1 INTERNET-DRAFT Editor: R. Harrison
2 draft-ietf-ldapbis-authmeth-13.txt Novell, Inc.
3 Obsoletes: 2829, 2830 October, 2004
4 Intended Category: Draft Standard
13 LDAP: Authentication Methods
15 Connection Level Security Mechanisms
21 By submitting this Internet-Draft, I accept the provisions of
22 Section 4 of RFC 3667. By submitting this Internet-Draft, I certify
23 that any applicable patent or other IPR claims of which I am aware
24 have been disclosed, and any of which I become aware will be
25 disclosed, in accordance with RFC 3668.
28 This document is intended to be, after appropriate review and
29 revision, submitted to the RFC Editor as a Standard Track document.
30 Distribution of this memo is unlimited. Technical discussion of
31 this document will take place on the IETF LDAP Revision Working
32 Group mailing list <ietf-ldapbis@OpenLDAP.org>. Please send
33 editorial comments directly to the author
34 <roger_harrison@novell.com>.
37 Internet-Drafts are working documents of the Internet Engineering
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39 other groups may also distribute working documents as Internet-
43 Internet-Drafts are draft documents valid for a maximum of six
44 months and may be updated, replaced, or obsoleted by other documents
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46 reference material or to cite them other than as "work in progress."
49 The list of current Internet-Drafts can be accessed at
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60 Copyright (C) The Internet Society (2004). All Rights Reserved.
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71 This document describes authentication methods and connection level
72 security mechanisms of the Lightweight Directory Access Protocol
76 This document details establishment of TLS (Transport Layer
77 Security) using the StartTLS operation.
80 This document details the simple Bind authentication method
81 including anonymous, unauthenticated, and plain-text password
82 mechanisms and the SASL (Simple Authentication and Security Layer)
83 Bind authentication method including DIGEST-MD5 and EXTERNAL
87 This document discusses various authentication and authorization
88 states through which a connection to an LDAP server may pass and the
89 actions that trigger these state changes.
95 1. Introduction.....................................................3
96 1.1. Relationship to Other Documents................................5
97 1.2. Conventions Used in this Document..............................6
98 1.2.1. Glossary of Terms............................................6
99 1.2.2. Security Terms and Concepts..................................6
100 1.2.3. Keywords.....................................................6
101 2. Implementation Requirements......................................6
102 3. StartTLS Operation...............................................7
103 3.1. Sequencing of the StartTLS Operation...........................7
104 3.1.1. StartTLS Request ............................................7
105 3.1.2. StartTLS Response............................................8
106 3.1.3. TLS Version Negotiation......................................8
107 3.1.4. Client Certificate...........................................8
108 3.1.5. Discovery of Resultant Security Level........................9
109 3.1.6. Server Identity Check........................................9
110 3.1.7. Refresh of Server Capabilities Information..................10
111 3.2. Effects of TLS on a Client's Authorization Identity...........10
112 3.2.1. TLS Connection Establishment Effects........................10
113 3.2.2. Client Assertion of Authorization Identity..................10
114 3.2.3. TLS Connection Closure Effects..............................10
115 3.3. TLS Ciphersuites..............................................11
116 3.3.1. TLS Ciphersuites Recommendations............................11
117 4. Associations....................................................12
118 4.1. Anonymous Association on Unbound Connections..................12
119 4.2. Anonymous Association After Failed Bind.......................12
120 4.3. Invalidated Associations......................................12
121 5. Bind Operation..................................................13
122 5.1. Simple Authentication Choice..................................13
123 5.2. SASL Authentication Choice....................................13
124 6. Anonymous Authentication Mechanism of Simple Bind...............13
125 7. Unauthenticated Authentication Mechanism of Simple Bind.........13
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133 8. Simple Authentication Mechanism of Simple Bind .................14
134 9. SASL Protocol Profile...........................................15
135 9.1. SASL Service Name for LDAP....................................15
136 9.2. SASL Authentication Initiation and Protocol Exchange..........15
137 9.3. Octet Where Negotiated Security Mechanisms Take Effect........16
138 9.4. Determination of Supported SASL Mechanisms....................16
139 9.5. Rules for Using SASL Security Layers..........................17
140 9.6 Support for Multiple Authentications...........................17
141 10. SASL EXTERNAL Authentication Mechanism.........................17
142 10.1. Implicit Assertion...........................................17
