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

[Rowland Penny]

On 10/12/14 16:33, Tim wrote:
> I think I will only need uid and gid due to fs stuff. There are only 
> Windows clients in that domain.
> So when the IDs are the same on both DCs, all will be fine I think.
>
> In RSAT there are no Unix attributes set. As an example: user1 has uid 
> 3000021 on DC1 (first provisioned one). DRS seems fine. On DC2 user1 
> gets uid 3000017.
> If I set ID in RSAT Unix attributes after choosing domain, the IDs 
> mentioned above will be overwritten? Standard in Unix attributes is 
> that ID is not set. E.g. I set ID 2000021 in RSAT this ID will be set 
> for user1 on both DCs because of use rfc2307 = yes?
>
> Regards
> Tim
>
> Am 10. Dezember 2014 16:10:58 MEZ, schrieb Rowland Penny 
> <rowlandpenny at googlemail.com>:
>
>     On 10/12/14 14:39, Tim wrote:
>
>         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 Tim 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 ids.
>         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 for 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 a separate member server to use as a fileserver, or use
>         sssd or nlscd to pull the RFC2307 attributes that you will
>         need to add to the users/groups. Whatever you do, you will
>         need to copy idmap.ldb to any secondary DC's. Rowland Did you
>         search on the samba wiki ???? :
>         https://wiki.samba.org/index.php/Local_user_management_and_authentication/sssd
>         Rowland
>
>
>
>     OK, another wikipage:https://wiki.samba.org/index.php/RFC2307_backend
>
>     The only way to ensure that your users have consistent uidNumbers &
>     gidNumbers on **any**  Unix machine, is to use the RFC2307 attributes.
>     The attributes are all available out of the box with Samba4, you just
>     have to give your users and groups the required attributes.
>
>     Once you have given your users & groups these attributes, you then have
>     to use something to pull these attributes. Winbind is available from
>     Samba, but winbind on the DC is different from the winbind that is used
>     on a member server or client. The winbind that is available on the DC
>     will not pull any RFC2307 attributes other than 'uidNumber' &
>     'gidNumber'. What this means is, if you want to use different
>     unixHomeDirectories & loginShell's, you need to use sssd or nlscd.
>
>     Rowland
>

By default, no users have a uidNumber and no groups have a gidNumber. If 
you use the UNIX_Attributes tab in ADUC, the default start number is 
10000, though you can change this, I wouldn't bother. Just update any 
users via ADUC, AD will then store the next uidNumber (or gidNumber) for 
you. If you then go to the DC and run 'getent passwd <the user you just 
updated on ADUC>', you will find that the users ID number will have 
changed to whatever you used in ADUC. This same command should give the 
same result on the second DC, though there may be a problem on both DC's 
if the cache hasn't cleared, if so, wait a short while, or run 'net 
cache flush'.

If you update users with ADUC, do not add users with samba-tool and try 
to add the users uidNumber at the same time, you could use a number that 
is already in use for another user. You can use the same number for a 
group as a user, they are different objects.

If you do use ADUC to add the users uidNumber and the user already has 
any info stored on the DC, you will need to change the ownership of this 
info to the user (the info will show as belonging to the users old 
uidNumber).

Rowland