OpenLDAP Everywhere Revisited

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Many readers have used our December 2002 article, “OpenLDAP Everywhere”, to achieve unified login company-wide. Since then, OpenLDAP and Linux have progressed. Here, we demonstrate the use of OpenLDAP as the core directory service for a mixed environment. The LDAP server provides a shared e-mail directory, login for Linux and Microsoft Windows clients, automount of home directories and file sharing for all clients. A simple mixed environment used in the examples in this article is shown in (Figure 1).

Figure 1. In the mixed environment, both Linux and Windows clients use a common LDAP infrastructure.

LDAP Server Installation and Configuration

The LDAP server we discuss was installed using RPM binary packages and openldap-2.2.13-2 on Fedora Core 3. The nss_ldap package also is required. For the most recent source from openldap.org, see the on-line Resources. Edit the server configuration file, /etc/openldap/slapd.conf, as shown in Listing 1. Lines beginning with whitespace are interpreted as a continuation of the previous line, so it's not necessary to use a backslash at the end of a long line.

The LDAP schema defines object classes and attributes that make up the directory entries. Red Hat's autofs schema fits our needs and was packaged with the RPM installation. If you find that you need to add an objectClass or an attribute to your directory, see the OpenLDAP admin guide.

We use the default database type ldbm. Our example uses the LDAP domain component. So, foo.com becomes dc=foo,dc=com.

The Manager has full write access to LDAP entries. Create the manager's password using /usr/sbin/slappasswd. Paste the encrypted password into the rootpw entry in slapd.conf.

The index lines enhance performance for attributes queried often. Access control restricts access to the userPassword entry. The user and manager may modify the entry. For all other entries, the manager has write access, and everyone else is granted read access.

Create the Directory Structure

Each entry in the directory is identified uniquely with a distinguished name (dn). The dn for foo.com is dn: dc=foo, dc=com. The organizationalUnit (ou) provides a method for grouping entries. The directory structure is shown in Listing 2.

We create the top level entries in LDAP Interchange Format (LDIF) and save them to top.ldif, as shown in Listing 3.

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IT IS VERY USEFUL TO SOLVE PROBLEM

Anonymous's picture

GOOD. It was very useful to solve the problem,

Thank you very much

LDBM and RedHat OpenLDAP Version

Quanah Gibson-Mount's picture

There are two things wrong with this article:

(1) It shows a setup using the LDBM databse. This is very unfortunate, since LDBM is not "data safe" and will happily corrupt or lose data without informing you. See http://www.openldap.org/faq/data/cache/756.html for more information on the problems with LDBM.

(2) It shows usage of the RedHat distributed version of OpenLDAP. RedHat traditionally does a very poor job of packaging OpenLDAP, and this remains the case to this day. In addition, 2.2.13 is a very old release at this point, on a historic version of OpenLDAP. 2.3 is the current release branch, with 2.3.20 the current stable release. There are at least 2 DOS vulnerabilities in the 2.2.13 OpenLDAP release, as well as hundreds of bugs that were fixed since then.

If you are using RedHat, and want to use OpenLDAP without updating the local RedHat OpenLDAP libraries, I suggest using CDS3 silver, available for *free* from Symas.com. CDS3 is a packaged version of OpenLDAP 2.3 with *additional* features over OpenLDAP.

--Quanah

--
Quanah Gibson-Mount
Product Engineer
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:

So long and thanks for all the spam?

Jason Elovich's picture

We appreciate the spam disguised as useful info, really.

Since CDS silver free

Anonymous's picture

Since CDS silver is a free packaging of OpenLDAP 2.3, I don't see this as spam, any more than me posting to let you know that I provide my own packages of OpenLDAP 2.3

Of course, both Quanah and I have vested interests in recommending that users (1) don't use ldbm, and (2) use 2.3 ... because we both end up helping the unfortunate users who get stuck after following advice like in this article on the openldap-software mailing list.

Since you don't ... well you can say whatever you like about both of these posts and we won't care.

Although you do help people

Anonymous's picture

Although you do help people Buchan and provide great packages, Quanah is more likely to insult people for not paying for support if the post actually makes it to the OpenLDAP list. It is extremely difficult to get any helpful support for OpenLDAP if you're not a guru or the topic is not absolutely, strictly limited to only OpenLDAP of the latest release.

Samba Schema

Compunuts-2's picture

I can't seem to find Samba Schema mentioned in "include /etc/openldap/schema/samba.schema" line. Can someone explain a little more on whether I really need samba schema and where I can download it? Thanks.

Location of samba schema

Dean's picture

In Debian this schema can be found in /usr/share/doc/samba-doc/examples/LDAP/samba.schema.gz, you can copy and extract this file into the schema directory. Samba doc's have to be installed of course.

You do need it. Try

Anonymous's picture

You do need it. Try googling for "samba.schema", or on your server "locate samba.schema"

automountMap vs. nisMap

drswalton's picture

Very useful article. I used their earlier articles as a guide to setting up OpenLDAP in my area, along with ones by Mick Bauer, and I couldn't have done it without them.

I only have one comment: the use of the automountMap objectClass. If you use the migrate_automount.pl script in recent versions of OpenLDAP, it uses the nisMap objectClass and nisMapName to describe automounts. I am not sure if one or the other is deprecated or both are supported.

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