INTERNET-DRAFT Kurt D. Zeilenga Intended Category: Experimental OpenLDAP Foundation Expires in six months 8 February 2004 LDAP Turn Operation 1. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. This document is intended to be, after appropriate review and revision, submitted to the RFC Editor for publication as an Experimental document. Distribution of this memo is unlimited. Technical discussion of this document will take place on the IETF LDAP Extensions mailing list . Please send editorial comments directly to the author . Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as ``work in progress.'' The list of current Internet-Drafts can be accessed at . The list of Internet-Draft Shadow Directories can be accessed at . Copyright (C) The Internet Society (2004). All Rights Reserved. Please see the Full Copyright section near the end of this document for more information. Abstract This specification describes a Lightweight Directory Access Protocol (LDAP) extended operation to reverse (or "turn") the roles of client and server for subsequent protocol exchanges in the session. Zeilenga LDAP Turn Op [Page 1] INTERNET-DRAFT draft-zeilenga-ldap-turn-00 8 February 2004 1. Background and Intent of Use The Lightweight Directory Access Protocol (LDAP) [RFC3377] is a client / server protocol which typically operates over reliable octet stream transports such as the Transport Control Protocol (TCP). Generally, the client initiates the stream by connecting to the server's listener at some well-known address. There are cases where it is desirable for the server to initiate the stream. While it certainly is possible to write a technical specification detailing how to implement server-initiated LDAP sessions, this would requiring designing new authentication and other security features to support server-initiated LDAP sessions. This document instead introduces an operation, the Turn operation, which may be used to reverse the client / server roles of the protocol peers. This allows the initiating protocol peer to be server (after reversal). As an additional feature, the Turn operation may be used to allow both peers to act in both roles. This is useful where both peers are directory servers which desire to issue, as LDAP clients, operations against the other. This may be useful in replicated environments. This operation is intended to used between protocol peers which have established a mutual agreement, by means outside of the protocol, which requires reversal of client / server roles or both peers to act both as client and server. 1.1 Terminology Protocol elements are described using ASN.1 [X.680] with implicit tags. The term "BER-encoded" means the element is to be encoded using the Basic Encoding Rules [X.690] under the restrictions detailed in Section 5.1 of [RFC2251]. 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. Turn Operation The Turn operation is defined as a LDAP Extended Operation [RFC2251, Section 4.12] identified by the IANA-ASSIGNED-OID. The function of the Turn Operation is to request that the client / server roles be reversed, or, optionally to request that both protocol peers to be Zeilenga LDAP Turn Op [Page 2] INTERNET-DRAFT draft-zeilenga-ldap-turn-00 8 February 2004 able to act both as client and server. 2.1. Turn Request The Turn request is an ExtendedRequest with the requestName field containing the IANA-ASSIGNED-OID and a requestValue field is a BER-encoded turnValue: turnValue ::= SEQUENCE { mutual BOOLEAN DEFAULT FALSE, identifier LDAPString, } A TRUE value of the mutual field indicates a request to allow both peers to act both as client and server while a FALSE value indicates a request to reserve the client and server roles. The value of the identifier field is a locally-defined policy identifier (typicallly associated with a mutual agreement for which this turn is be executed as part of). This policy identifier is called the turn indicator. 2.2. Turn Response A Turn response is an ExtendedResponse where the responseName and response fields are absent. A resultCode of success is returned if and only if the responder is willing and able to turn the session as requested. Otherwise, a different resultCode is returned. 3. Security Considerations It is generally recommended that before issuing the Turn operation the protocol peers: - establish each other identities through appropriate authentication mechanism, - establish appropriate data integrity, data confidentiality, and other protections, - establish an LDAP association between the initiating peer and the responding peer. And upon successful completion of turn: - establish an LDAP association in reverse. That is, for peer A connecting to peer B listening and where TLS and Zeilenga LDAP Turn Op [Page 3] INTERNET-DRAFT draft-zeilenga-ldap-turn-00 8 February 2004 SASL/EXTERNAL were to be used, the sequence of operations would be: A->B: StartTLS A->B: Bind(SASL,EXTERNAL) A->B: Turn B->A: Bind(SASL,EXTERNAL) 4. IANA Considerations Registration of the following values [RFC3383] is requested. 4.1. Object Identifier It is requested that IANA assign an LDAP Object Identifier to identify the LDAP Turn Operation as defined in this document. Subject: Request for LDAP Object Identifier Registration Person & email address to contact for further information: Kurt Zeilenga Specification: RFC XXXX Author/Change Controller: Author Comments: Identifies the LDAP Turn Operation 4.2. LDAP Protocol Mechanism It is requested that IANA register the LDAP Protocol Mechanism described in this document. Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID Description: LDAP Turn Operation Person & email address to contact for further information: Kurt Zeilenga Usage: Extended Operation Specification: RFC XXXX Author/Change Controller: Author Comments: none 5. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14 (also RFC 2119), March 1997. Zeilenga LDAP Turn Op [Page 4] INTERNET-DRAFT draft-zeilenga-ldap-turn-00 8 February 2004 [RFC2251] Wahl, M., T. Howes 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. [X.680] International Telecommunication Union - Telecommunication Standardization Sector, "Abstract Syntax Notation One (ASN.1) - Specification of Basic Notation", X.680(1997) (also ISO/IEC 8824-1:1998). [X.690] International Telecommunication Union - Telecommunication Standardization Sector, "Specification of ASN.1 encoding rules: Basic Encoding Rules (BER), Canonical Encoding Rules (CER), and Distinguished Encoding Rules (DER)", X.690(1997) (also ISO/IEC 8825-1:1998). 6. Informative References [RFC3383] Zeilenga, K., "IANA Considerations for LDAP", BCP 64 (also RFC 3383), September 2002. 7. Author's Address Kurt D. Zeilenga OpenLDAP Foundation Email: Kurt@OpenLDAP.org Intellectual Property Rights 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 Zeilenga LDAP Turn Op [Page 5] INTERNET-DRAFT draft-zeilenga-ldap-turn-00 8 February 2004 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. Full Copyright Copyright (C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. Zeilenga LDAP Turn Op [Page 6]