liveaverage/Set-Dhcp-Scope.ps1

## Set-Dhcp-Scope.ps1
############################
#AUTHOR:       JR Morgan
#CREATED:      20120417
#MODIFIED:     20140611
############################

<#
    .Synopsis
    Adds DHCP Scope to ALL specified DHCP servers. If split-scope is desired
	the script uses IP Math to automatically add the desired exlcude ranges.


    .Description
    Creates a DHCP based on user-provided parameters. For 50/50 split-scope config,
	the ordering of the DHCP Servers determines the upper/lower designation. The first
	DHCP server specified will host upper scope portion, while the second DHCP server will
	host the lower scope portion. Upper/Lower 'tags' are added to the description when using
	the Split50 switch.

    .Parameter DhcpServer
        An array of DHCP Server IP names or addresses that will host the new DHCP scopes

    .Parameter IPScope
        The desired IP Scope

    .Parameter IPMask
        The desired IP mask for the scope

    .Parameter Description
        A brief scope description. Upper/Lower tags will
		automatically be added if using the Split50 switch

    .Parameter Gateway
        The IP address of the router or gateway for this scope (Option 3)

	.Parameter Dns
        An array of DNS server IP addresses utilized by scope clients (Option 6).

    .Parameter Domain
     	The fully-qualified domain name for scope clients (Option 15)

    .Parameter StartAddress
	 	An optional parameter used to specify the start address for distribution.
		If no address is provided, the default StartAddress is the Network address +2

    .Parameter EndAddress
	 	An optional parameter used to specify the end address for distribution.
		If no address is provided, the default EndAddress is the Broadcast address -1

    .Parameter LeaseTime
	 	Integer value (in seconds) for the desired address lease times associated
		with the scope. Default: 691200

    .Parameter State
	 	Set the DHCP scope state to enable (1) or disable (0). Default: 0

	.Parameter ExcludeAll
		Excludes all addresses from distribution (Reservation required for IP distribution)

    .Parameter Split50
	 	Configure a 50/50 split-scope between specified DHCP servers.
		Ony two (2) DHCP servers may be specified. Exclusions are automatically
		calculated for each server.

	.Parameter NoRevLookup
		A switched parameter used to disable the automatic creation of a corresponding reverse lookup zone.
		DNS settings are retrieved using the 'Domain' parameter. If the reverse lookup zone already exists then
		creation is skipped.

	.Parameter NoDynamicDNS
		A switched parameter used to disable dynamic DNS updates for a specific scope.

	.Parameter OptionTftp
		Adds an array of TFTP servers using DHCP option 150

    .Parameter Invoke
        A switched parameter used to automatically invoke the netsh commands generated
        for a new scope. Use cautiously!

    .Notes
    This script assumes you're running this as a domain admin or at least have DHCP Administrators group membership.
    This script also assumes you would be using administrative credentials to actually invoke the generated
    netsh commands. Command invocation will not work if you don't have the necessary privileges.

    .Example
    Set-Dhcp-Scope.ps1 -DhcpServer grudcpr03,grudcpr04 -IPScope 172.20.229.0 -IPMask 255.255.255.0 -Description "Description" -Gateway 172.20.229.1 -Dns 172.20.227.219,172.20.242.119 -Domain domain.com -StartAddress 172.20.229.2 -Split50 -State 1
#>


#Parameters and required validation. Alias definitions for shorthand. Positional parameter options work, too.

Param
(
    [Parameter(ValueFromPipeline = $True, Mandatory = $True)]
    [ValidateCount(1,2)]
	[Alias("dhcp")]
    [String[]]
    $DhcpServer
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
    [ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
    [Alias("s")]
    [String]
    $IPScope
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
    [ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
    [Alias("m")]
    [String]
    $IPMask
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
    [Alias("desc")]
    [String]
    $Description = ""
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
    [ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
    [Alias("g")]
    [String]
    $Gateway
    ,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
    [Alias("n")]
    [String[]]
    $Dns
    ,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
    [Alias("d")]
    [String]
    $Domain = "gruadmin.gru.com"
    ,
	[Parameter(ValueFromPipeline = $True)]
    [ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
    [Alias("start")]
    [String]
    $StartAddress
	,
	[Parameter(ValueFromPipeline = $True)]
    [ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
    [Alias("end")]
    [String]
    $EndAddress
    ,
	[Parameter(ValueFromPipeline = $True, Mandatory = $False)]
	[Alias("l")]
	[Int]
	$LeaseTime = 691200
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $False)]
	[ValidateRange(0,1)]
	[Int]
	$State = 0
	,
	[Parameter(ValueFromPipeline = $True)]
    [Alias("Exclude")]
    [Switch]
    $ExcludeAll
	,
	[Parameter(ValueFromPipeline = $True)]
    [Alias("50")]
    [Switch]
    $Split50
	,
	[Parameter(ValueFromPipeline = $True)]
    [Switch]
    $NoRevLookup
	,
	[Parameter(ValueFromPipeline = $True)]
    [Switch]
	$NoDynamicDNS
	,
	[Parameter(ValueFromPipeline = $True)]
	[ValidatePattern('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')]
	[String[]]
	$OptionTftp
	,
    [Parameter(ValueFromPipeline = $False)]
    [Alias("x")]
    [Switch]
    $Invoke
)

