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Archive for April, 2009

I have recently spent some time working with Xpath queries as part of Event Log filtering in Windows Server 2008.  It’s a great feature, but one limitation I found was that it doesn’t appear possible to use the starts-with() function when querying Event Logs with either the UI or Wevtutil.exe.  Here’s an example.

Let’s say I enabled LDAP logging on a DC and want to filter the Directory Service event log to find all LDAP queries coming from a particular IP address.  The IP address is buried in one of the Data nodes of the Event XML, as shown in red below.

<Event xmlns=”http://schemas.microsoft.com/win/2004/08/events/event”>


    <Provider Name=”Microsoft-Windows-ActiveDirectory_DomainService” Guid=”{0e8478c5-3605-4e8c-8497-1e730c959516}” EventSourceName=”NTDS General” />

    <EventID Qualifiers=”16384″>1644</EventID>






    <TimeCreated SystemTime=”2009-04-29T20:39:00.886Z” />


    <Correlation />

    <Execution ProcessID=”648″ ThreadID=”792″ />

    <Channel>Directory Service</Channel>


    <Security UserID=”S-1-5-21-854245398-152049171-725345543-4606″ />



    <Data>CN=MyCo Enterprise Issuing CA 1, CN=Public Key Services,CN=Services,CN=Configuration,DC=MyCo,DC=Com</Data>

    <Data> (objectClass=cRLDistributionPoint) </Data>










So if I wanted to use Xpath to filter all events in the Directory Service Event Log from that IP address my query would look something like this:


  <Query Id=”0″ Path=”Directory Service”>

    <Select Path=”Directory Service”>*[System[(Level=4 or Level=0) and (EventID=1644)]] and *[EventData[Data[5]=’′]]</Select>



The query works well, but the problem is that the Data node within the XML contains the port number (4048) in addition to the IP address.  I want to find all queries issued from that client, regardless of the port used.  Here’s my attempt to use the starts-with() function to filter the event.


  <Query Id=”0″ Path=”Directory Service”>

    <Select Path=”Directory Service”>*[System[(Level=4 or Level=0) and (EventID=1644)]] and *[EventData[starts-with(Data[5],’′)]]</Select>



This fails with the error “The specified query is invalid“.  Back to the drawing board.  I posted a question to Technet Forums and got some good help from Ivan Ting at Microsoft.  He provided some Javascript that used starts-with() and this worked (after some fun messing around with default namespace issues).  Being something of a Javascript muppet (the antithesis of a Javascript guru), I decided to try my hand at a Powershell version.  Here’s what I came up with.

# Author: Tony Murray
# File name: LDAPEvents.ps1
# Date: 28th April 2009
# Purpose: Extracts LDAP Search information from Directory Service Event
# Log. Requires LDAP logging to be switched on.

# Function to create an object for XML document navigation
# Source: Technet Scriptcenter
function get-xpn ($text)
$rdr = [System.IO.StreamReader] $text
$trdr = [system.io.textreader]$rdr
$xpdoc = [System.XML.XPath.XPathDocument] $trdr

# Run Wevtutil.exe to export the Event log to file
# Could use Powershell to do this but it creates odd-looking xml!

$file = “c:\util\dumplog.xml”
& $env:windir\System32\wevtutil qe `”Directory Service` /e:Events | Out-File $file

# Remove the namespace from the xml file. It won’t work if it stays

$findStr = ” xmlns=`’http://schemas.microsoft.com/win/2004/08/events/event`’”
$ReplStr = “”
$newcontent = (Get-Content $file) -replace ($findStr,$ReplStr)
Set-Content $file $newcontent

# Invoke the navigator
$xb = get-xpn $file

# Define the Xpath query we want to use
$query = “//*[ System[(Level=4 or Level=0) and (EventID=1644)] `
and EventData[starts-with(Data[5],’′)]]”

# Create a CSV file with the output. Each line represents the details
# we want from a single Event.

Write-Output $xb.Select($query) | %{[xml] $_.OuterXml} | Select-Object `
@{name = “Date&Time”;Expression = {$_.Event.System.TimeCreated.SystemTime}}, `
@{name = “SearchBase”;Expression = {$_.Event.EventData.Data[0]}}, `
@{name = “Filter”;Expression = {$_.Event.EventData.Data[1]}}, `
@{name = “Visited”;Expression = {$_.Event.EventData.Data[2]}}, `
@{name = “Returned”;Expression = {$_.Event.EventData.Data[3]}}, `
#@{name = “SourceIP”;Expression = {$_.Event.EventData.Data[4]}}, `
@{name = “SearchScope”;Expression = {$_.Event.EventData.Data[5]}} `
| export-csv ds.csv -notype
# Replace the previous line with the following line to change the output format
#ConvertTo-HTML | Out-File “LDAPEvent.html”

Having to write a script is more effort than simply issuing the query from within Eventvwr, but it does have the advantage of allowing you to return only the information you are interested in – and in the format that you want.  Hopefully, my experience will save you a bit of time and effort if you are trying to achieve something similar.