143 10.2. Explicit Assertion...........................................18
144 10.3. SASL Authorization Identity..................................18
145 10.4. SASL Authorization Identity Syntax...........................18
146 11. SASL DIGEST-MD5 Authentication Mechanism.......................19
147 12. Security Considerations........................................19
148 12.1. General LDAP Security Considerations.........................19
149 12.1.1. Password-related Security Considerations...................20
150 12.2. StartTLS Security Considerations.............................20
151 12.3. Unauthenticated Mechanism Security Considerations............21
152 12.4. Simple Mechanism Security Considerations.....................21
153 12.5. SASL DIGEST-MD5 Mechanism Security Considerations............21
154 12.6. Related Security Considerations..............................22
155 13. IANA Considerations............................................22
156 Acknowledgments....................................................22
157 Normative References...............................................22
158 Informative References.............................................23
159 Author's Address...................................................24
160 Appendix A. Association State Transition Tables....................24
161 A.1. Association States............................................24
162 A.2. Actions that Affect Association State.........................25
163 A.3. Decisions Used in Making Association State Changes............25
164 A.4. Association State Transition Table............................25
165 Appendix B. Authentication and Authorization Concepts..............26
166 B.1. Access Control Policy.........................................26
167 B.2. Access Control Factors........................................26
168 B.3. Authentication, Credentials, Identity.........................27
169 B.4. Authorization Identity........................................27
170 Appendix C. RFC 2829 Change History................................27
171 Appendix D. RFC 2830 Change History................................31
172 Appendix E. RFC 2251 Change History................................32
173 Appendix F. Change History to Combined Document....................32
174 Added implementation requirement that server implementations ......45
175 Intellectual Property Rights.......................................45
182 The Lightweight Directory Access Protocol (LDAP) [Roadmap] is a
183 powerful protocol for accessing directories. It offers means of
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192 searching, retrieving and manipulating directory content, and ways
193 to access a rich set of security functions.
196 It is vital that these security functions be interoperable among all
197 LDAP clients and servers on the Internet; therefore there has to be
198 a minimum subset of security functions that is common to all
199 implementations that claim LDAP conformance.
202 Basic threats to an LDAP directory service include:
205 (1) Unauthorized access to directory data via data-retrieval
209 (2) Unauthorized access to directory data by monitoring others'
213 (3) Unauthorized access to reusable client authentication
214 information by monitoring others' access,
217 (4) Unauthorized modification of directory data,
220 (5) Unauthorized modification of configuration information,
223 (6) Denial of Service: Use of resources (commonly in excess) in a
224 manner intended to deny service to others,
227 (7) Spoofing: Tricking a user or client into believing that
228 information came from the directory when in fact it did not,
229 either by modifying data in transit or misdirecting the client's
230 connection. Tricking a user or client into sending privileged
231 information to a hostile entity that appears to be the directory
232 server but is not. Tricking a directory server into believing
233 that information came from a particular client when in fact it
234 came from a hostile entity, and
237 (8) Hijacking: An attacker seizes control of an established protocol
241 Threats (1), (4), (5), (6), (7) are (8) are active attacks. Threats
242 (2) and (3) are passive attacks.
245 Threats (1), (4), (5) and (6) are due to hostile clients. Threats
246 (2), (3), (7) and (8) are due to hostile agents on the path between
247 client and server or hostile agents posing as a server, e.g. IP
252 LDAP offers the following security mechanisms:
255 (1) Authentication by means of the Bind operation. The Bind
256 operation provides a simple method which supports anonymous,
257 unauthenticated, and authenticated with password mechanisms, and
258 the Secure Authentication and Security Layer (SASL) method which
259 supports a wide variety of authentication mechanisms,
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267 (2) Mechanisms to support vendor-specific access control facilities
268 (LDAP does not offer a standard access control facility)
271 (3) Data integrity protection by means of security layers in TLS or
275 (4) Data confidentiality protection by means of security layers in
276 TLS or SASL mechanisms,
279 (5) Server resource usage limitation by means of administrative
280 limits configured on the server, and
283 (6) Server authentication by means of the TLS protocol or SASL
287 LDAP may also be protected by means outside the LDAP protocol, e.g.
288 with IP-level security [RFC2401].