#region IPMath

Function ConvertTo-BinaryIP {
  <#
    .Synopsis
      Converts a Decimal IP address into a binary format.
    .Description
      ConvertTo-BinaryIP uses System.Convert to switch between decimal and binary format. The output from this function is dotted binary.
    .Parameter IPAddress
      An IP Address to convert.
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [Net.IPAddress]$IPAddress
  )

  Process {
    Return [String]::Join('.', $( $IPAddress.GetAddressBytes() |
      ForEach-Object { [Convert]::ToString($_, 2).PadLeft(8, '0') } ))
  }
}

Function ConvertTo-DecimalIP {
  <#
    .Synopsis
      Converts a Decimal IP address into a 32-bit unsigned integer.
    .Description
      ConvertTo-DecimalIP takes a decimal IP, uses a shift-like operation on each octet and returns a single UInt32 value.
    .Parameter IPAddress
      An IP Address to convert.
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [Net.IPAddress]$IPAddress
  )

  Process {
    $i = 3; $DecimalIP = 0;
    $IPAddress.GetAddressBytes() | ForEach-Object { $DecimalIP += $_ * [Math]::Pow(256, $i); $i-- }

    Return $DecimalIP
  }
}

Function ConvertTo-DottedDecimalIP {
  <#
    .Synopsis
      Returns a dotted decimal IP address from either an unsigned 32-bit integer or a dotted binary string.
    .Description
      ConvertTo-DottedDecimalIP uses a regular expression match on the input string to convert to an IP address.
    .Parameter IPAddress
      A string representation of an IP address from either UInt32 or dotted binary.
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [String]$IPAddress
  )

  Process {
    Switch -RegEx ($IPAddress) {
      "([01]{8}\.){3}[01]{8}" {
        Return [String]::Join('.', $( $IPAddress.Split('.') | ForEach-Object { [Convert]::ToUInt32($_, 2) } ))
      }
      "\d" {
        $IPAddress = [UInt32]$IPAddress
        $DottedIP = $( For ($i = 3; $i -gt -1; $i--) {
          $Remainder = $IPAddress % [Math]::Pow(256, $i)
          ($IPAddress - $Remainder) / [Math]::Pow(256, $i)
          $IPAddress = $Remainder
         } )

        Return [String]::Join('.', $DottedIP)
      }
      default {
        Write-Error "Cannot convert this format"
      }
    }
  }
}

Function ConvertTo-MaskLength {
  <#
    .Synopsis
      Returns the length of a subnet mask.
    .Description
      ConvertTo-MaskLength accepts any IPv4 address as input, however the output value
      only makes sense when using a subnet mask.
    .Parameter SubnetMask
      A subnet mask to convert into length
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [Alias("Mask")]
    [Net.IPAddress]$SubnetMask
  )

  Process {
    $Bits = "$( $SubnetMask.GetAddressBytes() | ForEach-Object { [Convert]::ToString($_, 2) } )" -Replace '[\s0]'

    Return $Bits.Length
  }
}

Function ConvertTo-Mask {
  <#
    .Synopsis
      Returns a dotted decimal subnet mask from a mask length.
    .Description
      ConvertTo-Mask returns a subnet mask in dotted decimal format from an integer value ranging
      between 0 and 32. ConvertTo-Mask first creates a binary string from the length, converts
      that to an unsigned 32-bit integer then calls ConvertTo-DottedDecimalIP to complete the operation.
    .Parameter MaskLength
      The number of bits which must be masked.
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [Alias("Length")]
    [ValidateRange(0, 32)]
    $MaskLength
  )

  Process {
    Return ConvertTo-DottedDecimalIP ([Convert]::ToUInt32($(("1" * $MaskLength).PadRight(32, "0")), 2))
  }
}

Function Get-NetworkAddress {
  <#
    .Synopsis
      Takes an IP address and subnet mask then calculates the network address for the range.
    .Description
      Get-NetworkAddress returns the network address for a subnet by performing a bitwise AND
      operation against the decimal forms of the IP address and subnet mask. Get-NetworkAddress
      expects both the IP address and subnet mask in dotted decimal format.
    .Parameter IPAddress
      Any IP address within the network range.
    .Parameter SubnetMask
      The subnet mask for the network.
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [Net.IPAddress]$IPAddress,

    [Parameter(Mandatory = $True, Position = 1)]
    [Alias("Mask")]
    [Net.IPAddress]$SubnetMask
  )

  Process {
    Return ConvertTo-DottedDecimalIP ((ConvertTo-DecimalIP $IPAddress) -BAnd (ConvertTo-DecimalIP $SubnetMask))
  }
}

