Samba AD schema extensions

From SambaWiki

Schema Extension in Samba Active Directory

Samba AD supports the same kind of schema extensions as Microsoft Active Directory. Schema updates in AD are a sensitive action and you must be prepared to do a full restore of the DC holding the role of schema master if something goes wrong.

This is even more true in Samba 4 given it does not always generate some critical attributes that are generated on Microsoft AD and this lack of attributes can lead to a un-start-able samba provision. This is why schema updates in Samba AD are currently disabled by default.

In order to allow them, the option dsdb:schema update allowed must be set to true in the smb.conf or passed on the command line.

Verified Schema Extensions

As getting an LDIF that won't ruin the provision can be hard, this page will list LDIFs that are known not to break the database.

Perform these updates only if you need them and if you know how to restore the provision on the schema master.

NIS Extensions

See Installing the NIS Extensions.


This extension allow you to store automount information in LDAP. In order to add this extension, follow these steps:

  • Download Automount_template.ldif.txt, this is a template that will be transformed in the next steps
  • Locate the rootDN of your provision: ldbsearch -H ldap://ip_of_server -U administrator -s base dn
  • Run cat automount_template.ldif | sed 's/DOMAIN_TOP_DN/value_of_rootDN_obtained_in_previous_step/' > automount.ldif
  • Split the resulting file into two, one containing the attributes, the other containing the objectclasses
  • Name the two new files automount_attrs.ldif and automount_classes.ldif
  • Stop Samba4 on the schema master
  • Copy automount_attrs.ldif and automount_classes.ldif to the schema master server (if you were working on a different server)
  • Apply the ldifs with commands similar to:
    • ldbmodify -H path_to_sam_ldb automount_attrs.ldif --option="dsdb:schema update allowed"=true
    • ldbmodify -H path_to_sam_ldb automount_classes.ldif --option="dsdb:schema update allowed"=true

Building your own schema extensions


Internal use and experimental Samba OIDs is reserved in Samba for use by Samba installations internally.

Wiki OIDs

If you use a OID from this range, please note your use below.

  • Attributes in examples in this wiki page
  • Classes in examples in this wiki page

Syntax for attributes

  • See Microsoft's Documentaion on choosing a syntax
  • You need to choose the Syntax ID attributeSyntax (eg, Samba will map that to the and OM ID (eg 4) for you.
  • Decide if this will be isSingleValued (TRUE or by default FALSE)


  • You need a clear, ideally globally unique, name for your attribute or class, this will be the ldapDisplayName and CN
  • Consider re-using names from [] if there is no existing example for LDAP
  • LDAP schema are traditionally camalCase with a lowercase initial letter

Fill in your this template