Sep 11, 2014

Kerberos event 4/Target account name is incorrect/ troubleshooting

This error is reported whenever the service provider (e.g. file server) cannot decrypt a service ticket that was sent to it. This is caused by the fact that the ticket was encrypted by one machine then sent to a different machine. In this case, the second machine doesn't have the private key to decrypt the ticket.

Troubleshooting steps

- make sure there is not duplicate SPN for the service you are trying to get. For example, if you want to access \\serverName1\sharePath and get above error; or on a file server you see kerberos event 4, you want to check if there is duplicate SPN host\serverName*. In the past, it takes a little effort to find duplicate SPNs, but started Windows7/2008, you can run setspn -X to find all duplicated SPNs in your domain

- make sure you don't have duplicate DNS entries for same server to different IPs (unless the server does have multiple IP, and all DNS entries are correct).

- if access using FQDN works but not short name (e.g. \\server.FQDN.com\sharePath works but not \\server\sharePath), and you have WINS in your environment, make sure the target server register correct 20h record (File Server) in WINS

- If your target computer has multiple names (mostly added by command netdom computername), then you should make sure you add SPNs for all the alias you have. For example, if you have a server has both names as server1 and server2, you should below spn registered in AD:

  • host/server1.fqdn.com
  • host/server1
  • host/server2.fqdn.com
  • host/server2
- make sure you don't have hosts file entries that resolve to wrong IP

- Log into the system that actually owns wrong IP, make sure it's not registering wrong name. For DNS, check NIC TCP/IP stack; for WINS, check "netdom computername localhost /enum", as well as check HKLM\CCS\Services\lanmanserver\parameters\OptionalNames

Mar 20, 2014

Script to reverse OU path so it can be sorted from top down - Excel macro & vb procedure

' This excel macro reverse OU path so it can be sorted from domain top to OU trees

' For example: CN=John Lan,OU=IT,OU=accounts,DC=johnlan,DC=com
' Will be reversed to: DC=com,DC=johnlan,OU=accounts,OU=IT,CN=John Lan

' if you want only a function that can reverse OU path (distinguished name), use function ReverseOU
' if you want to use it in excel, copy both ReverseOU and ReverseText as your macro

' How to use it in Excel
'
' 1. Hold down the ALT + F11 keys, and it opens the Microsoft Visual Basic for Applications window.
' 2. Click Insert > Module, and paste the following macro in the Modulewindow.
' 3. Then press F5, a dialog is displayed on the screen, and you need select a range to work with.
' 4. And then press OK, and all the text strings have been reversed.
' (c) JohnLan@gmail.com

' ReverseOU can be called from any vb script
Function ReverseOU(s)
    Dim temp
    Dim arrValue
        arrValue = Split(s, ",")
        xLen = UBound(arrValue) + 1
        'wscript.echo xLen
     
        For i = 0 To ((xLen - 1) / 2)
            'wscript.echo i
            'wscript.echo xLen-i-1
            temp = arrValue(i)
            arrValue(i) = arrValue(xLen - i - 1)
            arrValue(xLen - i - 1) = temp
            'wscript.echo "----------"
        Next
        ReverseOU = Join(arrValue, ",")
End Function

'Below is for excel
Sub ReverseText()
    Dim Rng As Range
    Dim WorkRng As Range
    On Error Resume Next
    xTitleId = "KutoolsforExcel"
    Set WorkRng = Application.Selection
    Set WorkRng = Application.InputBox("Range", xTitleId, WorkRng.Address, Type:=8)
    For Each Rng In WorkRng
        xOut = ReverseOU(Rng.Value)
        Rng.Value = xOut
    Next
End Sub