[Freeipa-devel] [RFC] Migrating existing environments to Trust - v2: reverse DNS lookup

[Sumit Bose]

On Fri, May 30, 2014 at 09:13:18AM -0400, Dmitri Pal wrote:
> On 05/30/2014 03:04 AM, Sumit Bose wrote:
> >On Thu, May 29, 2014 at 01:31:04PM -0400, Simo Sorce wrote:
> >>On Thu, 2014-05-29 at 18:50 +0200, Petr Spacek wrote:
> >>>On 29.5.2014 13:48, Sumit Bose wrote:
> >>>>== slapi-nis plugin/compat tree ==
> >>>>The compat tree offers a simplified LDAP tree with user and group data
> >>>>for legacy clients. No data for this tree is stored on disk but it is
> >>>>always created on the fly. It has to be noted that legacy clients might
> >>>>be one of the major users of the user-views because chances are that
> >>>>they were attached to the legacy systems with legacy ID management which
> >>>>should be replaced by IPA.
> >>>>
> >>>>In contrast to the extdom plugin it is not possible to determine the
> >>>>client based on the DN because connection might be anonymous. The
> >>>>Slapi_PBlock contains the IP address of the client in
> >>>>SLAPI_CONN_CLIENTNETADDR. Finding the matching client object in the IPA
> >>>>tree requires a reverse-DNS lookup which might be unreliable. If the
> >>>>reverse-DNS lookup was successful the slapi-nos plugin can follow the
> >>>>same steps as the extdom plugin to lookup up and apply the view.
> >>>Do we really want to base security decisions on reverse DNS resolution?
> >>No we do not want to play these games.
> >>
> >>>That
> >>>will be insecure. Attacker could tamper with reverse DNS to change UID/GID
> >>>mapping ... Maybe we can store IP->view mapping in the LDAP database. That
> >>>should be reliable if we assume that only TCP is used for connection to LDAP
> >>>database.
> >>It is not just about it being insecure, it is about it being wrong.
> >>As soon as you have a bunch of clients behind a NAT this pans goes belly
> >>up.
> >I do not like this one either. I just wanted to list to options I could
> >think of because I think supporting user-views on legacy clients is one
> >of the major use-cases for this feature.
> >
> >bye,
> >Sumit
> >
> >>>>As a alternative slapi-nis can provide one tree for each view.
> >>This is the only alternative, if we decide to pursue it.
> >>
> >>Simo.
> >>
> >>-- 
> >>Simo Sorce * Red Hat, Inc * New York
> >>
> >>_______________________________________________
> >>Freeipa-devel mailing list
> >>Freeipa-devel at redhat.com
> >>https://www.redhat.com/mailman/listinfo/freeipa-devel
> >_______________________________________________
> >Freeipa-devel mailing list
> >Freeipa-devel at redhat.com
> >https://www.redhat.com/mailman/listinfo/freeipa-devel
> 
> Please correct me as I might be confused.
> We have the compat tree now for legacy clients. It is also used by latest
> SSSD clients to do special lookups, right?

no, we discussed this with Alexander some time ago and he asked not to
use the compat tree from SSSD but the extdom plugin because of the given
limitations of the slapi-nis plugin.

> The data in this tree comes from the SSSD on the server running in server
> mode.
> I wonder if we can say: here are replicas A, B, C that have vanilla "default
> view", here are replicas K, L, M where the data is overwritten with a
> special view (i.e. UID/GID fro ma special area) and then we have replicas
> X,Y,Z that have a different overlay view.
> It will be assumed that replicas A,B,C, serve clients in one "zone", new and
> legacy, while K, L, M serve another zone and X, Y, Z serve the other one.
> Would that work?

Besides that it is very confusing it would be possible as long as the
overrides from the special views are done by slapi-nis because SSSD on
servers and replicas will always and only deliver the default view.

bye,
Sumit

> 
> 
> 
> -- 
> Thank you,
> Dmitri Pal
> 
> Sr. Engineering Manager IdM portfolio
> Red Hat, Inc.
> 
> _______________________________________________
> Freeipa-devel mailing list
> Freeipa-devel at redhat.com
> https://www.redhat.com/mailman/listinfo/freeipa-devel