LDAP Linux HOWTO
Luiz Ernesto Pinheiro Malere, malere@yahoo.com
v1.03, 28 September 2000
Information about installing, configuring, running and maintaining a
LDAP (Lightweight Directory Access Protocol) Server on a Linux machine
is presented on this document. There are also details about how to
create LDAP databases, how to update and delete information on the
database, how to implement roaming access and how to use Netscape
Address Book. This document is mostly based on the University of
Michigan LDAP information pages and on the OpenLDAP Administrator's
Guide.
______________________________________________________________________
Table of Contents
1. Introduction
1.1 What's LDAP ?
1.2 What's a Directory Service ?
1.3 How does LDAP work ?
1.4 LDAP backends, objects and attributes
1.5 New Versions of this Document
1.6 Opinions and Sugestions
1.7 History of Releases
1.8 Acknowledgments
1.9 Copyright and Disclaimer
2. Installing the LDAP Server
2.1 Pre-Requirements
2.2 Downloading the package
2.3 Unpacking the server
2.4 Configuring the software
2.5 Building the server
3. Configuring the LDAP Server
3.1 Configuration File Format
3.2 Global Directives
3.3 General Backend Options
3.4 General Database Directives
3.5 LDBM Backend-Specific Directives
3.6 Other Backend Databases
3.7 Access Control Examples
3.8 Configuration File Example
4. Running the LDAP Server
4.1 Command Line Options
4.2 Starting the LDAP server
4.3 Killing the LDAP server
5. Database Creation and Maintenance
5.1 Creating a Database online
5.2 Creating a Database offline
5.3 More on the LDIF format
5.4 The ldapsearch, ldapdelete and ldapmodify utilities
6. Additional Information and Features
6.1 Roaming Access
6.2 Netscape Address Book
6.3 LDAP Migration Tools
6.4 Authentication using LDAP
6.5 Graphical LDAP tools
6.6 Logs
7. References
7.1 URLs
7.2 Books
7.3 RFCs
______________________________________________________________________
1. Introduction
The main purpose of this document is to set up and use a LDAP
Directory Server on your Linux machine.You will learn how to install,
configure, run and maintain the LDAP server. After you also learn how
you can store, retrieve and update information on your Directory using
the LDAP clients and utilities. The daemon for the LDAP directory
server is called slapd and it runs on many different UNIX platforms.
There is another daemon that cares for replication between LDAP
servers. It's called slurpd and for the moment you don't need to worry
about it. In this document you run a slapd which provides directory
service for your local domain only, without replication, so without
slurpd.
This is a simple configuration for the server, good for starting but
easy to upgrade to another configuration later if you want. The
information presented on this document represents a nice
initialization on using the LDAP protocol. Possibly after reading this
document you would feel encouraged to expand the capabilities of your
server and even write your own clients, using the already avaiable C,
C++ and Java Development Kits.
1.1. What's LDAP ?
LDAP is a client-server protocol for accessing a directory service.
It was initially used as a front-end to X.500, but can also be used
with stand-alone and other kinds of directory servers.
1.2. What's a Directory Service ?
A directory is like a database, but tends to contain more descriptive,
attribute-based information. The information in a directory is
generally read much more often than it is written. As a consequence,
directories don't usually implement the complicated transaction or
roll-back schemes that regular databases use for doing 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 OK, 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.
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 LDAP directory tree or
LDAP backend database. An LDAP client connects to an LDAP server and
asks it a question. The server responds with the answer, or with a
pointer to where the client can get more 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. LDAP backends, objects and attributes
Slapd comes with three different backend databases you can choose
from. They are LDBM, a high-performance disk-based database; SHELL, a
database interface to arbitrary UNIX commands or shell scripts; and
PASSWD, a simple password file database.
In this document I assume that you choose the LDBM database.
The LDBM database works by assigning a compact four-byte unique
identifier to each entry in the database. It uses this identifier to
refer to entries in indexes. The database consists of one main index
file, called id2entry, which maps from an entry's unique identifier
(EID) to a text representation of the entry itself. Other index files
are maintained as well.
To import and export directory information between LDAP-based
directory servers, or to describe a set of changes which are to be
applied to a directory, the file format known as LDIF, for LDAP Data
Interchange Format, is typically used. An LDIF file stores information
in object-oriented hierarchies of entries. The LDAP software package
you're going to get comes with an utility to convert LDIF files to the
LDBM format
A common LDIF file looks like this:
dn: o=TUDelft, c=NL
o: TUDelft
objectclass: organization
dn: cn=Luiz Malere, o=TUDelft, c=NL
cn: Luiz Malere
sn: Malere
mail: malere@yahoo.com
objectclass: person
As you can see each entry is uniquely identified by a distinguished
name, or DN. the DN consists of the name of the entry plus a path of
names tracing the entry back to the top of the directory hierarchy.
In LDAP, an object class defines the collection of attributes that can
be used to define an entry. The LDAP standard provides these basic
types of object classes:
� Groups in the directory, including unordered lists of individual
objects or groups of objects.
� Locations, such as the country name and description.
� Organizations in the directory.
� People in the directory.
An entry can belong to more than one object class. For example, the
entry for a person is defined by the person object class, but may also
be defined by attributes in the inetOrgPerson, groupOfNames, and
organization objectclasses. The server's object class structure (its
schema) determines the total list of required and allowed attributes
for a particular entry.
Directory data is represented as attribute-value pairs. Any specific
piece of information is associated with a descriptive attribute.
