Request for Comments: 3673
Category: Standards Track
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 © 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 attributes.
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 APIs.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119].
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 220.127.116.11.4.1.418.104.22.168 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.
5. IANA Considerations
This document uses the OID 22.214.171.124.4.1.4126.96.36.199 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.
Request for LDAP Protocol Mechanism Registration
Object Identifier: 188.8.131.52.4.1.4184.108.40.206
All Op Attrs
Person & email address to contact for further information:
Kurt Zeilenga <email@example.com>
RFC3673 Author/Change Controller: IESG
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.
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 Director.
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", http://www.openldap.org/foundation/oid-delegate.txt. [PRIVATE] IANA, "Private Enterprise Numbers", http://www.iana.org/assignments/enterprise-numbers.
9. Author's Address
Kurt D. Zeilenga
10. Full Copyright Statement
Copyright © The Internet Society (2003). All Rights Reserved.
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