Function Get-BroadcastAddress {
  <#
    .Synopsis
      Takes an IP address and subnet mask then calculates the broadcast address for the range.
    .Description
      Get-BroadcastAddress returns the broadcast address for a subnet by performing a bitwise AND
      operation against the decimal forms of the IP address and inverted subnet mask.
      Get-BroadcastAddress expects both the IP address and subnet mask in dotted decimal format.
    .Parameter IPAddress
      Any IP address within the network range.
    .Parameter SubnetMask
      The subnet mask for the network.
  #>

  [CmdLetBinding()]
  Param(
    [Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
    [Net.IPAddress]$IPAddress,

    [Parameter(Mandatory = $True, Position = 1)]
    [Alias("Mask")]
    [Net.IPAddress]$SubnetMask
  )

  Process {
    Return ConvertTo-DottedDecimalIP $((ConvertTo-DecimalIP $IPAddress) -BOr `
      ((-BNot (ConvertTo-DecimalIP $SubnetMask)) -BAnd [UInt32]::MaxValue))
  }
}

Function Get-NetworkSummary ( [String]$IP, [String]$Mask ) {
  If ($IP.Contains("/"))
  {
    $Temp = $IP.Split("/")
    $IP = $Temp[0]
    $Mask = $Temp[1]
  }

  If (!$Mask.Contains("."))
  {
    $Mask = ConvertTo-Mask $Mask
  }

  $DecimalIP = ConvertTo-DecimalIP $IP
  $DecimalMask = ConvertTo-DecimalIP $Mask

  $Network = $DecimalIP -BAnd $DecimalMask
  $Broadcast = $DecimalIP -BOr
    ((-BNot $DecimalMask) -BAnd [UInt32]::MaxValue)
  $NetworkAddress = ConvertTo-DottedDecimalIP $Network
  $RangeStart = ConvertTo-DottedDecimalIP ($Network + 1)
  $RangeEnd = ConvertTo-DottedDecimalIP ($Broadcast - 1)
  $ScopeStart = ConvertTo-DottedDecimalIP ($Network + 2)
  $ScopeEnd = ConvertTo-DottedDecimalIP ($Broadcast + 1)
  $BroadcastAddress = ConvertTo-DottedDecimalIP $Broadcast
  $MaskLength = ConvertTo-MaskLength $Mask

  $BinaryIP = ConvertTo-BinaryIP $IP; $Private = $False
  Switch -RegEx ($BinaryIP)
  {
    "^1111"  { $Class = "E"; $SubnetBitMap = "1111" }
    "^1110"  { $Class = "D"; $SubnetBitMap = "1110" }
    "^110"   {
      $Class = "C"
      If ($BinaryIP -Match "^11000000.10101000") { $Private = $True } }
    "^10"    {
      $Class = "B"
      If ($BinaryIP -Match "^10101100.0001") { $Private = $True } }
    "^0"     {
      $Class = "A"
      If ($BinaryIP -Match "^00001010") { $Private = $True } }
   }

  $NetInfo = New-Object Object
  Add-Member NoteProperty "Network" -Input $NetInfo -Value $NetworkAddress
  Add-Member NoteProperty "Broadcast" -Input $NetInfo -Value $BroadcastAddress
  Add-Member NoteProperty "Range" -Input $NetInfo `
    -Value "$RangeStart - $RangeEnd"
  Add-Member NoteProperty "Mask" -Input $NetInfo -Value $Mask
  Add-Member NoteProperty "RangeStart" -Input $NetInfo -Value $RangeStart
  Add-Member NoteProperty "RangeEnd" -Input $NetInfo -Value $RangeEnd
  Add-Member NoteProperty "ScopeStart" -Input $NetInfo -Value $ScopeStart
  Add-Member NoteProperty "ScopeEnd" -Input $NetInfo -Value $ScopeEnd
  Add-Member NoteProperty "MaskLength" -Input $NetInfo -Value $MaskLength
  Add-Member NoteProperty "Hosts" -Input $NetInfo `
    -Value $($Broadcast - $Network - 1)
  Add-Member NoteProperty "Class" -Input $NetInfo -Value $Class
  Add-Member NoteProperty "IsPrivate" -Input $NetInfo -Value $Private

  Return $NetInfo
}

#endregion


$c = $null

$DecimalIP = ConvertTo-DecimalIP $IPScope
$DecimalMask = ConvertTo-DecimalIP $IPMask

#Basic Calculations in the event of missing Start/End:

$Network = $DecimalIP -BAnd $DecimalMask
$Broadcast = $DecimalIP -BOr
((-BNot $DecimalMask) -BAnd [UInt32]::MaxValue)
$NetworkAddress = ConvertTo-DottedDecimalIP $Network
$RangeStart = ConvertTo-DottedDecimalIP ($Network + 2)
$RangeEnd = ConvertTo-DottedDecimalIP ($Broadcast - 1)

foreach ($s in [array]$DhcpServer)
{
	$Desc = $null

	#Autogenerate upper/lower descriptions:
	if ($DhcpServer.count -gt 1 -and $Description -match "vlan" -and $Split50)
    {
		if ($s -eq $DhcpServer[0]) { $Desc = ($Description -replace "vlan","[upper] VLAN") }
		if ($s -eq $DhcpServer[1]) { $Desc = ($Description -replace "vlan","[lower] VLAN") }
	}
	elseif ($DhcpServer.count -gt 1 -and $Split50)
	{
		if ($s -eq $DhcpServer[0]) { $Desc = $Description + " [upper]" }
		if ($s -eq $DhcpServer[1]) { $Desc = $Description + " [lower]" }
	}
	else
	{
		$Desc = $Description
	}