For instance, the commonName, or cn, attribute is used to store a
person's name. A person named Jonas Salk can be represented in the
directory as
cn: Jonas Salk
Each person entered in the directory is defined by the collection of
attributes in the person object class. Other attributes used to define
this entry could include:
givenname: Jonas
surname: Salk
mail: jonass@airius.com
Required attributes include the attributes that must be present in
entries using the object class. All entries require the objectClass
attribute, which lists the object classes to which an entry belongs.
Allowed attributes include the attributes that may be present in
entries using the object class. For example, in the person object
class, the cn and sn attributes are required. The description,
telephoneNumber, seeAlso, and userpassword attributes are allowed but
are not required.
Each attribute has a corresponding syntax definition. The syntax
definition describes the type of information provided by the
attribute:
� bin binary
� ces case exact string (case must match during comparisons)
� cis case ignore string (case is ignored during comparisons)
� tel telephone number string (like cis but blanks and dashes `- '
are ignored during comparisons)
� dn distinguished name
Go to the first paragraph of ``section 3'' to know where the
objectclass and attribute definitions lay on your system.
1.5. New Versions of this Document
This document may receive corrections and updates based on the
feedback received by the readers. You should look at:
http://www.mobilesoft.com.br/HOWTO/LDAP-HOWTO.html
<http://www.mobilesoft.com.br/HOWTO/LDAP-HOWTO.html>
for new versions of this HOWTO.
1.6. Opinions and Sugestions
If you have any kind of doubt about some information avaiable on this
document,please contact me on the following email address:
malere@yahoo.com <mailto:malere@yahoo.com>
If you have commentaries and/or sugestions, please let me know too !
1.7. History of Releases
This section lists the releases of this document, sorted by date. Each
release carries the changes introduced on the earlier version, plus
newer additions and corrections:
v1.0: 20 June 1999, Initial version.
v1.01: 15 February 2000, added the following sections:
� LDAP Migration Tools
� Authentication using LDAP
� Graphical LDAP tools
� RFCs
v1.02: 13 September 2000, correction of typos and addition of the
following section:
� History of Releases
v1.03: 28 September 2000, presenting OpenLDAP 2.0, which comprises
Ldap v3, defined on the RFC2251 <ftp://ftp.isi.edu/in-
notes/rfc2251.txt>.
1.8. Acknowledgments
This Howto was result of an internship made by me on the TUDelft
University - Netherlands. I would like to thank the persons that
encouraged me to write this document: Rene van Leuken and Wim Tiwon.
Thank you very much. They are also Linux fans, just like me.
I would like to thank also Thomas Bendler, author of the German Ldap-
Howto, for his contributions to my document and Joshua Go, great
volunteer on the LDP project.
1.9. Copyright and Disclaimer
The LDAP Linux HOWTO is Copyrighted 1999 by Luiz Ernesto Pinheiro
Malere. It can be distributed freely. It cannot be modified. If you
have any kind of sugestion, please send me an email (I will update the
document if the sugestion proceeds).
If you want a translation, for example to Portuguese, you can send me
an email about it too.
No liability for the contents of this document can be accepted. I have
no responsability about the consequences of following the steps
provided in this document.
If you have questions, please contact, the Linux HOWTO coordinator, at
linux-howto@metalab.unc.edu <linux-howto@metalab.unc.edu>
2. Installing the LDAP Server
Five steps are necessary to install the server: Install the pre-
required packages (if not already installed), Download the server,
Unpack the software, Configure the Makefiles and Build the server.
2.1. Pre-Requirements
To be fully LDAPv3 compliant, OpenLDAP clients and servers require
installation of some aditional packages:
OpenSSL TLS libraries
Although 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 <http://www.openssl.org>
Kerberos Authentication Services
OpenLDAP clients and servers support Kerberos-based authentication
services. In particular, OpenLDAP supports 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
<http://www.pdc.kth.se/heimdal>.
MIT Kerberos is available from http://web.mit.edu/kerberos/www
<http://web.mit.edu/kerberos/www>. Use of strong authentication
services, such as those provided by Kerberos, is highly recommended.
Cyrus's Simple Authentication and Security Layer Libraries
Although some operating systems may provide these libraries 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
<http://asg.web.cmu.edu/sasl/sasl-library.html>. Cyrus SASL will make
use of OpenSSL and Kerberos/GSSAPI libraries if preinstalled.
Database Software
OpenLDAP's slapd primary database backend, LDBM, requires a compatible
database package for entry storage. LDBM is compatible with Sleepycat
Software's BerkeleyDB (recommended) or with the Free Software
Foundation's GNU Database Manager (GDBM). If neither of these packages
are available at configure time, you will not be able build slapd with
primary database backend support.
Your operating system may provide one of these two packages in the
base system or as an optional software component. You may need to
obtain the software and install it.
BerkeleyDB is available from Sleepycat Software's download page
http://www.sleepycat.com/download.html
<http://www.sleepycat.com/download.html>. There are several versions
available. At the time of this writing, the latest release, version
3.1, is recommended.
GDBM is available from FSF's download site
ftp://ftp.gnu.org/pub/gnu/gdbm <ftp://ftp.gnu.org/pub/gnu/gdbm>. At
the time of this writing, version 1.8 is the latest release.
Threads
OpenLDAP is designed to take advantage of threads. OpenLDAP supports
POSIX pthreads, Mach CThreads, and a number of other varieties.
configure script 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 <http://www.openldap.org/faq>.
TCP Wrappers
slapd 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.
2.2. Downloading the package
There are two free distributed LDAP servers: University of Michigan
LDAP server and OpenLDAP server. There's also the Netscape Directory
Server, which is free only under some conditions (educational
institutions get it free, for example).The OpenLDAP server is based on
the latest version of the University of Michigan Server and there are
mailing lists and additional documentation available for it. This
document assumes that you are using the OpenLDAP server.
