[Samba] idmap & migration to rfc2307

Rowland Penny rowlandpenny241155 at gmail.com
Tue Nov 10 19:58:47 UTC 2015

On 10/11/15 19:46, Michael Adam wrote:
> On 2015-11-10 at 15:31 +0000, Rowland Penny wrote:
>> On 10/11/15 13:38, Rowland Penny wrote:
>>> On 07/11/15 23:28, Michael Adam wrote:
>>>> Ok, why do you strictly need it?
>>>> I understand that it gives you a better feeling,
>>>> and it may be convenient but which scenario really
>>>> requires it? Most important is the central auth db.
>>>> If the IDs on the various DCs and members in the
>>>> domain do not have the same sets of unix IDs, then
>>>> nevertheless
>>>> - local login will work.
>>>> - ssh login will work.
>>>> - rsync will work if not using --numeric-ids.
>>>> - cifs mount will work.
>>> Hi Michael, as I am mid setup of a new test domain, I thought I would try
>>> it as you seemed to be suggesting i.e. without using rfc2307 attributes.
> Don't get me wrong, I think it would be great to be able to use
> the rfc2307 attributes on the DC. I just see a bunch of problems
> at least in environments where much has to be automated. In a
> smaller setup where everything is pretty much under manual
> control, this can very well work already today.
>>> I have come to the conclusion that by using the latest Samba on the DC
>>> with winbindd, you are using something that is very very similar to a
>>> samba domain member that uses the 'rid' backend.
> Well, if you do the default idmap.ldb style (non-rfc2307)
> mappings in the DC, it is more like the winbindd's tdb
> idmap backend in nature. (The main similarity to the rid
> backend lies in the fact that idmap.ldp does 'BOTH' type
> mappings, but I planned to introduce that for the tdb
> backend as well (at least optionally for a start).)
>>> You can connect a domain member using the 'rid' backend to the DC.
>>> You can login to the DC as a domain member
>>> You can login to the DC via ssh
>>> rsync seems to work.
>>> you can mount a share from the DC on a domain member, but unless you
>>> explicitly set the users local uid & gid in the mount command, the mount
>>> ends up belonging to the uid of the user on the DC.
>>> the [homes] share appears to be working again.
>>> Using the 'rid' backend, you get a user local group.
>>> So, even though what you say is mostly true, I still hold to my belief,
>>> the best option would be if all Samba machines could use the full set of
>>> RFC2307 attributes.
>> OK Michael, I have now given a user a uidNumber and Domain Users a
>> gidNumber, I have also changed the domain member to use the 'ad' backend.
>> So what's changed?
>> You no longer need the local uid & gid in the mount command.
>> The local user group has gone.
>> Something it didn't mention before, with the rid backend, if you opened the
>> mounted share in Caja (gui file browser), you didn't have full control i.e.
>> you couldn't right click and create an empty file. This now works with the
>> ad backend.
>> So in my opinion, as long as you use the 'ad' backend on domain members, you
>> can use the DC as a fileserver, provided you use a Samba version that uses
>> the separate winbindd deamon. I still wouldn't let users login to the DC and
>> I also don't see any reason to use sssd or nlscd any more.
> Thank you very much, Rowland, for sharing this information
> and status with us! It looks very reassuring. Let's work
> further to get the remaining rough edges smoothened.
> It might be interesting for many other users if you could
> share configuration details of your setup, e.g. on the
> samba wiki if you like. I'd appreciate that.

Ah, the information already is on the wiki and  the smb.conf on there is 
mine :-)

> This could turn into some kind of reference setup.
> Cheers - Michael

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