    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.

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    RFC 5020                      LDAP entryDN                   August 2007

    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 )

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    RFC 5020                      LDAP entryDN                   August 2007

       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

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    RFC 5020                      LDAP entryDN                   August 2007

    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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    RFC 5020                      LDAP entryDN                   August 2007

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    Acknowledgement

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       Internet Society.

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