[Samba] winbind offline logon

[bd730c5053df9efb]

Hi!

On Wednesday, January 10th, 2024 at 13:09, Rowland Penny via samba <samba at lists.samba.org> wrote:


> On Wed, 10 Jan 2024 14:52:12 +0000
> bd730c5053df9efb via samba samba at lists.samba.org wrote:
> 
> > I can confirm that on slackware too if I use rid as the backend for
> > the ad domain winbind works offline and the system doesn't slow to a
> > crawl for every process I try to start.
> 
> 
> The 'problem' (if it is a problem) with using the 'ad' backend is
> that everything has to be pulled from AD, it is my understanding that
> user information is only cached at login.
> 
> > Maybe if ad backend used to work, as stated previously in the thread,
> > it could be fixed since the rid backend has some drawbacks and ad
> > backend has some reasons to be the preferred option but at least for
> > now it is possible for me to use the rid backend until and if the ad
> > backend is fixed to allow offline logon working again. FWIW I'm using
> > samba 4.18.9 in slackware and 4.17.12-Debian in debian.
> 
> 
> What are the drawbacks of using the 'rid' backend that you see ?
> AD, whilst it has all the rfc2307 attributes, it only really uses a
> very small portion of them:
> 
> uidNumber
> gidNumber
> gecos
> uid
> loginShell
> unixHomeDirectory
> 
> If I run 'getent passwd rowland' on a Unix domain member using the
> 'rid' idmap backend', I get this:
> 
> rowland:*:11104:10513:Rowland Penny:/home/rowland:/bin/bash
> 
> Which would seem to be:
> username:??:UID:GID:?????:Home Directory:login shell
> 
> The '??' is I believe meant for the 'shadow' field.
> The '?????' is the gecos field, but 'rowland' doesn't have a 'gecos'
> attribute, so winbind must be filling in this field from either a
> combination of the givenName and sn attributes, or the displayName
> attribute, all three are in AD.
> 
> I cannot see any drawbacks there, which just leaves us with the user
> home directory and login shell. If you use the 'ad' backend, then you
> can set individual paths for home directories and shells, but what does
> this really give you and couldn't you live without this facility ?

I consider quite a nice feature to be able to specify different shells to different users, especially in a mixed environment with just windows users and users with more advanced requirements that could use linux/windows interchangeable, since this allows me to be able to specify which users can ssh into a machine and which can only log on to a windows workstation without having to modify sshd's config file to specify allowed users.

Also speaking of a mixed environment, as Kees replied earlier, it is still quite usefull that users get the same ID since we normally copy files from one machine to another, and scp is still my preferred method rather than setting up an smb mount. And even though smb shares have matured quite a lot since the beginning, nfs is still quite used to share a filesystem between linux servers.n

> 
> The only real thing that using the rfc2307 attributes gives you, is that
> your users & groups will have the same IDs everywhere in Unix land.
> However, do you really need this ? I thought you did, but testing
> proved otherwise.

I'm not saying that it is not possible to live without these features, but since there's evidence that at some point it was possible to have them I think it would be nice if it was possible to have them back.

> 
> The following presumes that no rfc2307 attributes are used:
> If I have a share on a DC (yes, I know you shouldn't, but this is
> theoretical) and my user 'rowland' saves a document to that share, it
> will end up belonging to a numeric ID in the '3000000' range.
> If 'rowland' creates another document in a share on a Unix domain
> member that uses the 'rid' backend, with the DOMAIN low range starting
> at '10000', the document will end up belonging to a numeric ID such as
> '11104'
> If you run 'ls' on both machines, the shares will be shown to belong to
> 'rowland', different machines, different IDs, but the same username. If
> you then copy one document from one share to another, it will show as
> belonging to 'rowland' on the new machine.
> 
> So I ask again, what are the drawbacks with using the 'rid' backend ?
> 
> Rowland
> 
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