It's latest tar gzipped version is avaiable on the following address:
http://www.openldap.org <http://www.openldap.org>
If you want to get the latest version of University of Michigan
Server, go to this address:
ftp://terminator.rs.itd.umich.edu/ldap
<ftp://terminator.rs.itd.umich.edu/ldap>
To write this document, I used two versions of the OpenLDAP package :
the latest stable version 1.2.11 and the newly released 2.0.4. My
operating system is a Slackware Linux with kernel 2.2.13.
On the OpenLDAP site you can always find the latest development and
stable versions of the OpenLDAP server. By the time this document was
updated, the latest stable version was openldap-stable-20000704.tgz.
The latest development version was openldap-2.0.4.tgz.
2.3. Unpacking the server
Now that you have the tar gzipped package on your local machine, you
can unpack it.
First copy the package to a desirable directory, for example
/usr/local.
Then use the following command:
tar xvzf openldap-stable.tgz
You can use this command too, as well:
gunzip openldap-stable.tgz | tar xvf -
2.4. Configuring the software
There are several options that you should like to customize so you can
build the best software to your site.
To configure the software you just need 2 steps:
� Edit the file ldapconfig.h.edit, located on the subdirectory
include beneath the directory where you unpacked the software.
� Run the configure script (if you are a tough guy, you can also edit
the Make-common file instead of running the configure script :^)
In the file include/ldapconfig.h.edit you can set options like the
location of the slapd and slurpd daemons. The file itself is well
commented and it's default settings also reflect the most common
administrator choices so, if you are in a hurry you can skip this
step:
vi include/ldapconfig.h.edit
The OpenLDAP server sources are distributed with a configuration
script for setting options like instalation directories, compiler and
linker flags. Type the following command on the directory where you
unpacked the software:
./configure --help
This will print all options that you can customize with the configure
script before you build the software. Some usefull options are --pre�
fix=pref , --exec-prefix=eprefix and --bindir=dir, for setting insta�
lation directories. Normally if you run configure without options, it
will auto-detect the appropriate settings and prepar to build things
on the default common location. So just type:
./configure
And watch the output to see if all went well
2.5. Building the server
After configuring the software you can start building it. First build
the dependencies, using the command:
make depend
After build the server, using the command:
make
If all goes well, the server will build as configured. If not, return
to the previous step to review the configuration settings. You should
check the platform specific hints, they are located in the path
doc/install/hints under the directory you unpacked the software.
Now install the binaries and man pages. You may need to be superuser
to do this (depending on where you are installing things):
su
make install
That's all, now you have the binary of the server and the binaries of
several other utilities. Go to the ``next'' section to see how to con�
figure the operation of your LDAP server.
The binary of the OpenLdap 2.0 server is called slapd. OpenLdap 2.0
was officially released on August, 30th and it comprises Ldap protocol
v3, as defined on the RFC 2251.
The main features of OpenLDAP 2.0 are:
� LDAPv2 and LDAPv3 Support (RFC2251-2256,2829-2831)
� Maintenance of interoperability with existing clients
� IPv4 and IPv6 support
� Strong Authentication (SASL) (RFC2829)
� Start TLS (RFC2830)
� Language Tags (RFC2596)
� DNS-based service location (RFC2247+"locate" I-D)
� Enhanced Standalone Server
� Named References/ManageDsaIT ("nameref" I-D)
� Enhanced Access Control subsystem
� Thread pooling
� Preemptive threading support
� Multiple listener support
� LDIFv1 (RFC2849)
� Improved platform/subsystem detection
Note: There will be a document on the Linux Documentation Project
(LDP) called LDAP Implementation HOWTO. This document will be a great
resource for those who want to explore the new features of OpenLDAP
2.0. The date for it's release is around December 2000.
On the latest versions of the OpenLDAP package, it's also possible to
test the recently built binaries. The package comes with a test
script, which you can run using the command:
make test
If anything goes wrong with the script you can just abort it hitting
Ctrl-C. In my case, the script stopped working before it's total
completion. Anyway I still could see some successfull messages about
my OpenLDAP configuration.
3. Configuring the LDAP Server
Once the software has been installed and built, you are ready to
configure it for use at your site. All slapd runtime configuration is
accomplished through the slapd.conf file, installed in the prefix
directory you specified in the configuration script or by default in
/usr/local/etc/openldap.
This section details the commonly used configuration directives on
slapd.conf. For a complete list, see slapd.conf(5) manual page. The
configuration file directives are separated into global, backend-
specific and data-specific categories. Here you will find descriptions
of directives, together with their default values (if any) and with
examples of their use.
3.1. Configuration File Format
The slapd.conf 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 a backend and/or database
directives, 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.
3.2. 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 <>.
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
examples for more details.
attributetype <RFC2252 Attribute Type Description>
This directive defines an attribute type.
defaultaccess { none | compare | search | read | write }
This directive specifies the default access to grant requesters when no access directives have been
specified. Any given access level implies all lesser access levels (e.g., read access implies search
and compare but not write).
Default:
defaultaccess read
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.
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.
loglevel <integer>
This directive specifies the level at which debugging statements and operation statistics should be
syslogged (currently logged to the syslogd(8) 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:
-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 255 or loglevel -1
This will cause lots and lots of debugging information to be syslogged.
Default:
loglevel 256
objectclass <RFC2252 Object Class Description>
This directive defines an object class.
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.
sizelimit <integer>
This directive specifies the maximum number of entries to return from a search operation.
Default:
sizelimit 500
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
3.3. General Backend Options
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.
backend <type>
This directive marks the beginning of a backend definition. <type> should be one of
ldbm, shell, passwd, or other supported backend type.
