[Samba] Domain member cannot authenticate when first domain controller is down

Jason Keltz jas at eecs.yorku.ca
Wed Mar 3 16:14:07 UTC 2021

Hi Dale/Josh,

I had opened a ticket about this issue back in December (at least I 
think this is similar):


I consider failover to be very important.  Unfortunately, the Samba 
developers haven't had time to work on it.  I've had a few users email 
me over the course of the last months stating similar problems.  Maybe 
you or anyone else who has the problem might add a similar "me too" to 
the bug so that the information is all available when the developers do 
have time to work on it, and we can all benefit.

I suppose there's still a benefit to having multiple DC for load 
balancing.  However, yes, when the DC goes out, in my experience, 
there's definately trouble.


On 3/3/2021 10:25 AM, Dale via samba wrote:
> Josh, I don't have the answer to your question, but if you ever figure 
> it out, I would like to know the answer, too.
> The 2nd DC that I built has been of very little use.  While building, 
> it passed all the tests in the wiki.  After building, I found some DNS 
> entries that were not created during the join. Rowland kindly helped 
> me add and/or edit the affected entries, and I hoped for better 
> results.  However, it was not to be.  If the 1st DC is removed from 
> the network, any kind of login or getent is interminably long or times 
> out.  So, while I easily see the theoretical value of having multiple 
> DC's, I'm having trouble seeing the actual, practical benefit of 
> having them.  There is no instant failover, and often times, there is 
> complete failure of necessary AD functions.  While it's certainly 
> possible the problem could be me, I cannot troubleshoot what the 
> problem is.
> Dale
> On 3/1/21 6:25 PM, Josh T via samba wrote:
>> Further fiddling with this has shown something strange. If I enter my 
>> username and password in an attempt to authenticate a domain user, it 
>> will take 60+ seconds for it to fail to log in. However, during said 
>> 60+ seconds, if I log in via SSH as a non-domain user, then the 
>> domain user login succeeds. What could cause that?
>> ________________________________
>> From: Roy Eastwood <spindles7 at gmail.com>
>> Sent: Saturday, February 27, 2021 1:27 AM
>> To: 'Josh T' <c3h4ohcooh3 at hotmail.com>; samba at lists.samba.org 
>> <samba at lists.samba.org>
>> Subject: Re: [Samba] Domain member cannot authenticate when first 
>> domain controller is down
>> On 27 February 2021 03:35 Josh T wrote:
>>> //Problem:
>>> I am unable to authenticate a domain user on a Samba domain member 
>>> while the
>>> first Samba directory controller DC1 is powered off and the second 
>>> Samba
>>> directory controller DC2 is powered on.
>>> While DC1 is powered on, I can log in as a domain user with no 
>>> problems. While
>>> DC1 is powered off, attempting to log in usually results in waiting 60+
>> seconds
>>> followed by a login failure message. If I had already logged in 
>>> prior to
>> powering
>>> off DC1, then I can see the same long delay and authentication 
>>> failures when
>>> entering my sudo password. Intermittently I can sometimes manage to 
>>> log in
>>> while DC1 is powered off, but there is still the 60+ second delay; I 
>>> haven't
>> been
>>> able to link this intermittent behavior to any of my own 
>>> troubleshooting
>> actions.
>>> In any case, a 60+ second delay is undesirable.
>>> //Environment description:
>>> The first Samba domain controller DC1 was created following these 
>>> instructions
>>> on the Samba wiki:
>>> https://wiki.samba.org/index.php/Setting_up_Samba_as_an_Active_Directory_ 
>>> Domain_Controller
>>> It was provisioned using the command "samba-tool domain provision 
>>> --use-
>>> rfc2307 --interactive".
>>> The BIND9_DLZ DNS backend was selected during provisioning.
>>> Samba version 4.11.6-Ubuntu was installed on DC1 using the apt command.
>>> The second Samba domain controller DC2 was created following these
>>> instructions on the Samba wiki:
>>> https://wiki.samba.org/index.php/Joining_a_Samba_DC_to_an_Existing_Active 
>>> _Directory
>>> It was joined using the command "samba-tool domain join 
>>> my.domain.tld --dns-
>>> backend=BIND9_DLZ --option='idmap_ldb:use rfc2307 = yes'".
>> The above is missing the letters  "DC" in the command line. This may 
>> be the
>> issue.
>> HTH
>> Roy

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