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How to list all  computers in a given active directory site

Posted on 2009-04-14
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Last Modified: 2012-05-06
Is there an easy way of showing all the computers currently in each active directory site within a domain ?
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Question by:drlargepants
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7 Comments
 
LVL 71

Expert Comment

by:Chris Dent
ID: 24139294

It's not amazingly easy, you have to grab the list of subnets and do a bit of IP math to figure out if each computer is part of that subnet (typically based on a lookup of a name in DNS).

You have a lot of them?

Chris
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Author Comment

by:drlargepants
ID: 24139336
A couple of 100 ?!  Its from an NT 4 migration, so ideally we need to know what is where and then create an OU for each site.
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LVL 71

Expert Comment

by:Chris Dent
ID: 24139394

Do you have a list of your IP ranges (network address and subnet mask)? And a list of the computers?

Chris
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Author Comment

by:drlargepants
ID: 24139531
Yeah can get that easy enough from angryip
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LVL 71

Expert Comment

by:Chris Dent
ID: 24139578

Then it's not so hard to do, I have a pile of VbScript subroutines for doing IP math and have done this kind of operation before for a much bigger domain.

It's reliant on being able to resolve the computer names to IP addresses, but I guess your infrastructure already allows that?

Chris
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Author Comment

by:drlargepants
ID: 24139791
yeah DNS is good to go :)
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LVL 71

Accepted Solution

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Chris Dent earned 80 total points
ID: 24146379

Cool, in that case we can have a play with this one. I've based this on files looking like this:

subnets.txt

192.168.2.0/24
10.45.0.0/23
172.16.0.0/22

computers.txt

computer1
computer2
computer3

It is possible to read the subnets from Active Directory instead of a file if they're configured there and you'd rather use those.

The file it creates a is a CSV file, you should be able to sort it by the Network Address field (in Excel) which will give you a break down of PCs within a given site. If we read subnets from AD we can add the site name as well.

Chris

Option Explicit
 
Const SUBNET_LIST = "subnets.txt"
Const COMPUTER_LIST = "computers.txt"
Const REPORT_FILE = "report.csv"
 
Function GetDNSAddresses(strComputerName)
  ' Return Type: Array
  '
  ' Returns an Array containing each IP Address for a given Node Name from a
  ' DNS Query
 
  Dim objShell : Set objShell = CreateObject("WScript.Shell")
  Dim objScriptExec : Set objScriptExec = objShell.Exec("nslookup " & strComputerName)
  Dim objStdOut : Set objStdOut = objScriptExec.StdOut
	
  Dim strIPAddress : strIPAddress = ""
  Do Until objStdOut.AtEndOfStream
    Dim strOut : strOut = objStdOut.ReadLine
    If InStr(strOut, "Name:") Then
      strIPAddress = objStdOut.ReadLine
	
      If InStr(strIPAddress, "Address:") > 0 Then
        strIPAddress = Trim(Replace(strIPAddress, "Address:", ""))
      ElseIf InStr(strIPAddress, "Addresses:") > 0 Then
        strIPAddress = Trim(Replace(strIPAddress, "Addresses:", ""))
      End If
    End If
  Loop
	
  GetDNSAddresses = Split(strIPAddress, ", ")
	
  Set objStdOut = Nothing
  Set objScriptExec = Nothing
  Set objShell = Nothing
End Function
 
Function ConvertIPToBinary(strIP)
  ' Converts an IP Address into Binary
 
  Dim arrOctets : arrOctets = Split(strIP, ".")
  Dim i
  For i = 0 to UBound(arrOctets)
    Dim intOctet : intOctet = CInt(arrOctets(i))
    Dim strBinOctet : strBinOctet = ""
    Dim j
    For j = 0 To 7
      If intOctet And (2^(7 - j)) Then
        strBinOctet = strBinOctet & "1"
      Else
        strBinOctet = strBinOctet & "0"
      End If
    Next
    arrOctets(i) = strBinOctet
  Next
  ConvertIPToBinary = Join(arrOctets, ".")
End Function
 
Function ConvertBinIPToDecimal(strBinIP)
  ' Convert binary form of an IP back to decimal
 
