OpenLDAP 2.1 Administrator's Guide
==================================

The OpenLDAP Project <http://www.openldap.org/>


Preface
=======

Copyright
---------

Copyright 1998-2002, The OpenLDAP Foundation, All Rights Reserved.

Copyright 1992-1996, Regents of the University of Michigan, All Rights
Reserved.

This document is considered a part of OpenLDAP Software.  This
document is subject to terms of conditions set forth in OpenLDAP
Software Copyright Notices and the OpenLDAP Public License. Complete
copies of the notices and associated license can be found in Appendix
B and C, respectively.

Scope of this Document
----------------------

This document provides a guide for installing OpenLDAP 2.1 Software
(http://www.openldap.org/software/) on UNIX (and UNIX-like) systems. 
The document is aimed at experienced system administrators but who may
not have prior experience operating LDAP-based directory software.

This document is meant to be used in conjunction with other OpenLDAP
information resources provided with the software package and on the
project's extensive site (http://www.OpenLDAP.org/) on the World Wide
Web.  The site makes available a number of resources.

OpenLDAP Resources

Resource                           URL
.................................. .................................. 
Document Catalog                   http://www.OpenLDAP.org/doc/
Frequently Asked Questions         http://www.OpenLDAP.org/faq/
Issue Tracking System              http://www.OpenLDAP.org/its/
Mailing Lists                      http://www.OpenLDAP.org/lists/
Software Pages                     http://www.OpenLDAP.org/software/
Support Pages                      http://www.OpenLDAP.org/support/

Acknowledgments
---------------

The OpenLDAP Project is comprised of a team of volunteers.  This
document would not be possible without their contribution of time and
energy.

The OpenLDAP Project would also like to thank the University of
Michigan LDAP for building the foundation of LDAP software and
information to which OpenLDAP Software is built upon.  This document
is based upon U-Mich LDAP document: The SLAPD and SLURPD
Administrators Guide.

Amendments
----------

Suggested enhancements and corrections to this document should be
submitted using the OpenLDAP Issue Tracking System
(http://www.openldap.org/its/).

About this document
-------------------

This document was produced using the Simple Document Format
(http://www.mincom.com/mtr/sdf/) documentation system developed by Ian
Clatworthy.  Tools for SDF are available from CPAN
(http://search.cpan.org/search?query=SDF).


1. Introduction to OpenLDAP Directory Services
==============================================

This document describes how to build, configure, and operate OpenLDAP
software to provide directory services.  This includes details on how
to configure and run the stand-alone LDAP daemon, slapd(8) and the
stand-alone LDAP update replication daemon, slurpd(8). It is intended
for newcomers and experienced administrators alike.  This section
provides a basic introduction to directory services and, in
particular, the directory services provided by slapd(8).

1.1. What is a directory service?
---------------------------------

A directory is a specialized database optimized for reading, browsing
and searching.  Directories tend to contain descriptive,
attribute-based information and support sophisticated filtering
capabilities. Directories generally do not support complicated
transaction or roll-back schemes found in database management systems
designed for handling high-volume complex updates.  Directory updates
are typically simple all-or-nothing changes, if they are allowed at
all.  Directories are tuned to give quick response to high-volume
lookup or search operations. They may have the ability to replicate
information widely in order to increase availability and reliability,
while reducing response time.  When directory information is
replicated, temporary inconsistencies between the replicas may be
okay, as long as they get in sync eventually.

There are many different ways to provide a directory service.
Different methods allow different kinds of information to be stored in
the directory, place different requirements on how that information
can be referenced, queried and updated, how it is protected from
unauthorized access, etc.  Some directory services are local,
providing service to a restricted context (e.g., the finger service on
a single machine). Other services are global, providing service to a
much broader context (e.g., the entire Internet).  Global services are
usually distributed, meaning that the data they contain is spread
across many machines, all of which cooperate to provide the directory
service. Typically a global service defines a uniform namespace which
gives the same view of the data no matter where you are in relation to
the data itself.  The Internet Domain Name System (DNS) is an example
of a globally distributed directory service.

1.2. What is LDAP?
------------------

LDAP stands for Lightweight Directory Access Protocol.  As the name
suggests, it is a lightweight protocol for accessing directory
services, specifically X.500-based directory services.  LDAP runs over
TCP/IP or other connection oriented transfer services.  The
nitty-gritty details of LDAP are defined in RFC2251 "The Lightweight
Directory Access Protocol (v3)" and other documents comprising the
technical specification RFC3377.  This section gives an overview of
LDAP from a user's perspective.

What kind of information can be stored in the directory? The LDAP
information model is based on entries. An entry is a collection of
attributes that has a globally-unique Distinguished Name (DN).  The DN
is used to refer to the entry unambiguously. Each of the entry's
attributes has a type and one or more values. The types are typically
mnemonic strings, like "cn" for common name, or "mail" for email
address. The syntax of values depend on the attribute type.  For
example, a cn attribute might contain the value Babs Jensen.  A mail
attribute might contain the value "babs@example.com". A jpegPhoto
attribute would contain a photograph in the JPEG (binary) format.

How is the information arranged? In LDAP, directory entries are
arranged in a hierarchical tree-like structure.  Traditionally, this
structure reflected the geographic and/or organizational boundaries. 
Entries representing countries appear at the top of the tree. Below
them are entries representing states and national organizations. Below
them might be entries representing organizational units, people,
printers, documents, or just about anything else you can think of. 
Figure 1.1 shows an example LDAP directory tree using traditional
naming.

** Unable to import figure intro_tree.gif **

Figure 1.1: LDAP directory tree (traditional naming)

The tree may also be arranged based upon Internet domain names. This
naming approach is becoming increasing popular as it allows for
directory services to be located using the DNS. Figure 1.2 shows an
example LDAP directory tree using domain-based naming.

** Unable to import figure intro_dctree.gif **

Figure 1.2: LDAP directory tree (Internet naming)

In addition, LDAP allows you to control which attributes are required
and allowed in an entry through the use of a special attribute called
objectClass.  The values of the objectClass attribute determine the
schema rules the entry must obey.

How is the information referenced? An entry is referenced by its
distinguished name, which is constructed by taking the name of the
entry itself (called the Relative Distinguished Name or RDN) and
concatenating the names of its ancestor entries. For example, the
entry for Barbara Jensen in the Internet naming example above has an
RDN of uid=babs and a DN of uid=babs,ou=People,dc=example,dc=com. The
full DN format is described in RFC2253, "Lightweight Directory Access
Protocol (v3):  UTF-8 String Representation of Distinguished Names."

How is the information accessed? LDAP defines operations for
interrogating and updating the directory.  Operations are provided for
adding and deleting an entry from the directory, changing an existing
entry, and changing the name of an entry. Most of the time, though,
LDAP is used to search for information in the directory. The LDAP
search operation allows some portion of the directory to be searched
for entries that match some criteria specified by a search filter.
Information can be requested from each entry that matches the
criteria.

For example, you might want to search the entire directory subtree at
and below dc=example,dc=com for people with the name Barbara Jensen,
retrieving the email address of each entry found. LDAP lets you do
this easily.  Or you might want to search the entries directly below
the st=California,c=US entry for organizations with the string Acme in
their name, and that have a fax number. LDAP lets you do this too. The
next section describes in more detail what you can do with LDAP and
how it might be useful to you.

How is the information protected from unauthorized access? Some
directory services provide no protection, allowing anyone to see the
information. LDAP provides a mechanism for a client to authenticate,
or prove its identity to a directory server, paving the way for rich
access control to protect the information the server contains.  LDAP
also supports privacy and integrity security services.

1.3. How does LDAP work?
------------------------

LDAP directory service is based on a client-server model. One or more
LDAP servers contain the data making up the directory information tree
(DIT).  The client connects to servers and asks it a question.  The
server responds with an answer and/or with a pointer to where the
client can get additional information (typically, another LDAP
server).  No matter which LDAP server a client connects to, it sees
the same view of the directory; a name presented to one LDAP server
references the same entry it would at another LDAP server. This is an
important feature of a global directory service, like LDAP.

1.4. What about X.500?
----------------------

Technically, LDAP is a directory access protocol to an X.500 directory
service, the OSI directory service. Initially, LDAP clients accessed
gateways to the X.500 directory service. This gateway ran LDAP between
the client and gateway and X.500's Directory Access Protocol (DAP)
between the gateway and the X.500 server.  DAP is a heavyweight
protocol that operates over a full OSI protocol stack and requires a
significant amount of computing resources.  LDAP is designed to
operate over TCP/IP and provides most of the functionality of DAP at a
much lower cost.

While LDAP is still used to access X.500 directory service via
gateways, LDAP is now more commonly directly implemented in X.500
servers.

The stand-alone LDAP daemon, or slapd(8), can be viewed as a
lightweight X.500 directory server.  That is, it does not implement
the X.500's DAP.  As a lightweight directory server, slapd(8)
implements only a subset of the X.500 models.

If you are already running a X.500 DAP service and you want to
continue to do so, you can probably stop reading this guide.  This
guide is all about running LDAP via slapd(8), without running X.500
DAP.  If you are not running X.500 DAP, want to stop running X.500
DAP, or have no immediate plans to run X.500 DAP, read on.

It is possible to replicate data from an LDAP directory server to a
X.500 DAP DSA.  This requires an LDAP/DAP gateway. OpenLDAP does not
provide such a gateway, but our replication daemon can be used to
replicate to such a gateway.  See the Replication with slurpd chapter
of this document for information regarding replication.

1.5. What is the difference between LDAPv2 and LDAPv3?
------------------------------------------------------

LDAPv3 was developed in the late 1990's to replace LDAPv2. LDAPv3 adds
the following features to LDAP:

     o    Strong Authentication via SASL

     o    Integrity and Confidentiality Protection via TLS (SSL)

     o    Internationalization through the use of Unicode

     o    Referrals and Continuations

     o    Schema Discovery

     o    Extensibility (controls, extended operations, and more)

LDAPv2 is considered historical.  As deploying both LDAPv2 and LDAPv3
simultaneously can be quite problematic, LDAPv2 should be avoided. 
LDAPv2 is disabled by default.

1.6. What is slapd and what can it do?
--------------------------------------

slapd(8) is an LDAP directory server that runs on many different
platforms. You can use it to provide a directory service of your very
own.  Your directory can contain pretty much anything you want to put
in it. You can connect it to the global LDAP directory service, or run
a service all by yourself. Some of slapd's more interesting features
and capabilities include:

LDAPv3: slapd implements version 3 of Lightweight Directory Access
Protocol. slapd supports LDAP over both IPv4 and IPv6.

Simple Authentication and Security Layer: slapd supports strong
authentication services through the use of SASL.  slapd's SASL
implementation utilizes Cyrus SASL software which supports a number of
mechanisms including DIGEST-MD5, EXTERNAL, and GSSAPI.

Transport Layer Security: slapd provides privacy and integrity
protections through the use of TLS (or SSL).  slapd's TLS
implementation utilizes OpenSSL software.

Topology control: slapd allows one to restrict access to the server
based upon network topology.  This feature utilizes TCP wrappers.

Access control: slapd provides a rich and powerful access control
facility, allowing you to control access to the information in your
database(s). You can control access to entries based on LDAP
authorization information, IP address, domain name and other criteria.
 slapd supports both static and dynamic access control information.

Internationalization: slapd supports Unicode and language tags.

Choice of database backends: slapd comes with a variety of different
database backends you can choose from. They include BDB, a
high-performance transactional database backend; LDBM, a lightweight
DBM based backend; SHELL, a backend interface to arbitrary shell
scripts; and PASSWD, a simple backend interface to the passwd(5) file.
 BDB utilizes Sleepycat Berkeley DB.  LDBM utilizes either Berkeley DB
or GDBM.

Multiple database instances: slapd can be configured to serve multiple
databases at the same time. This means that a single slapd server can
respond to requests for many logically different portions of the LDAP
tree, using the same or different database backends.

Generic modules API: If you require even more customization, slapd
lets you write your own modules easily. slapd consists of two distinct
parts: a front end that handles protocol communication with LDAP
clients; and modules which handle specific tasks such as database
operations. Because these two pieces communicate via a well-defined C
API, you can write your own customized modules which extend slapd in
numerous ways.  Also, a number of programmable database modules are
provided.  These allow you to expose external data sources to slapd
using popular programming languages (Perl, shell, SQL, and TCL).

Threads: slapd is threaded for high performance.  A single
multi-threaded slapd process handles all incoming requests using a
pool of threads.  This reduces the amount of system overhead required
while providing high performance.

Replication: slapd can be configured to maintain replica copies of its
database. This single-master/multiple-slave replication scheme is
vital in high-volume environments where a single slapd just doesn't
provide the necessary availability or reliability.  slapd also
includes experimental support for multi-master replication.

Configuration: slapd is highly configurable through a single
configuration file which allows you to change just about everything
you'd ever want to change.  Configuration options have reasonable
defaults, making your job much easier.

slapd also has its limitations, of course.  The main BDB backend does
not handle range queries or negation queries very well.

1.7. What is slurpd and what can it do?
---------------------------------------

slurpd(8) is a daemon that helps slapd provide replicated service. It
is responsible for distributing changes made to the master slapd
database out to the various slapd replicas. It frees slapd from having
to worry that some replicas might be down or unreachable when a change
comes through; slurpd handles retrying failed requests automatically. 
slapd and slurpd communicate through a simple text file that is used
to log changes.

See the Replication with slurpd chapter for information about how to
configure and run slurpd(8).


2. A Quick-Start Guide
======================

The following is a quick start guide to OpenLDAP 2.1 software,
including the stand-alone LDAP daemon, slapd(8).

It is meant to walk you through the basic steps needed to install and
configure OpenLDAP Software. It should be used in conjunction with the
other chapters of this document, manual pages, and other materials
provided with the distribution (e.g. the INSTALL document) or on the
OpenLDAP web site (in particular, the OpenLDAP Software FAQ).

If you intend to run OpenLDAP Software seriously, you should review
all of this document before attempting to install the software.

Note: This quick start guide does not use strong authentication nor
any integrity or confidential protection services.  These services are
described in other chapters of the OpenLDAP Administrator's Guide.



1.   Get the software

     You can obtain a copy of the software by following the
     instructions on the OpenLDAP download page
     (http://www.openldap.org/software/download/).  It is recommended
     that new users start with the latest release.



2.   Unpack the distribution

     Pick a directory for the source to live under, change directory
     to there, and unpack the distribution using the following
     commands:

          gunzip -c openldap-VERSION.tgz | tar xvfB -

     then relocate yourself into the distribution directory:

          cd openldap-VERSION

     You'll have to replace VERSION with the version name of the
     release.



3.   Review documentation

     You should now review the COPYRIGHT, LICENSE, README and INSTALL
     documents provided with the distribution. The COPYRIGHT and
     LICENSE provide information on acceptable use, copying, and
     limitation of warranty of OpenLDAP software.



     You should also review other chapters of this document. In
     particular, the Building and Installing OpenLDAP Software chapter
     of this document provides detailed information on prerequisite
     software and installation procedures.



4.   Run configure

     You will need to run the provided configure script to configure
     the distribution for building on your system.  The configure
     script accepts many command line options that enable or disable
     optional software features.  Usually the defaults are okay, but
     you may want to change them.  To get a complete list of options
     that configure accepts, use the --help option:

          ./configure --help

     However, given that you are using this guide, we'll assume you
     are brave enough to just let configure determine what's best:

          ./configure

     Assuming configure doesn't dislike your system, you can proceed
     with building the software.  If configure did complain, well,
     you'll likely need to go to the FAQ Installation Section
     (http://www.openldap.org/faq/ and/or actually read the Building
     and Installing OpenLDAP Software chapter of this document.



5.   Build the software.

     The next step is to build the software.  This step has two parts,
     first we construct dependencies and then we compile the software:

          make depend

          make

     Both makes should complete without error.



6.   Test the build.

     To ensure a correct build, you should run the test suite (it only
     takes a few minutes):

          make test

     Tests which apply to your configuration will run and they should
     pass.  Some tests, such as the replication test, may be skipped.



7.   Install the software.

     You are now ready to install the software; this usually requires
     super-user privileges:

          su root -c 'make install'

     Everything should now be installed under /usr/local (or whatever
     installation prefix was used by configure).



8.   Edit the configuration file.

     Use your favorite editor to edit the provided slapd.conf(5)
     example (usually installed as /usr/local/etc/openldap/slapd.conf)
     to contain a BDB database definition of the form:

          database        bdb

          suffix          "dc=<MY-DOMAIN>,dc=<COM>"

          rootdn          "cn=Manager,dc=<MY-DOMAIN>,dc=<COM>"

          rootpw          secret

          directory       /usr/local/var/openldap-data

     Be sure to replace <MY-DOMAIN> and <COM> with the appropriate
     domain components of your domain name.  For example, for
     example.com, use:

          database        bdb

          suffix          "dc=example,dc=com"

          rootdn          "cn=Manager,dc=example,dc=com"

          rootpw          secret

          directory       /usr/local/var/openldap-data

     If your domain contains additional components, such as
     eng.uni.edu.eu, use:

          database        bdb

          suffix          "dc=eng,dc=uni,dc=edu,dc=eu"

          rootdn          "cn=Manager,dc=eng,dc=uni,dc=edu,dc=eu"

          rootpw          secret

          directory       /usr/local/var/openldap-data

     Details regarding configuring slapd(8) can be found in the
     slapd.conf(5) manual page and the The slapd Configuration File
     chapter of this document.

Note: the directory specified must exist prior to starting slapd(8).



9.   Start SLAPD.

     You are now ready to start the stand-alone LDAP server, slapd(8),
     by running the command:

          su root -c /usr/local/libexec/slapd

     To check to see if the server is running and configured
     correctly, you can run a search against it with ldapsearch(1). 
     By default, ldapsearch is installed as /usr/local/bin/ldapsearch:

          ldapsearch -x -b '' -s base '(objectclass=*)' namingContexts

     Note the use of single quotes around command parameters to
     prevent special characters from being interpreted by the shell. 
     This should return:

          dn:

          namingContexts: dc=example,dc=com

     Details regarding running slapd(8) can be found in the slapd(8)
     manual page and the Running slapd chapter of this document.



