Authenticating an ADAM user against ADAM from C# - cannot bind


I have set up an ADAM instance and added some test users. From c# I can bind to ADAM using a windows account but I cannot bind using one of the ADAM users. (I can successfully bind the adam users in ldp) & I have made sure the users are enabled by setting msDS-UserAccountDisabled attribute to false. When I bind with my windows account I can successfully search & bring back properties for ADAM users but I am still struggling to authenticate them, when I try and bind with an ADAM user account I get the error :

Error: System.Runtime.InteropServices.COMException (0x8007052E): Logon failure: unknown user name or bad password. at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)

Here is the code I am using:

string userName = txtUserName.Text;
string password = txtPassword.Text;
string ADConnectionString = "LDAP://localhost:389/CN=sandbox,DC=ITOrg";
DirectoryEntry entry = new DirectoryEntry(ADConnectionString);

entry.Username = "myComputer\\Administrator";
entry.Password = "myPassword";
DirectorySearcher searcher = new DirectorySearcher(entry);
searcher.Filter = "(&(objectClass=user)(CN=" + userName + "))";
SearchResultCollection result = searcher.FindAll();
if (result.Count > 0)
    //bind with simple bind
    using (DirectoryEntry de = new DirectoryEntry(result[0].Path, userName, password,AuthenticationTypes.None))
         if (de.Guid != null) // this is the line where it dies
              Label1.Text = "Successfully authenticated";
              Label2.Text = result[0].Properties["displayName"][0].ToString();
              Label3.Text = result[0].Properties["telephoneNumber"][0].ToString();
          } else 
             Lable1.Text = "Unable to Authenticate";
    Lable1.Text = "UserName :" + userName + " not found"; 
} catch(Exception ex)
     Label1.Text = "Error searching: " + ex.ToString();

Thanks in advance for any help, much appreciated!

asked on Stack Overflow May 14, 2009 by samcooper11 • edited May 14, 2009 by samcooper11

1 Answer


It is probably a username format problem. When authenticating an ADAM user in SDS, you must use LDAP simple bind and use a name format supported by ADAM. ADAM technically allows you to use Digest auth as well, but that is not available in SDS (only SDS.Protocols), so that doesn't apply to your code approach.

You ARE using simple bind because you have AuthenticationTypes.None set so that part is ok. The part that is likely wrong then is the username format.

ADAM accepts the user's full DN, their displayName (if set and unique) and/or the userPrincipalName (if set and unique) as a "bindable" username, so start with the full DN of the user and seee if that works. If so, you can try the other user name values as well. Note that you can put whatever you want for displayName or userPrincipalName in ADAM. There is no validation. Just make sure the values are unique.

If you really want to do some type of bind authentication thing against ADAM, you'll get better perf and scale by using the ValidateCredentials method of PrincipalContext in .NET 3.5.

This kind of stuff is documented and discussed in the forums over at all the time and is a place I frequent much more often since it is my site. :) A friend tipped me off to this post or I would have never seen it.

answered on Stack Overflow May 14, 2009 by (unknown user)

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