  Dim arrOctets : arrOctets = Split(strBinIP, ".")
  Dim i
  For i = 0 to UBound(arrOctets)
    Dim intOctet : intOctet = 0
    Dim j
    For j = 0 to 7
      Dim intBit : intBit = CInt(Mid(arrOctets(i), j + 1, 1))
      If intBit = 1 Then
        intOctet = intOctet + 2^(7 - j)
      End If
    Next
    arrOctets(i) = CStr(intOctet)
  Next
 
  ConvertBinIPToDecimal = Join(arrOctets, ".")
End Function
 
Function MaskLengthToIP(intMask)
  ' Converts a mask length to the decimal format mask
 
  Dim intFullOctets : intFullOctets = (intMask - (intMask Mod 8)) / 8
  Dim i : Dim arrOctets(3)
  For i = 0 To (intFullOctets - 1)
    arrOctets(i) = "255"
  Next
 
  Dim intPartialOctetLen : intPartialOctetLen = intMask Mod 8
  Dim j, intOctet
  If intPartialOctetLen > 0 Then
    For j = 0 To (intPartialOctetLen - 1)
      intOctet = intOctet + 2^(7 - j)
    Next
    arrOctets(i) = intOctet : i = i + 1
  End If
 
  For j = i To 3
    arrOctets(j) = "0"
  Next
 
  MaskLengthToIP = Join(arrOctets, ".")
End Function
 
Function CalcNetworkAddress(strIP, strMask)
  ' Generates the Network Address from the IP and Mask
 
  ' Conversion of IP and Mask to binary
  Dim strBinIP : strBinIP = ConvertIPToBinary(strIP)
  Dim strBinMask : strBinMask = ConvertIPToBinary(strMask)
 
  ' Bitwise AND operation (except for the dot)
  Dim i, strBinNetwork
  For i = 1 to Len(strBinIP)
    Dim strIPBit : strIPBit = Mid(strBinIP, i, 1)
    Dim strMaskBit : strMaskBit = Mid(strBinMask, i, 1)
 
    If strIPBit = "1" And strMaskBit = "1" Then
      strBinNetwork = strBinNetwork & "1"
    ElseIf strIPBit = "." Then
      strBinNetwork = strBinNetwork & strIPBit
    Else
      strBinNetwork = strBinNetwork & "0"
    End If
  Next
 
  ' Conversion of Binary IP to Decimal
  CalcNetworkAddress= ConvertBinIPToDecimal(strBinNetwork)
End Function
 
 
'
' Main Code
'
 
Dim objFSO : Set objFSO = CreateObject("Scripting.FileSystemObject")
 
Dim objSubnetFile : Set objSubnetFile = objFSO.OpenTextFile(SUBNET_LIST, 1, False, 0)
Dim objSubnetList : Set objSubnetList = CreateObject("Scripting.Dictionary")
 
Do While Not objSubnetFile.AtEndOfStream
  Dim arrTemp : arrTemp = Split(objSubnetFile.ReadLine, "/")
  Dim strNetworkAddress : strNetworkAddress = arrTemp(0)
  Dim strMaskLength : strMaskLength = arrTemp(1)
 
  objSubnetList.Add strNetworkAddress, strMaskLength
Loop
 
Set objSubnetFile = Nothing
 
Dim objComputerFile : Set objComputerFile = objFSO.OpenTextFile(COMPUTER_LIST, 1, False, 0)
Dim objReportFile : Set objReportFile = objFSO.OpenTextFile(REPORT_FILE, 2, True, 0)
objReportFile.WriteLine "Client Name,Client IP,Network Address,Subnet Mask"
 
Do While Not objComputerFile.AtEndOfStream
  Dim strClientName : strClientName = objComputerFile.ReadLine
  Dim arrClientIPs : arrClientIPs = GetDNSAddresses(strClientName)
 
  Dim strClientIP
  For Each strClientIP in arrClientIPs
 
    For Each strNetworkAddress in objSubnetList
      Dim strIPMask : strIPMask = MaskLengthToIP(objSubnetList(strNetworkAddress))
      If strNetworkAddress = CalcNetworkAddress(strClientIP, strIPMask) Then
        objReportFile.WriteLine strClientName & "," & strClientIP & "," & strNetworkAddress & "," & strIPMask
        Exit For
      End If
    Next
  Next
Loop

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