RFC3673: Lightweight Directory Access Protocol version 3 (LDAPv3): All Operational Attributes

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Related keywords:  (Extension) (user mechanisms)

Network Working Group                                        K. Zeilenga
Request for Comments: 3673                           OpenLDAP Foundation
Category: Standards Track                                  December 2003

       Lightweight Directory Access Protocol version 3 (LDAPv3):
                       All Operational Attributes

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 Internet Society (2003).  All Rights Reserved.


   The Lightweight Directory Access Protocol (LDAP) supports a mechanism
   for requesting the return of all user attributes but not all
   operational attributes.  This document describes an LDAP extension
   which clients may use to request the return of all operational

1.  Overview

   X.500 [X.500] provides a mechanism for clients to request all
   operational attributes be returned with entries provided in response
   to a search operation.  This mechanism is often used by clients to
   discover which operational attributes are present in an entry.

   This documents extends the Lightweight Directory Access Protocol
   (LDAP) [RFC3377] to provide a simple mechanism which clients may use
   to request the return of all operational attributes.  The mechanism
   is designed for use with existing general purpose LDAP clients
   (including web browsers which support LDAP URLs) and existing LDAP

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in BCP 14 [RFC2119].

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2.  All Operational Attributes

   The presence of the attribute description "+" (ASCII 43) in the list
   of attributes in a Search Request [RFC2251] SHALL signify a request
   for the return of all operational attributes.

   As with all search requests, client implementors should note that
   results may not include all requested attributes due to access
   controls or other restrictions.  Client implementors should also note
   that certain operational attributes may be returned only if requested
   by name even when "+" is present.  This is because some operational
   attributes are very expensive to return.

   Servers supporting this feature SHOULD publish the Object Identifier as a value of the 'supportedFeatures'
   [RFC3674] attribute in the root DSE.

3.  Interoperability Considerations

   This mechanism is specifically designed to allow users to request all
   operational attributes using existing LDAP clients.  In particular,
   the mechanism is designed to be compatible with existing general
   purpose LDAP clients including those supporting LDAP URLs [RFC2255].

   The addition of this mechanism to LDAP is not believed to cause any
   significant interoperability issues (this has been confirmed through
   testing).  Servers which have yet to implement this specification
   should ignore the "+" as an unrecognized attribute description per
   [RFC2251, Section 4.5.1].  From the client's perspective, a server
   which does not return all operational attributes when "+" is
   requested should be viewed as having other restrictions.

   It is also noted that this mechanism is believed to require no
   modification of existing LDAP APIs.

4.  Security Considerations

   This document provides a general mechanism which clients may use to
   discover operational attributes.  Prior to the introduction of this
   mechanism, operational attributes were only returned when requested
   by name.  Some might have viewed this as obscurity feature.  However,
   this feature offers a false sense of security as the attributes were
   still transferable.

   Implementations SHOULD implement appropriate access controls
   mechanisms to restricts access to operational attributes.

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5.  IANA Considerations

   This document uses the OID to identify the
   feature described above.  This OID was assigned [ASSIGN] by OpenLDAP
   Foundation, under its IANA-assigned private enterprise allocation
   [PRIVATE], for use in this specification.

   Registration of this feature has been completed by IANA [RFC3674],

   Subject: Request for LDAP Protocol Mechanism Registration

   Object Identifier:

   Description: All Op Attrs

   Person & email address to contact for further information:
        Kurt Zeilenga <kurt@openldap.org>

   Usage: Feature

   Specification: RFC3673

   Author/Change Controller: IESG

   Comments: none

6.  Acknowledgment

   The "+" mechanism is believed to have been first suggested by Bruce
   Greenblatt in a November 1998 post to the IETF LDAPext Working Group
   mailing list.

7.  Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11.  Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

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   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard.  Please address the information to the IETF Executive

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2251]  Wahl, M., Howes, T. and S. Kille, "Lightweight Directory
              Access Protocol (v3)", RFC 2251, December 1997.

   [RFC3377]  Hodges, J. and R. Morgan, "Lightweight Directory Access
              Protocol (v3): Technical Specification", RFC 3377,
              September 2002.

   [RFC3674]  Zeilenga, K., "Feature Discovery in Lightweight Directory
              Access Protocol (LDAP)", RFC 3674, December 2003.

8.2.  Informative References

   [RFC2255]  Howes, T. and M. Smith, "The LDAP URL Format", RFC 2255,
              December 1997.

   [RFC3383]  Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
              Considerations for the Lightweight Directory Access
              Protocol (LDAP)", BCP 64, RFC 3383, September 2002.

   [X.500]    ITU-T Rec.  X.500, "The Directory: Overview of Concepts,
              Models and Service", 1993.

   [ASSIGN]   OpenLDAP Foundation, "OpenLDAP OID Delegations",

   [PRIVATE]  IANA, "Private Enterprise Numbers",

9.  Author's Address

   Kurt D. Zeilenga
   OpenLDAP Foundation

   EMail: Kurt@OpenLDAP.org

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10.  Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

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   The limited permissions granted above are perpetual and will not be
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   This document and the information contained herein is provided on an


   Funding for the RFC Editor function is currently provided by the
   Internet Society.

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