gensec returns the wrong error to kerberos errors like Ticket Expired and clock skew issues

Stefan Metzmacher metze at
Sat Nov 7 08:32:06 UTC 2015

Am 06.11.2015 um 03:22 schrieb Richard Sharpe:
> On Wed, Nov 4, 2015 at 11:23 AM, Jeremy Allison <jra at> wrote:
>> On Wed, Nov 04, 2015 at 11:14:50AM -0800, Richard Sharpe wrote:
>>> On Wed, Nov 4, 2015 at 10:22 AM, Jeremy Allison <jra at> wrote:
>>>> On Wed, Nov 04, 2015 at 10:00:48AM -0800, Richard Sharpe wrote:
>>>>> Hi folks,
>>>>> A capture I have indicates that when a Windows server gets a
>>>>> KRB5KRB_AP_ERR_TKT_EXPIRED error it returns
>>>>> STATUS_MORE_PROCESSING_REQUIRED along with an SPNEGO negTokenTarg with
>>>>> the Kerberos error blob in it.
>>>>> Samba, and it looks like gensec, folds that down to LOGON_FAILED,
>>>>> which makes it very hard for admins to figure out what the real error
>>>>> is.
>>>>> Is there a bugzilla on this?
>>>>> If I get a chance I will try to provide a fix.
>>>> I think that is intentional in order to prevent
>>>> username guessing attacks.
>>> That doesn't even pass the smell test. The KDC is responsible for
>>> preventing password guessing games.
>> Sure, but smbd is also. Remember we have our own passdb
>> code which has to implement the same protections.
>> However, I haven't looked at that bit of gensec recently
>> so you may be right here :-).
> It looks like perhaps in
> source3/librpc/crypto/gse.c:gse_get_server_auth_token in the default
> arm of the switch, if gse_min is KRB5KRB_AP_ERR_TKT_EXPIRED or
> KRB5KRB_AP_ERR_TKT_NYV we should return
> I will see if this produces a response more to the liking of Windows.

Can you file a bug report and attach network captures against windows
and against


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