[Freeipa-users] IPA, Samba and AD

[Simo Sorce]

On Sun, 2013-09-22 at 18:09 +0200, Fred van Zwieten wrote:
> Well, as explained in this thread, the problem here is that we have an
> IPA domain named "MYCOMP.EDU" _and_ an AD domain named "MYCOMP.EDU" as
> well. Both have there own DNS servers. It's beyond the scope of this
> mail to explain why we have named them exactly the same, and we do
> wish we didn't, but this is the current situation. Migrating any of
> these to another domain name would be the best solution but would
> involve quite a lot of work.
> 
> 
> So now we have a bunch of SAMBA services running on RHEL6.4 boxes that
> are IPA-clients and we would like to give the AD users access to them.
> How to proceed? We cannot use an IPA - AD trust, because both domains
> have the same name. We also cannot make the SAMBA services member of
> the AD domain, because the server itself is an IPA-member and
> krb5.conf already points to the IPA servers for domain MYCOMP.EDU..
> Also /etc/resolv points to the DNS services of IPA.

> See my problem? If not, read the whole mail thread..
> 
I haven't read all the thread way back, but what you *could* do is to
configure Samba in a completely independent way for the rest of the
machine.

Join just the samba file server to the Ad domain but use net rpc join
and configure samba with security = domain not security = ads, basically
treat the AD domain as a legacy NT4 domain.
It will allow you to use only NTLM, no kerberos.

The main issue will be how to provide users to the system.

If you can map the AD domain SIDs in a different ID range you could run
both the normal sssd and add on top winbindd configured with idmap rid
to map the Ad domain SIDs in a range that do not conflict and use fully
qualified names for users so you have no chance of conflict with the
native IPA users.

It *might* work, but you'd have to try to know and you need to fully
understand the nsswitch interactions as well as winbindd configuration
nuissances to pull it off. It will be a fragile setup, in any case.
> 
> 
> It get's even more complicated. The AD "MYCOMP.EDU" domain has a trust
> with an AD "OTHERCOMP.EDU" and users in "OTHERCOMP.EDU" must access
> resource in "MYCOMP.EDU". There is a trust between the AD domain
> "MYCOMP.EDU" and the AD domain "OTHERCOMP.EDU". This works. We have
> some shares on a NetApp filer who is member of the AD domain
> "MYCOMP.EDU" and people from "OTHERCOMP.EDU" can successfully access
> those shares (given correct group membership offcourse).
> 
> 
> Now, we would like to have peoply in the AD domains "OTHERCOMP.EDU"
> and "MYCOMP.EDU" to access shares served by SAMBA services on RHEL64
> machines that are IPA clients in the IPA domain "MYCOMP.EDU".
> 
> 
> As all out RHEL servers are IPA clients by default we also want the
> servers running SAMBA to stay IPA-clients for system level central
> administration of users, groups, sudo policies, hbac, etc.
> 
> 
> Now, how to proceed:
> 
> 
> I see 2 possible solutions (besides byting the bullet and name change
> one of the MYCOMP domains):

Byting the bullet will be by far the easiest I think, although
*changing* here really means installing a new domain and slowly phasing
off the old one.
> 
> Solution 1:
> Create an intermediary domain. This gives the following trust
> relationships:
> 
> 
> AD(OTHERCOMP.EDU) <--trusts-- AD(MYCOMP.EDU) <--trusts--
> AD(MYCOMP-INTERMEDIARY.EDU) <--trusts-- IPA(MYCOMP.EDU). I don't like
> this one and I am not even sure it solves my problem. Another problem
> involves adding to (virtual) Windows boxes to maintain this domain.

We do not have yet full support for transitive trusts, so it will not
work with any released buts, although we *are* getting close.

> 
> Solution 2:
> Make a SAMBA only domain. Make one of the SAMBA servers a PDC and one
> BDC. Make a NT-4 style trust to the AD domain MYCOMP.EDU. NT-4 style
> to have no Kerberos involvement as that is used for IPA. Also no DNS
> clashes as NT-4 style doesn't use DNS SRV records.

I do not recall how good the old NT domain stuff is wrt trusts, but it
is certainly a possibility, you have the same Winbindd issues as above
plus having to manage to add the necessary samba objectlasses in the IPA
tree manually when needed for the local users, or you'll have to keep a
separate database, if you do not care exporting samba share tfor IPA
users, you may just not create anything beyond a few admin users locally
on the samba boxes and rely entirely on winbindd to provide trusted
domain users. However at this point you can as well use the solution I
proposed you above.

> AD(OTHERCOMP.EDU) <--trusts-- AD(MYCOMP.EDU) <--nt-4-trusts--
> NT4(MYCOMP-SAMBA)
> 
> 
> 
> Now, giving correct group memberships and all, users in OTHERCOMP.EDU
> should be able to access shares in MYCOMP-SAMBA.
> 
> 
> Correct?
> 
Once you get through a correctly working trust you should be able to
deal with this relatively easily, yes.

Simo.

-- 
Simo Sorce * Red Hat, Inc * New York