[Samba] Samba SSSD authentication via userPrincipalName does not work because samba claims that the username does not exist.

[Nico Kadel-Garcia]

On Tue, Oct 13, 2020 at 10:30 AM Rowland penny via samba
<samba at lists.samba.org> wrote:
>
> On 13/10/2020 15:01, Markus Jansen via samba wrote:
> > Thank you very much for your hints.
> >
> > I got rid of SSSD and managed to get a successful kerberos
> > authentication via wbinfo -K and the UPN.
> >
> > But accessing via SMB (using MAC OS' smbutil or Finder) still fails with
> > "FAILED with error NT_STATUS_NO_SUCH_USER".
> >
> > As I'm using CentOS 8, I used authselect to configure winbind
> > integration to PAM (do I really need this for SMB?) and enabled
> > "with-krb5" and "with-pamaccess" - features to let /etc/pam.d/-files be
> > configured automatically.
> >
> > I'm really confused. What's missing?
> >
> Probably libpam-krb5 that Red-Hat has removed from RHEL8 and hence
> Centos8, I had to compile the Centos7 package and install it before I
> could get Centos8 to work correctly.
>
> BIG NOTE: this is just my opinion.
>
> I really do not think that red-hat wants you to use Samba with RHEL8, I
> think they really want you to use sssd with freeipa instead. They have
> removed openldap, smbldap-tools  and libpam-krb5 that I am aware of,
> there may be others.

This matches my direct observations. Also sssd has many options for
tuning that get *thrown out* with any security update of the software,
they are flushed by any run of authconfig which is often built into
related software updates. sssd is *not your friend* if you want any
tuning of your LDAP or related behavior, and it insists on pre-caching
all of your LDAP before completing the setup of sssd. SO it starts up,
times out on the pre-caching, and *fails* with no legible log of what
the problem was and no good way to tune it except to resttrict your
LDAP access to a wafer thin sliver of the upstream setup, *which
configuration gets overwritten!!!!* with updates of anything that uses
authconfig.

This iss a condemnation of authconfig's poor management of the
sophisticated options to sssd, but unless you're running something
like ansible or chef to replace your /etc/sssd/ files as needed, it's
an ongoing problem, A  backdoor also cannot rely on sssd to be working
correctly, so you're compelled to use something like SSH keys for an
ansible service account or direct root SSH access to support this.

> How wedded are you to Centos ? I personally would advise you to switch
> to Debian or Ubuntu, everything just works.

Just ditch sssd if you want actual reliable LDAP. It's handy if you
need no sophistaction of a smal LDAP setup, but I have real problems
with it for sophisticated production use. It's not a well integrated
wrapper for LDAP, Kerberos, and other settihngs.

> If you must use Centos8, then it is possible to get Linux to connect to
> a Samba share running on a Centos domain member, not sure about a Mac, I
> do not have one.