Laura Hunter and Brian Desmond will be doing a webcast discussing and demoing the new Active Directory features in Windows Server 2008 R2 as well as answering AD questions. They have a 90 minute slot and expect to spend ~45-60 minutes on R2 and the remainder taking questions on the presentation and AD in general.  They’d love to see you there. The webcast is hosted by O’Reilly and is free to attend. If you can’t make it, a recording will be available. Here are the details: 

Registration Link –


Date: Friday, April 24, 2009Time: 10am PT, San Francisco
6pm – London | 1pm – New York | Sat, Apr 25th at 3am – Sydney | Sat, Apr 25th at 2am – Tokyo | Sat, Apr 25th at 1am – Beijing | 10:30pm – Mumbai

In my last post, I provided a small batch file to support scheduled IFM dumps of an AD LDS instance.  Afterwards, I realised that batch files are sooo last century and decided to have a crack at the Powershell version.  I’m no Bwandon, but the script below seems to do the trick.

# Name: Create_IFM_Dump.ps1
# Author: Tony Murray
# Version: 1.0
# Date: 20/04/2009
# Comment: PowerShell script to create AD LDS IFM
# backup.  To be run nightly as a scheduled task.

# Declare variables$IFMDir = “c:\backup\adlds\Instance1″
$IFMName = “adamntds.dit”
$cmd = $env:SystemRoot + “\system32\dsdbutil.exe”
$flags = “`”ac i Instance1`” ifm `”create full c:\backup\adlds\Instance1`” q q”
$date = get-Date -f “yyyymmdd”
$backupfile = $date + “_adamntds.bak”
$DumpIFM = “{0} {1}” -f $cmd,$Flags

# Main

# Create the folder if it doesn’t exist if(test-path -path $IFMDir)
{write-host “The folder” $IFMDir “already exists”}
{New-Item $IFMDir -type directory}
# Clear the IFM folder (Dsdbutil needs folder to be empty before writing to it) Remove-Item $IFMDir\*

# Run Dsdbutil.exe to create the IFM dump file Invoke-expression $DumpIFM# Rename the dump file to give the backup a unique name

rename-item $IFMDir”\”$IFMName -newname $backupfile

# End Main


Microsoft Technet describes how to back up an AD LDS instance using either Windows Server Backup or Dsdbutil.exe.  Interestingly, the Dsdbutil method leverages the Install From Media (IFM) feature to perform the backup.  Here’s a small batch file that you can use to schedule the backup using the Task Scheduler.

@echo off
rd /s c:\backup\adlds\Instance1\ /q
%windir%\system32\dsdbutil.exe “ac i Instance1″ ifm “create full c:\backup\adlds\Instance1″ q q


If you’ve spent some time with Vista or Windows Server 2008 you’ll have noticed that there are some fundamental changes to the event viewer.  One of the changes is in the way in which event logs can be filtered.  In addition to the point-and-click filter selection you can now also enter an xpath query by accessing the XML tab (see screenshots below).  This gives you the ability to filter using a much wider range of criteria.  Basically, you can search using anything that is presented in the list of XML values.




The xpath queries take a bit of getting used to and as yet there don’t appear to be many publicly available examples.  Here are a few to get you started. This query searches the Security Event log for 4624 events that include a TargetUsername of “User1″ and corresponding to a logon type of “2″ (interactive). 

  <Query Id=”0″ Path=”Security”>
    <Select Path=”Security”>*[System[Provider[@Name='Microsoft-Windows-Security-Auditing'] and (EventID=4624)] and EventData[Data[@Name='TargetUserName']=’User1′] and EventData[Data[@Name='LogonType']=’2′]]</Select>

The query below also looks for 4624 events, but this time for those that include a WorkstationName of “Workstation1″ and a logon type of “3″ (network). 

  <Query Id=”0″ Path=”Security”>
    <Select Path=”Security”>*[System[Provider[@Name='Microsoft-Windows-Security-Auditing'] and (EventID=4624)] and EventData[Data[@Name='WorkstationName']=’Workstation1′] and EventData[Data[@Name='LogonType']=’3′]]</Select>

Even though Xpath can appear a little daunting at first it is worth spending a bit of time with as it’s potentially quite powerful.  As with Powershell it is something that is likely to be here to stay.

I really like the snapshot feature of Windows Server 2008 AD and have been using it quite a bit recently.  This week I had my first foray into snapshotting with AD LDS.  Everything is pretty much the same as for AD, the only obvious difference being that you can create the snapshots using either dsdbutil or ntdsutil with AD LDS.  I was somewhat surprised then to see a nasty looking error (see below) when I fired up Dsamain.exe to expose my freshly taken AD LDS snapshot.

C:\>dsamain -dbpath “C:\$SNAP_200904031033_VOLUMEC$\Program Files
\Microsoft ADAM\INSTANCE1\data\adamntds.dit” -ldapport 15005
EVENTLOG (Error): NTDS Database / Internal Processing : 1168
Internal error: An Active Directory Domain Services error has occurred.
Additional DataError value (decimal):
Error value (hex):

Internal ID:

EVENTLOG (Error): NTDS General / Internal Processing : 1003
Active Directory Domain Services could not be initialized.

The directory service cannot recover from this error.

User Action

Restore the local directory service from backup media.

Additional Data

Error value:
-1507 JET_errColumnNotFound, No such column

EVENTLOG (Informational): NTDS General / Service Control : 1004
Active Directory Domain Services was shut down successfully.

After a few minutes bafflement, I had another look through the Dsamain.exe command line options and saw this:

 -adlds       (optional) open AD/LDS DIT

It turns out the -adlds parameter is optional only in the sense that you don’t (and in fact must not) include it when using Dsamain.exe with AD.  It is mandatory when using AD LDS.

Once I included the -adlds parameter everything fired up normally.   Another case of RTFM for me. :-)