Get IP Range from CIDR address

This script takes an IP address in CIDR format (192.168.33.55/24) and will return the Subnet ID, First Host IP Address, Last Host IP Address, and the Broadcast Address. It does require the ConvertTo-CmnIpAddress, and New-CmnLogEntry functions. All can be found on the Github site

Function Get-CmnIpRange {
    <#
    .SYNOPSIS
        Takes in an IP address in CIDR format and returns the subnet, first IP address, last IP address, and broadcast address


    .DESCRIPTION
        Takes in an IP address in CIDR format and returns the subnet, minimum IP address, maximum IP address, and broadcast address.
        This function also needs ConvertTo-CmnIpAddress, and New-CmnLogEntry functions
        
    .PARAMETER subnet
        This is the IP address in CIDR format (eg 192.168.23.55/20)


    .PARAMETER logFile
        File for writing logs to (default is C:\Windows\Temp\Error.log).


    .PARAMETER logEntries
        Set to $true to write to the log file. Otherwise, it will just be write-verbose (default is $false).


    .PARAMETER maxLogSize
        Max size for the log (default is 5MB).


    .PARAMETER maxLogHistory
        Specifies the number of history log files to keep (default is 5).


    .EXAMPLE
        Get-CmnIpRange -subnet '192.168.23.55/20'
        Returns:
        Subnet       Broadcast      Min          Max
        ------       ---------      ---          ---
        192.168.16.0 192.168.31.255 192.168.16.1 192.168.31.254


    .LINK
        http://configman-notes.com


    .NOTES
        Author:     Jim Parris
        Email:      Jim@ConfigMan-Notes.com
        PSVer:      3.0
        Version:    1.0.0       
        Date:       yyyy-mm-dd
        Updated:        
    #>
 
    [CmdletBinding(ConfirmImpact = 'Low')]


    Param(
        [Parameter(Mandatory = $true, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true, HelpMessage = 'IP Subnet (using CIDR) to get range of')]
        [ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)/\d{1,2}$')]
        [String]$subnet,


        [Parameter(Mandatory = $false, HelpMessage = 'File for writing logs to (default is C:\Windows\Temp\Error.log).')]
        [String]$logFile = 'C:\Windows\Temp\Error.log',


        [Parameter(Mandatory = $false, HelpMessage = 'Set to $true to write to the log file. Otherwise, it will just be write-verbose (default is $false).')]
        [Boolean]$logEntries = $false,


        [Parameter(Mandatory = $false, HelpMessage = 'Max size for the log (default is 5MB).')]
        [Int]$maxLogSize = 5242880,


        [Parameter(Mandatory = $false, HelpMessage = 'Specifies the number of history log files to keep (default is 5).')]
        [Int]$maxLogHistory = 5
    )


    begin {
        #Build splat for log entries
        $NewLogEntry = @{
            LogFile       = $logFile;
            Component     = 'Get-CmnIpRange';
            logEntries    = $logEntries;
            maxLogSize    = $maxLogSize;
            maxLogHistory = $maxLogHistory;
        }


        # Create a hashtable with your output info
        $returnHashTable = @{ }


        # Log variables
        New-CmnLogEntry -entry 'Starting Function' -type 1 @NewLogEntry
        New-CmnLogEntry -entry "subnet = $subnet" -type 1 @NewLogEntry
        New-CmnLogEntry -entry "logFile = $logFile" -type 1 @NewLogEntry
        New-CmnLogEntry -entry "logEntries = $logEntries" -type 1 @NewLogEntry
        New-CmnLogEntry -entry "maxLogSize = $maxLogSize" -type 1 @NewLogEntry
        New-CmnLogEntry -entry "maxLogHistory = $maxLogHistory" -type 1 @NewLogEntry
    }


    process {
        New-CmnLogEntry -entry 'Beginning process loop' -type 1 @NewLogEntry
        
