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SASL pass-through autentication with a ldap-backend KDC

Hello list.

Reading http://www.openldap.org/doc/admin24/security.html#SASL password storage scheme, I understand autentication can be delegated to an external mechanisme. Such as, for instance, a kerberos server. In this case, it is advised to prevent changing passwords in the directory.

What happens if the autentication provider is an heimdal server, using OpenLDAP as its backend, and smbkrb5 overlay to keep ldap, samba and kerberos password synced ? Does pass-through still work ? And it is recommended then to make the userPassword attribute read-ony, but still use Exop PasswordChange to change samba and kerberos attributes ?

I didn't tested it yet, but it look very interesting if it works. Particulary because heimdal password change through kpassword doesn't use ExOp PasswordChange operation, but only update kerberos and samba passwords.

I know smbkrb5 has a special {smbkrb5} password storage scheme for redirecting autentication against kerberos password internally, not relying on a external SASL process. But it's only usable if smbkrb5 overlay is available (some of our slaves servers are centos-based, and don't have this overlay, but still need to autenticate users). And the trick of setting password-hash directive in slapd.conf to {smbkrb5} to prevent overwriting of userPassword attribute on PasswordChange operation with a normal value has the drawback than even pure ldap administrative accounts (syncrepl, for instance) get redirected to kerberos password for autentication, whereas only our users have principals currently.
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62