The /etc/openldap/schema/ directory holds LDAP definitions, previously located in the slapd.at.conf and slapd.oc.conf files. The /etc/openldap/schema/redhat/ directory holds customized schemas distributed by Red Hat for Red Hat Enterprise Linux.

All attribute syntax definitions and objectclass definitions are now located in the different schema files. The various schema files are referenced in /etc/openldap/slapd.conf using include lines, as shown in this example:

include		/etc/openldap/schema/core.schema 
include		/etc/openldap/schema/cosine.schema 
include		/etc/openldap/schema/inetorgperson.schema 
include		/etc/openldap/schema/nis.schema 
include		/etc/openldap/schema/rfc822-MailMember.schema 
include		/etc/openldap/schema/redhat/autofs.schema

It is possible to extend the schema used by OpenLDAP to support additional attribute types and object classes using the default schema files as a guide. To do this, create a local.schema file in the /etc/openldap/schema/ directory. Reference this new schema within slapd.conf by adding the following line below the default include schema lines:

include          /etc/openldap/schema/local.schema

Next, define new attribute types and object classes within the local.schema file. Many organizations use existing attribute types from the schema files installed by default and add new object classes to the local.schema file.

Extending the schema to match certain specialized requirements is quite involved and beyond the scope of this chapter. Refer to https://www.openldap.org/doc/admin/schema.html for information.