13.7. Configuring a System to Authenticate Using OpenLDAP
This section provides a brief overview of how to configure OpenLDAP user authentication. Unless you are an OpenLDAP expert, more documentation than is provided here is necessary. Refer to the references provided in Section 13.9 Additional Resources for more information.
- Install the Necessary LDAP Package
First, make sure that the appropriate packages are installed on both the LDAP server and the LDAP client machines. The LDAP server needs the openldap-servers package.
The openldap, openldap-clients, and nss_ldap packages need to be installed on all LDAP client machines.
- Edit the Configuration Files
On the server, edit the /etc/openldap/slapd.conf file on the LDAP server to make sure it matches the specifics of the organization. Refer to Section 13.6.1 Editing /etc/openldap/slapd.conf for instructions about editing slapd.conf.
On the client machines, both /etc/ldap.conf and /etc/openldap/ldap.conf need to contain the proper server and search base information for the organization.
To do this, run the graphical Authentication Configuration Tool (authconfig-gtk) and select Enable LDAP Support under the User Information tab.
It is also possible to edit these files by hand.
On the client machines, the /etc/nsswitch.conf must be edited to use LDAP.
To do this, run the Authentication Configuration Tool (authconfig-gtk) and select Enable LDAP Support under the User Information tab.
If editing /etc/nsswitch.conf by hand, add ldap to the appropriate lines.
For example:
passwd: files ldap shadow: files ldap group: files ldap
13.7.1. PAM and LDAP
To have standard PAM-enabled applications use LDAP for authentication, run the Authentication Configuration Tool (authconfig-gtk) and select Enable LDAP Support under the the Authentication tab. For more about configuring PAM, refer to Chapter 15 Pluggable Authentication Modules (PAM) and the PAM man pages.
13.7.2. Migrating Old Authentication Information to LDAP Format
The /usr/share/openldap/migration/ directory contains a set of shell and Perl scripts for migrating authentication information into LDAP format.
 | Note |
|---|---|
Perl must be installed on the system to use these scripts. |
First, modify the migrate_common.ph file so that it reflects the correct domain. The default DNS domain should be changed from its default value to something like:
$DEFAULT_MAIL_DOMAIN = "example"; |
The default base should also be changed, to something like:
$DEFAULT_BASE = "dc=example,dc=com"; |
The job of migrating a user database into a format that is LDAP readable falls to a group of migration scripts installed in the same directory. Using Table 13-1, decide which script to run to migrate the user database.
Run the appropriate script based on the existing name service.
The README and the migration-tools.txt files in the /usr/share/openldap/migration/ directory provide more details on how to migrate the information.
| Existing name service | Is LDAP running? | Script to Use |
|---|---|---|
| /etc flat files | yes | migrate_all_online.sh |
| /etc flat files | no | migrate_all_offline.sh |
| NetInfo | yes | migrate_all_netinfo_online.sh |
| NetInfo | no | migrate_all_netinfo_offline.sh |
| NIS (YP) | yes | migrate_all_nis_online.sh |
| NIS (YP) | no | migrate_all_nis_offline.sh |
Table 13-1. LDAP Migration Scripts