[Samba] Samba 4 two DCs no matching UID/GID

Tim rintimtim at gmx.net
Wed Dec 10 07:39:14 MST 2014

I found this. But I didn't find it related to DC idmapping replication.

I have two pieces of hardware. My goal is realize an active directory for the windows clients and a file server. The AD should have redundancy (this is why I provisioned two DCs). The file should integrate snapshots like a NetApp system (snapshots are done by rsnapshot). The snapshot functionality works so far by mounting cifs shares read only of the backup hardware. But I will try this via NFS due to permissions. Mounting cifs shares leads to irritating permissions of ~snapshot folders ("Everyone" has full permissions).

So how would sssd help to replicate the ids regarding idmapping to the secondary DC? It seems that this is my only problem.

Another option is to have only one DC with NFS regarding snapshots and a file server who is integrating the snapshots as mentioned above.

But then I have to backup the idmapping file of the file server or does it get the ids from the AD DC so that I don't have to backup?
The FS stores the ACL by using the IDs. I am using XFS.

Thanks in advance

Am 10. Dezember 2014 13:48:40 MEZ, schrieb Rowland Penny <rowlandpenny at googlemail.com>:
>On 10/12/14 12:21, rintimtim at gmx.net wrote:
>> Thanks for the advice of copying the idmap.ldb. That works.
>> After adding zum users the uid and gid begin to differ again. I read 
>> that it is not recommended to run a DC as a fileserver but in my case
>> it's not really an option. It's a network of twelve clients, so four 
>> servers are incommensurate to this amount of clients.
>> I searched regarding sssd, because my nsswitch.conf also has it. But 
>> how do I have to configure it all?
>> My actual nsswitch.conf provides the following:
>> passwd:     files sss
>> shadow:     files sss
>> group:      files sss
>> services:   files sss
>> netgroup:   files sss
>> Another alternative seems to be regarding the idmap.ldb with my 
>> unidirectional rsync replication of the sysvol-folder.
>> *Gesendet:* Mittwoch, 10. Dezember 2014 um 11:01 Uhr
>> *Von:* "Rowland Penny" <rowlandpenny at googlemail.com>
>> *An:* Tim <rintimtim at gmx.net>, samba at lists.samba.org
>> *Betreff:* Re: [Samba] Samba 4 two DCs no matching UID/GID
>> On 09/12/14 22:49, Tim wrote:
>>     But will this idmap.ldb change work for upcoming new users or
>>     groups so that uid/gid will not be different?
>>     The wiki tells us about built-in groups. Those have the right
>>     Am 9. Dezember 2014 23:03:44 MEZ, schrieb Rowland Penny
>>     <rowlandpenny at googlemail.com>:
>>         On 09/12/14 21:07, Tim wrote:
>>             Hello all, I have a fresh install of two CentOS 7
>>             machines. On DC1 I made a domain provision with
>>             --use-rfc2307. In DC2 I made a join as DC - both exactly
>>             as the wiki advised. In fact of its missing I added the
>>             idmap use rfc2307 yes parameter to smb.conf. I will have
>>             an extra share on both DCs. Today I realized, that wbinfo
>>             shows different UID/GID for the same users or groups on
>>             the DC's. I created the users/groups via RSAT. I don't
>>             have a Unix attributes tab in RSAT. Is that my problem
>>             different uid/gid? Thanks in advance Tim
>>         Hi, I think your problem is that idmap.ldb does not replicate
>>         to the new DC, this means that users get different UID's on
>>         the two DC's. If you run: ldbedit -e nano -H
>>         /var/lib/samba/private/idmap.ldb on each DC, you will be able
>>         to see the differences. The cure ? copy idmap.ldb from the
>>         first DC to any secondary DC's after the join. It is
>>         documented here:
>>         https://wiki.samba.org/index.php/Join_a_domain_as_a_DC , near
>>         the bottom of the page. Rowland
>> I take it that you didn't read this page on the wiki: 
>> https://wiki.samba.org/index.php/Samba_AD_DC_HOWTO
>> You are running into one of the problems why it is not recommended to
>> use the DC as a fileserver, you have two choices here, either set up
>> separate member server to use as a fileserver, or use sssd or nlscd
>> pull the RFC2307 attributes that you will need to add to the
>> Whatever you do, you will need to copy idmap.ldb to any secondary
>> Rowland
>Did you search on the samba wiki ???? : 
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