291 At the moment, imposition of access controls is done by means
292 outside the scope of LDAP.
295 Considering the above requirements, experience has shown that simply
296 allowing implementations to pick and choose among the possible
297 alternatives is not a strategy that leads to interoperability. In
298 the absence of mandates, clients will continue to be written that do
299 not support any security function supported by the server, or worse,
300 they will support only clear text passwords that provide inadequate
301 security for most circumstances.
304 It is desirable to allow clients to authenticate using a variety of
305 mechanisms including mechanisms where identities are represented as
306 distinguished names [X.501] [Models] in string form [LDAPDN] or are
307 used in different systems (e.g. user name in string form). Because
308 some authentication mechanisms transmit credentials in plain text
309 form and/or do not provide data security services, it is necessary
310 to ensure secure interoperability by identifying a mandatory-to-
311 implement mechanism for establishing transport-layer security
315 The set of security mechanisms provided in LDAP and described in
316 this document is intended to meet the security needs for a wide
317 range of deployment scenarios and still provide a high degree of
318 interoperability among various LDAP implementations and deployments.
319 Appendix B contains example deployment scenarios that list the
320 mechanisms that might be used to achieve a reasonable level of
321 security in various circumstances.
324 1.1. Relationship to Other Documents
327 This document is an integral part of the LDAP Technical
328 Specification [Roadmap].
331 This document obsoletes RFC 2829.
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339 Sections 2 and 4 of RFC 2830 are obsoleted by [Protocol]. The
340 remainder of RFC 2830 is obsoleted by this document.
343 1.2. Conventions Used in this Document
346 1.2.1. Glossary of Terms
349 The following terms are used in this document. To aid the reader,
350 these terms are defined here.
353 - "user" represents any human or application entity which is
354 accessing the directory using a directory client. A directory
355 client (or client) is also known as a directory user agent (DUA).
358 - "connection" refers to the underlying transport protocol
359 connection used to carry the protocol exchange.
362 - "TLS connection" refers to an LDAP connection with TLS
366 - "association" refers to the association that exists between the
367 connection to its current authorization state. As a shorthand,
368 an association with an authorization state of <state> can be
369 referred to as a "<state> association", e.g. an association with
370 an anonymous authorization state is an anonymous association.
373 1.2.2. Security Terms and Concepts
376 In general, security terms in this document are used consistently
377 with the definitions provided in [RFC2828]. In addition, several
378 terms and concepts relating to security, authentication, and
379 authorization are presented in Appendix C of this document. While
380 the formal definition of these terms and concepts is outside the
381 scope of this document, an understanding of them is prerequisite to
382 understanding much of the material in this document. Readers who are
383 unfamiliar with security-related concepts are encouraged to review
384 Appendix C before reading the remainder of this document.
390 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
391 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
392 document are to be interpreted as described in RFC 2119 [RFC2119].
395 2. Implementation Requirements
398 LDAP server implementations MUST support the anonymous
399 authentication mechanism of simple bind (as discussed in Section 6).
402 LDAP implementations that support any authentication mechanism other
403 than the anonymous authentication mechanism of simple bind MUST
404 support the DIGEST-MD5 [DIGEST-MD5] mechanism of SASL bind (as
405 detailed in section 11). DIGEST-MD5 is a reasonably strong
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412 authentication mechanism that provides (mandatory-to-implement) data
413 security (data integrity and data confidentiality) services.
416 LDAP impementations SHOULD support the simple (DN and password)
417 authentication mechanism of simple bind (as detailed in section 8).
418 Implementations that support this mechanism MUST be capable of
419 protecting it by establishment of TLS (as discussed in section 3) or
420 other suitable suitable data confidentiality and data integrity
421 protection (e.g. IPSec).