3.4. 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.
database <type>
This directive marks the beginning of a new database instance definition. <type> should be one of
ldbm, shell, passwd, or other supported database type.
Example:
database ldbm
This marks the beginning of a new LDBM backend database instance definition.
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
replica
replica 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 host= parameter specifies 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) is used.
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.
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.
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 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@EXAMPLE.COM"
rootpw <password>
This directive specifies a password for the DN given above that will always work, regardless of whether
an entry with the given DN exists or has a password. This directive is deprecated in favor of SASL based authentication.
Example:
rootpw secret
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.
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@EXAMPLE.COM"
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:
update ldap://master.example.net
3.5. LDBM Backend-Specific Directives
Directives in this category only apply to the LDBM backend database.
That is, they must follow a "database ldbm" line and come before any
other "database" line.
cachesize <integer>
This directive specifies the size in entries of the in-memory cache maintained by the LDBM backend database instance.
Default:
cachesize 1000
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 indexes.
Default:
dbcachesize 100000
dbnolocking
This option, if present, disables database locking. Enabling this option may improve performance at
the expense of data security.
dbnosync
This option causes on-disk database contents not be immediately synchronized with in memory changes upon change.
Enabling this option may improve performance at the expense of data security.
directory <directory>
This directive specifies the directory where the LDBM files containing the database and associated indexes live.
Default:
directory /usr/local/var/openldap-ldbm
index {<attrlist> | default} [pres,eq,approx,sub,none]
This directive specifies the indexes to maintain for the given attribute. If only an <attrlist> is given,
the default indexes are maintained.
Example:
index default pres,eq
index objectClass,uid
index cn,sn eq,sub,approx
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 objectClass and uid attribute types.
The third line causes equality, substring, and approximate indices to be maintained for cn and sn attribute types.
mode <integer>
This directive specifies the file protection mode that newly created database index files should have.
Default:
mode 0600
3.6. Other Backend Databases
slapd supports a number of backend database types besides the default
LDBM:
� ldbm: Berkeley or GNU DBM compatible backend
� passwd: Provides read-only access to /etc/passwd
� shell: Shell (extern program) backend
� sql: SQL Programmable backend
Take a look on the slapd.conf(5) manpage for details.
3.7. Access Control Examples
The access control facility presented on ``section 3.2'' 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. If it appears
alone it is the same as the following defaultaccess line.
defaultaccess read
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=".*, o=U of M, c=US"
by * search
access to dn=".*, c=US"
by * read
Read access is granted to entries under the c=US subtree, except for
those entries under the "o=University of Michigan, c=US" subtree, to
which search access is granted. If the order of these access
directives was reversed, the U-M-specific directive would never be
matched, since all U-M entries are also c=US entries.
The next example again shows the importance of ordering, both of the
access directives and the "by" clauses. It also shows the use of an
attribute selector to grant access to a specific attribute and various
<who> selectors.
access to dn=".*, o=U of M, c=US" attr=homePhone
by self write
by dn=".*, o=U of M, c=US" search
by domain=.*\.umich\.edu read
by * compare
access to dn=".*, o=U of M, c=US"
by self write
by dn=".*, o=U of M, c=US" search
by * none
This example applies to entries in the "o=U of M, c=US" subtree. To
all attributes except homePhone, the entry itself can write them,
other U-M entries can search by them, anybody else has no access. The
homePhone attribute is writable by the entry, searchable by other U-M
entries, readable by clients connecting from somewhere in the
umich.edu domain, and comparable by everybody else.
Sometimes it is usefull 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 too 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.
Note that the attr=member construct in the <what> clause is a
shorthand for the clause "dn=* attr=member" (i.e., it matches the
member attribute in all entries).
Note: Take a look on OpenLDAP Administrator's Guide at
http://www.openldap.org <http://openldap.org> to learn more about
Access Control on Ldap.
3.8. 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 LDBM 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
containing 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 is used only if no database
access controls match or when the target objects are not under the
control of any database (such as the Root DSE).
The next section of the configuration file defines an LDBM 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. Indexes are to be maintained
for several attributes, and the userPassword attribute is to be
protected from unauthorized access.
5. # ldbm definition for the example.com
6. database ldbm
7. suffix "dc=example, dc=com"
8. directory /usr/local/var/openldap
9. rootdn "cn=Manager, dc=example, dc=com"
10. rootpw secret
11. # replication directives
12. replogfile /usr/local/var/openldap/slapd.replog
13. replica host=slave1.example.com:389
14. binddn="cn=Replicator, dc=example, dc=com"
15. bindmethod=simple credentials=secret
16. replica host=slave2.example.com
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. # ldbm access control definitions
24. access to attr=userPassword
25. by self write
26. by anonymous auth
27. by dn="cn=Admin,dc=example,dc=com" write
28. by * none
29. access to *
30. by self write
31. by dn="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 11 specifies the
replication log file (where changes to the database are logged - this
file is written by slapd and read by slurpd). Lines 12 through 14
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 15 through 18 specify a second
replication site.
Lines 20 through 22 indicate the indexes to maintain for various
attributes.
Lines 24 through 32 specify access control for entries in the
database. For all 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 authenticated users.
The next section of the example configuration file defines another
LDBM database. This one handles queries involving the
dc=example,dc=net subtree. Note that without line 38, the read access
would be allowed due to the global access rule at line 4.
33. # ldbm definition for example.net
34. database ldbm
35. suffix "dc=example, dc=net"
36. directory /usr/local/var/ldbm-example-net
37. rootdn "cn=Manager, dc=example, dc=com"
38. access to * by users read
4. Running the LDAP Server
slapd 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.
4.1. Command Line Options
slapd 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://127.0.0.1:667" 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 667. 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:
-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.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.