10.  Add initial entries to your directory.

     You can use ldapadd(1) to add entries to your LDAP directory.
     ldapadd expects input in LDIF form. We'll do it in two steps:

     1.   create an LDIF file

     2.   run ldapadd

     Use your favorite editor and create an LDIF file that contains:

          dn: dc=<MY-DOMAIN>,dc=<COM>

          objectclass: dcObject

          objectclass: organization

          o: <MY ORGANIZATION>

          dc: <MY-DOMAIN>



          dn: cn=Manager,dc=<MY-DOMAIN>,dc=<COM>

          objectclass: organizationalRole

          cn: Manager

     Be sure to replace <MY-DOMAIN> and <COM> with the appropriate
     domain components of your domain name.  <MY ORGANIZATION> should
     be replaced with the name of your organization. When you cut and
     paste, be sure to trim any leading and trailing whitespace from
     the example.

          dn: dc=example,dc=com

          objectclass: dcObject

          objectclass: organization

          o: Example Company

          dc: example



          dn: cn=Manager,dc=example,dc=com

          objectclass: organizationalRole

          cn: Manager

     Now, you may run ldapadd(1) to insert these entries into your
     directory.

          ldapadd -x -D "cn=Manager,dc=<MY-DOMAIN>,dc=<COM>" -W -f
          example.ldif

     Be sure to replace <MY-DOMAIN> and <COM> with the appropriate
     domain components of your domain name.  You will be prompted for
     the "secret" specified in slapd.conf. For example, for
     example.com, use:

          ldapadd -x -D "cn=Manager,dc=example,dc=com" -W -f
          example.ldif

     where example.ldif is the file you created above.



     Additional information regarding directory creation can be found
     in the Database Creation and Maintenance Tools chapter of this
     document.



11.  See if it works.

     Now we're ready to verify the added entries are in your
     directory. You can use any LDAP client to do this, but our
     example uses the ldapsearch(1) tool.  Remember to replace
     dc=example,dc=com with the correct values for your site:

          ldapsearch -x -b 'dc=example,dc=com' '(objectclass=*)'

     This command will search for and retrieve every entry in the
     database.

You are now ready to add more entries using ldapadd(1) or another LDAP
client, experiment with various configuration options, backend
arrangements, etc.

Note that by default, the slapd(8) database grants read access to
everybody excepting the super-user (as specified by the rootdn
configuration directive).  It is highly recommended that you establish
controls to restrict access to authorized users. Access controls are
discussed in the Access Control section of The slapd Configuration
File chapter.  You are also encouraged to read the Security
Considerations, Using SASL and Using TLS sections.

The following chapters provide more detailed information on making,
installing, and running slapd(8).


3. The Big Picture - Configuration Choices
==========================================

This section gives a brief overview of various LDAP directory
configurations, and how your stand-alone LDAP server slapd(8) fits in
with the rest of the world.

3.1. Local Directory Service
----------------------------

In this configuration, you run a slapd which provides directory
service for your local domain only. It does not interact with other
directory servers in any way. This configuration is shown in Figure
3.1.

** Unable to import figure config_local.gif **

Figure 3.1: Local service configuration.

Use this configuration if you are just starting out (it's the one the
quick-start guide makes for you) or if you want to provide a local
service and are not interested in connecting to the rest of the world.
It's easy to upgrade to another configuration later if you want.

3.2. Local Directory Service with Referrals
-------------------------------------------

In this configuration, you run a slapd which provides directory
service for your local domain and configure it to return referrals to
a superior service capable of handling requests outside your local
domain. You may run this service yourself or use one provided to you.
This configuration is shown in Figure 3.2.

** Unable to import figure config_ref.gif **

Figure 3.2: Local service with referrals

Use this configuration if you want to provide local service and
participate in the Global Directory.

3.3. Replicated Directory Service
---------------------------------

The slurpd daemon is used to propagate changes from a master slapd to
one or more slave slapds. An example master-slave configuration is
shown in figure 3.3.

** Unable to import figure config_repl.gif **

Figure 3.3: Replicated Directory Services

This configuration can be used in conjunction with either of the first
two configurations in situations where a single slapd does not provide
the required reliability or availability.

3.4. Distributed Local Directory Service
----------------------------------------

In this configuration, the local service is partitioned into smaller
services, each of which may be replicated, and glued together with
superior and subordinate referrals.


4. Building and Installing OpenLDAP Software
============================================

This chapter details how to build and install the OpenLDAP Software
package including slapd(8), the stand-alone LDAP daemon and slurpd(8),
the stand-alone update replication daemon. Building and installing
OpenLDAP Software requires several steps: installing prerequisite
software, configuring OpenLDAP Software itself, making, and finally
installing.  The following sections describe this process in detail.

4.1. Obtaining and Extracting the Software
------------------------------------------

You can obtain OpenLDAP Software from the project's download page at
http://www.openldap.org/software/download/ or directly from the
project's FTP service at ftp://ftp.openldap.org/pub/OpenLDAP/.

The project makes available two series of packages for general use. 
The project makes releases as new features and bug fixes come
available.  Though the project takes steps to improve stablity of
these releases, it is common for problems to arise only after release.
 The stable release is the latest release which has demonstrated
stability through general use.

Users of OpenLDAP Software can choose, depending on their desire for
the latest features versus demonstrated stability, the most
appropriate series to install.

After downloading OpenLDAP Software, you need to extract the
distribution from the compressed archive file and change your working
directory to the top directory of the distribution:

     gunzip -c openldap-VERSION.tgz | tar xf -

     cd openldap-VERSION

You'll have to replace VERSION with the version name of the release.

You should now review the COPYRIGHT, LICENSE, README and INSTALL
documents provided with the distribution.  The COPYRIGHT and LICENSE
provide information on acceptable use, copying, and limitation of
warranty of OpenLDAP Software. The README and INSTALL documents
provide detailed information on prerequisite software and installation
procedures.

4.2. Prerequisite software
--------------------------

OpenLDAP Software relies upon a number of software packages
distributed by third parties.  Depending on the features you intend to
use, you may have to download and install a number of additional
software packages.  This section details commonly needed third party
software packages you might have to install.  Note that some of these
third party packages may depend on additional software packages. 
Install each package per the installation instructions provided with
it.

4.2.1. Transport Layer Security
-------------------------------

OpenLDAP clients and servers require installation of OpenSSL TLS
libraries to provide Transport Layer Security services.  Though some
operating systems may provide these libraries as part of the base
system or as an optional software component, OpenSSL often requires
separate installation.

OpenSSL is available from http://www.openssl.org/.

OpenLDAP Software will not be fully LDAPv3 compliant unless OpenLDAP's
configure detects a usable OpenSSL installation.

4.2.2. Kerberos Authentication Services
---------------------------------------

OpenLDAP clients and servers support Kerberos-based authentication
services. In particular, OpenLDAP supports the SASL/GSSAPI
authentication mechanism using either Heimdal or MIT Kerberos V
packages. If you desire to use Kerberos-based SASL/GSSAPI
authentication, you should install either Heimdal or MIT Kerberos V.

Heimdal Kerberos is available from http://www.pdc.kth.se/heimdal/. MIT
Kerberos is available from http://web.mit.edu/kerberos/www/.

Use of strong authentication services, such as those provided by
Kerberos, is highly recommended.

4.2.3. Simple Authentication and Security Layer
-----------------------------------------------

OpenLDAP clients and servers require installation of Cyrus's SASL
libraries to provide Simple Authentication and Security Layer
services.  Though some operating systems may provide this library as
part of the base system or as an optional software component, Cyrus
SASL often requires separate installation.

Cyrus SASL is available from
http://asg.web.cmu.edu/sasl/sasl-library.html. Cyrus SASL will make
use of OpenSSL and Kerberos/GSSAPI libraries if preinstalled.

OpenLDAP Software will not be fully LDAPv3 compliant unless OpenLDAP's
configure detects a usable Cyrus SASL installation.

4.2.4. Database Software
------------------------

OpenLDAP's slapd(8) primary database backend, BDB, requires Sleepycat
Software Berkeley DB, version 4. If not available at configure time,
you will not be able build slapd(8) with this primary database
backend.

Your operating system may provide Berkeley DB, version 4, in the base
system or as an optional software component.  If not, you'll have to
obtain and install it yourself.

Berkeley DB is available from Sleepycat Software's download page
http://www.sleepycat.com/download.html. There are several versions
available.  At the time of this writing, the latest release, version
4.1, is recommended. This package is required if you wish to use the
BDB database backend.

OpenLDAP's slapd(8) LDBM backend supports a variety of data base
managers including Berkeley DB and GDBM. GDBM is available from FSF's
download site ftp://ftp.gnu.org/pub/gnu/gdbm/.

4.2.5. Threads
--------------

OpenLDAP is designed to take advantage of threads.  OpenLDAP supports
POSIX pthreads, Mach CThreads, and a number of other varieties. 
configure will complain if it cannot find a suitable thread subsystem.
  If this occurs, please consult the Software|Installation|Platform
Hints section of the OpenLDAP FAQ http://www.openldap.org/faq/.

4.2.6. TCP Wrappers
-------------------

slapd(8) supports TCP Wrappers (IP level access control filters) if
preinstalled.  Use of TCP Wrappers or other IP-level access filters
(such as those provided by an IP-level firewall) is recommended for
servers containing non-public information.

4.3. Running configure
----------------------

Now you should probably run the configure script with the --help
option. This will give you a list of options that you can change when
building OpenLDAP.  Many of the features of OpenLDAP can be enabled or
disabled using this method.

        ./configure --help

The configure script will also look at various environment variables
for certain settings.  These environment variables include:

Table 4.1: Environment Variables

Variable                           Description
.................................. .................................. 
CC                                 Specify alternative C Compiler
CFLAGS                             Specify additional compiler flags
CPPFLAGS                           Specify C Preprocessor flags
LDFLAGS                            Specify linker flags
LIBS                               Specify additional libraries

Now run the configure script with any desired configuration options or
environment variables.

        [[env] settings] ./configure [options]

As an example, let's assume that we want to install OpenLDAP with BDB
backend and TCP Wrappers support.  By default, BDB is enabled and TCP
Wrappers is not.  So, we just need to specify --with-wrappers to
include TCP Wrappers support:

        ./configure --with-wrappers

However, this will fail to locate dependent software not installed in
system directories.  For example, if TCP Wrappers headers and
libraries are installed in /usr/local/include and /usr/local/lib
respectively, the configure script should be called as follows:

        env CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib" \
                ./configure --with-wrappers

Note: Some shells, such as those derived from the Bourne sh(1), do not
require use of the env(1) command.  In some cases, environmental
variables have to be specified using alternative syntaxes.

The configure script will normally auto-detect appropriate settings. 
If you have problems at this stage, consult any platform specific
hints and check your configure options, if any.

4.4. Building the Software
--------------------------

Once you have run the configure script the last line of output should
be:

        Please "make depend" to build dependencies

If the last line of output does not match, configure has failed, and
you will need to review its output to determine what went wrong. You
should not proceed until configure completes successfully.

To build dependencies, run:

        make depend

Now build the software, this step will actually compile OpenLDAP.

        make

You should examine the output of this command carefully to make sure
everything is built correctly. Note that this command builds the LDAP
libraries and associated clients as well as slapd(8) and slurpd(8).

4.5. Testing the Software
-------------------------

Once the software has been properly configured and successfully made,
you should run the test suite to verify the build.

        make test

Tests which apply to your configuration will run and they should pass.
Some tests, such as the replication test, may be skipped if not
supported by your configuration.

4.6. Installing the Software
----------------------------

Once you have successfully tested the software, you are ready to
install it.  You will need to have write permission to the
installation directories you specified when you ran configure.  By
default OpenLDAP Software is installed in /usr/local.  If you changed
this setting with the --prefix configure option, it will be installed
in the location you provided.

Typically, the installation requires super-user privileges. From the
top level OpenLDAP source directory, type:

        su root -c 'make install'

and enter the appropriate password when requested.

You should examine the output of this command carefully to make sure
everything is installed correctly. You will find the configuration
files for slapd(8) in /usr/local/etc/openldap by default.  See the
chapter The slapd Configuration File for additional information.


5. The slapd Configuration File
===============================

Once the software has been built and installed, you are ready to
configure slapd(8) for use at your site. The slapd runtime
configuration is primarily accomplished through the slapd.conf(5)
file, normally installed in the /usr/local/etc/openldap directory.

An alternate configuration file can be specified via a command-line
option to slapd(8) or slurpd(8). This chapter describes the general
format of the config file, followed by a detailed description of
commonly used config file directives.

5.1. Configuration File Format
------------------------------

The slapd.conf(5) file consists of three types of configuration
information: global, backend specific, and database specific.  Global
information is specified first, followed by information associated
with a particular backend type, which is then followed by information
associated with a particular database instance.  Global directives can
be overridden in backend and/or database directives, and backend
directives can be overridden by database directives.

Blank lines and comment lines beginning with a '#' character are
ignored.  If a line begins with white space, it is considered a
continuation of the previous line. The general format of slapd.conf is
as follows:

        # global configuration directives
        <global config directives>

        # backend definition
        backend <typeA>
        <backend-specific directives>

        # first database definition & config directives
        database <typeA>
        <database-specific directives>

        # second database definition & config directives
        database <typeB>
        <database-specific directives>

        # second database definition & config directives
        database <typeA>
        <database-specific directives>

        # subsequent backend & database definitions & config directives
        ...

A configuration directive may take arguments.  If so, they are
separated by white space.  If an argument contains white space, the
argument should be enclosed in double quotes "like this". If an
argument contains a double quote or a backslash character `\', the
character should be preceded by a backslash character `\'.

The distribution contains an example configuration file that will be
installed in the /usr/local/etc/openldap directory. A number of files
containing schema definitions (attribute types and object classes) are
also provided in the /usr/local/etc/openldap/schema directory.

5.2. Configuration File Directives
----------------------------------

This section details commonly used configuration directives.  For a
complete list, see the slapd.conf(5) manual page.  This section
separates the configuration file directives into global,
backend-specific and data-specific categories, describing each
directive and its default value (if any), and giving an example of its
use.

5.2.1. Global Directives
------------------------

Directives described in this section apply to all backends and
databases unless specifically overridden in a backend or database
definition.  Arguments that should be replaced by actual text are
shown in brackets <>.

5.2.1.1. access to <what> [ by <who> <accesslevel> <control> ]+
---------------------------------------------------------------

This directive grants access (specified by <accesslevel>) to a set of
entries and/or attributes (specified by <what>) by one or more
requesters (specified by <who>). See the Access Control section of
this chapter for a summary of basic usage.

Note: If no access directives are specified, the default access
control policy, access to * by * read, allows all both authenticated
and anonymous users read access.

5.2.1.2. attributetype <RFC2252 Attribute Type Description>
-----------------------------------------------------------

This directive defines an attribute type. Please see the Schema
Specification chapter for information regarding how to use this
directive.

5.2.1.3. idletimeout <integer>
------------------------------

Specify the number of seconds to wait before forcibly closing an idle
client connection.  An idletimeout of 0, the default, disables this
feature.

5.2.1.4. include <filename>
---------------------------

This directive specifies that slapd should read additional
configuration information from the given file before continuing with
the next line of the current file. The included file should follow the
normal slapd config file format.  The file is commonly used to include
files containing schema specifications.

Note: You should be careful when using this directive - there is no
small limit on the number of nested include directives, and no loop
detection is done.

5.2.1.5. loglevel <integer>
---------------------------

This directive specifies the level at which debugging statements and
operation statistics should be syslogged (currently logged to the
syslogd(8) LOG_LOCAL4 facility). You must have configured OpenLDAP
--enable-debug (the default) for this to work (except for the two
statistics levels, which are always enabled).  Log levels are
additive. To display what numbers correspond to what kind of
debugging, invoke slapd with -? or consult the table below. The
possible values for <integer> are:

Table 5.1: Debugging Levels

                             Level Description
.................................. .................................. 
                                -1 enable all debugging
                                 0 no debugging
                                 1 trace function calls
                                 2 debug packet handling
                                 4 heavy trace debugging
                                 8 connection management
                                16 print out packets sent and
                                   received
                                32 search filter processing
                                64 configuration file processing
                               128 access control list processing
                               256 stats log
                                   connections/operations/results
                               512 stats log entries sent
                              1024 print communication with shell
                                   backends
                              2048 print entry parsing debugging

Example:

 loglevel -1

This will cause lots and lots of debugging information to be logged.

Default:

 loglevel 256

5.2.1.6. objectclass <RFC2252 Object Class Description>
-------------------------------------------------------

This directive defines an object class. Please see the Schema
Specification chapter for information regarding how to use this
directive.

5.2.1.7. referral <URI>
-----------------------

This directive specifies the referral to pass back when slapd cannot
find a local database to handle a request.

Example:

        referral ldap://root.openldap.org

This will refer non-local queries to the global root LDAP server at
the OpenLDAP Project. Smart LDAP clients can re-ask their query at
that server, but note that most of these clients are only going to
know how to handle simple LDAP URLs that contain a host part and
optionally a distinguished name part.

5.2.1.8. sizelimit <integer>
----------------------------

This directive specifies the maximum number of entries to return from
a search operation.

Default:

        sizelimit 500

5.2.1.9. timelimit <integer>
----------------------------

This directive specifies the maximum number of seconds (in real time)
slapd will spend answering a search request. If a request is not
finished in this time, a result indicating an exceeded timelimit will
be returned.

Default:

        timelimit 3600

5.2.2. General Backend Directives
---------------------------------

Directives in this section apply only to the backend in which they are
defined. They are supported by every type of backend. Backend
directives apply to all databases instances of the same type and,
depending on the directive, may be overridden by database directives.

5.2.2.1. backend <type>
-----------------------

This directive marks the beginning of a backend declaration. <type>
should be one of the supported backend types listed in Table 5.2.

Table 5.2: Database Backends

Types                              Description
.................................. .................................. 
bdb                                Berkeley DB transactional backend
dnssrv                             DNS SRV backend
ldap                               Lightweight Directory Access
                                   Protocol (Proxy) backend
ldbm                               Lightweight DBM backend
meta                               Meta Directory backend
monitor                            Monitor backend
passwd                             Provides read-only access to
                                   passwd(5)
perl                               Perl Programmable backend
shell                              Shell (extern program) backend
sql                                SQL Programmable backend

Example:

        backend bdb

This marks the beginning of a new BDB backend definition.

5.2.3. General Database Directives
----------------------------------

Directives in this section apply only to the database in which they
are defined. They are supported by every type of database.