	$c += "netsh dhcp server \\$s add scope $IPScope $IPMask `"$Desc`"`r`n"
	$c += "netsh dhcp server \\$s scope $IPScope set state $State`r`n"

	if ([string]::IsNullOrEmpty($StartAddress))
	{
		$StartAddress = $RangeStart
	}

	if ([string]::IsNullOrEmpty($EndAddress))
	{
		$EndAddress = $RangeEnd
	}

	$c += "netsh dhcp server \\$s scope $IPScope add iprange $StartAddress $EndAddress`r`n"

	if (($Split50 -and $DhcpServer.count -gt 1) -or ($ExcludeAll -and $DhcpServer.count -gt 1))
	{
		#Scope Start decimal:
        $ssd = ConvertTo-DecimalIP $StartAddress
        #Scope End decimal:
        $sed = ConvertTo-DecimalIP $EndAddress

        #Math bytes:
        $th = [int64]$sed - [int64]$ssd

        #Halve the scope total hosts#:
        $hh = $th/2

        #Subtract from Scope End Decimal:
        #Lower Scope End (this is the end of the lower scope range):
        $lsedd = ConvertTo-DottedDecimalIP ($sed-$hh)

        #Upper Scope Start (this is beginning of the upper scope range):
        $ussdd = ConvertTo-DottedDecimalIP (($ssd+$hh)+1)

        #Config Upper scope (exclusions for lower scope)
        if ($s -eq $DhcpServer[0])
        {
        	if (-not $ExcludeAll)
			{
				$c += "netsh dhcp server \\$s scope $IPScope add excluderange $StartAddress $lsedd`r`n"
			}
			else
			{
				$c += "netsh dhcp server \\$s scope $IPScope add excluderange $StartAddress $EndAddress`r`n"
			}
        }

        #Config Lower scope (exclusions for upper scope)
        if ($s -eq $DhcpServer[1])
        {
			if (-not $ExcludeAll)
			{
				$c += "netsh dhcp server \\$s scope $IPScope add excluderange $ussdd $EndAddress`r`n"
			}
			else
			{
				$c += "netsh dhcp server \\$s scope $IPScope add excluderange $StartAddress $EndAddress`r`n"
			}
        }
	}
	#Lease Time:
	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 51 DWORD `"$LeaseTime`"`r`n"

	#Gateway:
	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 3 IPADDRESS `"$Gateway`"`r`n"

	#DNS Domain Name:
	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 15 STRING `"$Domain`"`r`n"

	#DNS Servers:
	$dnslist = $null

	foreach ($d in [array]$Dns)
	{
		$dnslist += "`"$d`" "
	}

	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 6 IPADDRESS $dnslist`r`n"
	$c += "`r`n"

	#TFTP Servers:
	$tftplist = $null

	if(([array]$OptionTftp).count -gt 0)
	{
		foreach ($ts in [array]$OptionTftp)
		{
			$tftplist += "`"$ts`" "
		}

		$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 150 IPADDRESS $tftplist`r`n"
		$c += "`r`n"
	}

	if ($NoDynamicDNS)
	{
		$c += "netsh dhcp server \\$s scope $IPScope set DnsConfig 0 0 0 0"
	}


}
	if (-not $NoRevLookup)
	{
		$revname = $IPScope.Split(".")
		$zones = (Invoke-Expression -Command "dnscmd $Domain /enumzones") | %{$_ -split "\s+"} | ?{ `
													$_.StartsWith("$($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa") `
													-or `
													$_.StartsWith("$($revname[0]).$($revname[1]).$($revname[2]).in-addr.arpa")}
		if (([string[]]$zones).count -lt 1)
		{
			$c += "dnscmd $Domain /zoneadd $($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa /dsprimary"
			$c += "dnscmd $Domain /Config $($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa /AllowUpdate 2"
			$c += "dnscmd $Domain /Config $($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa /Aging 1"
		}
		else
		{
			Write-Output "Skipping Reverse Lookup Zone creation. Detected pre-existing zone(s): `r`n $zones `r`n"
		}
	}


	Write-Output "Generated the following netsh commands:`r`n"
	Write-Output $c

    if ($Invoke)
    {
        Write-Host "Received Invoke parameter; executing all commands.`r`n"
        #Write-Host "These are the commands that were generated from your input:`n$($c)`n"
        #$execute = Read-Host "Definitely execute these commands? (USE CARE)? (Y/N)"

        #Double-check execution/invocation of netsh
        #if ($execute -match "Y")
        #{

        Invoke-Expression $c
        #}
    }
	############################
	#AUTHOR: JR Morgan
	#CREATED: 20120417
	#MODIFIED: 20140611
	############################

	<#
	.Synopsis
	Adds DHCP Scope to ALL specified DHCP servers. If split-scope is desired
	the script uses IP Math to automatically add the desired exlcude ranges.


