Book Image

Mastering OpenLDAP: Configuring, Securing and Integrating Directory Services

Book Image

Mastering OpenLDAP: Configuring, Securing and Integrating Directory Services

Overview of this book

This book is the ideal introduction to using OpenLDAP for Application Developers and will also benefit System Administrators running OpenLDAP. It prepares the reader to build a directory using OpenLDAP, and then employ this directory in the context of the network, taking a practical approach that emphasizes how to get things done. On occasion, it delves into theoretical aspects of LDAP, but only where understanding the theory helps to answer practical questions. The reader requires no knowledge of OpenLDAP, but even readers already familiar with the technology will find new things and techniques. This book is organized into three major sections: the first section covers the basics of LDAP directory services and the OpenLDAP server; the second focuses on building directory services with OpenLDAP; in the third section of the book, we look at how OpenLDAP is integrated with other applications and services on the network. This book not only demystifies OpenLDAP, but gives System Administrators and Application Developers a solid understanding of how to make use of OpenLDAP's directory services.The OpenLDAP directory server is a mature product that has been around (in one form or another) since 1995. It is an open-source server that provides network clients with directory services. All major Linux distributions include the OpenLDAP server, and many major applications, both open-source and proprietary, are directory aware and can make use of the services provided by OpenLDAP.The OpenLDAP directory server can be used to store organizational information in a centralized location, and make this information available to authorized applications. Client applications connect to OpenLDAP using the Lightweight Directory Access Protocol (LDAP) and can then search the directory and (if they have appropriate access) modify and manipulate records. LDAP servers are most frequently used to provide network-based authentication services for users; but there are many other uses for an LDAP server, including using the directory as an address book, a DNS database, an organizational tool, or even as a network object store for applications.
Table of Contents (17 chapters)
Mastering OpenLDAP
Credits
About the Author
About the Reviewers
Preface
Index

Directory Overlays


As the OpenLDAP project has grown, more and more features have been added. Initially, these features were added directly to the SLAPD server's code base. But as features were rolled into OpenLDAP, both the code and the configuration became increasingly complex.

To address this problem, OpenLDAP developers introduced a new concept in OpenLDAP 2.2 that made it easier to introduce new features while reducing the complexity of the underlying code. The developers introduced a modular system called overlays. An overlay is a chunk of code that can modify the behavior of the SLAPD.

When SLAPD receives a request for a database configured to use an overlay, the overlay is given an opportunity to perform processing on the request before any information is retrieved from the underlying database. As a result overlays can be used to perform additional processing of requests.

How is an overlay added to the directory server? It is through special directives in the slapd.conf file. The overlay...