Find If User is Member of Active Directory Group A

Question

I am using Active Directory to authenticate users for an intranet site. I would like to refine the users that are authenticated based on the group they are in in Active Directory. Can someone show me or point me to directions on how to find what groups a user is in in ASP.NET 4.0 (VB)?

Answer 1

I realize this post is quite old but I thought I might update it with processes I am using. (ASP.Net 4.0, VB)

If using integrated windows security, on a domain.

Page.User.IsInRole("domain\GroupName") will check to see if the authenticated user is a member of the specified group.

If you would like to check another users group membership other than the authenticated user.

Two stage for checking multiple groups with the same user principal:

Dim MyPrincipal As New System.Security.Principal.WindowsPrincipal _
     (New System.Security.Principal.WindowsIdentity("UserID"))
Dim blnValid1 As Boolean = MyPrincipal.IsInRole("domain\GroupName")

Single stage for checkin a single group:

Dim blnValid2 As Boolean = New System.Security.Principal.WindowsPrincipal _
     (New System.Security.Principal.WindowsIdentity("userID")).IsInRole("domain\GroupName")

NOTE:: The IsInRole method does work with nested groups. If you have a top level group with a sub group that is a member, and the user is a member of the sub group.

Answer 2

I think I have the ultimate function to get all AD groups of an user included nested groups without explicit recursion:

Imports System.Security.Principal

Private Function GetGroups(userName As String) As List(Of String)
    Dim result As New List(Of String)
    Dim wi As WindowsIdentity = New WindowsIdentity(userName)

    For Each group As IdentityReference In wi.Groups
        Try
            result.Add(group.Translate(GetType(NTAccount)).ToString())
        Catch ex As Exception
        End Try
    Next

    result.Sort()
    Return result
End Function

So just use GetGroups("userID"). Because this approach uses the SID of the user, no explicit LDAP call is done. If you use your own user name it will use the cached credentials and so this function is very fast.

The Try Catch is necessary because in large companyies the AD is so big that some SIDs are getting lost in space.

Answer 3

To just check if a user is member of a group including sub-groups just use:

    Public Function IsInGroup(ByVal objectName As String, groupName As String) As Boolean
        Try
            return New WindowsPrincipal(New WindowsIdentity(objectName)).IsInRole(groupName))
        Catch ex As Exception
        End Try

        Return False
    End Function

Answer 4

I found this here.

''' <summary>
''' Function to return all the groups the user is a member od
''' </summary>
''' <param name="_path">Path to bind to the AD</param>
''' <param name="username">Username of the user</param>
''' <param name="password">password of the user</param>
Private Function GetGroups(ByVal _path As String, ByVal username As String, _
                 ByVal password As String) As Collection
    Dim Groups As New Collection
    Dim dirEntry As New _
        System.DirectoryServices.DirectoryEntry(_path, username, password)
    Dim dirSearcher As New DirectorySearcher(dirEntry)
    dirSearcher.Filter = String.Format("(sAMAccountName={0}))", username)
    dirSearcher.PropertiesToLoad.Add("memberOf")
    Dim propCount As Integer
    Try
        Dim dirSearchResults As SearchResult = dirSearcher.FindOne()
        propCount = dirSearchResults.Properties("memberOf").Count
        Dim dn As String
        Dim equalsIndex As String
        Dim commaIndex As String
        For i As Integer = 0 To propCount - 1
            dn = dirSearchResults.Properties("memberOf")(i)
            equalsIndex = dn.IndexOf("=", 1)
            commaIndex = dn.IndexOf(",", 1)
            If equalsIndex = -1 Then
                Return Nothing
            End If
            If Not Groups.Contains(dn.Substring((equalsIndex + 1), _
                                  (commaIndex - equalsIndex) - 1)) Then
                Groups.Add(dn.Substring((equalsIndex + 1), & _
                                       (commaIndex - equalsIndex) - 1))
            End If
        Next
    Catch ex As Exception
        If ex.GetType Is GetType(System.NullReferenceException) Then
            MessageBox.Show("Selected user isn't a member of any groups " & _
                            "at this time.", "No groups listed", _
                            MessageBoxButtons.OK, MessageBoxIcon.Error)
            'they are still a good user just does not
            'have a "memberOf" attribute so it errors out.
            'code to do something else here if you want
        Else
            MessageBox.Show(ex.Message.ToString, "Search Error", & _
 MessageBoxButtons.OK, MessageBoxIcon.Error)
        End If
    End Try
    Return Groups
End Function
End Class

Answer 5

For those who may be interested, this is how I ended up coding it:

Dim ID As FormsIdentity = DirectCast(User.Identity, FormsIdentity)
    Dim ticket As FormsAuthenticationTicket = ID.Ticket
    Dim adTicketID As String = ticket.Name
    Dim adSearch As New DirectorySearcher
    adSearch.Filter = ("(userPrincipalName=" & adTicketID & ")")
    Dim adResults = adSearch.FindOne.Path
    Dim adResultsDirectory As New DirectoryEntry(adResults)
    Dim found As Boolean = False
    For Each entry In adResultsDirectory.Properties("memberOf")
        Response.Write(entry)
        Response.Write("<br/>")
        If entry = "CN=GroupName,CN=UserGroup,DC=my,DC=domain,DC=com" Then
            found = True
        End If

    Next
    If Not (found) Then
        Response.Redirect("login.aspx")
    End If