El mar, 26-06-2012 a las 13:39 -0400, Dmitri Pal escribió:
> On 06/26/2012 01:28 PM, Rich Megginson wrote: 
> > On 06/26/2012 11:13 AM, Dmitri Pal wrote: 
> > > On 06/26/2012 11:11 AM, Loris Santamaria wrote: 
> > > > El mar, 26-06-2012 a las 10:35 -0400, Dmitri Pal escribió:
> > > > > On 06/25/2012 09:02 PM, Loris Santamaria wrote: 
> > > > > > Hi,
> > > > > > 
> > > > > > while using freeIPA as a user database for a samba installation I 
> > > > > > found
> > > > > > a problem in the enforcement of password policies. FreeIPA password
> > > > > > policies are more detailed than samba's, in freeIPA one may enforce
> > > > > > password history and the number of character classes in a password, 
> > > > > > but
> > > > > > normally samba connects to freeIPA with the "Directory Manager" so 
> > > > > > those
> > > > > > policies are not enforced.
> > > > > > 
> > > > > > Reading the source of ipa_pwd_extop I see there are three 
> > > > > > possibilities
> > > > > > when changing passwords:
> > > > > > 
> > > > > >       * Password change by the user, with full enforcement of 
> > > > > > policies
> > > > > >       * Password change by an admin, with no enforcement of 
> > > > > > policies and
> > > > > >         the new password is set as expired so the user has to 
> > > > > > change it
> > > > > >         on next logon
> > > > > >       * Password change by Directory Manager, with no enforcement of
> > > > > >         policies and the password is not set as expired.
> > > > > > 
> > > > > > None of the aforementioned possibilities are ideal for samba, samba
> > > > > > should connect to freeIPA with a user privileged enough to change
> > > > > > password for all users but with fully enforced policies.
> > > > > > 
> > > > > > What do you think about this? Would you consider adding such 
> > > > > > feature?
> > > > > > Would you accept patches?
> > > > > > 
> > > > > Can you please explain why samba needs to connect to IPA and change
> > > > > the passwords?
> > > > > In what role you use samba? As a file server or as something else?
> > > > > I am not sure I follow why you need the password change functionality.
> > > > > There is a way to setup Samba FS with IPA without trying to make IPA a
> > > > > back end for Samba.
> > > > > I can try to dig some writeups on the matter if you are interested.
> > > > Samba 3 when used as a PDC/BDC can use a LDAP server as its user/group
> > > > database. To do that samba connects with a privileged user to the LDAP
> > > > directory and manages some attributes of users and groups in the
> > > > directory, adding the sambaSAMAccount objectclass and the sambaSID
> > > > attribute to users, groups and machines of the domain.
> > > > 
> > > > When users of Windows workstations in a samba domain change their
> > > > passwords samba updates the sambaNTPassword, userPassword,
> > > > sambaLastPwdChange, sambaPwdMustChange attributes of the corresponding
> > > > ldap user.
> > > > 
> > > > Using freeIPA as ldap user backend for samba works quite well, except
> > > > for the password policy problem mentioned in last mail and that it is
> > > > hard to mantain in sync the enabled/disabled status of an account. 
> > > 
> > > What is the value of using FreeIPA as a Samba back end in
> > > comparison to other variants?
> > > Why IPA is more interesting than say 389-DS or OpenLDAP or native
> > > Samba?
> > 
> > IPA will keep all of your passwords in sync - userPassword,
> > sambaNTPassword, sambaLMPassword, and your kerberos passwords.  389
> > cannot do this - the functionality that does this is provided by an
> > IPA password plugin.  Openldap has a similar plugin, but I think it
> > is "contrib" and not "officially supported".
> > 
> 
> 
> I know that Endi did the work to make 389 be a viable back end for
> Samba and it passed all the Samba torture tests so I am not sure I
> agree with you. Samba does the kerberos operations itself and uses
> LDAP as a storage only. This is why I am struggling to understand the
> use case. It seems that Loris has a different configuration that I do
> not quite understand, thus questions.
> 
> > > What other features of IPA are used in such setup?
> > > 
> > > Answering these (and may be other) questions would help us to
> > > understand how common is the use case that you brought up.

First of all, the use case is that of using Samba 3 as a Domain
Controller. Here in Venezuela the government itself promotes the use of
free software so most government agencies and industries won't install
Active Directory to administer windows desktops. There are some medium
to large deployments of Samba 3 as a domain controller here, and there
are a number of Linux desktops deployed in the same networks.

When you use Samba 3 as a Domain Controller with a largish number of
users and machines is mandatory to use a Ldap server as a backend, and
for that you have basically two choices which are of course OpenLdap and
389-DS, but those servers have to be combined with some administration
tools to be really useful.

The ideal choice for us is 389-DS with freeIPA as an administration
framework because of:

      * Really easy to use to administer users and groups. Those users
        and groups are visible from the samba domain and from linux
        machines in the IPA realm or from legacy unix and linux machines
        configured as ldap clients
      * ipa_pwd_extop keeps ldap, samba and kerberos passwords in sync.
        Well, this could be better
      * freeIPA sets up 389-ds very well, with sane indexes and
        permissions. For good performance with samba you just have to
        add indexes for some samba attributes

So you set up Samba 3 with freeIPA, and use the ipa tools to administer
users and groups, and those users and group can login in windows and
linux workstations.

To set up Samba 3 with freeIPA 2.x you have to:

      * extend the ipa user and group objects to have them add the
        sambaSAMAccount and SambaGroupType objectclasses
      * add a Distributed Numeric Assignment configuration to have
        389-DS generate the sambaSID for objects with the above
        objectClasses
      * add a script used by samba 3 when a windows machine tries to
        join the domain, so that ipa creates a new host if it doesn't
        exist
      * add indexes for common samba attributes.

The alternative to all this, using free software, would be using samba 4
and have Linux workstations join the Samba 4 domain, or use samba 4 for
the windows domain with a trust relationship to ipa 3 when it is ready. 

Thank you,
Loris Santamaria

-- 
Loris Santamaria   linux user #70506   xmpp:lo...@lgs.com.ve
Links Global Services, C.A.            http://www.lgs.com.ve
Tel: 0286 952.06.87  Cel: 0414 095.00.10  sip:1...@lgs.com.ve
------------------------------------------------------------
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a faster horse" - Henry Ford

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