        #Split IP and subnet 
        $IP = ($Subnet -split "\/")[0] 
        $SubnetBits = ($Subnet -split "\/")[1] 
        #Convert IP into binary. I know there are other ways to do this, but this is more fun!
        #Split IP into different octects and for each one, figure out the binary with leading zeros and add to the total 
        New-CmnLogEntry -entry "Converting $IP into binary." -type 1 @NewLogEntry
        $Octets = $IP -split "\." 
        $IPInBinary = @() 
        foreach ($Octet in $Octets) { 
            #convert to binary 
            $OctetInBinary = [convert]::ToString($Octet, 2) 
            #get length of binary string add leading zeros to make octet 
            $OctetInBinary = ("0" * (8 - ($OctetInBinary).Length) + $OctetInBinary) 
            $IPInBinary = $IPInBinary + $OctetInBinary 
            New-CmnLogEntry -entry "$Octet = $OctetInBinary" -type 1 @NewLogEntry
        } 
        # Now, we have an array of 4 elements, each with 8 bits. Let's make them on 32 bit value
        $IPInBinary = $IPInBinary -join "" 
        New-CmnLogEntry -entry "$IP in binary is $IPInBinary" -type 1 @NewLogEntry
        New-CmnLogEntry -entry 'Time to get subnet value' -type 1 @NewLogEntry
        $HostBits = 32 - $SubnetBits 
        # Now, we know how may bits are subnet, let's figure out how many of our IP address are in the network portion
        $NetworkIDInBinary = $IPInBinary.Substring(0, $SubnetBits) 
        $HostIDInBinary = $IPInBinary.Substring($SubnetBits, $HostBits)         
        $HostIDInBinary = $HostIDInBinary -replace "1", "0" 
        # Work out all the host IDs in that subnet by cycling through $i from 1 up to max $HostIDInBinary (i.e. 1s stringed up to $HostBits) 
        $iSubnet = [convert]::ToInt32($HostIDInBinary, 2)
        $iSubnetHostBinary = [convert]::toString($iSubnet, 2)
        $iSubnetInBinary = "$NetworkIDInBinary$("0" * ($HostIDInBinary.Length - $iSubnetHostBinary.Length) + $iSubnetHostBinary)"
        # Let's log the subnet
        New-CmnLogEntry -entry "Subnet in binary is $iSubnetInBinary" -type 1 @NewLogEntry
        $imin = [convert]::ToInt32($HostIDInBinary, 2) + 1
        $iMinHostBinary = [convert]::ToString($imin, 2)
        $iMinInBinary = "$NetworkIDInBinary$("0" * ($HostIDInBinary.Length - $iMinHostBinary.Length) + $iMinHostBinary)"
        # Let's log the first host address
        New-CmnLogEntry -entry "First Host Address in binary is $iMinInBinary" -type 1 @NewLogEntry
        $imax = [convert]::ToInt32(("1" * $HostBits), 2) - 1 
        $iMaxHostBinary = [Convert]::ToString($imax, 2)
        $iMaxInBinary = "$NetworkIDInBinary$("0" * ($HostIDInBinary.Length - $iMaxHostBinary.Length) + $iMaxHostBinary)"
        # Let's log the last host address
        New-CmnLogEntry -entry "Last Host Address in binary is $iMaxHostBinary" -type 1 @NewLogEntry
        $iBroadcast = [convert]::ToInt32(("1" * $HostBits), 2)
        $iBroadcastHostBinary = [Convert]::ToString($iBroadcast, 2)
        $iBroadcastInBinary = "$NetworkIDInBinary$("0" * ($HostIDInBinary.Length - $iBroadcastHostBinary.Length) + $iBroadcastHostBinary)"
        # Let's log the broadcast address
        New-CmnLogEntry -entry "Broadcast Address in binary is $iBroadcastInBinary" -type 1 @NewLogEntry
        # Time to build the return hash table
        $returnHashTable.Add('Subnet', (ConvertTo-CmnIpAddress -ipInBinary $iSubnetInBinary -logFIle $logFile -logEntries $logEntries -maxLogSize $maxLogSize -maxLogHistory $maxLogHistory))
        $returnHashTable.Add('Min', (ConvertTo-CmnIpAddress -ipInBinary $iMinInBinary -logFIle $logFile -logEntries $logEntries -maxLogSize $maxLogSize -maxLogHistory $maxLogHistory))
        $returnHashTable.Add('Max', (ConvertTo-CmnIpAddress -ipInBinary $iMaxInBinary -logFIle $logFile -logEntries $logEntries -maxLogSize $maxLogSize -maxLogHistory $maxLogHistory))
        $returnHashTable.Add('Broadcast', (ConvertTo-CmnIpAddress -ipInBinary $iBroadcastInBinary -logFIle $logFile -logEntries $logEntries -maxLogSize $maxLogSize -maxLogHistory $maxLogHistory))
    }


    End {
        # Done! Log the results and return
        $obj = New-Object -TypeName PSObject -Property $returnHashTable
        $obj.PSObject.TypeNames.Insert(0, 'CMN.IpRange')
        New-CmnLogEntry -entry "Returning $obj" -type 1 @NewLogEntry
        New-CmnLogEntry -entry 'Completing Function' -type 1 @NewLogEntry
        Return $obj
    }
} #End Get-CmnIpRange

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