[Samba] Moving to AD for idmap backend

Kees van Vloten keesvanvloten at gmail.com
Tue Nov 29 18:29:17 UTC 2022

On 29-11-2022 18:24, Michael Tokarev via samba wrote:
> 28.11.2022 21:58, Rowland Penny via samba wrote:
> ..
>> To be clear, whoever thought up the idea of assigning the uidNumber & 
>> gidNumber attributes for two domains from the same pool is, in my 
>> opinion, an idiot. Not even Windows does this, every DC has its own 
>> RID pool, you can look at a RID and know on which DC it was created.
> This and the next one are a very useful pieces of information.
> This in part explains why there should be non-overlapping ranges
> for domains, and why one or another way of auto-rid is better
> than rfc2307 attributes for that (and there are many more points
> why this is so, - basically, you can't control the uidNumber
> allocations whatsoever). Very useful.
> It needs to be in a WIKI somewhere, but I can't think for a
> place for it - there's no "guide" in there, just a bunch or
> random pieces of info, and actually, many issuse in there
> are due to lack of the "full picture" in some guide.
> The problem is that quite often, the things goes the other way
> around: not from windows and their domains and their users to
> linux, but from *linux* to windows.  In other words, first there
> were linux users, next was a question, - how can I access their
> unix home dirs from a windows machine?  But the users, together
> with their IDs, are already there, and their uids needs to be
> mapped TO domain users, not FROM.
> A good and right integration needs complete user remapping.
> Which sometimes seemed as a much bigger pain than dealing
> with uidNumber attributes in the AD. Especially at *first*,
> before first clashes, or before someone starts rewriting
> some other's files due to the same uid.
> The whole picture, the understanding of the actual reasons
> why the ranges (at least for the different domains) must not
> overlap, why some automatic idmapping is better, and all that,
> only comes with experience, usually quite good one, after a
> lot of trial and error and dealing with consequences of the
> initial bad decisions which weren't known to be bad at all.
> /mjt
Here is some information about Linux UIDs, GIDs and ranges, perhaps 
useful to somebody:


- Kees.

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