4.2. Starting the LDAP server
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.
4.3. Killing the LDAP server
To kill off slapd safely, you should give a command like this:
kill -TERM `cat $(ETCDIR)/slapd.pid`
Killing slapd by a more drastic method may cause its LDBM databases to
be corrupted, as it may need to flush various buffers before it exits.
Note that slapd writes its pid to a file called slapd.pid in the
directory you configured in slapd.conf file, for example:
/usr/local/var/slapd.pid
You can change the location of this pid file by changing the
SLAPD_PIDFILE variable in include/ldapconfig.h.edit
Slapd will also write its arguments to a file called slapd.args in the
directory you configured in slapd.conf file, for example
/usr/local/var/slapd.args
You can change the location of the args file by changing the
SLAPD_ARGSFILE variable in include/ldapconfig.h.edit.
5. Database Creation and Maintenance
This section tells you how to create a slapd database from scratch.
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).
The second method of database creation is to do it off-line, using the
index generation tools. 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.
5.1. Creating a Database online
The OpenLDAP software package comes with an utility called ldapadd,
used to add entries while the LDAP server is running. If you choose to
create the Database online, you can use the ldapadd tool to add
entries. After adding the first entries, you can still use ldapadd to
add more entries. You should be sure to set the following
configuration options on your sladp.conf file before starting slapd:
suffix <dn>
As described in the ``section 3'', this option says what 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 "o=TUDelft, c=NL"
You should be sure to specify a directory where the index files should
be created:
directory <directory>
For example:
directory /usr/local/tudelft
You need to make it so you can connect to slapd as somebody with
permission to add entries. This is done through the following two
options in the database definition:
rootdn <dn>
rootpw <passwd> /* Remember to use crypto password here !!! */
These options specify a DN and password that can be used to
authenticate as the "superuser" 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 configuration lines could be used.
index cn,sn,uid
index objectclass pres,eq
index default none
Once you have configured things to your liking, start up slapd,
connect with your LDAP client, and start adding entries. For example,
to add a the TUDelft entry followed by a Postmaster entry using the
ldapadd tool, you could create a file called /tmp/newentry with the
contents:
o=TUDelft, c=NL
objectClass=organization
description=Technical University of Delft Netherlands
cn=Postmaster, o=TUDelft, c=NL
objectClass=organizationalRole
cn=Postmaster
description= TUDelft postmaster - postmaster@tudelft.nl
and then use a command like this to actually create the entry:
ldapadd -f /tmp/newentry -D "cn=Manager, o=TUDelft, c=NL" -w secret
The above command assumes that you have set rootdn to "cn=Manager,
o=TUDelft, c=NL" and rootpw to "secret". If you don't want to type
the password on the command line, use the -W option for the ldapadd
command instead of -w "password". You will be prompted to enter the
password:
ldapadd -f /tmp/newentry -D "cn=Manager, o=TUDelft, c=NL" -W
Enter LDAP Password:
5.2. Creating a Database offline
The second method of database creation is to do it off-line, using the
index generation tools described below. This method is best if you
have many thousands of entries to create, which would take an
unacceptably long time using the LDAP method described above. These
tools read the slapd configuration file and an input LDIF file
containing a text representation of the entries to add. They produce
the LDBM index files directly. 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 preceding section, this option says what 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 "o=TUDelft, c=NL"
You should be sure to specify a directory where the index files should
be created:
directory <directory>
For example:
directory /usr/local/tudelft
Next, you probably want to increase the size of the in-core cache used
by each open index file. For best performance during index creation,
the entire index should fit in memory. If your data is too big for
this, or your memory too small, you can still make it pretty big and
let the paging system do the work. This size is set with the following
option:
dbcachesize <integer>
For example:
dbcachesize 50000000
This would create a cache 50 MB big, which is pretty big (at
University of Michigan, the database has about 125K entries, and the
biggest index file is about 45 MB). Experiment with this number a bit,
and the degree of parallelism (explained below), to see what works
best for your system. Remember to turn this number back down once your
index files are created and before you run slapd.
Finally, you need to specify which indexes 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
index default none
This would create presence, equality and approximate indexes for the
cn, sn, and uid attributes, and no indexes for any other attributes.
See the configuration file on ``section 3'' for more information on
this option.
Once you've configured things to your liking, you create the primary
database and associated indexes 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 (Take a look on the next section).
-f <slapdconfigfile>
Specifies the slapd configuration file that tells where to create the
indexes, what indexes 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 ldbm 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.
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.
There is another program called slapcat that 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.
5.3. More on the LDIF format
The LDAP Data Interchange Format (LDIF) is used to represent LDAP
entries in a simple text format. 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 (attrdesc) 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.
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.
5.4. The ldapsearch, ldapdelete and ldapmodify utilities
ldapsearch - ldapsearch is a shell accessible interface to the
ldap_search(3) library call. Use this utility to search for entries on
our LDAP databse backend.
The synopsis to call ldapsearch is the following (take a look at the
ldapsearch man page to see what each option mean):
ldapsearch [-n] [-u] [-v] [-k] [-K] [-t] [-A] [-B] [-L] [-R] [-d debuglevel] [-F sep] [-f file]
[-D binddn] [-W] [-w bindpasswd] [-h ldaphost] [-p ldapport] [-b searchbase] [-s base|one|sub]
[-a never|always|search|find] [-l timelimit] [-z sizelimit] filter [attrs...]
ldapsearch opens a connection to an LDAP server, binds, and performs a
search using the filter filter. The filter should conform to the
string representation for LDAP filters as defined in RFC 1558. If
ldapsearch finds one or more entries, the attributes specified by
attrs are retrieved and the entries and values are printed to standard
output. If no attrs are listed, all attributes are returned.
