Network Working Group                                        K. Zeilenga
Request for Comments: 5020                                 Isode Limited
Category: Standards Track                                    August 2007


       The Lightweight Directory Access Protocol (LDAP) entryDN
                         Operational Attribute

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document describes the Lightweight Directory Access Protocol
   (LDAP) / X.500 'entryDN' operational attribute.  The attribute
   provides a copy of the entry's distinguished name for use in
   attribute value assertions.

1.  Background and Intended Use

   In X.500 Directory Services [X.501], such as those accessible using
   the Lightweight Directory Access Protocol (LDAP) [RFC4510], an entry
   is identified by its distinguished name (DN) [RFC4512].  However, as
   an entry's DN is not an attribute of the entry, it is not possible to
   perform attribute value assertions [RFC4511] against it.

   This document describes the 'entryDN' operational attribute which
   holds a copy of the entry's distinguished name.  This attribute may
   be used in search filters.  For instance, searching the subtree
   <dc=example,dc=com> with the filter:

      (entryDN:componentFilterMatch:=or:{
          item:{ component "3", rule rdnMatch, value "ou=A" },
          item:{ component "3", rule rdnMatch, value "ou=B" } })

   would return entries in the subtree <ou=A,dc=example,dc=com> and
   entries in subtree <ou=B,dc=example,dc=com>, but would not return any
   other entries in the subtree <dc=example,dc=com>.

   In the above paragraph, DNs are presented using the string
   representation defined in [RFC4514], and the example search filter is
   presented using the string representation defined in [RFC4515] with
   whitespace (line breaks and indentation) added to improve
   readability.  The 'componentFilterMatch' and 'rdnMatch' rules are
   specified in [RFC3687].

   Schema definitions are provided using LDAP description formats
   [RFC4512].  Definitions provided here are formatted (line wrapped)
   for readability.

2.  'entryDN' Operational Attribute

   The 'entryDN' operational attribute provides a copy of the entry's
   current DN.

   The following is an LDAP attribute type description suitable for
   publication in subschema subentries.

      ( 1.3.6.1.1.20 NAME 'entryDN'
          DESC 'DN of the entry'
          EQUALITY distinguishedNameMatch
          SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
          SINGLE-VALUE
          NO-USER-MODIFICATION
          USAGE directoryOperation )

   Note that the DN of the entry cannot be modified through this
   attribute.

3.  Security Considerations

   As this attribute only provides an additional mechanism to access an
   entry's DN, the introduction of this attribute is not believed to
   introduce new security considerations.

4.  IANA Considerations

4.1.  Object Identifier Registration

   IANA has registered (upon Standards Action) an LDAP Object Identifier
   [RFC4520] for use in this document.

      Subject: Request for LDAP OID Registration
      Person & email address to contact for further information:
          Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
      Specification: RFC 5020
      Author/Change Controller: IESG
      Comments:
          Identifies the 'entryDN' attribute type

4.2.  'entryDN' Descriptor Registration

   IANA has registered (upon Standards Action) the LDAP 'entryDN'
   descriptor [RFC4520].

      Subject: Request for LDAP Descriptor Registration
      Descriptor (short name): entryDN
      Object Identifier: 1.3.6.1.1.20
      Person & email address to contact for further information:
          Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
      Usage: Attribute Type
      Specification: RFC 5020
      Author/Change Controller: IESG

5.  References

5.1.  Normative References

   [RFC4510]   Zeilenga, K., Ed., "Lightweight Directory Access Protocol
               (LDAP): Technical Specification Road Map", RFC 4510, June
               2006.

   [RFC4512]   Zeilenga, K., Ed., "Lightweight Directory Access Protocol
               (LDAP): Directory Information Models", RFC 4512, June
               2006.

   [X.501]     International Telecommunication Union - Telecommunication
               Standardization Sector, "The Directory -- Models,"
               X.501(1993) (also ISO/IEC 9594-2:1994).

5.2.  Informative References

   [RFC3687]   Legg, S., "Lightweight Directory Access Protocol (LDAP)
               and X.500 Component Matching Rules", RFC 3687, February
               2004.

   [RFC4511]   Sermersheim, J., Ed., "Lightweight Directory Access
               Protocol (LDAP): The Protocol", RFC 4511, June 2006.

   [RFC4514]   Zeilenga, K., Ed., "Lightweight Directory Access Protocol
               (LDAP): String Representation of Distinguished Names",
               RFC 4514, June 2006.

   [RFC4515]   Smith, M., Ed., and T. Howes, "Lightweight Directory
               Access Protocol (LDAP): String Representation of Search
               Filters", RFC 4515, June 2006.

   [RFC4520]   Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
               Considerations for the Lightweight Directory Access
               Protocol (LDAP)", BCP 64, RFC 4520, June 2006.

Author's Address

   Kurt D. Zeilenga
   Isode Limited

   EMail: Kurt.Zeilenga@Isode.COM

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