424 Implementations MAY support additional authentication mechanisms.
425 Some of these mechanisms are discussed below.
428 LDAP server implementations SHOULD support client assertion of
429 authorization identity via the SASL EXTERNAL mechanism (sections
433 LDAP server implementations SHOULD support the StartTLS operation,
434 and server implementations that do support the StartTLS operation
435 MUST support the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA ciphersuite.
438 3. StartTLS Operation
441 The Start Transport Layer Security (StartTLS) operation defined in
442 section 4.14 of [Protocol] provides the ability to establish TLS
443 [TLS] on an LDAP connection.
446 The goals of using the TLS [TLS] protocol with LDAP are to ensure
447 data confidentiality and integrity, and to optionally provide for
448 authentication. TLS expressly provides these capabilities, although
449 the authentication services of TLS are available to LDAP only in
450 combination with the SASL EXTERNAL authentication method (see
451 section 10), and then only if the SASL EXTERNAL implementation
452 chooses to make use of the TLS credentials.
455 3.1. Sequencing of the StartTLS Operation
458 This section describes the overall procedures clients and servers
459 must follow for TLS establishment. These procedures take into
460 consideration various aspects of the association including discovery
461 of resultant security level and assertion of the client's
462 authorization identity.
465 3.1.1. StartTLS Request
468 A client may send the StartTLS extended request at any time after
469 establishing an LDAP connection, except:
472 - when TLS is currently established on the connection,
473 - when a multi-stage SASL negotiation is in progress on the
475 - when it has not yet received responses for all operation
476 requests previously issued on the connection.
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484 As described in [Protocol] Section 4.14.2.2, a (detected) violation
485 of any of these requirements results in a return of the
486 operationsError resultCode.
489 Client implementers should ensure that they strictly follow these
490 operation sequencing requirements to prevent interoperability
491 issues. Operational experience has shown that violating these
492 requirements causes interoperability issues because there are race
493 conditions that prevent servers from detecting some violations of
494 these requirements due to server hardware speed, network latencies,
498 There is no general requirement that the client have or have not
499 already performed a Bind operation (section 4) before sending a
500 StartTLS operation request.
503 If the client did not establish a TLS connection before sending a
504 request and the server requires the client to establish a TLS
505 connection before performing that request, the server MUST reject
506 that request by sending a resultCode of confidentialityRequired.
509 3.1.2. StartTLS Response
512 The server will return an extended response with the resultCode of
513 success if it is willing and able to negotiate TLS.
516 It will return a resultCode other than success (documented in
517 [Protocol] section 4.13.2.2) if it is unwilling or unable to do so.
518 The state of the association is unaffected if a non-success
519 resultCode is returned.
522 In the successful case, the client (which has ceased to transfer
523 LDAP requests on the connection) MUST either begin a TLS negotiation
524 or close the connection. The client will send PDUs in the TLS Record
525 Protocol directly over the underlying transport connection to the
526 server to initiate [TLS] negotiation.
529 3.1.3. TLS Version Negotiation
532 Negotiating the version of TLS to be used is a part of the TLS
533 Handshake Protocol [TLS]. Please refer to that document for details.
536 3.1.4. Client Certificate
539 If an LDAP server requests a client to provide its certificate
540 during TLS negotiation and the client does not present a suitable
541 certificate (e.g. one that can be validated), the server may use a
542 local security policy to determine whether to successfully complete
546 If the client provides a certificate that can be validated,
547 information in the certificate may be used by the server in
548 establishing the client's authorization identity by use of the SASL
549 EXTERNAL mechanism as discussed in Section 9.
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557 3.1.5. Discovery of Resultant Security Level
560 After a TLS connection is established on an LDAP connection, both
561 parties are to individually decide whether or not to continue based
562 on the security level achieved. The procedure for ascertaining the
563 TLS connection's security level is implementation dependent.
566 If the client or server decides that the security level is not high
567 enough for it to continue, it SHOULD gracefully close the TLS
568 connection immediately after the TLS negotiation has completed (see
569 [Protocol] section 4.13.3.1 and section 3.2.3 below). The client
570 may then close the connection, attempt to StartTLS again, send an
571 unbind request, or send any other LDAP request.
