Hi Alex,

>The documentation is only conflicting if you are using it in a
conflicting way.



> The choice of Kerberos library is important. Samba AD DC with MIT Kerberos still is broken regarding trust to FreeIPA.

Pardon my ignorance, I am just going by the documentation as is w/ no prior knowledge ... where in the documentation is that specified?
The two main documentation pages I see when googling "freeipa AD trust" are:

https://www.freeipa.org/page/Active_Directory_trust_setup
https://www.freeipa.org/page/Windows_authentication_against_FreeIPA
>
  1. If you do not have AD then use Samba 4 instead of it. As of Samba 4.3, Samba AD can establish cross-realm trusts. The feature is still incomplete and lacks proper access controls but it can be configured to trust FreeIPA.

It has no caveats or warnings on how samba is to be compiled/configured.  

This older doc https://www.freeipa.org/page/IPAv3_AD_trust#Samba does, but is for IPaV3 (which I assumed was outdated).

I thought Samba by default used Heimdal , but you warn that kerberos is the broken implementation.
 

>The changes were pushed out with various Samba releases but I'd recommend looking at  Samba 4.7+ -- at least that has all bugs we knew about fixed in Samba AD DC based on Heimdal


I am using samba 4.8.3 compiled from source , is it recommended to instead use the Redhat RPM one (currently appears to be 4.7.1 )
I configured with
>./configure --enable-debug --enable-selftest --with-ads --with-systemd --with-winbind


The other confusing parts, at least to me, in regards to Samba setup ... do you know a working configuration using the samba internal-dns , or do you have to use the bind9 DLZ backend?   Regardless of the kerberos , I still think my preliminary issue is with DNS as I see the errors

> ipa: ERROR: Attempt to solve forest trust topology conflicts [Fri Aug 10 11:58:43.125865 2018] [:error] [pid 6169]
> ipa: ERROR: non-public: NTSTATUSError: (-1073741601, 'The specified domain did not exist.')


I understand this is the FreeIPA forum , and you can't be responsible for the documentation or limitations of Samba ... Its just YOUR documentation does say you can use Samba ... is that just in theory or is there an actual working case of it somewhere. 

Most ALL of the documentation I've seen seems very specific to "Windows 2008 DC" (or similar) , am I chasing a wild goose chase, or is there some exact specific combination of how you configure Samba  ( kerberos, DNS backend, etc) that it will work with FreeIPA.


Backing up to answer your basic question
> What is your use case, in the first place?
> You want to run Samba AD DC and establish a trust from it to FreeIPA?


Yes, I am trying to implement a SSO solution for log on accounts for both windows10 clients and linux clients (and other web/Oauth services that already integrate into freeipa)

It was my understanding, that the current/only way to do this was

1) Run Samba AD that has Users accounts
2) establish trust from freeipa -> Samba



On Mon, Aug 13, 2018 at 9:51 AM, Alexander Bokovoy <abokovoy@redhat.com> wrote:
On ma, 13 elo 2018, Alexander Bokovoy via FreeIPA-users wrote:
On pe, 10 elo 2018, D Anderson via FreeIPA-users wrote:
Hello all,

I am confused by some of the conflicting documentation about whether
this is possible or not.  Almost all of the documentation/working
examples seem to use an actual Windows Domain Controller.  Specifically
the part on DNS , as the Samba4 internal DNS server has several know
limitations.
The documentation is only conflicting if you are using it in a
conflicting way.

What is your use case, in the first place?

You want to run Samba AD DC and establish a trust from it to FreeIPA?

For long time Samba AD DC lacked support for forest trust, thus it was
not possible to use it against FreeIPA. In 2015-17 Red Hat together with
SerNet worked on improvements in this area in Samba. The changes were
pushed out with various Samba releases but I'd recommend looking at
Samba 4.7+ -- at least that has all bugs we knew about fixed in Samba AD
DC based on Heimdal -- if you run the process from IPA side.

The choice of Kerberos library is important. Samba AD DC with MIT
Kerberos still is broken regarding trust to FreeIPA. The fixes went out
recently to SSSD 1.16.3 (released today) and Samba 4.9RC2. FreeIPA part
of changes is still not released as we were waiting on the other
upstream changes first and were busy finishing FreeIPA 4.7.0 release
too.
Ah, I spoke too early: MIT version of Samba AD DC is still lacking the
fixes needed to support trust to FreeIPA upstream. The patchset is on
review and needs few more fixes to tests as we are correcting the way
how trusted domain object's account credentials are salted in Kerberos.
These changes yet to be committed upstream.


--
/ Alexander Bokovoy
Sr. Principal Software Engineer
Security / Identity Management Engineering
Red Hat Limited, Finland