Here are some examples of use of ldapsearch:
ldapsearch -b 'o=TUDelft,c=NL' 'objectclass=*'
ldapsearch -b 'o=TUDelft,c=NL' 'cn=Rene van Leuken'
ldasearch -u -b 'o=TUDelft,c=NL' 'cn=Luiz Malere' sn mail
The -b option stands for searchbase (initial search point) and the -u
option stands for userfriendly output information.
ldapdelete - ldapdelete is a shell accessible interface to the
ldap_delete(3) library call. Use this utility to delete entries on our
LDAP databse backend.
The synopsis to call ldapdelete is the following (take a look at the
ldapdelete man page to see what each option mean):
ldapdelete [-n] [-v] [-k] [-K] [-c] [-d debuglevel] [-f file] [-D binddn] [-W] [-w passwd]
[-h ldaphost] [-p ldapport] [dn]...
ldapdelete opens a connection to an LDAP server, binds, and deletes
one or more entries. If one or more dn arguments are provided, entries
with those Distinguished Names are deleted. Each dn should be a
string-represented DN as defined in RFC 1779. If no dn arguments are
provided, a list of DNs is read from standard input (or from file if
the -f flag is used).
Here are some examples of use of ldapdelete:
ldapdelete 'cn=Luiz Malere,o=TUDelft,c=NL'
ldapdelete -v 'cn=Rene van Leuken,o=TUDelft,c=NL' -D 'cn=Luiz Malere,o=TUDelft,c=NL' -W
The -v option stands for verbose mode, the -D option stands for Binddn
(the dn to authenticate against) and the -W option stands for password
prompt.
ldapmodify - ldapmodify is a shell accessible interface to the
ldap_modify(3) and ldap_add(3) library calls. Use this utility to
modify entries on our LDAP databse backend.
The synopsis to call ldapmodify is the following (take a look at the
ldapmodify man page to see what each option mean):
ldapmodify [-a] [-b] [-c] [-r] [-n] [-v] [-k] [-d debuglevel] [-D binddn] [-W] [-w passwd]
[-h ldaphost] [-p ldapport] [-f file]
ldapadd [-b] [-c] [-r] [-n] [-v] [-k] [-K] [-d debuglevel] [-D binddn] [-w passwd] [-h ldaphost]
[-p ldapport] [-f file]
ldapadd is implemented as a hard link to the ldapmodify tool. When
invoked as ldapadd the -a (add new entry) flag of ldapmodify is
turned on automatically. ldapmodify opens a connection to an
LDAP server, binds, and modifies or adds entries. The entry
information is read from standard input or from file through the use
of the -f option.
Here are some examples of use of ldapmodify:
Assuming that the file /tmp/entrymods exists and has the contents:
dn: cn=Modify Me, o=University of Michigan, c=US
changetype: modify
replace: mail
mail: modme@terminator.rs.itd.umich.edu
-
add: title
title: Grand Poobah
-
add: jpegPhoto
jpegPhoto: /tmp/modme.jpeg
-
delete: description
-
The command:
ldapmodify -b -r -f /tmp/entrymods
will replace the contents of the "Modify Me" entry's mail
attribute with the value "modme@terminator.rs.itd.umich.edu", add a
title of "Grand Poobah", and the contents of the file /tmp/modme.jpeg
as a jpegPhoto, and completely remove the description attribute.
The same modifications as above can be performed using the older
ldapmodify input format:
cn=Modify Me, o=University of Michigan, c=US
mail=modme@terminator.rs.itd.umich.edu
+title=Grand Poobah
+jpegPhoto=/tmp/modme.jpeg
-description
And plus the command bellow:
ldapmodify -b -r -f /tmp/entrymods
Assuming that the file /tmp/newentry exists and has the contents:
dn: cn=Barbara Jensen, o=University of Michigan, c=US
objectClass: person
cn: Barbara Jensen
cn: Babs Jensen
sn: Jensen
title: the world's most famous manager
mail: bjensen@terminator.rs.itd.umich.edu
uid: bjensen
The command:
ldapadd -f /tmp/entrymods
Assuming that the file /tmp/newentry exists and has the contents:
dn: cn=Barbara Jensen, o=University of Michigan, c=US
changetype: delete
The command:
ldapmodify -f /tmp/entrymods
will remove Babs Jensen's entry.
The -f option stands for file (read the modification information from
a file instead of standard input), the -b option stands for binary
(any values starting with a '/' on the input file are interpreted as
binaries), the -r stands for replace (replace existing values by
default).
6. Additional Information and Features
In this section you will find information about the Netscape Address
Book, a LDAP client that can be used to query your Directory. Also
presented are details on how to implement Roaming Access using the
Netscape Navigator, version 4.5 or above and your LDAP server. There
has been a lot of talk on the OpenLDAP mailing lists about Roaming
Access, since this is a feature that is not totally implemented. Most
of the people don't like the way Netscape Navigator operates with the
LDAP server while making downloads and uploads to it. So, if after
reading this you find that the Roaming Access is not working the way
you would like, nevermind. A lot of people passed through this
situation already. The purpose of introducing this feature here is
more for giving people an idea about the capabilities of the LDAP
protocol. To finish you will see some information about safely killing
the slapd process and about slapd logs.
6.1. Roaming Access
The goal of Roaming Access is that wherever you are on the Net, you
can retrieve your bookmarks, preferences, mail filters, etc. using
Netscape Navigator and a LDAP server. This is a very nice feature.
