Configuring Your System to Authenticate Using OpenLDAP
This section provides a brief overview of how to configure a Red Hat Linux system to authenticate using OpenLDAP. Unless you are an OpenLDAP expert, you will probably need more documentation than is provided here. Please refer to the references provided in the Section called Additional Resources for more information.
Install the Necessary LDAP Packages
First, you should make sure that the appropriate packages are installed on both the LDAP server and the LDAP client machines. The LDAP server needs the openldap-server package.
The LDAP client machines need the following packages installed: openldap, openldap-clients, and nss_ldap.
Edit the Configuration Files
On the Server, Edit slapd.conf
Edit the /etc/openldap/slapd.conf file on the LDAP server to make sure it matches the specifics of your organization. Please refer to the Section called slapd.conf for instructions on editing slapd.conf.
On the Clients, Edit /etc/ldap.conf and /etc/openldap/ldap.conf
On all client machines, both /etc/ldap.conf and /etc/openldap/ldap.conf need to contain the proper server and search base information for your organization.
The simplest way to do this is to run the authconfig application and select Use LDAP on the the User Information Configuration screen.
You can also edit these files by hand.
On the Clients, Edit /etc/nsswitch.conf
On all client machines, the /etc/nsswitch.conf must be edited to use LDAP.
The simplest way to do this is to run the authconfig application and select Use LDAP on the the User Information Configuration screen.
If editing /etc/nsswitch.conf by hand, add ldap to the appropriate fields.
For example:
passwd: files ldap shadow: files ldap group: files ldap |
PAM and LDAP
To have standard PAM-enabled applications use LDAP for authentication, run authconfig and select Use LDAP Authentication on the the Authentication Configuration screen. For more on configuring PAM consult, Chapter 7 and the PAM man pages.
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 |
|---|---|
You must have Perl installed on your system to use these scripts. |
First, you will need to modify the migrate_common.ph file so that it reflects your domain. The default DNS domain should be changed from its default value to something like:
$DEFAULT_MAIL_DOMAIN = "your_company"; |
The default base should also be changed, to something like:
$DEFAULT_BASE = "dc=your_company,dc=com"; |
The job of migrating a user database into a format LDAP can read falls to a group of migration scripts installed with the nss_ldap package. Using Table 18-1, decide which script to run in order to migrate your user database.
Table 18-1. LDAP Migration Scripts
| 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 |
Run the appropriate script based on your 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.