[Samba] domain-free multi-user use cases

[Jeremy Allison]

On Sat, Oct 23, 2021 at 03:59:42AM -0400, Eric Levy via samba wrote:
>
>The most basic mount to a file server is single user, represented by
>(1). I have come to understand, in part from a discussion in this
>group, that a multiuser mount is not possible without the addition of a
>domain server, represented by class (2). As explained, a multiuser
>mount is one for which various files are owned by different users
>within the same mounted view, and the differences in ownership in the
>mounted view reflect the actual ownership of the server (though in
>general a user mapping may be employed).

No, that's not true unless you are dealing with multiple servers
and multiple clients. Even then, if all the clients had the same
local users and all the servers had the same local users (i.e.
user "Sam" on all clients maps to user "Sam" on all servers)
then you don't need a domain setup.

You can see why this would quickly become unscalable though :-).

Any client with multiple local users can attempt to connect
to a Samba server as different users, so long as the different
users are logged in simultaneously and try and access the
same mounted drive.

E.g. For Windows,if "user1" mounts drive Z:, and then "user2" tries
to access Z: then the client will attempt a multiplexed
SMB2_SESSIONSETUP + TREE_CONNECT to the server as "user2".

With no domain that means no kerberos so all logons will be
done using NTLM, which isn't really what you want security-wise.

But if all clients have local users: user1, user2,..., userN
and all servers have local users: user1, user2,..., userN
and each user password is the same for that user across all
clients and servers then each client can connect as multiple
users, authenticating via NTLM and all will work.

You'd be nuts to try and do this for more than one or
two users though, which is why NT Domains and AD Domains
were invented.