	.Description
	Creates a DHCP based on user-provided parameters. For 50/50 split-scope config,
	the ordering of the DHCP Servers determines the upper/lower designation. The first
	DHCP server specified will host upper scope portion, while the second DHCP server will
	host the lower scope portion. Upper/Lower 'tags' are added to the description when using
	the Split50 switch.

	.Parameter DhcpServer
	An array of DHCP Server IP names or addresses that will host the new DHCP scopes

	.Parameter IPScope
	The desired IP Scope

	.Parameter IPMask
	The desired IP mask for the scope

	.Parameter Description
	A brief scope description. Upper/Lower tags will
	automatically be added if using the Split50 switch

	.Parameter Gateway
	The IP address of the router or gateway for this scope (Option 3)

	.Parameter Dns
	An array of DNS server IP addresses utilized by scope clients (Option 6).

	.Parameter Domain
	The fully-qualified domain name for scope clients (Option 15)

	.Parameter StartAddress
	An optional parameter used to specify the start address for distribution.
	If no address is provided, the default StartAddress is the Network address +2

	.Parameter EndAddress
	An optional parameter used to specify the end address for distribution.
	If no address is provided, the default EndAddress is the Broadcast address -1

	.Parameter LeaseTime
	Integer value (in seconds) for the desired address lease times associated
	with the scope. Default: 691200

	.Parameter State
	Set the DHCP scope state to enable (1) or disable (0). Default: 0

	.Parameter ExcludeAll
	Excludes all addresses from distribution (Reservation required for IP distribution)

	.Parameter Split50
	Configure a 50/50 split-scope between specified DHCP servers.
	Ony two (2) DHCP servers may be specified. Exclusions are automatically
	calculated for each server.

	.Parameter NoRevLookup
	A switched parameter used to disable the automatic creation of a corresponding reverse lookup zone.
	DNS settings are retrieved using the 'Domain' parameter. If the reverse lookup zone already exists then
	creation is skipped.

	.Parameter NoDynamicDNS
	A switched parameter used to disable dynamic DNS updates for a specific scope.

	.Parameter OptionTftp
	Adds an array of TFTP servers using DHCP option 150

	.Parameter Invoke
	A switched parameter used to automatically invoke the netsh commands generated
	for a new scope. Use cautiously!

	.Notes
	This script assumes you're running this as a domain admin or at least have DHCP Administrators group membership.
	This script also assumes you would be using administrative credentials to actually invoke the generated
	netsh commands. Command invocation will not work if you don't have the necessary privileges.

	.Example
	Set-Dhcp-Scope.ps1 -DhcpServer grudcpr03,grudcpr04 -IPScope 172.20.229.0 -IPMask 255.255.255.0 -Description "Description" -Gateway 172.20.229.1 -Dns 172.20.227.219,172.20.242.119 -Domain domain.com -StartAddress 172.20.229.2 -Split50 -State 1
	#>


	#Parameters and required validation. Alias definitions for shorthand. Positional parameter options work, too.

	Param
	(
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[ValidateCount(1,2)]
	[Alias("dhcp")]
	[String[]]
	$DhcpServer
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[Alias("s")]
	[String]
	$IPScope
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[Alias("m")]
	[String]
	$IPMask
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[Alias("desc")]
	[String]
	$Description = ""
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[Alias("g")]
	[String]
	$Gateway
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[Alias("n")]
	[String[]]
	$Dns
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $True)]
	[Alias("d")]
	[String]
	$Domain = "gruadmin.gru.com"
	,
	[Parameter(ValueFromPipeline = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[Alias("start")]
	[String]
	$StartAddress
	,
	[Parameter(ValueFromPipeline = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[Alias("end")]
	[String]
	$EndAddress
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $False)]
	[Alias("l")]
	[Int]
	$LeaseTime = 691200
	,
	[Parameter(ValueFromPipeline = $True, Mandatory = $False)]
	[ValidateRange(0,1)]
	[Int]
	$State = 0
	,
	[Parameter(ValueFromPipeline = $True)]
	[Alias("Exclude")]
	[Switch]
	$ExcludeAll
	,
	[Parameter(ValueFromPipeline = $True)]
	[Alias("50")]
	[Switch]
	$Split50
	,
	[Parameter(ValueFromPipeline = $True)]
	[Switch]
	$NoRevLookup
	,
	[Parameter(ValueFromPipeline = $True)]
	[Switch]
	$NoDynamicDNS
	,
	[Parameter(ValueFromPipeline = $True)]
	[ValidatePattern('^(?:(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]\|2[0-4][0-9]\|[01]?[0-9][0-9]?)$')]
	[String[]]
	$OptionTftp
	,
	[Parameter(ValueFromPipeline = $False)]
	[Alias("x")]
	[Switch]
	$Invoke
	)

