(255|254|252|248|240|224|192|128|0)$" if ($IP -match $RegEx) { return $true } else { return $false } } try { if ($address -eq "" ) { $address = read-host "Enter subnet mask to validate" } if (IsSubNetMaskValid $address) { "✔️ subnet mask $Address is valid" exit 0 # success } else { write-warning "Invalid subnet mask: $address" exit 1 } } catch { "⚠️ Error: $($Error[0]) ($($MyInvocation.MyCommand.Name):$($_.InvocationInfo.ScriptLineNumber))" exit 1 }