5.2.3.1. database <type>
------------------------

This directive marks the beginning of a database instance declaration.
<type> should be one of the supported backend types listed in Table
5.2.

Example:

        database bdb

This marks the beginning of a new BDB database instance declaration.

5.2.3.2. readonly { on | off }
------------------------------

This directive puts the database into "read-only" mode. Any attempts
to modify the database will return an "unwilling to perform" error.

Default:

        readonly off

5.2.3.3. replica
----------------

        replica uri=ldap[s]://<hostname>[:<port>] | host=<hostname>[:<port>]
                [bindmethod={ simple | kerberos | sasl }]
                ["binddn=<DN>"]
                [mech=<mech>]
                [authcid=<identity>]
                [authzid=<identity>]
                [credentials=<password>]
                [srvtab=<filename>]

This directive specifies a replication site for this database. The
uri= parameter specifies a scheme, a host and optionally a port where
the slave slapd instance can be found. Either a domain name or IP
address may be used for <hostname>. If <port> is not given, the
standard LDAP port number (389 or 636) is used.

host is deprecated in favor of the uri parameter.

uri allows the replica LDAP server to be specified as an LDAP URI such
as ldap://slave.example.com:389 or ldaps://slave.example.com:636.

The binddn= parameter gives the DN to bind as for updates to the slave
slapd. It should be a DN which has read/write access to the slave
slapd's database, typically given as a rootdn in the slave's config
file. It must also match the updatedn directive in the slave slapd's
config file. Since DNs are likely to contain embedded spaces, the
entire "binddn=<DN>" string should be enclosed in double quotes.

The bindmethod is simple or kerberos or sasl, depending on whether
simple password-based authentication or Kerberos authentication or
SASL authentication is to be used when connecting to the slave slapd.

Simple authentication should not be used unless adequate integrity and
privacy protections are in place (e.g. TLS or IPSEC).  Simple
authentication requires specification of binddn and credentials
parameters.

Kerberos authentication is deprecated in favor of SASL authentication
mechanisms, in particular the KERBEROS_V4 and GSSAPI mechanisms. 
Kerberos authentication requires binddn and srvtab parameters.

SASL authentication is generally recommended.  SASL authentication
requires specification of a mechanism using the mech parameter.
Depending on the mechanism, an authentication identity and/or
credentials can be specified using authcid and credentials
respectively.  The authzid parameter may be used to specify an
authorization identity.

See the chapter entitled Replication with slurpd for more information
on how to use this directive.

5.2.3.4. replogfile <filename>
------------------------------

This directive specifies the name of the replication log file to which
slapd will log changes. The replication log is typically written by
slapd and read by slurpd. Normally, this directive is only used if
slurpd is being used to replicate the database. However, you can also
use it to generate a transaction log, if slurpd is not running. In
this case, you will need to periodically truncate the file, since it
will grow indefinitely otherwise.

See the chapter entitled Replication with slurpd for more information
on how to use this directive.

5.2.3.5. rootdn <dn>
--------------------

This directive specifies the DN that is not subject to access control
or administrative limit restrictions for operations on this database. 
The DN need not refer to an entry in this database or even in the
directory. The DN may refer to a SASL identity.

Entry-based Example:

        rootdn "cn=Manager,dc=example,dc=com"

SASL-based Example:

        rootdn "uid=root,cn=example.com,cn=digest-md5,cn=auth"

See the SASL Authentication section for information on SASL
authentication identities.

5.2.3.6. rootpw <password>
--------------------------

This directive can be used to specifies a password for the DN for the
rootdn (when the rootdn is set to a DN within the database).

Example:

        rootpw secret

It is also permissible to provide hash of the password in RFC 2307
form.  slappasswd(8) may be used to generate the password hash.

Example:

        rootpw {SSHA}ZKKuqbEKJfKSXhUbHG3fG8MDn9j1v4QN

The hash was generated using the command slappasswd -s secret.

5.2.3.7. suffix <dn suffix>
---------------------------

This directive specifies the DN suffix of queries that will be passed
to this backend database. Multiple suffix lines can be given, and at
least one is required for each database definition.

Example:

        suffix "dc=example,dc=com"

Queries with a DN ending in "dc=example,dc=com" will be passed to this
backend.

Note: When the backend to pass a query to is selected, slapd looks at
the suffix line(s) in each database definition in the order they
appear in the file. Thus, if one database suffix is a prefix of
another, it must appear after it in the config file.

5.2.3.8. updatedn <dn>
----------------------

This directive is only applicable in a slave slapd. It specifies the
DN allowed to make changes to the replica.  This may be the DN
slurpd(8) binds as when making changes to the replica or the DN
associated with a SASL identity.

Entry-based Example:

        updatedn "cn=Update Daemon,dc=example,dc=com"

SASL-based Example:

        updatedn "uid=slurpd,cn=example.com,cn=digest-md5,cn=auth"

See the Replication with slurpd chapter for more information on how to
use this directive.

5.2.3.9. updateref <URL>
------------------------

This directive is only applicable in a slave slapd. It specifies the
URL to return to clients which submit update requests upon the
replica. If specified multiple times, each URL is provided.

Example:

        updateref       ldap://master.example.net

5.2.4. BDB Database Directives
------------------------------

Directives in this category only apply to a BDB database. That is,
they must follow a "database bdb" line and come before any subsequent
"backend" or "database" line.  For a complete reference of BDB
configuration directives, see slapd-bdb(5).

5.2.4.1. directory <directory>
------------------------------

This directive specifies the directory where the BDB files containing
the database and associated indices live.

Default:

        directory /usr/local/var/openldap-data

5.2.5. LDBM Database Directives
-------------------------------

Directives in this category only apply to a LDBM database. That is,
they must follow a "database ldbm" line and come before any subsequent
"backend" or "database" line.  For a complete reference of LDBM
configuration directives, see slapd-ldbm(5).

5.2.5.1. cachesize <integer>
----------------------------

This directive specifies the size in entries of the in-memory cache
maintained by the LDBM backend database instance.

Default:

        cachesize 1000

5.2.5.2. dbcachesize <integer>
------------------------------

This directive specifies the size in bytes of the in-memory cache
associated with each open index file. If not supported by the
underlying database method, this directive is ignored without comment.
Increasing this number uses more memory but can cause a dramatic
performance increase, especially during modifies or when building
indices.

Default:

        dbcachesize 100000

5.2.5.3. dbnolocking
--------------------

This option, if present, disables database locking. Enabling this
option may improve performance at the expense of data security.

5.2.5.4. dbnosync
-----------------

This option causes on-disk database contents to not be immediately
synchronized with in memory changes upon change.  Enabling this option
may improve performance at the expense of data integrity.

5.2.5.5. directory <directory>
------------------------------

This directive specifies the directory where the LDBM files containing
the database and associated indices live.

Default:

        directory /usr/local/var/openldap-data

5.2.5.6. index {<attrlist> | default} [pres,eq,approx,sub,none]
---------------------------------------------------------------

This directive specifies the indices to maintain for the given
attribute. If only an <attrlist> is given, the default indices are
maintained.

Example:

        index default pres,eq
        index uid
        index cn,sn pres,eq,sub
        index objectClass eq

The first line sets the default set of indices to maintain to present
and equality.  The second line causes the default (pres,eq) set of
indices to be maintained for the uid attribute type. The third line
causes present, equality, and substring indices to be maintained for
cn and sn attribute types.  The fourth line causes an equality index
for the objectClass attribute type.

By default, no indices are maintained.  It is generally advised that
minimally an equality index upon objectClass be maintained.

        index objectClass eq

5.2.5.7. mode <integer>
-----------------------

This directive specifies the file protection mode that newly created
database index files should have.

Default:

        mode 0600

5.3. Access Control
-------------------

Access to slapd entries and attributes is controlled by the access
configuration file directive. The general form of an access line is:

        <access directive> ::= access to <what>
                [by <who> <access> <control>]+
        <what> ::= * |
                [dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
                [filter=<ldapfilter>] [attrs=<attrlist>]
        <basic-style> ::= regex | exact
        <scope-style> ::= base | one | subtree | children
        <attrlist> ::= <attr> | <attr> , <attrlist>
        <attr> ::= <attrname> | entry | children
        <who> ::= * | [anonymous | users | self
                        | dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
                [dnattr=<attrname>]
                [group[/<objectclass>[/<attrname>][.<basic-style>]]=<regex>]
                [peername[.<basic-style>]=<regex>]
                [sockname[.<basic-style>]=<regex>]
                [domain[.<basic-style>]=<regex>]
                [sockurl[.<basic-style>]=<regex>]
                [set=<setspec>]
                [aci=<attrname>]
        <access> ::= [self]{<level>|<priv>}
        <level> ::= none | auth | compare | search | read | write
        <priv> ::= {=|+|-}{w|r|s|c|x}+
        <control> ::= [stop | continue | break]

where the <what> part selects the entries and/or attributes to which
the access applies, the <who> part specifies which entities are
granted access, and the <access> part specifies the access granted.
Multiple <who> <access> <control> triplets are supported, allowing
many entities to be granted different access to the same set of
entries and attributes. Not all of these access control options are
described here; for more details see the slapd.access(5) man page.

5.3.1. What to control access to
--------------------------------

The <what> part of an access specification determines the entries and
attributes to which the access control applies.  Entries are commonly
selected in two ways: by DN and by filter.  The following qualifiers
select entries by DN:

        by *
        by dn[.<basic-style>]=<regex>
        by dn.<scope-style>=<DN>

The first form is used to select all entries.  The second form may be
used to select entries by matching a regular expression against the
target entry's normalized DN.   (The second form is not discussed
further in this document.)  The third form is used to select entries
which are within the requested scope of DN.  The <DN> is a string
representation of the Distinguished Name, as described in RFC2253.

The scope can be either base, one, subtree, or children.  Where base
matches only the entry with provided DN, one matches the entries whose
parent is the provided DN, subtree matches all entries in the subtree
whose root is the provided DN, and children matches all entries under
the DN (but not the entry named by the DN).

For example, if the directory contained entries named:

        0: o=suffix
        1: cn=Manager,o=suffix
        2: ou=people,o=suffix
        3: uid=kdz,ou=people,o=suffix
        4: cn=addresses,uid=kdz,ou=people,o=suffix
        5: uid=hyc,ou=people,o=suffix

Then:

     dn.base="ou=people,o=suffix" match 2;

     dn.one="ou=people,o=suffix" match 3, and 5;

     dn.subtree="ou=people,o=suffix" match 2, 3, 4, and 5; and

     dn.children="ou=people,o=suffix" match 3, 4, and 5.

Entries may also be selected using a filter:

        by filter=<ldap filter>

where <ldap filter> is a string representation of an LDAP search
filter, as described in RFC2254.  For example:

        by filter=(objectClass=person)

Note that entries by be select by both DN and filter by include both
qualifiers in the <what> clause.

        by dn.one="ou=people,o=suffix" filter=(objectClass=person)

Attributes within an entry are selected by including a comma-separated
list of attribute names in the <what> selector:

        attrs=<attribute list>

There are two special psuedo attributes entry and children.  To read
(and hence return) an target entry, the subject must have read access
to the target's entry attribute.  To add or delete an entry, the
subject must have write access to the entry's entry attribute AND must
have write access to the entry's parent's children attribute.  To
rename an entry, the subject must have write access to entry's entry
attribute AND have write access to both the old parent's and new
parent's children attributes.  The complete examples at the end of
this section should help clear things up.

Lastly, there is a special entry selector "*" that is used to select
any entry.  It is used when no other <what> selector has been
provided.  It's equivalent to "dn=.*"

5.3.2. Who to grant access to
-----------------------------

The <who> part identifies the entity or entities being granted access.
Note that access is granted to "entities" not "entries." The following
table summarizes entity specifiers:

Table 5.3: Access Entity Specifiers

Specifier                          Entities
.................................. .................................. 
*                                  All, including anonymous and
                                   authenticated users
anonymous                          Anonymous (non-authenticated)
                                   users
users                              Authenticated users
self                               User associated with target entry
dn[.<basic-style>]=<regex>         Users matching a regular
                                   expression
dn.<scope-style>=<DN>              Users within scope of a DN

The DN specifier behaves much like <what> clause DN specifiers.

Other control factors are also supported. For example, a <who> can be
restricted by a regular expression matching the client's domain name:

        domain=<regular expression>

or by an entry listed in a DN-valued attribute in the entry to which
the access applies:

        dnattr=<dn-valued attribute name>

The dnattr specification is used to give access to an entry whose DN
is listed in an attribute of the entry (e.g., give access to a group
entry to whoever is listed as the owner of the group entry).

5.3.3. The access to grant
--------------------------

The kind of <access> granted can be one of the following:

Table 5.4: Access Levels

Level                               Privileges Description
...................... ....................... ...................... 
none                                           no access
auth                                        =x needed to bind
compare                                    =cx needed to compare
search                                    =scx needed to apply search
                                               filters
read                                     =rscx needed to read search
                                               results
write                                   =wrscx needed to
                                               modify/rename

Each level implies all lower levels of access. So, for example,
granting someone write access to an entry also grants them read,
search, compare, and auth access.  However, one may use the privileges
specifier to grant specific permissions.

5.3.4. Access Control Evaluation
--------------------------------

When evaluating whether some requester should be given access to an
entry and/or attribute, slapd compares the entry and/or attribute to
the <what> selectors given in the configuration file. For each entry,
access controls provided in the database which holds the entry (or the
first database if not held in any database) apply first, followed by
the global access directives.  Within this priority, access directives
are examined in the order in which they appear in the config file. 
Slapd stops with the first <what> selector that matches the entry
and/or attribute. The corresponding access directive is the one slapd
will use to evaluate access.

Next, slapd compares the entity requesting access to the <who>
selectors within the access directive selected above in the order in
which they appear. It stops with the first <who> selector that matches
the requester. This determines the access the entity requesting access
has to the entry and/or attribute.

Finally, slapd compares the access granted in the selected <access>
clause to the access requested by the client. If it allows greater or
equal access, access is granted. Otherwise, access is denied.

The order of evaluation of access directives makes their placement in
the configuration file important. If one access directive is more
specific than another in terms of the entries it selects, it should
appear first in the config file. Similarly, if one <who> selector is
more specific than another it should come first in the access
directive. The access control examples given below should help make
this clear.

5.3.5. Access Control Examples
------------------------------

The access control facility described above is quite powerful. This
section shows some examples of its use. First, some simple examples:

        access to * by * read

This access directive grants read access to everyone.

        access to *
                by self write
                by anonymous auth
                by * read

This directive allows users to modify their own entries, allows
authenticate, and allows all others to read.  Note that only the first
by <who> clause which matches applies.  Hence, the anonymous users are
granted auth, not read.  The last clause could just as well have been
"by users read".

It is often desirable to restrict operations based upon the level of
protection in place.  The following shows how security strength
factors (SSF) can be used.

        access to *
                by ssf=128 self write
                by ssf=64 anonymous auth
                by ssf=64 users read

This directive allows users to modify their own entries if security
protections have of strength 128 or better have been established,
allows simple authentication and read access when 64 or better
security protections have been established.

The following example shows the use of a regular expression to select
the entries by DN in two access directives where ordering is
significant.

        access to dn.children="dc=example,dc=com"
                by * search
        access to dn.children="dc=com"
                by * read

Read access is granted to entries under the dc=com subtree, except for
those entries under the dc=example,dc=com subtree, to which search
access is granted.  No access is granted to dc=com as neither access
directive matches this DN.  If the order of these access directives
was reversed, the trailing directive would never be reached, since all
entries under dc=example,dc=com are also under dc=com entries.

Also note that if no access to directive matches or no by <who>
clause, access is denied.  That is, every access to directive ends
with an implicit by * none clause and every access list ends with an
implicit access to * by * none directive.

The next example again shows the importance of ordering, both of the
access directives and the by <who> clauses.  It also shows the use of
an attribute selector to grant access to a specific attribute and
various <who> selectors.

        access to dn.subtree="dc=example,dc=com" attr=homePhone
                by self write
                by dn.children=dc=example,dc=com" search
                by domain=.*\.example\.com read
        access to dn.subtree="dc=example,dc=com"
                by self write
                by dn.children="dc=example,dc=com" search
                by anonymous auth

This example applies to entries in the "dc=example,dc=com" subtree. To
all attributes except homePhone, an entry can write to itself, entries
under example.com entries can search by them, anybody else has no
access (implicit by * none) excepting for authentication/authorization
(which is always done anonymously).  The homePhone attribute is
writable by the entry, searchable by entries under example.com,
readable by clients connecting from somewhere in the example.com
domain, and otherwise not readable (implicit by * none).  All other
access is denied by the implicit access to * by * none.

Sometimes it is useful to permit a particular DN to add or remove
itself from an attribute. For example, if you would like to create a
group and allow people to add and remove only their own DN from the
member attribute, you could accomplish it with an access directive
like this:

        access to attr=member,entry
                by dnattr=member selfwrite

The dnattr <who> selector says that the access applies to entries
listed in the member attribute. The selfwrite access selector says
that such members can only add or delete their own DN from the
attribute, not other values. The addition of the entry attribute is
required because access to the entry is required to access any of the
entry's attributes.

5.4. Configuration File Example
-------------------------------

The following is an example configuration file, interspersed with
explanatory text. It defines two databases to handle different parts
of the X.500 tree; both are BDB database instances. The line numbers
shown are provided for reference only and are not included in the
actual file. First, the global configuration section:

  1.    # example config file - global configuration section
  2.    include /usr/local/etc/schema/core.schema
  3.    referral ldap://root.openldap.org
  4.    access to * by * read

Line 1 is a comment. Line 2 includes another config file which
contains core schema definitions. The referral directive on line 3
means that queries not local to one of the databases defined below
will be referred to the LDAP server running on the standard port (389)
at the host root.openldap.org.

Line 4 is a global access control.  It applies to all entries (after
any applicable database-specific access controls).

The next section of the configuration file defines a BDB backend that
will handle queries for things in the "dc=example,dc=com" portion of
the tree. The database is to be replicated to two slave slapds, one on
truelies, the other on judgmentday. Indices are to be maintained for
several attributes, and the userPassword attribute is to be protected
from unauthorized access.

