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Re: [Samba] idmap config ad





On 28.01.2019 16:15, Rowland Penny via samba wrote:
On Mon, 28 Jan 2019 15:38:41 +0100
Viktor Trojanovic via samba <samba@xxxxxxxxxxxxxxx> wrote:

On 28.01.2019 15:27, Rowland Penny via samba wrote:
On Mon, 28 Jan 2019 09:10:58 -0500
Sonic via samba <samba@xxxxxxxxxxxxxxx> wrote:

Trying to use the idmap config ad on a domain member. The AD is an
actual Windows server and when logged in the AD server running ADUC
the NIS domain field on the UNIX attributes tab only shows a dash
and is cannot be changed.
Does Domain Users have a gidNumber attribute containing a number
inside the 10000-99999' range ?

Do any Active directory groups have such a gidNumber ?

Domain member is RHEL 7.6 running Samba 4.8.3.

Pertinent part of smb.conf:
=====================================
[global]
          security = ADS
          workgroup = MYDOMAIN
          realm = MYDOMAIN.LOCAL
          server string = mydomain

          kerberos method = secrets and keytab
          winbind refresh tickets = yes

          idmap config * : backend = tdb
          idmap config * : range = 3000-8999
          idmap config MYDOMAIN : backend = ad
          idmap config MYDOMAIN : schema_mode = rfc2307
          idmap config MYDOMAIN : range = 10000-99999
          idmap config MYDOMAIN : unix_nss_info = yes

          vfs objects = acl_xattr
          map acl inherit = yes
          store dos attributes = yes
=====================================

The documentation seems to strictly point to using a Samba AD with
the RSAT utility and here we're logged right on to the Windows AD
using the native ADUC application.
ADUC is part of RSAT and the Samba 'ad' backend works in the same
way that the Unix Attributes tab dows.

Rowland
Hi Rowland,

I read this post and started wondering myself. If the DC is a Windows
one, then I assume uid and gid creation is being handled
automatically by Windows Server. If that's correct, then I assume the
ad backend is the best one to use as the disadvantages mentioned in
the wiki all disappear, leaving only advantages. So, one only had to
make sure that the uids and gids created in the AD are within the
range mentioned in the smb.conf. Which begs the question, is it
possible to influence this?

It all depends on what you mean by 'automatic creation' ;-)

If you create a user or group on ADUC, the user is created as a Windows
user or group, without any rfc2307 attributes, it gets a unique 'RID'.
If you want a Windows user or group to be known to Unix, you need to
add the relevant rfc2307 attributes and make the Unix aware of them
(that's where Samba comes in). On ADUC, you use the Unix Attributes
tabs for this, you will also have to install IDMU. If everything is
installed correctly, you should be able to add rfc2307 attributes to a
user by selecting the user, right clicking on the user and selecting
'Properties', you should then be able to select the 'Unix Attibutes'
tab and add the required attributes, but they will not be added unless
you set the Primary group.

Not very automatic, is it ?

Rowland

No, it's not :) I clearly mixed up a couple of things. I thought that the rfc2307 attributes are created by the Windows DC when in fact all that is created automatically is the RID.

I'm still having a bit of a hard time figuring out when to use the rid backend over the ad one. Clearly, the big advantage of the ad backend is that everything is kept inside the AD. While this means you need to figure out a way how to manage the required attributes manually, this immensely simplifies a restore should something go wrong. And you don't have to worry about growth or granular control etc.

So, with the rid backend, I don't need to manage attributes manually which makes things easier at the time of setting up the member server but apart from that, I only see disadvantages, especially if you want room for growth, which is why, in a production environment, I'd probably always stick to the ad backend.

So, a few questions come to mind:

- Did I miss something important?
- When would you actually choose the rid backend over the ad one?
- Can you mix the two, i.e. have rid on one member and ad on the other? I assume that, even if possible, it wouldn't make sense since you already went through the trouble of creating the rfc2307 attributes, you may just as well use them on all members! - If you set up your member and came to the conclusion you needed the other backend, most likely from rid to ad, how would you switch?

Viktor


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