First article in a series “OpenLDAP tutorial”.The presentation is done step by step by showing all the details necessary for the final operation. The exposed installation has a minimum configuration for correct operation. Other articles will follow to improve the installation on different aspects. It is advisable to follow this series of posts in order:

1. This article, installation and basic configuration.
2. Modify the default settings
3. Enable the production of Openldap Log file
4. Remotly configuration management by the administrator
5. Organization and data types
6. Adding data to the directory
7. Using OpenLDAP to protect access to a website
8. OpenLDAP password policy – Managing users accounts

Prerequisite: Nothing about the OpenLDAP server.

OpenLDAP tutorial, step 1: Properly configure the host Debian / Ubuntu

The server installation procedure systematically sets up a database.  The DIT (like an instance in relational databases) is selected based on the domain name of the host machine.

hostname -f

This command returns the full qualified name of the machine. Example: desktop.meddeb.net. In this case the database will have as DIT: dc=meddeb,dc=net (the right part of the name from the 1st dot met). If the configuration does not suit you, it should be modified (files /etc/hostname and /etc/hosts).

OpenLDAP tutorial, step 2: Install the OpenLDAP server on Debian / Ubuntu

sudo apt-get purge slapd
sudo apt-get install slapd

The installation process will start and request the password of the server administrator. In addition to the executable binary files, it is installed the files in folders:

• /usr/lib/ldap/ : OpenLDAP overlay libraries, binary native files.
• /etc/ldap/schema/ : OpenLDAP schemas availables, text files.
• /etc/ldap/slap.d/ : Dynamic configuration, text files.
• /var/lib/ldap/ : Installed database files.
• /var/run/slapd/ : Run settings, text files.

OpenLDAP tutorial, step 3: Install the OpenLDAP client utilities

sudo apt-get install ldap-utils

This installs the Openldap client utilities , including the ldapsearch query tool. The configuration file of those tools, /etc/ldap/ldap.conf, may be very useful. It allows to set defaults queries parameters. This simplifies the interaction with the server. a typical contents of this file is:

BASE   dc=meddeb,dc=net
URI    ldap://localhost
SIZELIMIT      12
TIMELIMIT      15
DEREF          never
# TLS certificates (needed for GnuTLS)
TLS_CACERT      /etc/ssl/certs/ca-certificates.crt

OpenLDAP tutorial, step 4: Check the installation.

slapd -V ↵
@(#) $OpenLDAP: slapd  (Ubuntu) (Mar 17 2014 21:20:08) $
        buildd@aatxe:/build/buildd/openldap-2.4.31/debian/build/servers/slap

In this sample, the installed server version is 2.4.31

ldapsearch -Y external  -H ldapi:/// -b cn=config "(objectClass=olcGlobal)" -LLL ↵
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
dn: cn=config
objectClass: olcGlobal
cn: config
olcArgsFile: /var/run/slapd/slapd.args
olcLogLevel: none
olcPidFile: /var/run/slapd/slapd.pid
olcToolThreads: 1

This gives the global part of the configuration. This is a default setting. Notice the runtime parameters folder: /var/run/slapd/. Notice, also, the olcLogLevel parameter set to none. This value must be modified for better operation.

sudo ldapsearch -Y external  -H ldapi:/// -b dc=meddeb,dc=net -LLL ↵

ASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
dn: dc=meddeb,dc=net
objectClass: top
objectClass: dcObject
objectClass: organization
o: meddeb.net
dc: meddeb

dn: cn=admin,dc=meddeb,dc=net
objectClass: simpleSecurityObject
objectClass: organizationalRole
cn: admin
description: LDAP administrator

This gives the only two entries created by default in the directory:

• dc=meddeb,dc=net, who is the DIT of the directory.
• cn=admin,dc=meddeb,dc=net, who is the administrator of the directory and his password given during installation.

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