574 3.1.6. Server Identity Check
577 The client MUST check its understanding of the server's hostname
578 against the server's identity as presented in the server's
579 Certificate message in order to prevent man-in-the-middle attacks.
582 Matching is performed according to these rules:
585 - The client MUST use the server name provided by the user (or
586 other trusted entity) as the value to compare against the server
587 name as expressed in the server's certificate. A hostname
588 derived from user input is to be considered provided by the user
589 only if derived in a secure fashion (e.g., DNSSEC).
592 - If a subjectAltName extension of type dNSName is present in the
593 certificate, it SHOULD be used as the source of the server's
597 - The string values to be compared MUST be prepared according to
598 the rules described in [Matching].
601 - The "*" wildcard character is allowed. If present, it applies
602 only to the left-most name component.
605 For example, *.bar.com would match a.bar.com and b.bar.com, but
606 it would not match a.x.bar.com nor would it match bar.com. If
607 more than one identity of a given type is present in the
608 certificate (e.g. more than one dNSName name), a match in any
609 one of the set is considered acceptable.
612 If the hostname does not match the dNSName-based identity in the
613 certificate per the above check, user-oriented clients SHOULD either
614 notify the user (clients may give the user the opportunity to
615 continue with the connection in any case) or terminate the
616 connection and indicate that the server's identity is suspect.
617 Automated clients SHOULD close the connection, returning and/or
618 logging an error indicating that the server's identity is suspect.
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627 Beyond the server identity checks described in this section, clients
628 SHOULD be prepared to do further checking to ensure that the server
629 is authorized to provide the service it is observed to provide. The
630 client may need to make use of local policy information in making
634 3.1.7. Refresh of Server Capabilities Information
637 Upon TLS session establishment, the client SHOULD discard or refresh
638 all information about the server it obtained prior to the initiation
639 of the TLS negotiation and not obtained through secure mechanisms.
640 This protects against man-in-the-middle attacks that may have
641 altered any server capabilities information retrieved prior to TLS
645 The server may advertise different capabilities after TLS
646 establishment. In particular, the value of supportedSASLMechanisms
647 may be different after TLS has been negotiated (specifically, the
648 EXTERNAL and PLAIN [PLAIN] mechanisms are likely to be listed only
649 after a TLS negotiation has been performed).
652 3.2. Effects of TLS on a Client's Authorization Identity
655 This section describes the effects on a client's authorization
656 identity brought about by establishing TLS on an LDAP connection.
657 The default effects are described first, and next the facilities for
658 client assertion of authorization identity are discussed including
659 error conditions. Finally, the effects of closing the TLS connection
663 Authorization identities and related concepts are described in
667 3.2.1. TLS Connection Establishment Effects
670 The decision to keep or invalidate the established state of the
671 association (section 4.3) after TLS connection establishment is a
672 matter of local server policy.
675 3.2.2. Client Assertion of Authorization Identity
678 After successfully establishing a TLS session, a client may request
679 that its certificate exchanged during the TLS establishment be
680 utilized to determine the authorization identity of the association.
681 The client accomplishes this via an LDAP Bind request specifying a
682 SASL mechanism of EXTERNAL [SASL] (section 10).
685 3.2.3. TLS Connection Closure Effects
688 The decision to keep or invalidate the established state of the
689 association after TLS closure is a matter of local server policy.
692 3.3. TLS Ciphersuites
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700 Several issues should be considered when selecting TLS ciphersuites
701 that are appropriate for use in a given circumstance. These issues
702 include the following:
705 - The ciphersuite's ability to provide adequate confidentiality
706 protection for passwords and other data sent over the LDAP
707 connection. Client and server implementers should recognize that
708 some TLS ciphersuites provide no confidentiality protection
709 while other ciphersuites that do provide confidentiality
710 protection may be vulnerable to being cracked using brute force
711 methods, especially in light of ever-increasing CPU speeds that
712 reduce the time needed to successfully mount such attacks.
