On 05/11/2011 09:25 PM, JR Aquino wrote:
On May 11, 2011, at 10:51 AM, Sigbjorn Lie wrote:
On Wed, May 11, 2011 14:42, Stephen Gallagher wrote:
On Tue, 2011-05-10 at 23:42 +0200, Sigbjorn Lie wrote:
I would like to see the ipa client scripts and possibly the admin tools
in a nice Solaris package. This would make my job a lot easier as we have a lot
running Solaris. :)
For the server part I agree with you, keep it at RHEL.
SSSD @ Solaris / HP-UX / AIX ... well there isn't much (if any) of the
UNIX vendors selling their iron as client machines anymore. And I don't
see a considerable benefit in adding SSSD to servers, who will be well
connected to the network
Actually, SSSD is still valuable on server systems (and is used very
often in datacenters). The reason is that it can allow a server to ride out an
outage in the LDAP
and/or Kerberos server and still handle authentication and identity requests
from its cache.
We've expressed interest several times in working WITH other platforms
to help them port the SSSD, but we've received no real commitment to assisting
with it. We have a
lot on our plates already, so it is difficult for us to justify spending time
competitors' offerings :)
Also, SSSD has additional features with FreeIPA integration that
nss_ldap and pam_krb5 do not. Specifically, it has support for managing
FreeIPA's host-based access control model. This is
a very valuable piece of the puzzle and should not be ignored.
I see you're having a valid point about the outage support. This could be
worked around using the
"High Availability Add-on" in RHEL, sharing an IP address between your IPA
servers, which you
would switch to the currently active IPA server.
Not only is there a question of high availability with regard to lookups into
ldap. But there is also a problem of scale and overhead.
nss_ldap and pam_ldap perform a lookup per iteration in many cases.
Consider for example. 4 data centers with 100 servers each, all tied back to
ldap for uid/gid mappings and pam_ldap for authentication and authorization.
If you have a task that logs into each of these 400 servers and performs a
'sudo ls -la /home' for example,
your ldap servers are going to incur the cost of looking up each file on each
server, the cost of each authentication, and the cost of performing several
ldap lookups from the sudo binary.
SSSD is not only beneficial during periods of network inaccessibility, but also
crucial with regard to scale.
With regards to IPA's host-based access control: What about doing access
control through using
netgroups via the tcp wrappers?
You could still be configuring host based access control in IPA as it's
netgroups for the host groups.
Host based access control is currently a mess in the Linux Community.
There are currently a few ways to go about it.
^ This method implies that the changes in your central database must eventually
be pushed to flatfile configs on the end hosts.
While this works pretty well in small environments, it can fall apart and have
serious scale issues when dealing with hundreds or thousands of hosts.
(Yes, even when using something like Satellite or Puppet)
Consider the case of Active Directory where you scratch your head and go: "Gee, I'm
SURE that i pushed that GPO, but for some reason, this set of hosts didn't get the
pam_ldap + pam_check_host_attr
^ This issue has a sheer drop off problem with scale. In this approach, you
need to fill the user objects with every host that the user is permitted to
When the number of users/administrators grow along with the number of hosts you
have, you get: n^users * n^hosts and the administrative overhead becomes
These are all workarounds, I assume having the functionality available trough
the native sssd
would be of an advantage. But this way you would the mentioned extra
functionality of SSSD without
having to do the work of supporting your competitors operating systems. :)
There have been _some_ discussions surrounding a pam module that could be used
as a very base level of hbac support since there are a lot of pre-required
dependancies for sssd.
The advantage would be theoretical portability, and the loss would be caching.
I have personally written such a pam plugin prototype in python, and it
functions just fine in linux installations. the c code that calls the python
script is not compatible with open_pam,
so there is still work to be done to support the BSD / MAC solutions, but I
believe its just a matter of some syntax changes...
I hope this information helps clarify these points.
I wasen't going at SSSD for not being usable. I was trying to make a
suggestion for a alternative solution for using IPA with *nix OS' that
does not currently have SSSD.
I do agree that the host access controls in SSSD would be of great
benefit to any server. This is not a part of IPA I've not spent a lot of
time testing....yet....and I did not think about it before sending my email.
Back to the discussion, wouldn't nscd be able to cope with some of the
caching for ldap passwd,group, etc lookups? Not providing an offline
identity like SSSD would, but enough for the folder listings example you
You could also extend the High Availability configuration I mentioned
earlier with 1 high-available IP per IPA host, and serve them in a round
robin DNS. This would distribute the load of the LDAP server in IPA, and
provide high availability in case of a IPA server becoming unavailable.
The way I see it for our customers; when it comes to IPA integration
as-it-is-today, an ipa-client-install script for other *nix that would
configure kerberos, ldap client, and retrieves the host's keytab from
the IPA server would make a great improvement for IPA. Then the SSSD
could come at a later point.
What I see as one of the selling points of IPA over any "*nix client for
Active Directory", is the ability to use the operating system built in
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