	#region IPMath

	Function ConvertTo-BinaryIP {
	<#
	.Synopsis
	Converts a Decimal IP address into a binary format.
	.Description
	ConvertTo-BinaryIP uses System.Convert to switch between decimal and binary format. The output from this function is dotted binary.
	.Parameter IPAddress
	An IP Address to convert.
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[Net.IPAddress]$IPAddress
	)

	Process {
	Return [String]::Join('.', $( $IPAddress.GetAddressBytes() \|
	ForEach-Object { [Convert]::ToString($_, 2).PadLeft(8, '0') } ))
	}
	}

	Function ConvertTo-DecimalIP {
	<#
	.Synopsis
	Converts a Decimal IP address into a 32-bit unsigned integer.
	.Description
	ConvertTo-DecimalIP takes a decimal IP, uses a shift-like operation on each octet and returns a single UInt32 value.
	.Parameter IPAddress
	An IP Address to convert.
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[Net.IPAddress]$IPAddress
	)

	Process {
	$i = 3; $DecimalIP = 0;
	$IPAddress.GetAddressBytes() \| ForEach-Object { $DecimalIP += $_ * [Math]::Pow(256, $i); $i-- }

	Return $DecimalIP
	}
	}

	Function ConvertTo-DottedDecimalIP {
	<#
	.Synopsis
	Returns a dotted decimal IP address from either an unsigned 32-bit integer or a dotted binary string.
	.Description
	ConvertTo-DottedDecimalIP uses a regular expression match on the input string to convert to an IP address.
	.Parameter IPAddress
	A string representation of an IP address from either UInt32 or dotted binary.
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[String]$IPAddress
	)

	Process {
	Switch -RegEx ($IPAddress) {
	"([01]{8}\.){3}[01]{8}" {
	Return [String]::Join('.', $( $IPAddress.Split('.') \| ForEach-Object { [Convert]::ToUInt32($_, 2) } ))
	}
	"\d" {
	$IPAddress = [UInt32]$IPAddress
	$DottedIP = $( For ($i = 3; $i -gt -1; $i--) {
	$Remainder = $IPAddress % [Math]::Pow(256, $i)
	($IPAddress - $Remainder) / [Math]::Pow(256, $i)
	$IPAddress = $Remainder
	} )

	Return [String]::Join('.', $DottedIP)
	}
	default {
	Write-Error "Cannot convert this format"
	}
	}
	}
	}

	Function ConvertTo-MaskLength {
	<#
	.Synopsis
	Returns the length of a subnet mask.
	.Description
	ConvertTo-MaskLength accepts any IPv4 address as input, however the output value
	only makes sense when using a subnet mask.
	.Parameter SubnetMask
	A subnet mask to convert into length
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[Alias("Mask")]
	[Net.IPAddress]$SubnetMask
	)

	Process {
	$Bits = "$( $SubnetMask.GetAddressBytes() \| ForEach-Object { [Convert]::ToString($_, 2) } )" -Replace '[\s0]'

	Return $Bits.Length
	}
	}

	Function ConvertTo-Mask {
	<#
	.Synopsis
	Returns a dotted decimal subnet mask from a mask length.
	.Description
	ConvertTo-Mask returns a subnet mask in dotted decimal format from an integer value ranging
	between 0 and 32. ConvertTo-Mask first creates a binary string from the length, converts
	that to an unsigned 32-bit integer then calls ConvertTo-DottedDecimalIP to complete the operation.
	.Parameter MaskLength
	The number of bits which must be masked.
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[Alias("Length")]
	[ValidateRange(0, 32)]
	$MaskLength
	)

	Process {
	Return ConvertTo-DottedDecimalIP ([Convert]::ToUInt32($(("1" * $MaskLength).PadRight(32, "0")), 2))
	}
	}

	Function Get-NetworkAddress {
	<#
	.Synopsis
	Takes an IP address and subnet mask then calculates the network address for the range.
	.Description
	Get-NetworkAddress returns the network address for a subnet by performing a bitwise AND
	operation against the decimal forms of the IP address and subnet mask. Get-NetworkAddress
	expects both the IP address and subnet mask in dotted decimal format.
	.Parameter IPAddress
	Any IP address within the network range.
	.Parameter SubnetMask
	The subnet mask for the network.
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[Net.IPAddress]$IPAddress,

	[Parameter(Mandatory = $True, Position = 1)]
	[Alias("Mask")]
	[Net.IPAddress]$SubnetMask
	)

	Process {
	Return ConvertTo-DottedDecimalIP ((ConvertTo-DecimalIP $IPAddress) -BAnd (ConvertTo-DecimalIP $SubnetMask))
	}
	}

	Function Get-BroadcastAddress {
	<#
	.Synopsis
	Takes an IP address and subnet mask then calculates the broadcast address for the range.
	.Description
	Get-BroadcastAddress returns the broadcast address for a subnet by performing a bitwise AND
	operation against the decimal forms of the IP address and inverted subnet mask.
	Get-BroadcastAddress expects both the IP address and subnet mask in dotted decimal format.
	.Parameter IPAddress
	Any IP address within the network range.
	.Parameter SubnetMask
	The subnet mask for the network.
	#>