  5.    # BDB definition for the example.com
  6.    database bdb
  7.    suffix "dc=example,dc=com"
  8.    directory /usr/local/var/openldap-data
  9.    rootdn "cn=Manager,dc=example,dc=com"
 10.    rootpw secret
 11.    # replication directives
 12.    replogfile /usr/local/var/openldap/slapd.replog
 13.    replica uri=ldap://slave1.example.com:389
 14.            binddn="cn=Replicator,dc=example,dc=com"
 15.            bindmethod=simple credentials=secret
 16.    replica uri=ldaps://slave2.example.com:636
 17.            binddn="cn=Replicator,dc=example,dc=com"
 18.            bindmethod=simple credentials=secret
 19.    # indexed attribute definitions
 20.    index uid pres,eq
 21.    index cn,sn,uid pres,eq,approx,sub
 22.    index objectClass eq
 23.    # database access control definitions
 24.    access to attr=userPassword
 25.            by self write
 26.            by anonymous auth
 27.            by dn.base="cn=Admin,dc=example,dc=com" write
 28.            by * none
 29.    access to *
 30.            by self write
 31.            by dn.base="cn=Admin,dc=example,dc=com" write
 32.            by * read

Line 5 is a comment. The start of the database definition is marked by
the database keyword on line 6. Line 7 specifies the DN suffix for
queries to pass to this database. Line 8 specifies the directory in
which the database files will live.

Lines 9 and 10 identify the database super-user entry and associated
password. This entry is not subject to access control or size or time
limit restrictions.

Lines 11 through 18 are for replication. Line 12 specifies the
replication log file (where changes to the database are logged - this
file is written by slapd and read by slurpd). Lines 13 through 15
specify the hostname and port for a replicated host, the DN to bind as
when performing updates, the bind method (simple) and the credentials
(password) for the binddn. Lines 16 through 18 specify a second
replication site.  See the Replication with slurpd chapter for more
information on these directives.

Lines 20 through 22 indicate the indices to maintain for various
attributes.

Lines 24 through 32 specify access control for entries in this
database.  As this is the first database, the controls also apply to
entries not held in any database (such as the Root DSE).  For all
applicable entries, the userPassword attribute is writable by the
entry itself and by the "admin" entry.  It may be used for
authentication/authorization purposes, but is otherwise not readable.
All other attributes are writable by the entry and the "admin" entry,
but may be read by all users (authenticated or not).

The next section of the example configuration file defines another BDB
database. This one handles queries involving the dc=example,dc=net
subtree but is managed by the same entity as the first database.  Note
that without line 39, the read access would be allowed due to the
global access rule at line 4.

 33.    # BDB definition for example.net
 34.    database bdb
 35.    suffix "dc=example,dc=net"
 36.    directory /usr/local/var/openldap-data-net
 37.    rootdn "cn=Manager,dc=example,dc=com"
 38.    index objectClass eq
 39.    access to * by users read


6. Running slapd
================

slapd(8) is designed to be run as a stand-alone server.  This allows
the server to take advantage of caching, manage concurrency issues
with underlying databases, and conserve system resources.  Running
from inetd(8) is NOT an option.

6.1. Command-Line Options
-------------------------

slapd(8) supports a number of command-line options as detailed in the
manual page.  This section details a few commonly used options.

        -f <filename>

This option specifies an alternate configuration file for slapd. The
default is normally /usr/local/etc/openldap/slapd.conf.

        -h <URLs>

This option specifies alternative listener configurations.  The
default is ldap:/// which implies LDAP over TCP on all interfaces on
the default LDAP port 389.  You can specify specific host-port pairs
or other protocol schemes (such as ldaps:// or ldapi://).  For
example, -h "ldaps:// ldap://127.0.0.1:666" will create two listeners:
one for LDAP over SSL on all interfaces on the default LDAP/SSL port
636, and one for LDAP over TCP on the localhost (loopback) interface
on port 666. Hosts may be specified using IPv4 dotted-decimal form or
using host names.  Port values must be numeric.

        -n <service-name>

This option specifies the service name used for logging and other
purposes.  The default service name is slapd.

        -l <syslog-local-user>

This option specifies the local user for the syslog(8) facility. 
Values can be LOCAL0, LOCAL1, LOCAL2, ..., and LOCAL7.  The default is
LOCAL4.  This option may not be supported on all systems.

        -u user -g group

These options specify the user and group, respectively, to run as. 
user can be either a user name or uid.  group can be either a group
name or gid.

        -r directory

This option specifies a run-time directory.  slapd will chroot(2) to
this directory after opening listeners but before reading any
configuration files or initializing any backends.



        -d <level> | ?

This option sets the slapd debug level to <level>. When level is a `?'
character, the various debugging levels are printed and slapd exits,
regardless of any other options you give it. Current debugging levels
are

Table 6.1: Debugging Levels

                             Level Description
.................................. .................................. 
                                -1 enable all debugging
                                 0 no debugging
                                 1 trace function calls
                                 2 debug packet handling
                                 4 heavy trace debugging
                                 8 connection management
                                16 print out packets sent and
                                   received
                                32 search filter processing
                                64 configuration file processing
                               128 access control list processing
                               256 stats log
                                   connections/operations/results
                               512 stats log entries sent
                              1024 print communication with shell
                                   backends
                              2048 print entry parsing debugging

You may enable multiple levels by specifying the debug option once for
each desired level.  Or, since debugging levels are additive, you can
do the math yourself. That is, if you want to trace function calls and
watch the config file being processed, you could set level to the sum
of those two levels (in this case,  -d 65).  Or, you can let slapd do
the math, (e.g.  -d 1 -d 64).  Consult <ldap_log.h> for more details.

Note: slapd must have been compiled with -DLDAP_DEBUG defined for any
debugging information beyond the two stats levels to be available.

6.2. Starting slapd
-------------------

In general, slapd is run like this:

        /usr/local/etc/libexec/slapd [<option>]*

where /usr/local/etc/libexec is determined by configure and <option>
is one of the options described above (or in slapd(8)). Unless you
have specified a debugging level (including level 0), slapd will
automatically fork and detach itself from its controlling terminal and
run in the background.

6.3. Stopping slapd
-------------------

To kill off slapd safely, you should give a command like this

        kill -INT `cat /usr/local/var/slapd.pid`

where /usr/local/var is determined by configure.

Killing slapd by a more drastic method may cause information loss or
database corruption.


7. Database Creation and Maintenance Tools
==========================================

This section tells you how to create a slapd database from scratch,
and how to do trouble shooting if you run into problems. There are two
ways to create a database. First, you can create the database on-line
using LDAP. With this method, you simply start up slapd and add
entries using the LDAP client of your choice. This method is fine for
relatively small databases (a few hundred or thousand entries,
depending on your requirements). This method works for database types
which support updates.

The second method of database creation is to do it off-line using
special utilities provided with slapd. This method is best if you have
many thousands of entries to create, which would take an unacceptably
long time using the LDAP method, or if you want to ensure the database
is not accessed while it is being created. Note that not all database
types support these utilitites.

7.1. Creating a database over LDAP
----------------------------------

With this method, you use the LDAP client of your choice (e.g., the
ldapadd(1)) to add entries, just like you would once the database is
created.  You should be sure to set the following options in the
configuration file before starting slapd(8).

        suffix <dn>

As described in the General Database Directives section, this option
defines which entries are to be held by this database. You should set
this to the DN of the root of the subtree you are trying to create. 
For example:

        suffix "dc=example,dc=com"

You should be sure to specify a directory where the index files should
be created:

        directory <directory>

For example:

        directory /usr/local/var/openldap-data

You need to create this directory with appropriate permissions such
that slapd can write to it.

You need to configure slapd so that you can connect to it as a
directory user with permission to add entries. You can configure the
directory to support a special super-user or root user just for this
purpose. This is done through the following two options in the
database definition:

        rootdn <dn>
        rootpw <passwd>

For example:

        rootdn "cn=Manager,dc=example,dc=com"
        rootpw secret

These options specify a DN and password that can be used to
authenticate as the super-user entry of the database (i.e., the entry
allowed to do anything). The DN and password specified here will
always work, regardless of whether the entry named actually exists or
has the password given. This solves the chicken-and-egg problem of how
to authenticate and add entries before any entries yet exist.

Finally, you should make sure that the database definition contains
the index definitions you want:

        index {<attrlist> | default} [pres,eq,approx,sub,none]

For example, to index the cn, sn, uid and objectclass attributes, the
following index directives could be used:

        index cn,sn,uid pres,eq,approx,sub
        index objectClass eq

This would create presence, equality, approximate, and substring
indices for the cn, sn, and uid attributes and an equality index for
the objectClass attribute.  Note that not all index types are
available with all attribute types.  See The slapd Configuration File
section for more information on this option.

Once you have configured things to your liking, start up slapd,
connect with your LDAP client, and start adding entries.  For example,
to add an organization entry and an organizational role entry using
the ldapadd tool, you could create an LDIF file called entries.ldif
with the contents:

        # Organization for Example Corporation
        dn: dc=example,dc=com
        objectClass: dcObject
        objectClass: organization
        dc: example
        o: Example Corporation
        description: The Example Corporation

        # Organizational Role for Directory Manager
        dn: cn=Manager,dc=example,dc=com
        objectClass: organizationalRole
        cn: Manager
        description: Directory Manager

and then use a command like this to actually create the entry:

        ldapadd -f entries.ldif -x -D "cn=Manager,dc=example,dc=com" -w secret

The above command assumes settings provided in the above examples.

7.2. Creating a database off-line
---------------------------------

The second method of database creation is to do it off-line, using the
slapd database tools described below. This method is best if you have
many thousands of entries to create, which would take an unacceptably
long time to add using the LDAP method described above. These tools
read the slapd configuration file and an input file containing a text
representation of the entries to add. For database types which support
the tools, they produce the database files directly (otherwise you
must use the on-line method above). There are several important
configuration options you will want to be sure and set in the config
file database definition first:

        suffix <dn>

As described in the General Database Directives section, this option
defines which entries are to be held by this database. You should set
this to the DN of the root of the subtree you are trying to create. 
For example:

        suffix "dc=example,dc=com"

You should be sure to specify a directory where the index files should
be created:

        directory <directory>

For example:

        directory /usr/local/var/openldap-data

Finally, you need to specify which indices you want to build.  This is
done by one or more index options.

        index {<attrlist> | default} [pres,eq,approx,sub,none]

For example:

        index cn,sn,uid pres,eq,approx,sub
        index objectClass eq

This would create presence, equality, approximate, and substring
indices for the cn, sn, and uid attributes and an equality index for
the objectClass attribute.  Note that not all index types are
available with all attribute types.  See The slapd Configuration File
section for more information on this option.

7.2.1. The slapadd program
--------------------------

Once you've configured things to your liking, you create the primary
database and associated indices by running the slapadd(8) program:

        slapadd -l <inputfile> -f <slapdconfigfile>
                [-d <debuglevel>] [-n <integer>|-b <suffix>]

The arguments have the following meanings:

        -l <inputfile>

Specifies the LDIF input file containing the entries to add in text
form (described below in the The LDIF text entry format section).

        -f <slapdconfigfile>

Specifies the slapd configuration file that tells where to create the
indices, what indices to create, etc.

        -d <debuglevel>

Turn on debugging, as specified by <debuglevel>. The debug levels are
the same as for slapd.  See the Command-Line Options section in
Running slapd.

        -n <databasenumber>

An optional argument that specifies which database to modify.  The
first database listed in the configuration file is 1, the second 2,
etc. By default, the first database in the configuration file is used.
Should not be used in conjunction with -b.

        -b <suffix>

An optional argument that specifies which database to modify.  The
provided suffix is matched against a database suffix directive to
determine the database number. Should not be used in conjunction with
-n.

7.2.2. The slapindex program
----------------------------

Sometimes it may be necessary to regenerate indices (such as after
modifying slapd.conf(5)). This is possible using the slapindex(8)
program.  slapindex is invoked like this

        slapindex -f <slapdconfigfile>
                [-d <debuglevel>] [-n <databasenumber>|-b <suffix>]

Where the -f, -d, -n and -b options are the same as for the slapadd(1)
program.  slapindex rebuilds all indices based upon the current
database contents.

7.2.3. The slapcat program
--------------------------

The slapcat program is used to dump the database to an LDIF file. 
This can be useful when you want to make a human-readable backup of
your database or when you want to edit your database off-line.  The
program is invoked like this:

        slapcat -l <filename> -f <slapdconfigfile>
                [-d <debuglevel>] [-n <databasenumber>|-b <suffix>]

where -n or -b is used to select the database in the slapd.conf(5)
specified using -f.  The corresponding LDIF output is written to
standard output or to the file specified using the -l option.

7.3. The LDIF text entry format
-------------------------------

The LDAP Data Interchange Format (LDIF) is used to represent LDAP
entries in a simple text format.  This section provides a brief
description of the LDIF entry format which complements ldif(5) and the
technical specification RFC2849.

The basic form of an entry is:

        # comment
        dn: <distinguished name>
        <attrdesc>: <attrvalue>
        <attrdesc>: <attrvalue>

        ...

Lines starting with a '#' character are comments.  An attribute
description may be a simple attribute type like cn or objectClass or
1.2.3 (an OID associated with an attribute type) or may include
options such as cn;lang_en_US or userCertificate;binary.

A line may be continued by starting the next line with a single space
or tab character.  For example:

        dn: cn=Barbara J Jensen,dc=example,dc=
         com
        cn: Barbara J
          Jensen

is equivalent to:

        dn: cn=Barbara J Jensen,dc=example,dc=com
        cn: Barbara J Jensen

Multiple attribute values are specified on separate lines. e.g.,

        cn: Barbara J Jensen
        cn: Babs Jensen

If an <attrvalue> contains non-printing characters or begins with a
space, a colon (':'), or a less than ('<'), the <attrdesc> is followed
by a double colon and the base64 encoding of the value.  For example,
the value " begins with a space" would be encoded like this:

        cn:: IGJlZ2lucyB3aXRoIGEgc3BhY2U=

You can also specify a URL containing the attribute value. For
example, the following specifies the jpegPhoto value should be
obtained from the file /path/to/file.jpeg.

        cn:< file:///path/to/file.jpeg

Multiple entries within the same LDIF file are separated by blank
lines. Here's an example of an LDIF file containing three entries.

        # Barbara's Entry
        dn: cn=Barbara J Jensen,dc=example,dc=com
        cn: Barbara J Jensen
        cn: Babs Jensen
        objectClass: person
        sn: Jensen

        # Bjorn's Entry
        dn: cn=Bjorn J Jensen,dc=example,dc=com
        cn: Bjorn J Jensen
        cn: Bjorn Jensen
        objectClass: person
        sn: Jensen
        # Base64 encoded JPEG photo
        jpegPhoto:: /9j/4AAQSkZJRgABAAAAAQABAAD/2wBDABALD
         A4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkzODdASFxOQ
         ERXRTc4UG1RV19iZ2hnPk1xeXBkeFxlZ2P/2wBDARESEhgVG

        # Jennifer's Entry
        dn: cn=Jennifer J Jensen,dc=example,dc=com
        cn: Jennifer J Jensen
        cn: Jennifer Jensen
        objectClass: person
        sn: Jensen
        # JPEG photo from file
        jpegPhoto:< file:///path/to/file.jpeg

Notice that the jpegPhoto in Bjorn's entry is base 64 encoded and the
jpegPhoto in Jennifer's entry is obtained from the location indicated
by the URL.

Note: Trailing spaces are not trimmed from values in an LDIF file. Nor
are multiple internal spaces compressed. If you don't want them in
your data, don't put them there.


8. Schema Specification
=======================

This chapter describes how to extend the user schema used by slapd(8).
The first section, Distributed Schema Files details optional schema
definitions provided in the distribution and where to obtain other
definitions. The second section, Extending Schema, details how to
define new schema items.

This chapter does not discuss how to extend system schema used by
slapd(8) as this requires source code modification.  System schema
includes all operational attribute types or any object class which
allows or requires an operational attribute (directly or indirectly).

8.1. Distributed Schema Files
-----------------------------

OpenLDAP is distributed with a set of schema specifications for your
use.  Each set is defined in a file suitable for inclusion (using the
include directive) in your slapd.conf(5) file.  These schema files are
normally installed in the /usr/local/etc/openldap/schema directory.

Table 8.1: Provided Schema Specifications

File                                                      Description
.................................. .................................. 
core.schema                                  OpenLDAP core (required)
cosine.schema                      Cosine and Internet X.500 (useful)
inetorgperson.schema                           InetOrgPerson (useful)
misc.schema                                   Assorted (experimental)
nis.schema                         Network Information Services (FYI)
openldap.schema                       OpenLDAP Project (experimental)

To use any of these schema files, you only need to include the desired
file in the global definitions portion of your slapd.conf(5) file. 
For example:

        # include schema
        include /usr/local/etc/openldap/schema/core.schema
        include /usr/local/etc/openldap/schema/cosine.schema
        include /usr/local/etc/openldap/schema/inetorgperson.schema

Additional files may be available.  Please consult the OpenLDAP FAQ
(http://www.openldap.org/faq/).

Note: You should not modify any of the schema items defined in
provided files.

8.2. Extending Schema
---------------------

Schema used by slapd(8) may be extended to support additional
syntaxes, matching rules, attribute types, and object classes.  This
chapter details how to add user application attribute types and object
classes using the syntaxes and matching rules already supported by
slapd.  slapd can also be extended to support additional syntaxes,
matching rules and system schema, but this requires some programming
and hence is not discussed here.

There are five steps to defining new schema:

1.   obtain Object Identifer

2.   choose a name prefix

3.   create local schema file

4.   define custom attribute types (if necessary)

5.   define custom object classes

8.2.1. Object Identifiers
-------------------------

Each schema element is identified by a globally unique Object
Identifier (OID).  OIDs are also used to identify other objects. They
are commonly found in protocols described by ASN.1.  In particular,
they are heavily used by the Simple Network Management Protocol
(SNMP). As OIDs are hierarchical, your organization can obtain one OID
and branch it as needed.  For example, if your organization were
assigned OID 1.1, you could branch the tree as follows:

Table 8.2: Example OID hierarchy

OID                                                        Assignment
.................................. .................................. 
1.1                                                Organization's OID
1.1.1                                                   SNMP Elements
1.1.2                                                   LDAP Elements
1.1.2.1                                                AttributeTypes
1.1.2.1.1                                                 myAttribute
1.1.2.2                                                 ObjectClasses
1.1.2.2.1                                               myObjectClass

You are, of course, free to design a hierarchy suitable to your
organizational needs under your organization's OID.  No matter what
hierarchy you choose, you should maintain a registry of assignments
you make.  This can be a simple flat file or something more
sophisticated such as the OpenLDAP OID Registry
(http://www.openldap.org/faq/index.cgi?file=197).

