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Re: How to change a schema attribute definition or how to change the slapd configuration?

Hi Andrew

Thank you for your input. Unfortunately, that gives me a different problem because when you install OpenLDAP on Ubuntu 12.04, it automatically installs the nis schema, which clashes with the 2307bis schema, which is why I was originally trying to find a way of just changing the definition of posixGroup, since OpenLDAP won't allow you to remove schema definitions.

I've yet to figure out how to remove the installation that Ubuntu does and put in a replacement installation that uses 2307bis instead of nis.

I think, given issues I'm hitting elsewhere, I *may* end up using Google to manage groups that are email-only, and write a script that reads all of the posixGroup entries and creates equivalent groupOfUniqueNames entries which can then by synced up to Google so that I have at least got email versions of the security groups. This is probably, in the long term, a much cleaner way of dealing with things.

Thank you, though, for all of the feedback.



On 10 January 2013 12:37, Andrew Findlay <andrew.findlay@skills-1st.co.uk> wrote:
On Thu, Jan 10, 2013 at 10:51:41AM +0000, Philip Colmer wrote:

> What I want to do is use the LDAP store for two purposes: Linux authentication
> and syncing with Google Apps for profile/group information and SSO. To that
> end, and specifically focussing on groups, I need a group in LDAP to serve two
> purposes: to act as a security group (i.e. it needs a gidNumber and be a
> posixGroup so that Linux will use it for group membership and ACLs) and to act
> as an email group (at a minimum have a list of members, an owner, a description
> and an email address).
> In my approach to the choice of classes to use here, I find myself being
> somewhat constrained by the tools I want to use. Atlassian Crowd is being used
> as the means of providing Google SSO and OpenID functionality. When it comes to
> groups, Crowd "prefers" groupOfNames or groupOfUniqueNames. Although I can
> reconfigure Crowd to "see" posixGroup entries instead of groupOfUniqueNames
> entries, it doesn't see the members, presumably because they are UIDs and not
> DNs.
> I'm also using LDAP Account Manager as the primary tool to allow administrators
> and staff manage information stored in LDAP. For group management, it supports
> both posixGroup and groupOfUniqueNames.

Can you persuade that tool to work with other classes?

> I can, in theory at least, add extensibleObject to the groups defined as
> posixGroup so that I can then add description, displayName, mail and owner.
> That gives me a different problem when it comes to syncing the groups up to
> Google, though, because it also (like Crowd) seems to be expecting attribute
> values for members to be DNs.

I think you would do best to use RFC2307bis if all of your tools can
work with it. Any recent Linux distro should have NSS and PAM
libraries that accept DN-style group membership, so I would use
'member' rather than the 'memberUID' attribute for groups.
You may need to adjust some settings in /etc/ldap.conf or similar.

2307bis prefers the use of groupOfMembers as the structural class.
This is better than groupOfNames or groupOfUniqueNames because it
permits empty groups.

In 2307bis, posixGroup is AUXILIARY [amusing, given my earlier comments
on changing standard stuff :-)]. So you could have group entries that
are both groupOfMembers and posixGroup. If your tools really cannot cope
with groupOfMembers then you could consider groupOfNames with posixGroup,
but you will then have to put a bogus member in each group to satisfy
the definition of groupOfNames.

I would avoid using extensibleObject as that removes all the limits on
what may be in an entry.

If you still need to add a mail address to your groups, you will also
need to define an auxiliary class of your own to permit it.

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