Re: Kerberos issue running OpenLDAP on Mac OS X Mavericks

[Dan White <dwhite@olp.net>]

Putting the email list back into the CC.

On 03/20/14 10:16 -0500, Denis Ahearn wrote:
> Thanks for responding Dan.  We have spent the past several days taking the
> information you provided and trying to get smarter about how OpenLDAP and
> Kerberos work on Mac OS X Mavericks.  Unfortunately we haven't made much
> progress.  I think it may be because the way we are trying to use OpenLDAP
> is not the standard way that  Apple intends it to be used from a server or
> client standpoint, so there doesn't seem to be any documentation available
> that speaks directly to our use case.  Responses to your questions are
> listed below.
>
> > > If you are authenticating against Active Directory, how does slapd fit
> > > into the picture?
>
> Our Rails app authenticates using Active Directory only in staging and
> production. We're using OpenLDAP (slapd) in our local development
> environments to simulate this (i.e. to provide a local LDAP server that
> serves the purpose that Active Directory does in production).  To test
> locally, we define an organization, groups and users in ldif files that get
> loaded into OpenLDAP using ldapadd.
>
> > > Do you have an authz-regex rule mapping the authentication identity to
> > > this? Can you reproduce this problem with ldapsearch/ldapwhoami, using
> > > the same parameters as your ruby code?
>
> Are you referring to setting an authz-regex rule in slapd.conf?  If so, we
> do not have any authz-regex rules in our slapd.conf.  I attached the
> slapd.conf and ldap.conf files that are being used with OpenLDAP if that
> helps.
>
> > > It appears your client has a kerberos ticket, and is attempting GSSAPI
> > > authentication. You can verify that with klist or your OS's kerberos
> > > utilities.
>
> I ran the klist command on the Mac that is having this issue.  Output is
> below:
>
> $ klist
>
> Credentials cache: API:77A8E90B-01BF-4F18-A94E-035C3AB25A59
>
>        Principal: dahearn@BWD.INT
>
>  Issued    Expires    Principal
>
>
> > > The client side Ruby code may allow you to configure a sasl mechanism.
> > > If not, see ldap.conf(5) and set an appropriate LDAPSASL_MECH
> > > environment variable or set SASL_MECH within your home .ldaprc file
> > > (to, for instance, DIGEST-MD5).
>
> We tried the suggestions you listed above, none of which seemed to have any
> effect on OpenLDAP's behavior (output in slapd.log is exactly the same).

I'm still not clear if ruby is attempting SASL GSSAPI authentication or
not.  Your syslog (auth facility) may tell you that. Since you have a
ticket, it's certainly possible.

You can disable GSSAPI in a couple of additional ways:

1) Remove the SASL GSSAPI shared library, assuming your cyrus sasl install
was compiled using shared libraries. pluginviewer (or saslpluginview)
should list the mechanisms which are installed.

2) Configure a slapd.conf SASL configuration, on the server, which
explicitly lists which mechanisms you wish to offer. The FAQ at:

http://www.cyrussasl.org/mediawiki/index.php/FAQ

details how to *enable* GSSAPI for slapd. Find out where cyrus sasl is
looking for config files (e.g. /usr/lib/sasl2 or /etc/sasl2) and create a
slapd.conf file with this line:

mech_list: PLAIN LOGIN DIGEST-MD5

Are you performing pass-through authentication? In that case, try running
saslauthd in debug mode for testing.

> We are only using OpenLDAP in our development environment as a way to store
> groups and users for testing purposes, and to provide an LDAP server that
> our application can talk to in the same way it talks to Active Directory in
> our production environment.  We rely upon logic in the application (the
> Ruby Devise and CanCan gems) to provide the necessary authentication and
> authorization services.  What I think we need to do is make OpenLDAP not
> use Kerberos or other authentication mechanisms, but I haven't been able to
> figure out if this is possible and if so, how to do that.  Does this sound
> like the way to go?  If so, can you provide any assistance in setting this
> up?  Is there anything else I can send you to help you understand our setup?

Replace the ruby authentication step with a ldapsearch/ldapwhoami call
(with a -d -1 option for debugging on the client side). Or see if you can
specify a debug option within Ruby (assuming it is using libldap). If you
can figure out how your ruby code is connecting to the server in this way,
your problem will likely stand out pretty quickly. A wireshark trace of the
ruby ldap connection may help with that as well.

--
Dan White