For more information about Object Identifers (and a listing service)
see http://www.alvestrand.no/harald/objectid/.

     Under no circumstances should you hijack OID namespace!

To obtain a registered OID at no cost, apply for an OID under the
Internet Assigned Numbers Authority (IANA) maintained Private
Enterprise arc.  Any private enterprise (organization) may request an
OID to be assigned under this arc.  Just fill out the IANA form at
http://www.iana.org/cgi-bin/enterprise.pl and your official OID will
be sent to you usually within a few days.  Your base OID will be
something like 1.3.6.1.4.1.X where X is an integer.

Note: Don't let the "MIB/SNMP" statement on the IANA page confuse you.
 OIDs obtained using this form may be used for any purpose including
identifying LDAP schema elements.

Alternatively, OID name space may be available from a national
authority (e.g., ANSI, BSI).

For private experiments, OIDs under 1.1 may be used.  The OID 1.1 arc
is regarded as dead name space.

8.2.2. Name Prefix
------------------

In addition to assigning a unique object identifier to each schema
element, you should provide a least one textual name for each element.
 The name should be both descriptive and not likely to clash with
names of other schema elements.  In particular, any name you choose
should not clash with present or future Standard Track names.

To reduce (but not eliminate) the potential for name clashes, the
convention is to prefix names of non-Standard Track with a few letters
to localize the changes to your organization.  The smaller the
organization, the longer your prefix should be.

In the examples below, we have chosen a short prefix 'my' (to save
space).  Such a short prefix would only be suitable for a very large,
global organization.  In general, we recommend something like 'deFirm'
(German company) or 'comExample' (elements associated with
organization associated with example.com).

8.2.3. Local schema file
------------------------

The objectclass and attributeTypes configuration file directives can
be used to define schema rules on entries in the directory.  It is
customary to create a file to contain definitions of your custom
schema items.  We recommend you create a file local.schema in
/usr/local/etc/openldap/schema/local.schema and then include this file
in your slapd.conf(5) file immediately after other schema include
directives.

        # include schema
        include /usr/local/etc/openldap/schema/core.schema
        include /usr/local/etc/openldap/schema/cosine.schema
        include /usr/local/etc/openldap/schema/inetorgperson.schema
        # include local schema
        include /usr/local/etc/openldap/schema/local.schema

8.2.4. Attribute Type Specification
-----------------------------------

The attributetype directive is used to define a new attribute type. 
The directive uses the same Attribute Type Description (as defined in
RFC2252) used by the attributeTypes attribute found in the subschema
subentry, e.g.:

        attributetype <RFC2252 Attribute Type Description>

where Attribute Type Description is defined by the following BNF:

      AttributeTypeDescription = "(" whsp
            numericoid whsp              ; AttributeType identifier
          [ "NAME" qdescrs ]             ; name used in AttributeType
          [ "DESC" qdstring ]            ; description
          [ "OBSOLETE" whsp ]
          [ "SUP" woid ]                 ; derived from this other
                                         ; AttributeType
          [ "EQUALITY" woid              ; Matching Rule name
          [ "ORDERING" woid              ; Matching Rule name
          [ "SUBSTR" woid ]              ; Matching Rule name
          [ "SYNTAX" whsp noidlen whsp ] ; Syntax OID
          [ "SINGLE-VALUE" whsp ]        ; default multi-valued
          [ "COLLECTIVE" whsp ]          ; default not collective
          [ "NO-USER-MODIFICATION" whsp ]; default user modifiable
          [ "USAGE" whsp AttributeUsage ]; default userApplications
          whsp ")"

      AttributeUsage =
          "userApplications"     /
          "directoryOperation"   /
          "distributedOperation" / ; DSA-shared
          "dSAOperation"          ; DSA-specific, value depends on server


where whsp is a space (' '), numericoid is a globally unique OID in
dotted-decimal form (e.g. 1.1.0), qdescrs is one or more names, woid
is either the name or OID optionally followed by a length specifier
(e.g {10}).

For example, the attribute types name and cn are defined in
core.schema as:

        attributeType ( 2.5.4.41 NAME 'name'
                DESC 'name(s) associated with the object'
                EQUALITY caseIgnoreMatch
                SUBSTR caseIgnoreSubstringsMatch
                SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768} )
        attributeType ( 2.5.4.3 NAME ( 'cn' 'commonName' )
                DESC 'common name(s) assciated with the object'
                SUP name )

Notice that each defines the attribute's OID, provides a short name,
and a brief description.  Each name is an alias for the OID. slapd(8)
returns the first listed name when returning results.

The first attribute, name, holds values of directoryString (UTF-8
encoded Unicode) syntax.  The syntax is specified by OID
(1.3.6.1.4.1.1466.115.121.1.15 identifies the directoryString syntax).
 A length recommendation of 32768 is specified.  Servers should
support values of this length, but may support longer values The field
does NOT specify a size constraint, so is ignored on servers (such as
slapd) which don't impose such size limits.  In addition, the equality
and substring matching uses case ignore rules.  Below are tables
listing commonly used syntax and matching rules (OpenLDAP supports
these and many more).

Table 8.3: Commonly Used Syntaxes

Name                   OID                     Description
...................... ....................... ...................... 
boolean                1.3.6.1.4.1.1466.115.121.1.7 boolean value
distinguishedName      1.3.6.1.4.1.1466.115.121.1.12 DN
directoryString        1.3.6.1.4.1.1466.115.121.1.15 UTF-8 string
IA5String              1.3.6.1.4.1.1466.115.121.1.26 ASCII string
Integer                1.3.6.1.4.1.1466.115.121.1.27 integer
Name and Optional UID  1.3.6.1.4.1.1466.115.121.1.34 DN plus UID
Numeric String         1.3.6.1.4.1.1466.115.121.1.36 numeric string
OID                    1.3.6.1.4.1.1466.115.121.1.38 object identifier
Octet String           1.3.6.1.4.1.1466.115.121.1.40 arbitary octets
Printable String       1.3.6.1.4.1.1466.115.121.1.44 printable string



Table 8.4: Commonly Used Matching Rules

Name                   Type                    Description
...................... ....................... ...................... 
booleanMatch           equality                boolean
octetStringMatch       equality                octet string
objectIdentiferMatch   equality                OID
distinguishedNameMatch equality                DN
uniqueMemberMatch      equality                Name with optional UID
numericStringMatch     equality                numerical
numericStringOrderingMatch ordering            numerical
numericStringSubstringsMatch substrings        numerical
caseIgnoreMatch        equality                case insensitive,
                                               space insensitive
caseIgnoreOrderingMatch ordering               case insensitive,
                                               space insensitive
caseIgnoreSubstringsMatch substrings           case insensitive,
                                               space insensitive
caseExactMatch         equality                case sensitive, space
                                               insensitive
caseExactOrderingMatch ordering                case sensitive, space
                                               insensitive
caseExactSubstringsMatch substrings            case sensitive, space
                                               insensitive
caseIgnoreIA5Match     equality                case insensitive,
                                               space insensitive
caseIgnoreIA5OrderingMatch ordering            case insensitive,
                                               space insensitive
caseIgnoreIA5SubstringsMatch substrings        case insensitive,
                                               space insensitive
caseExactIA5Match      equality                case sensitive, space
                                               insensitive
caseExactIA5OrderingMatch ordering             case sensitive, space
                                               insensitive
caseExactIA5SubstringsMatch substrings         case sensitive, space
                                               insensitive

The second attribute, cn, is a subtype of name hence it inherits the
syntax, matching rules, and usage of name. commonName is an
alternative name.

Neither attribute is restricted to a single value.  Both are meant for
usage by user applications.  Neither is obsolete nor collective.

The following subsections provide a couple of examples.

8.2.4.1. myUniqueName
---------------------

Many organizations maintain a single unique name for each user. Though
one could use displayName (RFC2798), this attribute is really meant to
be controlled by the user, not the organization.  We could just copy
the definition of displayName from inetorgperson.schema and replace
the OID, name, and description, e.g:

        attributetype ( 1.1.2.1.1 NAME 'myUniqueName'
                DESC 'unique name with my organization'
                EQUALITY caseIgnoreMatch
                SUBSTR caseIgnoreSubstringsMatch
                SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
                SINGLE-VALUE )

However, if we want this name to be included in name assertions [e.g.
(name=*Jane*)], the attribute could alternatively be defined as a
subtype of name, e.g.:

        attributetype ( 1.1.2.1.1 NAME 'myUniqueName'
                DESC 'unique name with my organization'
                SUP name )

8.2.4.2. myPhoto
----------------

Many organizations maintain a photo of each each user.  A myPhoto
attribute type could be defined to hold a photo. Of course, one could
use just use jpegPhoto (RFC2798) (or a subtype) to hold the photo. 
However, you can only do this if the photo is in JPEG File Interchange
Format. Alternatively, an attribute type which uses the Octet String
syntax can be defined, e.g.:

        attributetype ( 1.1.2.1.2 NAME 'myPhoto'
                DESC 'a photo (application defined format)'
                SYNTAX 1.3.6.1.4.1.1466.115.121.1.40
                SINGLE-VALUE )

In this case, the syntax doesn't specify the format of the photo. It's
assumed (maybe incorrectly) that all applications accessing this
attribute agree on the handling of values.

If you wanted to support multiple photo formats, you could define a
separate attribute type for each format, prefix the photo with some
typing information, or describe the value using ASN.1 and use the
;binary transfer option.

Another alternative is for the attribute to hold a URI pointing to the
photo.  You can model such an attribute after labeledURI (RFC2079) or
simply create a subtype, e.g.:

        attributetype ( 1.1.2.1.3 NAME 'myPhotoURI'
                DESC 'URI and optional label referring to a photo'
                SUP labeledURI )

8.2.5. Object Class Specification
---------------------------------

The objectclasses directive is used to define a new object class.  The
directive uses the same Object Class Description (as defined in
RFC2252) used by the objectClasses attribute found in the subschema
subentry, e.g.:

        objectclass <RFC2252 Object Class Description>

where Object Class Description is defined by the following BNF:

        ObjectClassDescription = "(" whsp
                numericoid whsp      ; ObjectClass identifier
                [ "NAME" qdescrs ]
                [ "DESC" qdstring ]
                [ "OBSOLETE" whsp ]
                [ "SUP" oids ]       ; Superior ObjectClasses
                [ ( "ABSTRACT" / "STRUCTURAL" / "AUXILIARY" ) whsp ]
                        ; default structural
                [ "MUST" oids ]      ; AttributeTypes
                [ "MAY" oids ]       ; AttributeTypes
                whsp ")"

where whsp is a space (' '), numericoid is a globally unique OID in
numeric form (e.g. 1.1.0), qdescrs is one or more names, and oids is
one or more names and/or OIDs.

8.2.5.1. myPhotoObject
----------------------

To define an auxiliary object class which allows myPhoto to be added
to any existing entry.

        objectclass ( 1.1.2.2.1 NAME 'myPhotoObject'
                DESC 'mixin myPhoto'
                AUXILIARY
                MAY myPhoto )

8.2.5.2. myPerson
-----------------

If your organization would like have a private structural object class
to instantiate users, you can subclass one of the existing person
classes, such as inetOrgPerson (RFC2798), and add any additional
attributes which you desire.

        objectclass ( 1.1.2.2.2 NAME 'myPerson'
                DESC 'my person'
                SUP inetOrgPerson
                MUST ( myUniqueName $ givenName )
                MAY myPhoto )

The object class inherits the required/allowed attribute types of
inetOrgPerson but requires myUniqueName and givenName and allows
myPhoto.

8.2.6. OID Macros
-----------------

To ease the management and use of OIDs, slapd(8) supports Object
Identifier macros.  The objectIdentifier directive is used to equate a
macro (name) with a OID.  The OID may possibly be derived from a
previously defined OID macro.   The slapd.conf(5) syntax is:

        objectIdentifier <name> { <oid> | <name>[:<suffix>] }

The following demonstrates definition of a set of OID macros and their
use in defining schema elements:

        objectIdentifier myOID  1.1
        objectIdentifier mySNMP myOID:1
        objectIdentifier myLDAP myOID:2
        objectIdentifier myAttributeType        myLDAP:1
        objectIdentifier myObjectClass  myLDAP:2
        attributetype ( myAttributeType:3 NAME 'myPhotoURI'
                DESC 'URI and optional label referring to a photo'
                SUP labeledURI )
        objectclass ( myObjectClass:1 NAME 'myPhotoObject'
                DESC 'mixin myPhoto'
                AUXILIARY
                MAY myPhoto )


9. Security Considerations
==========================

OpenLDAP Software is designed to run in a wide variety of computing
environments from tightly-controlled closed networks to the global
Internet.  Hence, OpenLDAP Software provides many different security
mechanisms.  This chapter describes these mechanisms and discusses
security considerations for using OpenLDAP Software.

9.1. Network Security
---------------------

9.1.1. Selective Listening
--------------------------

By default, slapd(8) will listen on both the IPv4 and IPv6 "any"
addresses.  It is often desirable to have slapd listen on select
address/port pairs.  For example, listening only on the IPv4 address
127.0.0.1 will disallow remote access to the directory server. E.g.:

        slapd -h ldap://127.0.0.1

While the server can be configured to listen on a particular interface
address, this doesn't necessarily restrict access to the server to
only those networks accessible via that interface.   To selective
restrict remote access, it is recommend that an IP Firewall be used to
restrict access.

See Command-line Options and slapd(8) for more information.

9.1.2. IP Firewall
------------------

IP firewall capabilities of the server system can be used to restrict
access based upon the client's IP address and/or network interface
used to communicate with the client.

Generally, slapd(8) listens on port 389/tcp for LDAP over TCP (e.g. 
ldap://) and port 636/tcp for LDAP over SSL (e.g.  ldaps://).  Note
that LDAP over TCP sessions can be protected by TLS through the use of
StartTLS.  StartTLS is the Standard Track mechanism for protecting
LDAP sessions with TLS.

As specifics of how to configure IP firewall are dependent on the
particular kind of IP firewall used, no examples are provided here.
See the document associated with your IP firewall.

9.1.3. TCP Wrappers
-------------------

OpenLDAP supports TCP Wrappers.  TCP Wrappers provide a rule-based
access control system for controlling TCP/IP access to the server. For
example, the host_options(5) rule:

        slapd: 10.0.0.0/255.0.0.0 127.0.0.1 : ALLOW
        slapd: ALL : DENY

allows only incoming connections from the private network 10.0.0.0 and
localhost (127.0.0.1) to access the directory service. Note that IP
addresses are used as slapd(8) is not normally configured to perform
reverse lookups.

It is noted that TCP wrappers require the connection to be accepted.
As significant processing is required just to deny a connection, it is
generally advised that IP firewall protection be used instead of TCP
wrappers.

See hosts_access(5) for more information on TCP wrapper rules.

9.2. Integrity and Confidentiality Protection
---------------------------------------------

Transport Layer Security (TLS) can be used to provide integrity and
confidentiality protection.  OpenLDAP supports both StartTLS and
ldaps://.  See the Using TLS chapter for more information.

A number of Simple Authentication and Security Layer (SASL)
mechanisms, such as DIGEST-MD5 and GSSAPI, also provide integrity and
confidentiality protection.  See the Using SASL chapter for more
information.

9.2.1. Security Strength Factors
--------------------------------

The server uses Security Strength Factors (SSF) to indicate the
relative strength of protection.  A SSF of zero (0) indicates no
protections are in place.  A SSF of one (1) indicates integrity
protection are in place.  A SSF greater than one (>1) roughly
correlates to the effective encryption key length.  For example, DES
is 56, 3DES is 112, and AES 128, 192, or 256.

A number of administrative controls rely on SSFs associated with TLS
and SASL protection in place on an LDAP session.

security controls disallow operations when appropriate protections are
not in place.  For example:

        security ssf=1 update_ssf=112

requires integrity protection for all operations and encryption
protection, 3DES equivalent, for update operations (e.g. add, delete,
modify, etc.).  See slapd.conf(5) for details.

For fine-grained control, SSFs may be used in access controls.  See
Access Control section of the The slapd Configuration File for more
information.

9.3. Authentication Methods
---------------------------

9.3.1. "simple" method
----------------------

The LDAP "simple" method has three modes of operation:

o    anonymous,

o    unauthenticated, and

o    user/password authenticated.

Anonymous access is obtained by providing no name and no password to
the "simple" bind operation.  Unauthenticated access is obtained by
providing a name but no password.  Authenticated access is obtain by
providing a valid name and password.

An anonymous bind results in an anonymous authorization. Anonymous
bind mechanism is enabled by default, but can be disabled by
specifying "disallow bind_anon" in slapd.conf(5).

An unauthenticated bind results in an anonymous authorization.
Unauthenticated bind mechanism is disabled by default, but can be
enabled by specifying "allow bind_anon_cred" in slapd.conf(5). As a
number of LDAP applications mistakenly generate unauthenticated bind
request when authenticated access was intended (that is, they do not
ensure a password was provided), this mechanism should generally not
be enabled.

A successful user/password authenticated bind results in a user
authorization identity, the provided name, being associated with the
session.  User/password authenticated bind is enabled by default.
However, as this mechanism offers no evesdropping protection (e.g.,
the password is set in the clear), it is recommended that it be used
only in tightly controlled systems or when the LDAP session is
protected by other means (e.g., TLS, IPSEC).  Where the administrator
relies on TLS to protect the password, it is recommended that
unprotected authentication be disabled.  This is done by setting
"disallow bind_simple_unprotected" in slapd.conf(5). The security
directive's simple_bind option provides fine grain control over the
level of confidential protection to require for simple user/password
authentication.

The user/password authenticated bind mechanism can be completely
disabled by setting "disallow bind_simple".

Note: An unsuccessful bind always results in the session having an
anonymous authorization state.

9.3.2. SASL method
------------------

The LDAP SASL method allows use of any SASL authentication mechanism. 
The Using SASL discusses use of SASL.


10. Using SASL
==============

OpenLDAP clients and servers are capable of authenticating via the
Simple Authentication and Security Layer (SASL) framework, which is
detailed in RFC2222.   This chapter describes how to make use of SASL
in OpenLDAP.