715 Client and server implementers should carefully consider the
716 value of the password or data being protected versus the level
717 of confidentially protection provided by the ciphersuite to
718 ensure that the level of protection afforded by the ciphersuite
722 - The ciphersuite's vulnerability (or lack thereof) to man-in-the-
723 middle attacks. Ciphersuites vulnerable to man-in-the-middle
724 attacks SHOULD NOT be used to protect passwords or sensitive
725 data, unless the network configuration is such that the danger
726 of a man-in-the-middle attack is tolerable.
729 3.3.1. TLS Ciphersuites Recommendations
732 [[TODO: Kurt will have someone from security to look at this and
733 will propose how to handle discussion of specific TLS ciphersuites
737 As of the writing of this document, the following recommendations
738 regarding TLS ciphersuites are applicable. Because circumstances are
739 constantly changing, this list must not be considered exhaustive,
740 but is hoped that it will serve as a useful starting point for
744 The following ciphersuites defined in [TLS] MUST NOT be used for
745 confidentiality protection of passwords or data:
748 TLS_NULL_WITH_NULL_NULL
749 TLS_RSA_WITH_NULL_MD5
750 TLS_RSA_WITH_NULL_SHA
753 The following ciphersuites defined in [TLS] can be cracked easily
754 (less than a day of CPU time on a standard CPU in 2000) and are NOT
755 RECOMMENDED for use in confidentiality protection of passwords or
759 TLS_RSA_EXPORT_WITH_RC4_40_MD5
760 TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5
761 TLS_RSA_EXPORT_WITH_DES40_CBC_SHA
762 TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA
763 TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA
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770 TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
771 TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA
772 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
773 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
776 The following ciphersuites are vulnerable to man-in-the-middle
780 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
781 TLS_DH_anon_WITH_RC4_128_MD5
782 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
783 TLS_DH_anon_WITH_DES_CBC_SHA
784 TLS_DH_anon_WITH_3DES_EDE_CBC_SHA
790 Every LDAP connection has an associated authorization state referred
791 to as the "association". The Bind operation defined in section 4.2
792 of [Protocol] and discussed further in section 5 below allows
793 information to be exchanged between the client and server to change
794 the authorization state of the association.
797 4.1. Anonymous Association on Unbound Connections
800 Prior to the successful completion of a Bind operation and during
801 any subsequent authentication exchange, the association has an
802 anonymous authorization state. Among other things this implies that
803 the client need not send a Bind Request in the first PDU of the
804 connection. The client may send any operation request prior to
805 binding, and the server MUST treat it as if it had been performed
806 after an anonymous bind operation (section 6). This association
807 state is sometimes referred to as an implied anonymous bind.
810 4.2. Anonymous Association After Failed Bind
813 Upon receipt of a Bind request, the association is moved to an
814 anonymous state and only upon successful completion of the
815 authentication exchange (and the Bind operation) is the association
816 moved to an authenticated state. Thus, a failed Bind operation
817 produces an anonymous association.
820 4.3. Invalidated Associations
823 The server may move the association to an invalidated state at any
824 time, e.g. if an established security layer between the client and
825 server has unexpectedly failed or been compromised. While the
826 connection has an invalid association, the server may reject any
827 operation request other than Bind, Unbind, and StartTLS by
828 responding with a resultCode of strongAuthRequired to indicate that
829 the server requires stronger authentication before it will attempt
830 to perform the requested operation. In practice, this means that the
831 client needs to bind to(re)establish a suitably strong authorization
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840 state on the association before the server will attempt to perform
841 the requested operation.
847 The Bind operation ([Protocol] section 4.2) allows authentication
848 information to be exchanged between the client and server to
849 establish a new authorization state on the association.
852 The Bind request typically specifies the desired authentication
853 identity. Some Bind mechanisms also allow the client to specify the
854 authorization identity. If the authorization identity is not
855 specified, the server derives it from the authentication identity in
856 an implementation-specific manner.
859 If the authorization identity is specified the server MUST verify
860 that the client's authentication identity is permitted to assume
861 (e.g. proxy for) the asserted authorization identity. The server
862 MUST reject the Bind operation with an invalidCredentials resultCode
863 in the Bind response if the client is not so authorized.
