[Samba] Problem with Domain SID

Marcus Haarmann marcus.haarmann at midoco.de
Thu Aug 17 12:20:39 GMT 2006

Hi Andre,

The machine was off-network for two days only. 
The problem is not machine based, but server based. The server SID has
definetely changed since the user was created (and the machine joined the
I found out in the meantime that the users SID contains the domain SID (this
can be retrieved in registry under HKEY_USERS, strip the last two bytes and
you have the domain SID), where it was created with. Unfortunately, there is
no simple way setting it in samba (like net setsid ... for domain SID, only
the PDC sid can be set). I have done this using a hex editor, patching
secrets.tdb (SID of PDC and Domain, these are identical, at our site). 
So, the problem is half-way solved.
The server now has the old sid again, which was presumably changed more than
half a year ago (modification time of secrets.tdb was December 2005). I
cannot say why the entrustment from this special machine has been broken,
but now I am able to log on to the domain as any user on all machines again.
(which have joined the domain before the SID change).
The only thing is that we added one machine after the modification of the
Domain-SID, we have to see how this machine behaves. I am now trying to
reactivate the old profile of the user who was not able to log in.
For the machine which joined the domain after the SID change, we might have
to rejoin the machine to the domain, unless anybody can tell me how this
trustment can be reassigned without a profile change ...


-----Original Message-----
From: samba-bounces+marcus.haarmann=midoco.de at lists.samba.org
[mailto:samba-bounces+marcus.haarmann=midoco.de at lists.samba.org] On Behalf
Of Andre Timmermann
Sent: Thursday, August 17, 2006 12:52 PM
To: Liste SAMBA
Subject: Re: [Samba] Problem with Domain SID

Hi Marcus.

Am Donnerstag, den 17.08.2006, 08:48 +0200 schrieb Marcus Haarmann:

> The problem is: the whole samba environment was not changed at all. So 
> why did the SID change ? I cannot say when the SID changed so there 
> might be no available backup of the secrets files any more.
> And: is there a way to retrieve the old SID of the PDC from the 
> registry of any client machine (all the other machines are still 
> unchanged and the users can log into the domain on their machines).
> Then we could set it to the old value and all the other machines would 
> be trusted without a rejoin for the domain and loss of profile data.

Is ist possible, that this special Windows-Machine was offline for a longer

A friend of mine told me, that WinXP changes its SID from time to time
(2 weeks i think), but the last entry is kept. This would make the machine
unusable after 4 weeks of downtime.

So perhaps your client changes his SID and thinks that your server is not
trusted any more.

Another idea: I noticed, that if you pull the network cable off a running
winXP-Machine, it is possible that it loses its domain-membership.


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