[Samba] 'LDAP_PROTOCOL_ERROR' when NTLMSSP_NEGOTIATE bind request

[Nicolas Martinussen]

I've found a way to reproduce the issue I have with a small C# code executed on Windows. It gets me almost the same packets when I do a capture, I also get the 'LDAP_PROTOCOL_ERROR' in the Samba logs, and when I try it against a Windows DC, it works.

Here is the code:

using System.DirectoryServices.Protocols;
using System.Net;

class Program
{
    static void Main()
    {
        string ldapServer = "dc-01.ad.mydomain.com";
        
        LdapConnection ldap = new LdapConnection(ldapServer);
        ldap.AuthType = AuthType.Ntlm;
        ldap.Credential = new NetworkCredential("ldap", "PASSWORD", "MYDOMAIN");

        ldap.Bind();
    }
}

It seems like AuthType.Ntlm isn't supported by the Samba code. When I try the same code with AuthType.Basic, in that case, it works (I get the "Strong authentication is required for this operation.", but that's normal as I use LDAP and not LDAPS).

> I wonder if this could be an authentication problem ?
> If I run this ldapsearch on a Unix domain member against one of my DCs:
> 
> ldapsearch -x -H ldap://dc03.samdom.example.com -D
> CN=rowland,CN=Users,dc=samdom,dc=example,dc=com -w xxxxxxxxxxx -b
> 'dc=samdom,dc=example,dc=com' -s sub
> 
> I get this:
> 
> ldap_bind: Strong(er) authentication required (8)
>         additional info: BindSimple: Transport encryption required.
> 
> If I go to the DC and add this to its smb.conf:
> 
> ldap server require strong auth = no

I've also tried that but it still sadly doesn't work...

> Then restart it, if I then rerun the ldapsearch on the Unix domain
> member, I get the entire AD domain dumped.
> 
> After that, I am lost :-)
> 
> Rowland

Nicolas