There are several industry standard authentication mechanisms that can
be used with SASL, including Kerberos V4, GSSAPI, and DIGEST-MD.  The
standard client tools provided with OpenLDAP, such as ldapsearch(1)
and ldapmodify(1), will by default attempt to authenticate the user to
the slapd(8) server using SASL. Basic authentication service can be
set up by the LDAP administrator with a few steps, allowing users to
be authenticated to the slapd server as their LDAP entry.  With a few
extra steps, some users and services can be allowed to exploit SASL's
proxy authorization feature, allowing them to authenticate themselves
and then switch their identity to that of another user or service.

This chapter assumes you have read Cyrus SASL for System
Administrators, provided with the Cyrus SASL package (in
doc/sysadmin.html) and have a working Cyrus SASL installation.  You
should use the Cyrus SASL sample_client and sample_server to test your
SASL installation before attempting to make use of it in OpenLDAP.

Note that in the following text the term user is used to describe a
person or application entity who is connecting to the LDAP server via
an LDAP client, such as ldapsearch(1).  That is, the term user not
only applies to both an individual using an LDAP client, but to an
application entity which issues LDAP client operations without direct
user control.  For example, an e-mail server which uses LDAP
operations to access information held in an LDAP server is an
application entity.

10.1. SASL Security Considerations
----------------------------------

SASL offers many different authentication mechanisms.  This section
briefly outlines security considerations.

Some mechanisms, such as PLAIN and LOGIN, offer no greater security
over LDAP "simple" authentication.  Like "simple" authentication, such
mechanisms should not be used unless you have adequate security
protections in place.  It is recommended that these mechanisms be used
only in conjunction with Transport Layer Security (TLS).  Use of PLAIN
and LOGIN are not discussed further in this document.

The DIGEST-MD5 mechanism is the mandatory-to-implement authentication
mechanism for LDAPv3.  Though DIGEST-MD5 is not a strong
authentication mechanism in comparison with trusted third party
authentication systems (such as Kerberos or public key systems), yet
it does offer significant protections against a number of attacks. 
Unlike the CRAM-MD5 mechanism, it prevents chosen plaintext attacks. 
DIGEST-MD5 is favored over the weaker and even more dangerous use of
plaintext password mechanisms.  The CRAM-MD5 mechanism is deprecated
in favor of DIGEST-MD5.  Use of DIGEST-MD5 is discussed below.

The KERBEROS_V4 mechanism utilizes Kerberos IV to provide secure
authentication services.  There is also a GSSAPI based mechanism which
is generally used in conjunction with Kerberos V.  Kerberos is viewed
as a secure, distributed authentication system suitable for both small
and large enterprises.  Use of KERBEROS_V4 and GSSAPI are discussed
below.

The EXTERNAL mechanism utilizes authentication services provided by
lower level network services such as TLS (TLS).  When used in
conjunction with TLS X.509-based public key technology, EXTERNAL
offers strong authentication.  Use of EXTERNAL is discussed in the
Using TLS chapter.

There are other strong authentication mechanisms to choose from,
including OTP (one time passwords) and SRP (secure remote passwords).
These mechanisms are not discussed in this document.

10.2. SASL Authentication
-------------------------

Getting basic SASL authentication running involves a few steps. The
first step configures your slapd server environment so that it can
communicate with client programs using the security system in place at
your site. This usually involves setting up a service key, a public
key, or other form of secret. The second step concerns mapping
authentication identities to LDAP DN's, which depends on how entries
are laid out in your directory. An explanation of the first step will
be given in the next section using Kerberos V4 as an example
mechanism. The steps necessary for your site's authentication
mechanism will be similar, but a guide to every mechanism available
under SASL is beyond the scope of this chapter. The second step is
described in the section Mapping Authentication identities to LDAP
entries.

10.2.1. KERBEROS_V4
-------------------

This section describes the use of the SASL KERBEROS_V4 mechanism with
OpenLDAP.  It will be assumed that you are familiar with the workings
of the Kerberos IV security system, and that your site has Kerberos IV
deployed.  Your users should be familiar with authentication policy,
how to receive credentials in a Kerberos ticket cache, and how to
refresh expired credentials.

Client programs will need to be able to obtain a session key for use
when connecting to your LDAP server. This allows the LDAP server to
know the identity of the user, and allows the client to know it is
connecting to a legitimate server. If encryption layers are to be
used, the session key can also be used to help negotiate that option.

The slapd server runs the service called "ldap", and the server will
require a srvtab file with a service key.  SASL aware client programs
will be obtaining an "ldap" service ticket with the user's ticket
granting ticket (TGT), with the instance of the ticket matching the
hostname of the OpenLDAP server. For example, if your realm is named
EXAMPLE.COM and the slapd server is running on the host named
directory.example.com, the /etc/srvtab file on the server will have a
service key

        ldap.directory@EXAMPLE.COM

When an LDAP client is authenticating a user to the directory using
the KERBEROS_IV mechanism, it will request a session key for that same
principal, either from the ticket cache or by obtaining a new one from
the Kerberos server.  This will require the TGT to be available and
valid in the cache as well.  If it is not present or has expired, SASL
will print out the message

        ldap_sasl_interactive_bind_s: Local error

When the service ticket is obtained, it will be passed to the LDAP
server as proof of the user's identity.  The server will extract the
identity and realm out of the service ticket using SASL library calls,
and convert them into an authentication request DN of the form

        uid=<username>,cn=<realm>,cn=<mechanism>,cn=auth

So in our above example, if the user's name were "adamson", the
authentication request DN would be:

        uid=adamsom,cn=example.com,cn=kerberos_v4,cn=auth

This authentication request DN by itself could be placed into ACL's
and groupOfNames "member" attributes, since it is of legitimate LDAP
DN format. The section Mapping Authentication identities to LDAP
entries, however, tells how to map that DN into the DN of a person's
own LDAP entry.

Also note that this example, being for Kerberos, shows the <realm>
portion of the DN being filled in with the Kerberos realm of the
company. Several other authentication mechanisms do not employ the
concept of a realm, so the ",cn=<realm>" portion of the authentication
request DN would not appear.

10.2.2. GSSAPI
--------------

This section describes the use of the SASL GSSAPI mechanism and
Kerberos V with OpenLDAP. Since Kerberos V is being used, the
information is very similar to the previous section.  It will be
assumed that you have Kerberos V deployed, you are familiar with the
operation of the system, and that your users are trained in its use. 
This section also assumes you have familiarized yourself with the use
of the GSSAPI mechanism by reading Configuring GSSAPI and Cyrus SASL
(provided with Cyrus SASL in the doc/gssapi file) and successfully
experimented with the Cyrus provided sample_server and sample_client
applications.  General information about Kerberos is available at
http://web.mit.edu/kerberos/www/.

To use the GSSAPI mechanism with slapd(8) one must create a service
key with a principal for ldap service within the realm for the host on
which the service runs.  For example, if you run slapd on
directory.example.com and your realm is EXAMPLE.COM, you need to
create a service key with the principal:

        ldap/directory.example.com@EXAMPLE.COM

When slapd(8) runs, it must have access to this key.  This is
generally done by placing the key into a keytab, such as
/etc/krb5.keytab.

To use the GSSAPI mechanism to authenticate to the directory, the user
obtains a Ticket Granting Ticket (TGT) prior to running the LDAP
client.  When using OpenLDAP client tools, the user may mandate use of
the GSSAPI mechanism by specifying -Y GSSAPI as a command option.

For the purposes of authentication and authorization, slapd(8)
associates a non-mapped authentication request DN of the form:

        uid=<principal>,cn=<realm>,cn=gssapi,cn=auth

Continuing our example, a user with the Kerberos principal
kurt@EXAMPLE.COM would have the associated DN:

        uid=kurt,cn=example.com,cn=gssapi,cn=auth

and the principal ursula@FOREIGN.REALM would have the associated DN:

        uid=ursula,cn=foreign.realm,cn=gssapi,cn=auth

10.2.3. DIGEST-MD5
------------------

This section describes the use of the SASL DIGEST-MD5 mechanism using
secrets stored either in the directory itself or in Cyrus SASL's own
database. DIGEST-MD5 relies on the client and the server sharing a
"secret", usually a password. The server generates a challenge and the
client a response proving that it knows the shared secret. This is
much more secure than simply sending the secret over the wire.

Cyrus SASL supports several shared-secret mechanisms. To do this, it
needs access to the plaintext password (unlike mechanisms which pass
plaintext passwords over the wire, where the server can store a hashed
version of the password).

Secret passwords are normally stored in Cyrus SASL's own sasldb
database, but if OpenLDAP has been compiled with Cyrus SASL 2.1 it is
possible to store the secrets in the LDAP database itself. With Cyrus
SASL 1.5, secrets may only be stored in the sasldb.  In either case it
is very important to apply file access controls and LDAP access
controls to prevent exposure of the passwords.

The configuration and commands discussed in this section assume the
use of Cyrus SASL 2.1. If you are using version 1.5 then certain
features will not be available, and the command names will not have
the trailing digit "2".

To use secrets stored in sasldb, simply add users with the saslpasswd2
command:

       saslpasswd2 -c <username>

The passwords for such users must be managed with the saslpasswd2
command.

To use secrets stored in the LDAP directory, place plaintext passwords
in the userPassword attribute. It will be necessary to add an option
to slapd.conf to make sure that passwords changed through LDAP are
stored in plaintext:

       password-hash   {CLEARTEXT}

Passwords stored in this way can be managed either with ldappasswd or
by simply modifying the userPassword attribute.

Wherever the passwords are stored, a mapping will be needed from SASL
authentication IDs to regular DNs. The DIGEST-MD5 mechanism produces
authentication IDs of the form:

        uid=<username>,cn=<realm>,cn=digest-md5,cn=auth

NOTE that if the default realm is used, the realm name is omitted from
the ID, giving:

        uid=<username>,cn=digest-md5,cn=auth

See Mapping Authentication identities to LDAP entries below for
information on mapping such IDs to DNs.

With suitable mappings in place, users can specify SASL IDs when
performing LDAP operations, and the password stored in sasldb or in
the directory itself will be used to verify the authentication. For
example, the user identified by the directory entry:

       dn: cn=Andrew Findlay+uid=u000997,dc=example,dc=com
       objectclass: inetOrgPerson
       objectclass: person
       sn: Findlay
       uid: u000997
       userPassword: secret

can issue commands of the form:

       ldapsearch -U u000997 -b dc=example,dc=com 'cn=andrew*'

or can specify the realm explicitly:

       ldapsearch -U u000997@myrealm -b dc=example,dc=com 'cn=andrew*'

If several SASL mechanisms are supported at your site, it may be
necessary to specify which one to use, e.g.:

       ldapsearch -Y DIGEST-MD5 -U u000997 -b dc=example,dc=com 'cn=andrew*'

Note: in each of the above cases, no authorization identity (e.g. -X)
was provided.   Unless you are attempting SASL Proxy Authorization, no
authorization identity should be specified.  The server will infer an
authorization identity from authentication identity (as described
below).

10.2.4. Mapping Authentication identities to LDAP entries
---------------------------------------------------------

The authentication mechanism in the slapd server will use SASL library
calls to obtain the authenticated user's "username", based on whatever
underlying authentication mechanism was used.  This username is in the
namespace of the authentication mechanism, and not in the LDAP
namespace. As stated in the sections above, that username is
reformatted into an authentication request DN of the form

        uid=<username>,cn=<realm>,cn=<mechanism>,cn=auth

or

        uid=<username>,cn=<mechanism>,cn=auth

depending on whether or not <mechanism> employs the concept of
"realms". Note also that the realm part will be omitted if the default
realm was used in the authentication.

It is not intended that you should add LDAP entries of the above form
to your LDAP database. Chances are you have an LDAP entry for each of
the people that will be authenticating to LDAP, laid out in your
directory tree, and the tree does not start at cn=auth. But if your
site has a clear mapping between the "username" and an LDAP entry for
the person, you will be able to configure your LDAP server to
automatically map a authentication request DN to the user's
authentication DN.

Note: it is not required that the authentication request DN nor the
user's authentication DN resulting from the mapping refer to an entry
held in the directory.  However, additional capabilities become
available (see below).

The LDAP administrator will need to tell the slapd server how to map
an authentication request DN to a user's authentication DN. This is
done by adding one or more sasl-regexp directives to the slapd.conf(5)
file.  This directive takes two arguments:

        sasl-regexp   <search pattern>   <replacement pattern>

The authentication request DN is compared to the search pattern using
the regular expression functions regcomp() and regexec(), and if it
matches, it is rewritten as the replacement pattern. If there are
multiple sasl-regexp directives, only the first whose search pattern
matches the authentication identity is used. The string that is output
from the replacement pattern should be the authentication DN of the
user, in a legitimate LDAP DN format. It can also be an LDAP URL,
which is discussed below.

The search pattern can contain any of the regular expression
characters listed in regexec(3C). The main characters of note are dot
".", asterisk "*", and the open and close parenthesis "(" and ")". 
Essentially, the dot matches any character, the asterisk allows zero
or more repeats of the immediately preceding character or pattern, and
terms in parenthesis are remembered for the replacement pattern.

The replacement pattern will produce the final authentication DN of
the user.  Anything from the authentication request DN that matched a
string in parenthesis in the search pattern is stored in the variable
"$1". That variable "$1" can appear in the replacement pattern, and
will be replaced by the string from the authentication request DN. If
there were multiple sets of parentheses in the search pattern, the
variables $2, $3, etc are used.

For example, suppose the user's authentication identity is written as
the DN string

        uid=adamson,cn=example.com,cn=kerberos_v4,cn=auth

and the user's actual LDAP entry is

        uid=adamson,ou=person,dc=example,dc=com

The sasl-regexp directive in slapd.conf(5) could be written

        sasl-regexp
          uid=(.*),cn=example.com,cn=kerberos_v4,cn=auth
          uid=$1,ou=person,dc=example,dc=com

An even more lenient rule could be written as

        sasl-regexp
          uid=(.*),cn=.*,cn=auth
          uid=$1,ou=person,dc=example,dc=com

Be careful about setting the search pattern too leniently, however,
since it may mistakenly allow people to become authenticated as a DN
to which they should not have access. It is better to write several
strict directives than one lenient directive which has security holes.
If there is only one authentication mechanism in place at your site,
and zero or one realms in use, you might be able to map between
authentication identities and LDAP DN's with a single sasl-regexp
directive.

Don't forget to allow for the case where the realm is omitted as well
as the case with an explicitly specified realm. This may well require
a separate sasl-regexp directive for each case, with the
explicit-realm entry being listed first.

Some sites may have people's DN's spread to multiple areas of the LDAP
tree, such as if there were an ou=accounting tree and an
ou=engineering tree, with people interspersed between them. Or there
may not be enough information in the authentication identity to
isolate the DN, such as if the above person's LDAP entry looked like

        dn: cn=mark adamson,ou=person,dc=example,dc=com
        objectclass: Person
        cn: mark adamson
        uid: adamson

In this case, the information in the authentication identity can only
be used to search for the user's DN, not derive it directly. For both
of these situations, and others, the replacement pattern in the
sasl-regexp directives will need to produce an LDAP URL, described in
the next section.

10.2.5. Performing searches for a person's DN
---------------------------------------------

When there is not enough information in the authentication identity to
derive a person's authentication DN directly, the sasl-regexp
directives in the slapd.conf(5) file will need to produce an LDAP URL.
 This URL will then be used to perform an internal search of the LDAP
database to find the person's authentication DN.

An LDAP URL, similar to other URL's, is of the form

        ldap://<host>/<base>?<attrs>?<scope>?<filter>

This contains all of the elements necessary to perform an LDAP search:
 the name of the server <host>, the LDAP DN search base <base>, the
LDAP attributes to retrieve <attrs>, the search scope <scope> which is
one of the three options "base", "one", or "sub", and lastly an LDAP
search filter <filter>.  Since the search is for an LDAP DN within the
current server, the <host> portion should be empty.  The <attrs> field
is also ignored since only the DN is of concern.  These two elements
are left in the format of the URL to maintain the clarity of what
information goes where in the string.

Suppose that the person in the example from above did in fact have an
authentication username of "adamson" and that information was kept in
the attribute "uid" in their LDAP entry. The sasl-regexp directive
might be written as

        sasl-regexp
          uid=(.*),cn=example.com,cn=kerberos_v4,cn=auth
          ldap:///ou=person,dc=example,dc=com??sub?(uid=$1)

This will initiate an internal search of the LDAP database inside the
slapd server. If the search returns exactly one entry, it is accepted
as being the DN of the user. If there are more than one entries
returned, or if there are zero entries returned, the authentication
fails and the user's connection is left bound as the authentication
request DN.

Note that if the search scope <scope> in the URL is "base", then the
only LDAP entry that will be returned is the searchbase DN <base>, so
the actual search of the database is skipped. This is equivalent to
setting the replacement pattern in the directive to a DN directly, as
in the section above.

The attributes that are used in the search filter <filter> in the URL
should be indexed to allow faster searching. If they are not, the
authentication step alone can take uncomfortably long periods, and
users may assume the server is down.

A more complex site might have several realms in use, each mapping to
a different sub-tree in the directory. These can be handled with
statements of the form:

        # Match Engineering realm
       sasl-regexp
           uid=(.*),cn=engineering.example.com,cn=digest-md5,cn=auth
           ldap:///dc=eng,dc=example,dc=com??sub?(&(uid=$1)(objectClass=person))

        # Match Accounting realm
       sasl-regexp
           uid=(.*),cn=accounting.example.com,cn=digest-md5,cn=auth
           ldap:///dc=accounting,dc=example,dc=com??sub?(&(uid=$1)(objectClass=person))

        # Default realm is customers.example.com
       sasl-regexp
           uid=(.*),cn=digest-md5,cn=auth
           ldap:///dc=customers,dc=example,dc=com??sub?(&(uid=$1)(objectClass=person))

Note that the explicitly-named realms are handled first, to avoid the
realm name becoming part of the UID. Note also the limitation of
matches to those entries with (objectClass=person) to avoid matching
other entries that happen to refer to the UID.

See slapd.conf(5) for more detailed information.

10.3. SASL Proxy Authorization
------------------------------

The SASL offers a feature known as proxy authorization, which allows
an authenticated user to request that they act on the behalf of
another user.  This step occurs after the user has obtained an
authentication DN, and involves sending an authorization identity to
the server. The server will then make a decision on whether or not to
allow the authorization to occur. If it is allowed, the user's LDAP
connection is switched to have a binding DN derived from the
authorization identity, and the LDAP session proceeds with the access
of the new authorization DN.

