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Posted 6 Oct 2004

Accessing LDAP User list using VB.NET

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This article will explain how to access LDAP service using VB.NET.


Reading list of all LDAP users

Compared to VB 6.0, .NET framework has given very easy access to the network solutions like LDAP. I have seen lots of people asking questions on LDAP access using .NET. In this article, I will try to explain how to retrieve list of all LDAP users.


 Public Function GetAllUsers(ByVal ldapServerName As String) As Hashtable 

 'To retrieve list of all  LDAP users 

 'This function returns HashTable
 _ldapServerName = ldapServerName

 Dim sServerName As String = "mail"

 Dim oRoot As DirectoryEntry = New DirectoryEntry("LDAP://" & ldapServerName & _
 Dim oSearcher As DirectorySearcher = New DirectorySearcher(oRoot)
 Dim oResults As SearchResultCollection
 Dim oResult As SearchResult
 Dim RetArray As New Hashtable()


  oResults = oSearcher.FindAll     

  For Each oResult In oResults

   If Not oResult.GetDirectoryEntry().Properties("cn").Value = "" Then
    RetArray.Add( oResult.GetDirectoryEntry().Properties("uid").Value, _
   End If


 Catch e As Exception

  'MsgBox("Error is " & e.Message)
  Return RetArray

 End Try

 Return RetArray
 End Function


As a basic, when we are writing applications that are related with LDAP, we need to take reference to the System.DirectoryServices namespace. To add the reference, just right click on the project and select "Add References". This will present the interface to select the .NET components that can be referred in the project. In this list, select System.DirectoryServices.dll and click Add. Now, in the project, open the form and add the following line at the top:

Imports System.DirectoryServices

After doing this operation, System.DirectoryServices is accessible in the application.

LDAP Implementation:

Normally, all elements and objects of LDAP are stored in a tree structure. To access this tree structure, we need to have a root element using which we can iterate through all child elements.

Obtaining a Root Element of LDAP:

Dim oRoot As DirectoryEntry = New DirectoryEntry("LDAP://" & _
     ldapServerName & "/ou=People,dc=mydomainname,dc=com")

Using this line, we can obtain the root of the LDAP tree structure.

Now, next job is to find all the entries of users from the LDAP tree. For this search operation, .NET Framework has provided a class, i.e. DirectorySearcher.

Dim oSearcher As DirectorySearcher = New DirectorySearcher(oRoot)

This class expects a parameter of DirectoryEntry and returns data in SearchResultCollection.

To access the SearchResultCollection, we need to use SearchResult object. The search result will contain the fields that we have specified in the load properties. To specify which property is to be loaded, we need to pass the field name as a string to the PropertiesToLoad method of the searcher object.

For example:


Make sure that you specify correct field names.

Now, the FindAll method of the object searcher will return the SearchResults collection. This collection will contain SearchResult (as specified above) and will have directory entries with the loaded properties.

In this example I have put all the values in a HashTable with Unique ID (UID) as key and Common Name (cn) as value.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Chandrashekhar Kulkarni
Web Developer
India India
Web Development:
.Net 2.0,,, Classic ASP, VBScript, Javascript, HTML, DHTML,

Perl, PHP, Linux, Apache, IIS.

Desktop Developement:, VB 6, COM/DCOM, Winsock, MAPI, CDO, Outlook Object Model, LDAP, C, C++, Foxpro 2.5, Clipper.

MS SQL - Server, MySQL, PostgreSQL

Enterprise Architect, Microsoft Project, Rational Rose, UML.

Has Nine+ years of experience with IT and now working in Project Manager's Role.

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Comments and Discussions

Questiondemo ldap server? Pin
ayman.metwally@gizasystems.com28-Apr-12 2:52
memberayman.metwally@gizasystems.com28-Apr-12 2:52 
memberTONITACHIKILA19-Oct-07 9:30 
Chandrashekhar Kulkarni21-Oct-07 6:55
memberChandrashekhar Kulkarni21-Oct-07 6:55 
TONITACHIKILA22-Oct-07 10:04
memberTONITACHIKILA22-Oct-07 10:04 
Questionnot working Pin
eforr9-Aug-07 7:59
membereforr9-Aug-07 7:59 
QuestionGives an error,.....plz help Pin
ASysSolvers14-Jun-07 5:14
memberASysSolvers14-Jun-07 5:14 
GeneralGroups for a user. Pin
ra-rag8-Jun-07 10:35
memberra-rag8-Jun-07 10:35 
GeneralLDAP Pin
Jagjot2-Apr-07 1:20
memberJagjot2-Apr-07 1:20 
Thanks for your contribition.

1) I am wondering how can i know what is my LDAP server(on the fly if its possible)
2) i am in the begining of creating an application to generete support tickets, but i want my web page to be opened and authintacated before ticket it raised. like get the user ID, email etc. information.

Can you help me with working example.

Thanks in advance
GeneralRe: LDAP Pin
Chandrashekhar Kulkarni2-Apr-07 22:40
memberChandrashekhar Kulkarni2-Apr-07 22:40 
GeneralListBox mulptiple selection Pin
bernie_0111-May-07 18:12
memberbernie_0111-May-07 18:12 

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