	[CmdLetBinding()]
	Param(
	[Parameter(Mandatory = $True, Position = 0, ValueFromPipeline = $True)]
	[Net.IPAddress]$IPAddress,

	[Parameter(Mandatory = $True, Position = 1)]
	[Alias("Mask")]
	[Net.IPAddress]$SubnetMask
	)

	Process {
	Return ConvertTo-DottedDecimalIP $((ConvertTo-DecimalIP $IPAddress) -BOr `
	((-BNot (ConvertTo-DecimalIP $SubnetMask)) -BAnd [UInt32]::MaxValue))
	}
	}

	Function Get-NetworkSummary ( [String]$IP, [String]$Mask ) {
	If ($IP.Contains("/"))
	{
	$Temp = $IP.Split("/")
	$IP = $Temp[0]
	$Mask = $Temp[1]
	}

	If (!$Mask.Contains("."))
	{
	$Mask = ConvertTo-Mask $Mask
	}

	$DecimalIP = ConvertTo-DecimalIP $IP
	$DecimalMask = ConvertTo-DecimalIP $Mask

	$Network = $DecimalIP -BAnd $DecimalMask
	$Broadcast = $DecimalIP -BOr
	((-BNot $DecimalMask) -BAnd [UInt32]::MaxValue)
	$NetworkAddress = ConvertTo-DottedDecimalIP $Network
	$RangeStart = ConvertTo-DottedDecimalIP ($Network + 1)
	$RangeEnd = ConvertTo-DottedDecimalIP ($Broadcast - 1)
	$ScopeStart = ConvertTo-DottedDecimalIP ($Network + 2)
	$ScopeEnd = ConvertTo-DottedDecimalIP ($Broadcast + 1)
	$BroadcastAddress = ConvertTo-DottedDecimalIP $Broadcast
	$MaskLength = ConvertTo-MaskLength $Mask

	$BinaryIP = ConvertTo-BinaryIP $IP; $Private = $False
	Switch -RegEx ($BinaryIP)
	{
	"^1111" { $Class = "E"; $SubnetBitMap = "1111" }
	"^1110" { $Class = "D"; $SubnetBitMap = "1110" }
	"^110" {
	$Class = "C"
	If ($BinaryIP -Match "^11000000.10101000") { $Private = $True } }
	"^10" {
	$Class = "B"
	If ($BinaryIP -Match "^10101100.0001") { $Private = $True } }
	"^0" {
	$Class = "A"
	If ($BinaryIP -Match "^00001010") { $Private = $True } }
	}

	$NetInfo = New-Object Object
	Add-Member NoteProperty "Network" -Input $NetInfo -Value $NetworkAddress
	Add-Member NoteProperty "Broadcast" -Input $NetInfo -Value $BroadcastAddress
	Add-Member NoteProperty "Range" -Input $NetInfo `
	-Value "$RangeStart - $RangeEnd"
	Add-Member NoteProperty "Mask" -Input $NetInfo -Value $Mask
	Add-Member NoteProperty "RangeStart" -Input $NetInfo -Value $RangeStart
	Add-Member NoteProperty "RangeEnd" -Input $NetInfo -Value $RangeEnd
	Add-Member NoteProperty "ScopeStart" -Input $NetInfo -Value $ScopeStart
	Add-Member NoteProperty "ScopeEnd" -Input $NetInfo -Value $ScopeEnd
	Add-Member NoteProperty "MaskLength" -Input $NetInfo -Value $MaskLength
	Add-Member NoteProperty "Hosts" -Input $NetInfo `
	-Value $($Broadcast - $Network - 1)
	Add-Member NoteProperty "Class" -Input $NetInfo -Value $Class
	Add-Member NoteProperty "IsPrivate" -Input $NetInfo -Value $Private

	Return $NetInfo
	}

	#endregion


	$c = $null

	$DecimalIP = ConvertTo-DecimalIP $IPScope
	$DecimalMask = ConvertTo-DecimalIP $IPMask

	#Basic Calculations in the event of missing Start/End:

	$Network = $DecimalIP -BAnd $DecimalMask
	$Broadcast = $DecimalIP -BOr
	((-BNot $DecimalMask) -BAnd [UInt32]::MaxValue)
	$NetworkAddress = ConvertTo-DottedDecimalIP $Network
	$RangeStart = ConvertTo-DottedDecimalIP ($Network + 2)
	$RangeEnd = ConvertTo-DottedDecimalIP ($Broadcast - 1)

	foreach ($s in [array]$DhcpServer)
	{
	$Desc = $null

	#Autogenerate upper/lower descriptions:
	if ($DhcpServer.count -gt 1 -and $Description -match "vlan" -and $Split50)
	{
	if ($s -eq $DhcpServer[0]) { $Desc = ($Description -replace "vlan","[upper] VLAN") }
	if ($s -eq $DhcpServer[1]) { $Desc = ($Description -replace "vlan","[lower] VLAN") }
	}
	elseif ($DhcpServer.count -gt 1 -and $Split50)
	{
	if ($s -eq $DhcpServer[0]) { $Desc = $Description + " [upper]" }
	if ($s -eq $DhcpServer[1]) { $Desc = $Description + " [lower]" }
	}
	else
	{
	$Desc = $Description
	}

