rfc2830.txt

<VC++网络游戏建摸与实现>源代码


RFC 2830     LDAPv3: Extension for Transport Layer Security     May 2000


5.  Effects of TLS on a Client's Authorization Identity

   This section describes the effects on a client's authorization
   identity brought about by establishing TLS on an LDAP association.
   The default effects are described first, and next the facilities for
   client assertion of authorization identity are discussed including
   error conditions. Lastly, the effects of closing the TLS connection
   are described.

   Authorization identities and related concepts are defined in
   [AuthMeth].

5.1.  TLS Connection Establishment Effects

5.1.1.  Default Effects

   Upon establishment of the TLS connection onto the LDAP association,
   any previously established authentication and authorization
   identities MUST remain in force, including anonymous state. This
   holds even in the case where the server requests client
   authentication via TLS -- e.g. requests the client to supply its
   certificate during TLS negotiation (see [TLS]).

5.1.2.  Client Assertion of Authorization Identity

   A client MAY either implicitly request that its LDAP authorization
   identity be derived from its authenticated TLS credentials or it MAY
   explicitly provide an authorization identity and assert that it be
   used in combination with its authenticated TLS credentials. The
   former is known as an implicit assertion, and the latter as an
   explicit assertion.

5.1.2.1.  Implicit Assertion

   An implicit authorization identity assertion is accomplished after
   TLS establishment by invoking a Bind request of the SASL form using
   the "EXTERNAL" mechanism name [SASL, LDAPv3] that SHALL NOT include
   the optional credentials octet string (found within the
   SaslCredentials sequence in the Bind Request). The server will derive
   the client's authorization identity from the authentication identity
   supplied in the client's TLS credentials (typically a public key
   certificate) according to local policy. The underlying mechanics of
   how this is accomplished are implementation specific.








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5.1.2.2.  Explicit Assertion

   An explicit authorization identity assertion is accomplished after
   TLS establishment by invoking a Bind request of the SASL form using
   the "EXTERNAL" mechanism name [SASL, LDAPv3] that SHALL include the
   credentials octet string. This string MUST be constructed as
   documented in section 9 of [AuthMeth].

5.1.2.3.  Error Conditions

   For either form of assertion, the server MUST verify that the
   client's authentication identity as supplied in its TLS credentials
   is permitted to be mapped to the asserted authorization identity. The
   server MUST reject the Bind operation with an invalidCredentials
   resultCode in the Bind response if the client is not so authorized.

   Additionally, with either form of assertion, if a TLS session has not
   been established between the client and server prior to making the
   SASL EXTERNAL Bind request and there is no other external source of
   authentication credentials (e.g.  IP-level security [IPSEC]), or if,
   during the process of establishing the TLS session, the server did
   not request the client's authentication credentials, the SASL
   EXTERNAL bind MUST fail with a result code of
   inappropriateAuthentication.

   After the above Bind operation failures, any client authentication
   and authorization state of the LDAP association is lost, so the LDAP
   association is in an anonymous state after the failure.  TLS
   connection state is unaffected, though a server MAY end the TLS
   connection, via a TLS close_notify message, based on the Bind failure
   (as it MAY at any time).

5.2.  TLS Connection Closure Effects

   Closure of the TLS connection MUST cause the LDAP association to move
   to an anonymous authentication and authorization state regardless of
   the state established over TLS and regardless of the authentication
   and authorization state prior to TLS connection establishment.

6.  Security Considerations

   The goals of using the TLS protocol with LDAP are to ensure
   connection confidentiality and integrity, and to optionally provide
   for authentication. TLS expressly provides these capabilities, as
   described in [TLS].






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   All security gained via use of the Start TLS operation is gained by
   the use of TLS itself. The Start TLS operation, on its own, does not
   provide any additional security.

   The use of TLS does not provide or ensure for confidentiality and/or
   non-repudiation of the data housed by an LDAP-based directory server.
   Nor does it secure the data from inspection by the server
   administrators.  Once established, TLS only provides for and ensures
   confidentiality and integrity of the operations and data in transit
   over the LDAP association, and only if the implementations on the
   client and server support and negotiate it.

   The level of security provided though the use of TLS depends directly
   on both the quality of the TLS implementation used and the style of
   usage of that implementation. Additionally, an active-intermediary
   attacker can remove the Start TLS extended operation from the
   supportedExtension attribute of the root DSE. Therefore, both parties
   SHOULD independently ascertain and consent to the security level
   achieved once TLS is established and before beginning use of the TLS
   connection. For example, the security level of the TLS connection
   might have been negotiated down to plaintext.

   Clients SHOULD either warn the user when the security level achieved
   does not provide confidentiality and/or integrity protection, or be
   configurable to refuse to proceed without an acceptable level of
   security.

   Client and server implementors SHOULD take measures to ensure proper
   protection of credentials and other confidential data where such
   measures are not otherwise provided by the TLS implementation.

   Server implementors SHOULD allow for server administrators to elect
   whether and when connection confidentiality and/or integrity is
   required, as well as elect whether and when client authentication via
   TLS is required.

7.  Acknowledgements

   The authors thank Tim Howes, Paul Hoffman, John Kristian, Shirish
   Rai, Jonathan Trostle, Harald Alvestrand, and Marcus Leech for their
   contributions to this document.










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8.  References

   [AuthMeth]     Wahl, M., Alvestrand, H., Hodges, J. and R. Morgan,
                  "Authentication Methods for LDAP", RFC 2829, May 2000.

   [IPSEC]        Kent, S. and R. Atkinson, "Security Architecture for
                  the Internet Protocol", RFC 2401, November 1998.

   [LDAPv3]       Wahl, M., Kille S. and T. Howes, "Lightweight
                  Directory Access Protocol (v3)", RFC 2251, December
                  1997.

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

   [SASL]         Myers, J., "Simple Authentication and Security Layer
                  (SASL)", RFC 2222, October 1997.

   [TLS]          Dierks, T. and C. Allen. "The TLS Protocol Version
                  1.0", RFC 2246, January 1999.

9.  Authors' Addresses

   Jeff Hodges
   Oblix, Inc.
   18922 Forge Drive
   Cupertino, CA 95014
   USA

   Phone: [phone]
   EMail: [e-mail]

   RL "Bob" Morgan
   Computing and Communications
   University of Washington
   Seattle, WA
   USA

   Phone: [phone]
   EMail: [e-mail]

   Mark Wahl
   Sun Microsystems, Inc.
   8911 Capital of Texas Hwy #4140
   Austin TX 78759
   USA

   EMail: [e-mail]



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10.  Intellectual Property Rights Notices

   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.






























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11.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  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
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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
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Acknowledgement

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



















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