Imagine that wherever you access the Web, you can have your own
settings on the browser. If you will travel and you need to access
that currency site that is stored on your local bookmarks, don't
worry. Upload the bookmarks and other configuration files to a LDAP
server and you can retrieve them all later, independent of the place
you will be.
To implement Roaming Access you have to follow these steps:
� Change your attributes description file
� Change your objectclass description file
� Change the LDIF file to include profiles
� Configure Netscape Navigator to use the LDAP server as a Roaming
Access Server
� Restart the LDAP server with the new settings.
- Changing the attributes file: You need to add new attributes on the
attribute list present on the file slapd.at.conf (this is a file you
include on your slapd.conf and it's normally located at
/usr/local/etc/openldap):
attribute nsLIPtrURL ces
attribute nsLIPrefs ces
attribute nsLIProfileName cis
attribute nsLIData bin
attribute nsLIElementType cis
attribute nsLIServerType cis
attribute nsLIVersion cis
- Changing the objectclass file: You also have to add some new classes
to your slapd.oc.conf (this is another file you include on your
slapd.conf and it's normally located at /usr/local/etc/openldap) in
order to enable Roaming Access:
objectclass nsLIPtr
requires
objectclass
allows
nsliptrurl,
owner
objectclass nsLIProfile
requires
objectclass,
nsliprofilename
allows
nsliprefs,
uid,
owner
objectclass nsLIProfileElement
requires
objectclass,
nslielementtype
allows
owner,
nslidata,
nsliversion
objectclass nsLIServer
requires
objectclass,
serverhostname
allows
description,
cn,
nsserverport,
nsliservertype,
serverroot
- Changing the LDIF file: Now you have to modify your LDIF file,
adding profiles entries to each user that wish to try the Roaming
Access feature of Netscape. Look an example of a simple LDIF file with
profiles entries:
dn: o=myOrg,c=NL
o: myOrg
objectclass: organization
dn: cn=seallers,ou=People,o=myOrg,c=NL
cn: seallers
userpassword: myPassword
objectclass: top
objectclass: person
dn: nsLIProfileName=seallers,ou=Roaming,o=myOrg,c=NL
changetype: add
objectclass: top
owner: cn=seallers,ou=People,o=myOrg,c=NL
objectclass: top
objectclass: nsLIProfile
The next step is to configure Netscape to enable the Roaming Access
against your LDAP server. Just follow the sequence:
- Go to Menu Edit -> Preferences -> Roaming User
Now you have to first enable Roaming Access for this profile, clicking
on the checkbox corresponding to this option.
- Fill the username box with an appropriate value, for instance john
Pull down the arrow of the Roaming User option on the left side of the
Preferences Window to see the suboptions of Roaming Access.
- Click on Server Information and enable the option LDAP Server and
fill the boxes with the following information:
Address: ldap://myHost/nsLIProfileName=$USERID,ou=Roaming,o=myOrg,c=NL
User DN: cn=$USERID,ou=People,o=myOrg,c=NL
IMPORTANT: Netscape automatically substitutes the $USERID variable for
the name of the profile you selected before running the browser. So if
you selected the profile seallers, it will substitute $USERID for
seallers, if you selected profile gonzales, it will substitute $USERID
for gonzales. If you are not familiar with profiles, run the Profile
Manager application that comes on the Netscape Comunicator package.
It's an application designed to satisfy the multiple users of a
browser on the same machine, so each one can have their own settings
on the browser.
The final step is to restart the server. Take a look on the ``section
4.2'' to see how you do that safely and on ``section 4'' to see how to
start it again.
6.2. Netscape Address Book
Once you have your LDAP server up and running, you can access it with
many different clients (e.g. ldapsearch command line utility). A very
interesting one is the Netscape Address Book. It's available from
version 4.x of Netscape but you have to use the 4.5 or above version
for a stable interoperation with your LDAP server.
Just follow the sequence:
Open Netscape Navigator -> Go to Communicator Menu -> Address Book
The Netscape Address Book will be launched with some default LDAP
directories. You have to add your own LDAP directory too!
Go to File Menu -> New Directory
Fill the boxes with your server information. For example:
- Description: TUDelft
- LDAP Server: dutedin.et.tudelft.nl
- Server Root: o=TUDelft, c=NL
The default LDAP port is 389. Don't change it, unless you changed this
option while building your server.
Now, make simple queries to your server, using the box Show Names
Containing, or advanced queries, using the Search for button.
6.3. LDAP Migration Tools
The LDAP Migration Tools are a collection of Perl scripts used to
convert configuration files to the LDIF format. The scripts are
provided by PADL Software Ltd. I recommend you to take a look at the
license terms before using them, even being free. If you plan to use
your LDAP server to authenticate users, this tools may be very useful.
Use the Migration Tools to convert your NIS or password archives to
the LDIF format, making these files compatible with your LDAP Server.
Apply also these Perl Scripts to migrate users, groups, aliases,
hosts, netgroups, networks, protocols, RPCs and services from existing
nameservices (NIS, flat files and NetInfo) to the LDIF format. To
download the LDAP Migration Tools and get more information, go to the
following address:
http://www.padl.com/tools.html
The package comes with a README file and the name of the script files
are intuitive. Take a first look on the README file and then start
applying the scripts.
6.4. Authentication using LDAP
Your LDAP server can authenticate users using a mechanism called PAM
(Pluggable Authentication Modules). Since the beginnings of UNIX,
authenticating a user has been accomplished via the user entering a
password and the system checking if the entered password corresponds
to the encrypted official password that is stored in /etc/passwd.
That was in the beginning. Since then, a number of new ways for
authenticating users became popular, including more complicated
replacements for the /etc/passwd file and hardware devices called
Smart cards. The problem is that each time a new authentication schema
is developed, it requires all the necessary programs (login, ftpd
etc...) to be rewritten to support it. PAM provides a way to develop
programs that are independent of authentication scheme. These programs
need "authentication modules" to be attatched to them at run-time in
order to work.
