Re: How to fetch attributes of LDAP entry?

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From: Dennis Dobslaf (dobslaf_at_kdvz.de)
Date: 02/25/05 

Date: Fri, 25 Feb 2005 08:30:27 +0100

> That feature is by design - if you think about it - you never actually
> 'see' passwords anywhere in Windows.
>
> When you create the DirectoryEntry object you do so with a username
> and password. This call doesn't attach to the AD with a bad username
> and password. That's why the user is considered authenticated if
> found.

That's what I thought (at first). I'm not the LDAP guru so I searched in
msdn and found this:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sds/sds/active_directory_authentication_from_asp__net.asp

I used the LdapAuthentication class from the link above. The following
method throws an Exception:

public bool IsAuthenticated(String domain, String username, String pwd)
     {
       String domainAndUsername = domain + @"\" + username;
       DirectoryEntry entry = new
DirectoryEntry(_path,domainAndUsername, pwd);
                                        
       try
       {
         //Bind to the native AdsObject to force authentication.
         Object obj = entry.NativeObject;
                
         DirectorySearcher search = new DirectorySearcher(entry);
                
         search.Filter = "(SAMAccountName=" + username + ")";
         search.PropertiesToLoad.Add("cn");
         SearchResult result = search.FindOne();
                
         if(null == result)
         {
           return false;
         }
                
         //Update the new path to the user in the directory.
         _path = result.Path;
         _filterAttribute = (String)result.Properties["cn"][0];
       }
       catch (Exception ex)
       {
         throw new Exception("Error authenticating user. " + ex.Message);
       }
                
       return true;
     }

@ Object obj = entry.NativeObject;

It throws an System.Runtime.InteropServices.COMException with the
message "Der Authentifizierungmethode ist unbekannt" same as "unknown
authentication mode" in english.
I tried to add AuthenticationTypes.Anonymous to the DirectoryEntry
object but then it seems that he doesn't search for any authentication,
but no other AuthType worked.
Also I could not use the Filter "SAMAccountName" (if I uses
'Anonymous'), I have to search for the 'cn'. I don't know if our LDAP is
different to others (it's openldap). If it is so, I have to search for
the solution on other places.

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