The decision to allow an authorization to proceed depends on the rules
and policies of the site where LDAP is running, and thus cannot be
made by SASL alone. The SASL library leaves it up to the server to
make the decision. The LDAP administrator sets the guidelines of who
can authorize to what identity by adding information into the LDAP
database entries. By default, the authorization features are disabled,
and must be explicitly configured by the LDAP administrator before
use.

10.3.1. Uses of Proxy Authorization
-----------------------------------

This sort of service is useful when one entity needs to act on the
behalf of many other users. For example, users may be directed to a
web page to make changes to their personal information in their LDAP
entry. The users authenticate to the web server to establish their
identity, but the web server CGI cannot authenticate to the LDAP
server as that user to make changes for them. Instead, the web server
authenticates itself to the LDAP server as a service identity, say,

        cn=WebUpdate,dc=example,dc=com

and then it will SASL authorize to the DN of the user. Once so
authorized, the CGI makes changes to the LDAP entry of the user, and
as far as the slapd server can tell for its ACLs, it is the user
themself on the other end of the connection. The user could have
connected to the LDAP server directly and authenticated as themself,
but that would require the user to have more knowledge of LDAP
clients, knowledge which the web page provides in an easier format.

Proxy authorization can also be used to limit access to an account
that has greater access to the database. Such an account, perhaps even
the root DN specified in slapd.conf(5), can have a strict list of
people who can authorize to that DN. Changes to the LDAP database
could then be only allowed by that DN, and in order to become that DN,
users must first authenticate as one of the persons on the list. This
allows for better auditing of who made changes to the LDAP database. 
If people were allowed to authenticate directly to the priviliged
account, possibly through the rootpw slapd.conf(5) directive or
through a userPassword attribute, then auditing becomes more
difficult.

Note that after a successful proxy authorization, the original
authentication DN of the LDAP connection is overwritten by the new DN
from the authorization request. If a service program is able to
authenticate itself as its own authentication DN and then authorize to
other DN's, and it is planning on switching to several different
identities during one LDAP session, it will need to authenticate
itself each time before authorizing to another DN (or use a different
proxy authorization mechanism).  The slapd server does not keep record
of the service program's ability to switch to other DN's. On
authentication mechanisms like Kerberos this will not require multiple
connections being made to the Kerberos server, since the user's TGT
and "ldap" session key are valid for multiple uses for the several
hours of the ticket lifetime.

10.3.2. SASL Authorization Identities
-------------------------------------

The SASL authorization identity is sent to the LDAP server via the -X
switch for ldapsearch(1) and other tools, or in the *authzid parameter
to the lutil_sasl_defaults() call. The identity can be in one of two
forms, either

        u:<username>

or

        dn:<dn>

In the first form, the <username> is from the same namespace as the
authentication identities above. It is the user's username as it is
refered to by the underlying authentication mechanism. Authorization
identities of this form are converted into a DN format by the same
function that the authentication process used, producing an
authorization request DN of the form

        uid=<username>,cn=<realm>,cn=<mechanism>,cn=auth

That authorization request DN is then run through the same sasl-regexp
process to convert it into a legitimate authorization DN from the
database. If it cannot be converted due to a failed search from an
LDAP URL, the authorization request fails with "inappropriate access".
 Otherwise, the DN string is now a legitimate authorization DN ready
to undergo approval.

If the authorization identity was provided in the second form, with a
"dn:" prefix, the string after the prefix is already in authorization
DN form, ready to undergo approval.

10.3.3. Proxy Authorization Rules
---------------------------------

Once slapd has the authorization DN, the actual approval process
begins. There are two attributes that the LDAP administrator can put
into LDAP entries to allow authorization:

        saslAuthzTo
        saslAuthzFrom

Both can be multivalued.  The saslAuthzTo attribute is a source rule,
and it is placed into the entry associated with the authentication DN
to tell what authorization DNs the authenticated DN is allowed to
assume.  The second attribute is a destination rule, and it is placed
into the entry associated with the requested authorization DN to tell
which authenticated DNs may assume it.

The choice of which authorization policy attribute to use is up to the
administrator.  Source rules are checked first in the person's
authentication DN entry, and if none of the saslAuthzTo rules specify
the authorization is permitted, the saslAuthzFrom rules in the
authorization DN entry are then checked. If neither case specifies
that the request be honored, the request is denied. Since the default
behaviour is to deny authorization requests, rules only specify that a
request be allowed; there are no negative rules telling what
authorizations to deny.

The value(s) in the two attributes are of the same form as the output
of the replacement pattern of a sasl-regexp directive: either a DN or
an LDAP URL. For example, if a saslAuthzTo value is a DN, that DN is
one the authenticated user can authorize to. On the other hand, if the
saslAuthzTo value is an LDAP URL, the URL is used as an internal
search of the LDAP database, and the authenticated user can become ANY
DN returned by the search. If an LDAP entry looked like:

        dn: cn=WebUpdate,dc=example,dc=com
        saslAuthzTo: ldap:///dc=example,dc=com??sub?(objectclass=Person)

then any user who authenticated as cn=WebUpdate,dc=example,dc=com
could authorize to any other LDAP entry under the search base
"dc=example,dc=com" which has an objectClass of "Person".

10.3.3.1. Notes on Proxy Authorization Rules
--------------------------------------------

An LDAP URL in a saslAuthzTo or saslAuthzFrom attribute will return a
set of DNs.  Each DN returned will be checked. Searches which return a
large set can cause the authorization process to take an uncomfortably
long time. Also, searches should be performed on attributes that have
been indexed by slapd.

To help produce more sweeping rules for saslAuthzFrom and saslAuthzTo,
the values of these attributes are allowed to be DNs with regular
expression characters in them. This means a source rule like

        saslAuthzTo: uid=.*,dc=example,dc=com

would allow that authenticated user to authorize to any DN that
matches the regular expression pattern given. This regular expression
comparison can be evaluated much faster than an LDAP search for
(uid=*).

Also note that the values in an authorization rule must be one of the
two forms: an LDAP URL or a DN (with or without regular expression
characters). Anything that does not begin with "ldap://" is taken as a
DN. It is not permissable to enter another authorization identity of
the form "u:<username>" as an authorization rule.

10.3.3.2. Policy Configuration
------------------------------

The decision of which type of rules to use, saslAuthzFrom or
saslAuthzTo, will depend on the site's situation. For example, if the
set of people who may become a given identity can easily be written as
a search filter, then a single destination rule could be written. If
the set of people is not easily defined by a search filter, and the
set of people is small, it may be better to write a source rule in the
entries of each of those people who should be allowed to perform the
proxy authorization.

By default, processing of proxy authorization rules is disabled. The
sasl-authz-policy directive must be set in the slapd.conf(5) file to
enable authorization. This directive can be set to none for no rules
(the default), from for source rules, to for destination rules, or
both for both source and destination rules.

Destination rules are extremely powerful. If ordinary users have
access to write the saslAuthzTo attribute in their own entries, then
they can write rules that would allow them to authorize as anyone
else. As such, when using destination rules, the saslAuthzTo attribute
should be protected with an ACL that only allows privileged users to
set its values.


11. Using TLS
=============

OpenLDAP clients and servers are capable of using the Transport Layer
Security (TLS) framework to provide integrity and confidentiality
protections and to support LDAP authentication using the SASL EXTERNAL
mechanism.

11.1. TLS Certificates
----------------------

TLS uses X.509 certificates to carry client and server identities. All
servers are required to have valid certificates, whereas client
certificates are optional. Clients must have a valid certificate in
order to authenticate via SASL EXTERNAL. For more information on
creating and managing certificates, see the OpenSSL documentation.

11.1.1. Server Certificates
---------------------------

The DN of a server certificate must use the CN attribute to name the
server, and the CN must carry the server's fully qualified domain
name. Additional alias names and wildcards may be present in the
subjectAltName certificate extension. More details on server
certificate names are in RFC2830.

11.1.2. Client Certificates
---------------------------

The DN of a client certificate can be used directly as an
authentication DN. Since X.509 is a part of the X.500 standard and
LDAP is also based on X.500, both use the same DN formats and
generally the DN in a user's X.509 certificate should be identical to
the DN of their LDAP entry. However, sometimes the DNs may not be
exactly the same, and so the mapping facility described in Mapping
Authentication identities to LDAP entries can be applied to these DNs
as well.

11.2. TLS Configuration
-----------------------

After obtaining the required certificates, a number of options must be
configured on both the client and the server to enable TLS and make
use of the certificates. At a minimum, the clients must be configured
with the filename containing all of the Certificate Authority (CA)
certificates it will trust. The server must be configured with the CA
certificates and also its own server certificate and private key.

Typically a single CA will have issued the server certificate and all
of the trusted client certificates, so the server only needs to trust
that one signing CA. However, a client may wish to connect to a
variety of secure servers managed by different organizations, with
server certificates generated by many different CAs. As such, a client
is likely to need a list of many different trusted CAs in its
configuration.

11.2.1. Server Configuration
----------------------------

The configuration directives for slapd belong in the global directives
section of slapd.conf(5).

11.2.1.1. TLSCACertificateFile <filename>
-----------------------------------------

This directive specifies the PEM-format file containing certificates
for the CA's that slapd will trust. The certificate for the CA that
signed the server certificate must be included among these
certificates. If the signing CA was not a top-level (root) CA,
certificates for the entire sequence of CA's from the signing CA to
the top-level CA should be present. Multiple certificates are simply
appended to the file; the order is not significant.

11.2.1.2. TLSCACertificatePath <path>
-------------------------------------

This directive specifies the path of a directory that contains
individual CA certificates in separate files.  In addition, this
directory must be specially managed using the OpenSSL c_rehash
utility. When using this feature, the OpenSSL library will attempt to
locate certificate files based on a hash of their name and serial
number. The c_rehash utility is used to generate symbolic links with
the hashed names that point to the actual certificate files. As such,
this option can only be used with a filesystem that actually supports
symbolic links. In general, it is simpler to use the
TLSCACertificateFile directive instead.

11.2.1.3. TLSCertificateFile <filename>
---------------------------------------

This directive specifies the file that contains the slapd server
certificate. Certificates are generally public information and require
no special protection.

11.2.1.4. TLSCertificateKeyFile <filename>
------------------------------------------

This directive specifies the file that contains the private key that
matches the certificate stored in the TLSCertificateFile file. Private
keys themselves are sensitive data and are usually password encrypted
for protection. However, the current implementation doesn't support
encrypted keys so the key must not be encrypted and the file itself
must be protected carefully.

11.2.1.5. TLSCipherSuite <cipher-suite-spec>
--------------------------------------------

This directive configures what ciphers will be accepted and the
preference order. <cipher-suite-spec> should be a cipher specification
for OpenSSL. You can use the command

        openssl ciphers -v ALL

to obtain a verbose list of available cipher specifications. Besides
the individual cipher names, the specifiers HIGH, MEDIUM, LOW, EXPORT,
and EXPORT40 may be helpful, along with TLSv1, SSLv3, and SSLv2.

11.2.1.6. TLSRandFile <filename>
--------------------------------

This directive specifies the file to obtain random bits from when
/dev/urandom is not available. If the system provides /dev/urandom
then this option is not needed, otherwise a source of random data must
be configured. Some systems (e.g. Linux) provide /dev/urandom by
default, while others (e.g. Solaris) require the installation of a
patch to provide it, and others may not support it at all. In the
latter case, EGD or PRNGD should be installed, and this directive
should specify the name of the EGD/PRNGD socket. The environment
variable RANDFILE can also be used to specify the filename. Also, in
the absence of these options, the .rnd file in the slapd user's home
directory may be used if it exists. To use the .rnd file, just create
the file and copy a few hundred bytes of arbitrary data into the file.
The file is only used to provide a seed for the pseudo-random number
generator, and it doesn't need very much data to work.

11.2.1.7. TLSVerifyClient { never | allow | try | demand }
----------------------------------------------------------

This directive specifies what checks to perform on client certificates
in an incoming TLS session, if any. This option is set to never by
default, in which case the server never asks the client for a
certificate. With a setting of allow the server will ask for a client
certificate; if none is provided the session proceeds normally. If a
certificate is provided but the server is unable to verify it, the
certificate is ignored and the session proceeds normally, as if no
certificate had been provided. With a setting of try the certificate
is requested, and if none is provided, the session proceeds normally.
If a certificate is provided and it cannot be verified, the session is
immediately terminated. With a setting of demand the certificate is
requested and a valid certificate must be provided, otherwise the
session is immediately terminated.

Note: The server must request a client certificate in order to use the
SASL EXTERNAL authentication mechanism with a TLS session. As such, a
non-default TLSVerifyClient setting must be configured before SASL
EXTERNAL authentication may be attempted, and the SASL EXTERNAL
mechanism will only be offered to the client if a valid client
certificate was received.

11.2.2. Client Configuration
----------------------------

Most of the client configuration directives parallel the server
directives. The names of the directives are different, and they go
into ldap.conf(5) instead of slapd.conf(5), but their functionality is
mostly the same. Also, while most of these options may be configured
on a system-wide basis, they may all be overridden by individual users
in their .ldaprc files.

11.2.2.1. TLS_CACERT <filename>
-------------------------------

This is equivalent to the server's TLSCACertificateFile option. As
noted in the TLS Configuration section, a client typically may need to
know about more CAs than a server, but otherwise the same
considerations apply.

11.2.2.2. TLS_CACERTDIR <path>
------------------------------

This is equivalent to the server's TLSCACertificatePath option. The
specified directory must be managed with the OpenSSL c_rehash utility
as well.

11.2.2.3. TLS_CERT <filename>
-----------------------------

This directive specifies the file that contains the client
certificate. This is a user-only directive and can only be specified
in a user's .ldaprc file.

11.2.2.4. TLS_KEY <filename>
----------------------------

This directive specifies the file that contains the private key that
matches the certificate stored in the TLS_CERT file. The same
constraints mentioned for TLSCertificateKeyFile apply here. This is
also a user-only directive.

11.2.2.5. TLS_RANDFILE <filename>
---------------------------------

This directive is the same as the server's TLSRandFile option.

11.2.2.6. TLS_REQCERT { never | allow | try | demand }
------------------------------------------------------

This directive is equivalent to the server's TLSVerifyClient option.
However, for clients the default value is demand and there generally
is no good reason to change this setting.

11.2.2.7. TLS { never | hard }
------------------------------

This directive specifies whether client connections should use TLS by
default. The default setting is never which specifies that connections
will be opened in the clear unless TLS is explicitly specified using
an "ldaps://" URL. When set to hard all connections will be
established with TLS, as if an "ldaps://" URL was specified. Note that
the use of ldaps is a holdover from LDAPv2 and this setting is
incompatible with the LDAPv3 StartTLS request. As such, it's best not
to use this option.


12. Constructing a Distributed Directory Service
================================================

For many sites, running one or more slapd(8) that hold an entire
subtree of data is sufficient. But often it is desirable to have one
slapd refer to other directory services for a certain part of the tree
(which may or may not be running slapd).

slapd supports subordinate and superior knowledge information.
Subordinate knowledge information is held in referral objects
(RFC3296).

12.1. Subordinate Knowledge Information
---------------------------------------

Subordinate knowledge information may be provided to delegate a
subtree. Subordinate knowledge information is maintained in the
directory as a special referral object at the delegate point. The
referral object acts as a delegation point, gluing two services
together. This mechanism allows for hierarchical directory services to
be constructed.

A referral object has a structural object class of referral and has
the same Distinguished Name as the delegated subtree.  Generally, the
referral object will also provide the auxiliary object class
extensibleObject. This allows the entry to contain appropriate
Relative Distinguished Name values.  This is best demonstrated by
example.

If the server a.example.net holds dc=example,dc=net and wished to
delegate the subtree ou=subtree,dc=example,dc=net to another server
b.example.net, the following named referral object would be added to
a.example.net:

        dn: dc=subtree,dc=example,dc=net
        objectClass: referral
        objectClass: extensibleObject
        dc: subtree
        ref: ldap://b.example.net/dc=subtree,dc=example,dc=net

The server uses this information to generate referrals and search
continuations to subordinate servers.

For those familiar with X.500, a named referral object is similar to
an X.500 knowledge reference held in a subr DSE.

12.2. Superior Knowledge Information
------------------------------------

Superior knowledge information may be specified using the referral
directive.  The value is a list of URIs referring to superior
directory services.  For servers without immediate superiors, such as
for a.example.net in the example above, the server can be configured
to use a directory service with global knowledge, such as the OpenLDAP
Root Service (http://www.openldap.org/faq/index.cgi?file=393).

        referral        ldap://root.openldap.org/

However, as a.example.net is the immediate superior to b.example.net,
b.example.net would be configured as follows:

        referral        ldap://a.example.net/

The server uses this information to generate referrals for operations
acting upon entries not within or subordinate to any of the naming
contexts held by the server.

For those familiar with X.500, this use of the ref attribute is
similar to an X.500 knowledge reference held in a Supr DSE.

12.3. The ManageDsaIT Control
-----------------------------

Adding, modifying, and deleting referral objects is generally done
using ldapmodify(1) or similar tools which support the ManageDsaIT
control.  The ManageDsaIT control informs the server that you intend
to manage the referral object as a regular entry.  This keeps the
server from sending a referral result for requests which interrogate
or update referral objects.

The ManageDsaIT control should not be specified when managing regular
entries.

The -M option of ldapmodify(1) (and other tools) enables ManageDsaIT. 
For example:

        ldapmodify -M -f referral.ldif -x -D "cn=Manager,dc=example,dc=net" -W

or with ldapsearch(1):

        ldapsearch -M -b "dc=example,dc=net" -x "(objectclass=referral)" '*' ref

Note: the ref attribute is operational and must be explicitly
requested when desired in search results.


13. Replication with slurpd
===========================

In certain configurations, a single slapd(8) instance may be
insufficient to handle the number of clients requiring directory
service via LDAP. It may become necessary to run more than one slapd
instance.  At many sites, for instance, there are multiple slapd
servers: one master and one or more slaves.  DNS can be setup such
that a lookup of ldap.example.com returns the IP addresses of these
servers, distributing the load among them (or just the slaves). This
master/slave arrangement provides a simple and effective way to
increase capacity, availability and reliability.

slurpd(8) provides the capability for a master slapd to propagate
changes to slave slapd instances, implementing the master/slave
replication scheme described above.  slurpd runs on the same host as
the master slapd instance.

