Intermittent failure to authenticate using NTLM with NT_STATUS_ACCESS_DENIED

[Richard Sharpe]

On Thu, Oct 8, 2015 at 9:22 PM, Stefan Metzmacher <metze at samba.org> wrote:
> Am 09.10.2015 um 01:19 schrieb Jeremy Allison:
>> On Thu, Oct 08, 2015 at 04:11:19PM -0700, Richard Sharpe wrote:
>>> Hi folks,
>>>
>>> We are intermittently seeing NTLM auth failing with
>>> NT_STATUS_ACCESS_DENIED and we see this message in winbindd.log:
>>>
>>> [2015/10/08 15:34:33.393987,  3, pid=3549, effective(0, 0), real(0,
>>> 0), class=winbind]
>>> ../source3/winbindd/winbindd_pam.c:1426(winbind_samlogon_retry_loop)
>>>   winbind_samlogon_retry_loop: sam_logon returned ACCESS_DENIED.
>>> Maybe the trust account password was changed and we didn't know it.
>>> Killing connections to domain SOMEDOM
>>>
>>> Now, the real reason seems to be that one of the DCs in that domain
>>> disallows NTLM authentication and whenever winbindd finds that DC we
>>> get this problem.
>>>
>>> Is there some way to tell Windindd not to use that DC?
>>>
>>> Also, I notice that in some instances in winbind_samlogon_retry_loop
>>> we move to another DC but not in this case. We simply retry with the
>>> same DC.
>>>
>>> I suspect that we should move to another DC in this case as well.
>>>
>>> Any comments?
>>
>> Yep - getting  ACCESS_DENIED should certainly trigger adding
>> the DC to the negative connection cache.
>
> But not an the first failure!

Hmmm, why not. If it is returning ACCESS_DENIED either someone has
changed the machine account password without telling us or that DC
does not like NTLM passthrough ...

> BTW: which Samba version are you using?

4.3.0-- and master

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)