functions/Test-SubnetInSubnet.ps1
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function Test-SubnetInSubnet { <# .SYNOPSIS Determines if one subnet is fully contained within another subnet. .DESCRIPTION The Test-SubnetInSubnet function checks whether a given subnet (FirstSubnet) is completely contained within another subnet (SecondSubnet). It validates both inputs are in CIDR notation and returns true if the first subnet is fully contained within the second subnet. .PARAMETER FirstSubnet The subnet to check if it's contained within the SecondSubnet. Must be in CIDR notation (e.g. 192.168.1.0/24). .PARAMETER SecondSubnet The potential containing subnet. Must be in CIDR notation (e.g. 192.168.0.0/16). .EXAMPLE Test-SubnetInSubnet -FirstSubnet "192.168.1.0/24" -SecondSubnet "192.168.0.0/16" Returns: True (because 192.168.1.0/24 is contained within 192.168.0.0/16) .EXAMPLE Test-SubnetInSubnet -FirstSubnet "10.0.0.0/8" -SecondSubnet "192.168.0.0/16" Returns: False (because 10.0.0.0/8 is not contained within 192.168.0.0/16) .NOTES File Name : Test-SubnetInSubnet.ps1 Prerequisite : PowerShell 5.1 or higher Copyright : MIT License .LINK https://github.com/imanedr/psnetworking .OUTPUTS System.Boolean Returns True if FirstSubnet is contained within SecondSubnet, False otherwise. #> [CmdletBinding()] param ( [ValidateScript({ if ($_ -match "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\/\d{1,2}") { $true } else { throw "$_ is invalid. Use CIDR format for subnets or x.x.x.x-x.x.x.y for ranges." } })] [string]$FirstSubnet, [ValidateScript({ if ($_ -match "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\/\d{1,2}") { $true } else { throw "$_ is invalid. Use CIDR format for subnets or x.x.x.x-x.x.x.y for ranges." } })] [string]$SecondSubnet ) $ipCalc = Get-IPCalc -CIDR $FirstSubnet $firstCheck = Test-IpInSubnet -IPv4Address $ipCalc.Subnet.IPAddressToString -SubnetOrRange $SecondSubnet $secondCheck = Test-IpInSubnet -IPv4Address $ipCalc.Broadcast.IPAddressToString -SubnetOrRange $SecondSubnet if ($firstCheck -and $secondCheck){ Write-Output $true } else { Write-Output $false } } |