The authentication module for LDAP is available as a tar ball on the
following address:
http://www.padl.com/pam_ldap.html
Here I assume that your Linux distribution is already PAM prepared. If
not take a look at this URL: http://www.kernel.org/pub/linux/libs/pam
<http://www.kernel.org/pub/linux/libs/pam>. Various Linux
distributions use different standard settings related to PAM. Usually,
the PAM configuration files reside on the /etc/pam.d/ directory. There
you can find a file for each service running on your box. As an
example, if you want to use the LDAP server for logging users in after
your Linux boot up, you should make your Linux PAM compatible (as
described in the beginning of this paragraph), install the LDAP PAM
module and edit a file called login in the PAM configuration directory
(/etc/pam.d/) with the following content:
#%PAM-1.0
auth required /lib/security/pam_securetty.so
auth required /lib/security/pam_nologin.so
auth sufficient /lib/security/pam_ldap.so
auth required /lib/security/pam_unix_auth.so try_first_pass
account sufficient /lib/security/pam_ldap.so
account required /lib/security/pam_unix_acct.so
password required /lib/security/pam_cracklib.so
password required /lib/security/pam_ldap.so
password required /lib/security/pam_pwdb.so use_first_pass
session required /lib/security/pam_unix_session.so
6.5. Graphical LDAP tools
� Kldap
Kldap is a graphical LDAP client written for KDE. Kldap has a nice
interface and is able to show all the information tree stored on your
Directory. You can check some screenshots from the application and
download it at:
http://www.mountpoint.ch/oliver/kldap
� GQ
GQ is another graphical LDAP client with a simpler interface. It was
written for GNOME. It also runs under KDE, the same way Kldap runs
under GNOME. The address for downloading and getting more information
is:
http://biot.com/gq/
6.6. Logs
Slapd uses the syslog(8) facility to generate logs. The default user
of the syslog(8) facility is LOCAL4, but values from LOCAL0, LOCAL1,
up to LOCAL7 are allowed.
In order to enable the generation of logs you have to edit your
syslog.conf file, usually located in the /etc directory.
Create a line like this:
local4.* /usr/adm/ldalog
This will use the default user LOCAL4 for the syslog facility. If you
are not familiar with the sintax of this line, take a look at the man
pages of syslog, syslog.conf and syslogd. If you want to change the
default user or to specify the level of the logs generated, you have
the following options while starting slapd:
-s syslog-level This option tells slapd at what level debugging
statements should be logged to the syslog(8) facility. The level
describes the severity of the message, and is a keyword from the
following ordered list (higher to lower): emerg, alert, crit, err,
warning, notice, info, and debug. Ex: slapd -f myslapd.conf -s debug
-l syslog-local-user Selects the local user of the syslog(8)
facility. Values can be LOCAL0, LOCAL1, and so on, up to LOCAL7. The
default is LOCAL4. However, this option is only permitted on systems
that support local users with the syslog(8) facility.
Now take a look at the logs generated. They can help you tremendously
in solving problems with queries, updates, binding, etc.
7. References
On this section you will find additional documentation about LDAP:
useful URLs, cool books and definition RFCs.
7.1. URLs
Here are the URLs that contain very useful information about LDAP.
From these URLs, this HOWTO was made, so if after reading this
document you need more specific information, you probably will find
here:
� University of Michigan LDAP Page:
http://www.umich.edu/~dirsvcs/ldap/index.html
<http://www.umich.edu/~dirsvcs/ldap/index.html>
� University of Michigan LDAP Documentation Page:
http://www.umich.edu/~dirsvcs/ldap/doc/
<http://www.umich.edu/~dirsvcs/ldap/doc/>
� OpenLDAP Administrator's Guide:
http://www.openldap.org/doc/admin
<http://www.openldap.org/doc/admin>
� Manually Implementing Roaming Access:
http://help.netscape.com/products/client/communicator/manual_roaming2.html
<http://help.netscape.com/products/client/communicator/manual_roaming2.html>
� Customizing LDAP Settings for Communicator 4.5:
http://developer.netscape.com/docs/manuals/communicator/ldap45.htm
<http://developer.netscape.com/docs/manuals/communicator/ldap45.htm>
� Introducing to Directory Service (X.500):
http://www.nic.surfnet.nl/surfnet/projects/x500/introducing/
<http://www.nic.surfnet.nl/surfnet/projects/x500/introducing/>
� Linux Directory Service:
http://www.rage.net/ldap/ <http://www.rage.net/ldap/>
7.2. Books
These are the most popular and useful books about LDAP:
� Implementing LDAP by Mark Wilcox
� LDAP: Programming Directory-Enabled Applications with Lightweight
Directory Access Protocol by Howes and Smith
� Understanding and Deploying LDAP Directory Servers by Howes, Smith,
and Good
7.3. RFCs
The RFCs that support the LDAP development efforts:
� RFC 1558: A String Representation of LDAP Search Filters
� RFC 1777: Lightweight Directory Access Protocol
� RFC 1778: The String Representation of Standard Attribute Syntaxes
� RFC 1779: A String Representation of Distinguished Names
� RFC 1781: Using the OSI Directory to Achieve User Friendly Naming
� RFC 1798: Connectionless LDAP
� RFC 1823: The LDAP Application Programming Interface
� RFC 1959: An LDAP URL Format
� RFC 1960: A String Representation of LDAP Search Filters
� RFC 2251: Lightweight Directory Access Protocol (v3)
� RFC 2307: LDAP as a Network Information Service