6 INTERNET-DRAFT Kurt D. Zeilenga
7 Intended Category: Experimental OpenLDAP Foundation
8 Expires in six months 8 February 2004
13 <draft-zeilenga-ldap-turn-00.txt>
16 1. Status of this Memo
18 This document is an Internet-Draft and is in full conformance with all
19 provisions of Section 10 of RFC2026.
21 This document is intended to be, after appropriate review and
22 revision, submitted to the RFC Editor for publication as an
23 Experimental document. Distribution of this memo is unlimited.
24 Technical discussion of this document will take place on the IETF LDAP
25 Extensions mailing list <ldapext@ietf.org>. Please send editorial
26 comments directly to the author <Kurt@OpenLDAP.org>.
28 Internet-Drafts are working documents of the Internet Engineering Task
29 Force (IETF), its areas, and its working groups. Note that other
30 groups may also distribute working documents as Internet-Drafts.
31 Internet-Drafts are draft documents valid for a maximum of six months
32 and may be updated, replaced, or obsoleted by other documents at any
33 time. It is inappropriate to use Internet-Drafts as reference
34 material or to cite them other than as ``work in progress.''
36 The list of current Internet-Drafts can be accessed at
37 <http://www.ietf.org/ietf/1id-abstracts.txt>. The list of
38 Internet-Draft Shadow Directories can be accessed at
39 <http://www.ietf.org/shadow.html>.
41 Copyright (C) The Internet Society (2004). All Rights Reserved.
43 Please see the Full Copyright section near the end of this document
49 This specification describes a Lightweight Directory Access Protocol
50 (LDAP) extended operation to reverse (or "turn") the roles of client
51 and server for subsequent protocol exchanges in the session.
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62 1. Background and Intent of Use
64 The Lightweight Directory Access Protocol (LDAP) [RFC3377] is a client
65 / server protocol which typically operates over reliable octet stream
66 transports such as the Transport Control Protocol (TCP). Generally,
67 the client initiates the stream by connecting to the server's listener
68 at some well-known address.
70 There are cases where it is desirable for the server to initiate the
71 stream. While it certainly is possible to write a technical
72 specification detailing how to implement server-initiated LDAP
73 sessions, this would requiring designing new authentication and other
74 security features to support server-initiated LDAP sessions.
76 This document instead introduces an operation, the Turn operation,
77 which may be used to reverse the client / server roles of the
78 protocol peers. This allows the initiating protocol peer to be server
81 As an additional feature, the Turn operation may be used to allow both
82 peers to act in both roles. This is useful where both peers are
83 directory servers which desire to issue, as LDAP clients, operations
84 against the other. This may be useful in replicated environments.
86 This operation is intended to used between protocol peers which have
87 established a mutual agreement, by means outside of the protocol,
88 which requires reversal of client / server roles or both peers to act
89 both as client and server.
94 Protocol elements are described using ASN.1 [X.680] with implicit
95 tags. The term "BER-encoded" means the element is to be encoded using
96 the Basic Encoding Rules [X.690] under the restrictions detailed in
97 Section 5.1 of [RFC2251].
99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
101 document are to be interpreted as described in BCP 14 [RFC2119].
106 The Turn operation is defined as a LDAP Extended Operation [RFC2251,
107 Section 4.12] identified by the IANA-ASSIGNED-OID. The function of
108 the Turn Operation is to request that the client / server roles be
109 reversed, or, optionally to request that both protocol peers to be
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118 able to act both as client and server.
123 The Turn request is an ExtendedRequest with the requestName field
124 containing the IANA-ASSIGNED-OID and a requestValue field is a
125 BER-encoded turnValue:
127 turnValue ::= SEQUENCE {
128 mutual BOOLEAN DEFAULT FALSE,
129 identifier LDAPString,
132 A TRUE value of the mutual field indicates a request to allow both
133 peers to act both as client and server while a FALSE value indicates a
134 request to reserve the client and server roles.
136 The value of the identifier field is a locally-defined policy
137 identifier (typicallly associated with a mutual agreement for which
138 this turn is be executed as part of). This policy identifier is
139 called the turn indicator.
144 A Turn response is an ExtendedResponse where the responseName and
145 response fields are absent. A resultCode of success is returned if
146 and only if the responder is willing and able to turn the session as
147 requested. Otherwise, a different resultCode is returned.
150 3. Security Considerations
152 It is generally recommended that before issuing the Turn operation the
155 - establish each other identities through appropriate authentication
157 - establish appropriate data integrity, data confidentiality, and
159 - establish an LDAP association between the initiating peer and the
162 And upon successful completion of turn:
163 - establish an LDAP association in reverse.
165 That is, for peer A connecting to peer B listening and where TLS and
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174 SASL/EXTERNAL were to be used, the sequence of operations would be:
177 A->B: Bind(SASL,EXTERNAL)
179 B->A: Bind(SASL,EXTERNAL)
182 4. IANA Considerations
184 Registration of the following values [RFC3383] is requested.
187 4.1. Object Identifier
189 It is requested that IANA assign an LDAP Object Identifier to identify
190 the LDAP Turn Operation as defined in this document.
192 Subject: Request for LDAP Object Identifier Registration
193 Person & email address to contact for further information:
194 Kurt Zeilenga <kurt@OpenLDAP.org>
195 Specification: RFC XXXX
196 Author/Change Controller: Author
198 Identifies the LDAP Turn Operation
201 4.2. LDAP Protocol Mechanism
203 It is requested that IANA register the LDAP Protocol Mechanism
204 described in this document.
206 Subject: Request for LDAP Protocol Mechanism Registration
207 Object Identifier: IANA-ASSIGNED-OID
208 Description: LDAP Turn Operation
209 Person & email address to contact for further information:
210 Kurt Zeilenga <kurt@openldap.org>
211 Usage: Extended Operation
212 Specification: RFC XXXX
213 Author/Change Controller: Author
217 5. Normative References
219 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
220 Requirement Levels", BCP 14 (also RFC 2119), March 1997.
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227 INTERNET-DRAFT draft-zeilenga-ldap-turn-00 8 February 2004
230 [RFC2251] Wahl, M., T. Howes and S. Kille, "Lightweight Directory
231 Access Protocol (v3)", RFC 2251, December 1997.
233 [RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
234 Protocol (v3): Technical Specification", RFC 3377,
237 [X.680] International Telecommunication Union -
238 Telecommunication Standardization Sector, "Abstract
239 Syntax Notation One (ASN.1) - Specification of Basic
240 Notation", X.680(1997) (also ISO/IEC 8824-1:1998).
242 [X.690] International Telecommunication Union -
243 Telecommunication Standardization Sector, "Specification
244 of ASN.1 encoding rules: Basic Encoding Rules (BER),
245 Canonical Encoding Rules (CER), and Distinguished
246 Encoding Rules (DER)", X.690(1997) (also ISO/IEC
250 6. Informative References
252 [RFC3383] Zeilenga, K., "IANA Considerations for LDAP", BCP 64
253 (also RFC 3383), September 2002.
261 Email: Kurt@OpenLDAP.org
265 Intellectual Property Rights
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299 Copyright (C) The Internet Society (2004). All Rights Reserved.
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337 Zeilenga LDAP Turn Op [Page 6]