13.1. Overview
--------------

slurpd(8) provides replication services "in band". That is, it uses
the LDAP protocol to update a slave database from the master. Perhaps
the easiest way to illustrate this is with an example. In this
example, we trace the propagation of an LDAP modify operation from its
initiation by the LDAP client to its distribution to the slave slapd
instance.

Sample replication scenario:

1.   The LDAP client submits an LDAP modify operation to the slave
     slapd.

2.   The slave slapd returns a referral to the LDAP client referring
     the client to the master slapd.

3.   The LDAP client submits the LDAP modify operation to the master
     slapd.

4.   The master slapd performs the modify operation, writes out the
     change to its replication log file and returns a success code to
     the client.

5.   The slurpd process notices that a new entry has been appended to
     the replication log file, reads the replication log entry, and
     sends the change to the slave slapd via LDAP.

6.   The slave slapd performs the modify operation and returns a
     success code to the slurpd process.

Note: ldapmodify(1) and other tools distributed as part of OpenLDAP
Software do not support automatic referral chasing.

13.2. Replication Logs
----------------------

When slapd is configured to generate a replication logfile, it writes
out a file containing LDIF change records.  The replication log gives
the replication site(s), a timestamp, the DN of the entry being
modified, and a series of lines which specify the changes to make. In
the example below, Barbara (uid=bjensen) has replaced the description
value.  The change is to be propagated to the slapd instance running
on slave.example.net Changes to various operational attributes, such
as modifiersName and modifyTimestamp, are included in the change
record and will be propagated to the slave slapd.

        replica: slave.example.com:389
        time: 809618633
        dn: uid=bjensen,dc=example,dc=com
        changetype: modify
        replace: multiLineDescription
        description: A dreamer...
        -
        replace: modifiersName
        modifiersName: uid=bjensen,dc=example,dc=com
        -
        replace: modifyTimestamp
        modifyTimestamp: 20000805073308Z
        -

The modifications to modifiersName and modifyTimestamp operational
attributes were added by the master slapd.

13.3. Command-Line Options
--------------------------

This section details commonly used slurpd(8) command-line options.

        -d <level> | ?

This option sets the slurpd debug level to  <level>. When level is a
`?' character, the various debugging levels are printed and slurpd
exits, regardless of any other options you give it. Current debugging
levels (a subset of slapd's debugging levels) are

Table 13.1: Debugging Levels

                             Level Description
.................................. .................................. 
                                 4 heavy trace debugging
                                64 configuration file processing
                             65535 enable all debugging

Debugging levels are additive. That is, if you want heavy trace
debugging and want to watch the config file being processed, you would
set level to the sum of those two levels (in this case, 68).

        -f <filename>

This option specifies an alternate slapd configuration file.  Slurpd
does not have its own configuration file. Instead, all configuration
information is read from the slapd configuration file.

        -r <filename>

This option specifies an alternate slapd replication log file. Under
normal circumstances, slurpd reads the name of the slapd replication
log file from the slapd configuration file. However, you can override
this with the -r flag, to cause slurpd to process a different
replication log file. See the Advanced slurpd Operation section for a
discussion of how you might use this option.

        -o

Operate in "one-shot" mode. Under normal circumstances, when slurpd
finishes processing a replication log, it remains active and
periodically checks to see if new entries have been added to the
replication log.  In one-shot mode, by comparison, slurpd processes a
replication log and exits immediately. If the -o option is given, the
replication log file must be explicitly specified with the -r option. 
See the One-shot mode and reject files section for  a discussion of
this mode.

        -t <directory>

Specify an alternate directory for slurpd's temporary copies of
replication logs. The default location is /usr/tmp.

13.4. Configuring slurpd and a slave slapd instance
---------------------------------------------------

To bring up a replica slapd instance, you must configure the master
and slave slapd instances for replication, then shut down the master
slapd so you can copy the database. Finally, you bring up the master
slapd instance, the slave slapd instance, and the slurpd instance.
These steps are detailed in the following sections. You can set up as
many slave slapd instances as you wish.

13.4.1. Set up the master slapd
-------------------------------

The following section assumes you have a properly working slapd(8)
instance. To configure your working slapd(8) server as a replication
master, you need to make the following changes to your slapd.conf(5).

1.   Add a replica directive for each replica. The binddn= parameter
     should match the updatedn option in the corresponding slave slapd
     configuration file, and should name an entry with write
     permission to the slave database (e.g., an entry listed as
     rootdn, or allowed access via access directives in the slave
     slapd configuration file).

2.   Add a replogfile directive, which tells slapd where to log
     changes. This file will be read by slurpd.

13.4.2. Set up the slave slapd
------------------------------

Install the slapd software on the host which is to be the slave slapd
server. The configuration of the slave server should be identical to
that of the master, with the following exceptions:

1.   Do not include a replica directive. While it is possible to
     create "chains" of replicas, in most cases this is inappropriate.

2.   Do not include a replogfile directive.

3.   Do include an updatedn line. The DN given should match the DN
     given in the binddn= parameter of the corresponding replica=
     directive in the master slapd config file.

4.   Make sure the DN given in the updatedn directive has permission
     to write the database (e.g., it is listed as rootdn or is allowed
     access by one or more access directives).

5.   Use the updateref directive to define the URL the slave should
     return if an update request is received.

13.4.3. Shut down the master slapd
----------------------------------

In order to ensure that the slave starts with an exact copy of the
master's data, you must shut down the master slapd. Do this by sending
the master slapd process an interrupt signal with kill-INT <pid>,
where <pid> is the process-id of the master slapd process.

If you like, you may restart the master slapd in read-only mode while
you are replicating the database. During this time, the master slapd
will return an "unwilling to perform" error to clients that attempt to
modify data.

13.4.4. Copy the master slapd's database to the slave
-----------------------------------------------------

Copy the master's database(s) to the slave. For an BDB and LDBM
databases, you must copy all database files located in the database
directory specified in slapd.conf(5). In general, you should copy each
file found in the database  directory unless you know it is not used
by slapd(8).

Note: This copy process assumes homogeneous servers with identically
configured OpenLDAP installations. Alternatively, you may use slapcat
to output the master's database in LDIF format and use the LDIF with
slapadd to populate the slave. Using LDIF avoids any potential
incompatibilities due to differing server architectures or software
configurations.  See the Database Creation and Maintenance Tools
chapter for details on these tools.

13.4.5. Configure the master slapd for replication
--------------------------------------------------

To configure slapd to generate a replication logfile, you add a "
replica" configuration option to the master slapd's config file. For
example, if we wish to propagate changes to the slapd instance running
on host slave.example.com:

        replica uri=ldap://slave.example.com:389
                binddn="cn=Replicator,dc=example,dc=com"
                bindmethod=simple credentials=secret

In this example, changes will be sent to port 389 (the standard LDAP
port) on host slave.example.com. The slurpd process will bind to the
slave slapd as "cn=Replicator,dc=example,dc=com" using simple
authentication with password "secret".

If we wish to perform the same replication using ldaps on port 636:

        replica uri=ldaps://slave.example.com:636
                binddn="cn=Replicator,dc=example,dc=com"
                bindmethod=simple credentials=secret

The host option is deprecated in favor of uri, but the following
replica configuration is still supported:

        replica host=slave.example.com:389
                binddn="cn=Replicator,dc=example,dc=com"
                bindmethod=simple credentials=secret

Note that the DN given by the binddn= directive must exist in the
slave slapd's database (or be the rootdn specified in the slapd config
file) in order for the bind operation to succeed.  The DN should also
be listed as the updatedn for the database in the slave's
slapd.conf(5).

Note: The use of strong authentication and transport security is
highly recommended.

13.4.6. Restart the master slapd and start the slave slapd
----------------------------------------------------------

Restart the master slapd process. To check that it is generating
replication logs, perform a modification of any entry in the database,
and check that data has been written to the log file.

13.4.7. Start slurpd
--------------------

Start the slurpd process. Slurpd should immediately send the test
modification you made to the slave slapd. Watch the slave slapd's
logfile to be sure that the modification was sent.

        slurpd -f <masterslapdconfigfile>

13.5. Advanced slurpd Operation
-------------------------------

13.5.1. Replication errors
--------------------------

When slurpd propagates a change to a slave slapd and receives an error
return code, it writes the reason for the error and the replication
record to a reject file. The reject file is located in the same
directory as the per-replica replication logfile, and has the same
name, but with the string ".rej" appended. For example, for a replica
running on host slave.example.com, port 389, the reject file, if it
exists, will be named

        /usr/local/var/openldap/replog.slave.example.com:389.rej

A sample rejection log entry follows:

        ERROR: No such attribute
        replica: slave.example.com:389
        time: 809618633
        dn: uid=bjensen,dc=example,dc=com
        changetype: modify
        replace: description
        description: A dreamer...
        -
        replace: modifiersName
        modifiersName: uid=bjensen,dc=example,dc=com
        -
        replace: modifyTimestamp
        modifyTimestamp: 20000805073308Z
        -

Note that this is precisely the same format as the original
replication log entry, but with an ERROR line prepended to the entry.

13.5.2. One-shot mode and reject files
--------------------------------------

It is possible to use slurpd to process a rejection log with its
"one-shot mode." In normal operation, slurpd watches for more
replication records to be appended to the replication log file. In
one-shot mode, by contrast, slurpd processes a single log file and
exits. Slurpd ignores ERROR lines at the beginning of replication log
entries, so it's not necessary to edit them out before feeding it the
rejection log.

To use one-shot mode, specify the name of the rejection log on the
command line as the argument to the -r flag, and specify one-shot mode
with the -o flag. For example, to process the rejection log file
/usr/local/var/openldap/replog.slave.example.com:389 and exit, use the
command

        slurpd -r /usr/tmp/replog.slave.example.com:389 -o


A. Generic configure Instructions
=================================

Basic Installation
==================

   These are generic installation instructions.

   The `configure' shell script attempts to guess correct values for
various system-dependent variables used during compilation.  It uses
those values to create a `Makefile' in each directory of the package.
It may also create one or more `.h' files containing system-dependent
definitions.  Finally, it creates a shell script `config.status' that
you can run in the future to recreate the current configuration, a file
`config.cache' that saves the results of its tests to speed up
reconfiguring, and a file `config.log' containing compiler output
(useful mainly for debugging `configure').

   If you need to do unusual things to compile the package, please try
to figure out how `configure' could check whether to do them, and mail
diffs or instructions to the address given in the `README' so they can
be considered for the next release.  If at some point `config.cache'
contains results you don't want to keep, you may remove or edit it.

   The file `configure.in' is used to create `configure' by a program
called `autoconf'.  You only need `configure.in' if you want to change
it or regenerate `configure' using a newer version of `autoconf'.

The simplest way to compile this package is:

  1. `cd' to the directory containing the package's source code and type
     `./configure' to configure the package for your system.  If you're
     using `csh' on an old version of System V, you might need to type
     `sh ./configure' instead to prevent `csh' from trying to execute
     `configure' itself.

     Running `configure' takes awhile.  While running, it prints some
     messages telling which features it is checking for.

  2. Type `make' to compile the package.

  3. Optionally, type `make check' to run any self-tests that come with
     the package.

  4. Type `make install' to install the programs and any data files and
     documentation.

  5. You can remove the program binaries and object files from the
     source code directory by typing `make clean'.  To also remove the
     files that `configure' created (so you can compile the package for
     a different kind of computer), type `make distclean'.  There is
     also a `make maintainer-clean' target, but that is intended mainly
     for the package's developers.  If you use it, you may have to get
     all sorts of other programs in order to regenerate files that came
     with the distribution.

Compilers and Options
=====================

   Some systems require unusual options for compilation or linking that
the `configure' script does not know about.  You can give `configure'
initial values for variables by setting them in the environment.  Using
a Bourne-compatible shell, you can do that on the command line like
this:
     CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure

Or on systems that have the `env' program, you can do it like this:
     env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure

Compiling For Multiple Architectures
====================================

   You can compile the package for more than one kind of computer at the
same time, by placing the object files for each architecture in their
own directory.  To do this, you must use a version of `make' that
supports the `VPATH' variable, such as GNU `make'.  `cd' to the
directory where you want the object files and executables to go and run
the `configure' script.  `configure' automatically checks for the
source code in the directory that `configure' is in and in `..'.

   If you have to use a `make' that does not supports the `VPATH'
variable, you have to compile the package for one architecture at a time
in the source code directory.  After you have installed the package for
one architecture, use `make distclean' before reconfiguring for another
architecture.

Installation Names
==================

   By default, `make install' will install the package's files in
`/usr/local/bin', `/usr/local/man', etc.  You can specify an
installation prefix other than `/usr/local' by giving `configure' the
option `--prefix=PATH'.

   You can specify separate installation prefixes for
architecture-specific files and architecture-independent files.  If you
give `configure' the option `--exec-prefix=PATH', the package will use
PATH as the prefix for installing programs and libraries.
Documentation and other data files will still use the regular prefix.

   In addition, if you use an unusual directory layout you can give
options like `--bindir=PATH' to specify different values for particular
kinds of files.  Run `configure --help' for a list of the directories
you can set and what kinds of files go in them.

   If the package supports it, you can cause programs to be installed
with an extra prefix or suffix on their names by giving `configure' the
option `--program-prefix=PREFIX' or `--program-suffix=SUFFIX'.

Optional Features
=================

   Some packages pay attention to `--enable-FEATURE' options to
`configure', where FEATURE indicates an optional part of the package.
They may also pay attention to `--with-PACKAGE' options, where PACKAGE
is something like `gnu-as' or `x' (for the X Window System).  The
`README' should mention any `--enable-' and `--with-' options that the
package recognizes.

   For packages that use the X Window System, `configure' can usually
find the X include and library files automatically, but if it doesn't,
you can use the `configure' options `--x-includes=DIR' and
`--x-libraries=DIR' to specify their locations.

Specifying the System Type
==========================

   There may be some features `configure' can not figure out
automatically, but needs to determine by the type of host the package
will run on.  Usually `configure' can figure that out, but if it prints
a message saying it can not guess the host type, give it the
`--host=TYPE' option.  TYPE can either be a short name for the system
type, such as `sun4', or a canonical name with three fields:
     CPU-COMPANY-SYSTEM

See the file `config.sub' for the possible values of each field.  If
`config.sub' isn't included in this package, then this package doesn't
need to know the host type.

   If you are building compiler tools for cross-compiling, you can also
use the `--target=TYPE' option to select the type of system they will
produce code for and the `--build=TYPE' option to select the type of
system on which you are compiling the package.

Sharing Defaults
================

   If you want to set default values for `configure' scripts to share,
you can create a site shell script called `config.site' that gives
default values for variables like `CC', `cache_file', and `prefix'.
`configure' looks for `PREFIX/share/config.site' if it exists, then
`PREFIX/etc/config.site' if it exists.  Or, you can set the
`CONFIG_SITE' environment variable to the location of the site script.
A warning: not all `configure' scripts look for a site script.

Operation Controls
==================

   `configure' recognizes the following options to control how it
operates.

`--cache-file=FILE'
     Use and save the results of the tests in FILE instead of
     `./config.cache'.  Set FILE to `/dev/null' to disable caching, for
     debugging `configure'.

`--help'
     Print a summary of the options to `configure', and exit.

`--quiet'
`--silent'
`-q'
     Do not print messages saying which checks are being made.  To
     suppress all normal output, redirect it to `/dev/null' (any error
     messages will still be shown).

`--srcdir=DIR'
     Look for the package's source code in directory DIR.  Usually
     `configure' can determine that directory automatically.

`--version'
     Print the version of Autoconf used to generate the `configure'
     script, and exit.

`configure' also accepts some other, not widely useful, options.



B. OpenLDAP Software Copyright Notices
======================================

B.1. OpenLDAP Copyright Notice
------------------------------

Copyright 1998-2003 The OpenLDAP Foundation, Redwood City, California,
USA All rights reserved.

Redistribution and use in source and binary forms are permitted only
as authorized by the OpenLDAP Public License.  A copy of this license
is available at http://www.OpenLDAP.org/license.html or in file
LICENSE in the top-level directory of the distribution.

OpenLDAP is a registered trademark of the OpenLDAP Foundation.

Individual files and/or contributed packages may be copyright by other
parties and their use subject to additional restrictions.

This work is derived from the University of Michigan LDAP v3.3
distribution.  Information concerning this software is available at
<http://www.umich.edu/~dirsvcs/ldap/>.

This work also contains materials derived from public sources.

Additional information about OpenLDAP software can be obtained at
<http://www.OpenLDAP.org/>.

B.2. University of Michigan Copyright Notice
--------------------------------------------

Portions Copyright 1992-1996 Regents of the University of Michigan.
All rights reserved.

Redistribution and use in source and binary forms are permitted
provided that this notice is preserved and that due credit is given to
the University of Michigan at Ann Arbor. The name of the University
may not be used to endorse or promote products derived from this
software without specific prior written permission. This software is
provided ``as is'' without express or implied warranty.


C. OpenLDAP Public License
==========================

The OpenLDAP Public License
  Version 2.7, 7 September 2001

Redistribution and use of this software and associated documentation
("Software"), with or without modification, are permitted provided
that the following conditions are met:

1. Redistributions of source code must retain copyright statements
   and notices,

2. Redistributions in binary form must reproduce applicable copyright
   statements and notices, this list of conditions, and the following
   disclaimer in the documentation and/or other materials provided
   with the distribution, and

3. Redistributions must contain a verbatim copy of this document.

The OpenLDAP Foundation may revise this license from time to time.
Each revision is distinguished by a version number.  You may use
this Software under terms of this license revision or under the
terms of any subsequent revision of the license.

THIS SOFTWARE IS PROVIDED BY THE OPENLDAP FOUNDATION AND ITS
CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT
SHALL THE OPENLDAP FOUNDATION, ITS CONTRIBUTORS, OR THE AUTHOR(S)
OR OWNER(S) OF THE SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

The names of the authors and copyright holders must not be used in
advertising or otherwise to promote the sale, use or other dealing
in this Software without specific, written prior permission.  Title
to copyright in this Software shall at all times remain with
copyright holders.

OpenLDAP is a registered trademark of the OpenLDAP Foundation.

Copyright 1999-2001 The OpenLDAP Foundation, Redwood City,
California, USA.  All Rights Reserved.  Permission to copy and
distribute verbatim copies of this document is granted.

