draft-zeilenga-ldap-turn-xx.txt [plain text]
INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Experimental OpenLDAP Foundation
Expires in six months 8 February 2004
LDAP Turn Operation
<draft-zeilenga-ldap-turn-00.txt>
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 <ldapext@ietf.org>. Please send editorial
comments directly to the author <Kurt@OpenLDAP.org>.
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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.
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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
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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
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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 <kurt@OpenLDAP.org>
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 <kurt@openldap.org>
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.
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[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
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