	$c += "netsh dhcp server \\$s add scope $IPScope $IPMask `"$Desc`"`r`n"
	$c += "netsh dhcp server \\$s scope $IPScope set state $State`r`n"

	if ([string]::IsNullOrEmpty($StartAddress))
	{
	$StartAddress = $RangeStart
	}

	if ([string]::IsNullOrEmpty($EndAddress))
	{
	$EndAddress = $RangeEnd
	}

	$c += "netsh dhcp server \\$s scope $IPScope add iprange $StartAddress $EndAddress`r`n"

	if (($Split50 -and $DhcpServer.count -gt 1) -or ($ExcludeAll -and $DhcpServer.count -gt 1))
	{
	#Scope Start decimal:
	$ssd = ConvertTo-DecimalIP $StartAddress
	#Scope End decimal:
	$sed = ConvertTo-DecimalIP $EndAddress

	#Math bytes:
	$th = [int64]$sed - [int64]$ssd

	#Halve the scope total hosts#:
	$hh = $th/2

	#Subtract from Scope End Decimal:
	#Lower Scope End (this is the end of the lower scope range):
	$lsedd = ConvertTo-DottedDecimalIP ($sed-$hh)

	#Upper Scope Start (this is beginning of the upper scope range):
	$ussdd = ConvertTo-DottedDecimalIP (($ssd+$hh)+1)

	#Config Upper scope (exclusions for lower scope)
	if ($s -eq $DhcpServer[0])
	{
	if (-not $ExcludeAll)
	{
	$c += "netsh dhcp server \\$s scope $IPScope add excluderange $StartAddress $lsedd`r`n"
	}
	else
	{
	$c += "netsh dhcp server \\$s scope $IPScope add excluderange $StartAddress $EndAddress`r`n"
	}
	}

	#Config Lower scope (exclusions for upper scope)
	if ($s -eq $DhcpServer[1])
	{
	if (-not $ExcludeAll)
	{
	$c += "netsh dhcp server \\$s scope $IPScope add excluderange $ussdd $EndAddress`r`n"
	}
	else
	{
	$c += "netsh dhcp server \\$s scope $IPScope add excluderange $StartAddress $EndAddress`r`n"
	}
	}
	}
	#Lease Time:
	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 51 DWORD `"$LeaseTime`"`r`n"

	#Gateway:
	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 3 IPADDRESS `"$Gateway`"`r`n"

	#DNS Domain Name:
	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 15 STRING `"$Domain`"`r`n"

	#DNS Servers:
	$dnslist = $null

	foreach ($d in [array]$Dns)
	{
	$dnslist += "`"$d`" "
	}

	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 6 IPADDRESS $dnslist`r`n"
	$c += "`r`n"

	#TFTP Servers:
	$tftplist = $null

	if(([array]$OptionTftp).count -gt 0)
	{
	foreach ($ts in [array]$OptionTftp)
	{
	$tftplist += "`"$ts`" "
	}

	$c += "netsh dhcp server \\$s scope $IPScope set optionvalue 150 IPADDRESS $tftplist`r`n"
	$c += "`r`n"
	}

	if ($NoDynamicDNS)
	{
	$c += "netsh dhcp server \\$s scope $IPScope set DnsConfig 0 0 0 0"
	}


	}
	if (-not $NoRevLookup)
	{
	$revname = $IPScope.Split(".")
	$zones = (Invoke-Expression -Command "dnscmd $Domain /enumzones") \| %{$_ -split "\s+"} \| ?{ `
	$_.StartsWith("$($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa") `
	-or `
	$_.StartsWith("$($revname[0]).$($revname[1]).$($revname[2]).in-addr.arpa")}
	if (([string[]]$zones).count -lt 1)
	{
	$c += "dnscmd $Domain /zoneadd $($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa /dsprimary"
	$c += "dnscmd $Domain /Config $($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa /AllowUpdate 2"
	$c += "dnscmd $Domain /Config $($revname[2]).$($revname[1]).$($revname[0]).in-addr.arpa /Aging 1"
	}
	else
	{
	Write-Output "Skipping Reverse Lookup Zone creation. Detected pre-existing zone(s): `r`n $zones `r`n"
	}
	}



	Write-Output "Generated the following netsh commands:`r`n"
	Write-Output $c

	if ($Invoke)
	{
	Write-Host "Received Invoke parameter; executing all commands.`r`n"
	#Write-Host "These are the commands that were generated from your input:`n$($c)`n"
	#$execute = Read-Host "Definitely execute these commands? (USE CARE)? (Y/N)"

	#Double-check execution/invocation of netsh
	#if ($execute -match "Y")
	#{

	Invoke-Expression $c
	#}
	}