866 5.1. Simple Authentication Choice
869 The simple authentication choice of the Bind Operation provides
870 three authentication mechanisms:
873 1. an anonymous authentication mechanism (section 6),
876 2. an unauthenticated authentication mechanism (section 7), and
879 3. a simple authentication mechanism using credentials consisting
880 of a name (in the form of an LDAP distinguished name [LDAPDN])
881 and a password (section 8).
884 5.2. SASL Authentication Choice
887 The sasl authentication choice of the Bind Operation provides
888 facilities for using any SASL mechanism (sections 9-11) including
889 authentication mechanisms and other services (e.g. data security
893 6. Anonymous Authentication Mechanism of Simple Bind
896 An LDAP client may use the anonymous authentication mechanism of the
897 simple Bind choice to explicitly establish an anonymous association
898 by sending a Bind request with a name value of zero length and with
899 the simple authentication choice containing a password value of zero
903 7. Unauthenticated Authentication Mechanism of Simple Bind
906 An LDAP client may use the unauthenticated authentication mechanism
907 of the simple Bind choice to establish an anonymous association by
908 sending a Bind request with a name value, a distinguished name in
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915 LDAP string form [LDAPDN], of non-zero length, and specifying the
916 the simple authentication choice containing a password value of zero
920 Unauthenticated binds can have significant security issues (see
921 section 12.3). Servers SHOULD by default reject unauthenticated bind
922 requests with a resultCode of invalidCredentials, and clients may
923 need to actively detect situations where they would unintentionally
924 make an unauthenticated bind request.
927 8. Simple Authentication Mechanism of Simple Bind
930 An LDAP client may use the simple authentication mechanism of the
931 simple Bind choice to establish an authenticated association by
932 sending a Bind request with a name value, a distinguished name in
933 LDAP string form [LDAPDN], and specifying the simple authentication
934 choice containing an OCTET STRING password value of non-zero length.
937 Servers that map the DN sent in the bind request to a directory
938 entry with an associated set of one or more passwords used with this
939 mechanism, will compare the presented password to that set of
940 passwords. The presented password is considered valid if it matches
941 any member of this set.
944 If the DN is syntactically invalid, the server returns the
945 invalidDNSyntax result code. If the DN is syntactically correct but
946 not valid for purposes of authentication, or the password is not
947 valid for the DN, or the server otherwise considers the credentials
948 to be invalid, the server returns the invalidCredentials result
949 code. The server is only to return the success result code when the
950 credentials are valid and the server is willing to provide service
951 to the entity these credentials identify.
954 Server behavior is undefined for bind requests specifying the simple
955 authentication mechanism with a zero-length name value and a
956 password value of non-zero length.
960 The simple authentication mechanism of simple bind is not suitable
961 for authentication in environments where there is no network or
962 transport layer confidentiality. LDAP implementations SHALL NOT
963 support this mechanism unless they are capable of protecting it by
964 establishment of TLS (as discussed in section 3) or other suitable
965 data confidentiality and data integrity protection(e.g. IPSec). LDAP
966 implementations SHOULD support authentication with the "simple"
967 authentication choice when the connection is protected against
968 eavesdropping using TLS, as defined in section 3. LDAP
969 implementations SHOULD NOT support authentication with the "simple"
970 authentication choice unless the data on the connection is protected
971 using TLS or other data confidentiality and data integrity
975 9. SASL Protocol Profile
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980 Internet-Draft LDAP Authentication Methods 25 October 2004
983 LDAP allows authentication via any SASL mechanism [SASL]. As LDAP
984 includes native anonymous and simple (plain text) authentication
985 methods, the ANONYMOUS [ANONYMOUS] and PLAIN [PLAIN] SASL mechanisms
986 are typically not used with LDAP.
989 Each protocol that utilizes SASL services is required to supply
990 certain information profiling the way they are exposed through the
991 protocol ([SASL] section 5). This section explains how each of these
992 profiling requirements are met by LDAP.
995 9.1. SASL Service Name for LDAP
998 The SASL service name for LDAP is "ldap", which has been registered
999 with the IANA as a SASL service name.
1002 9.2. SASL Authentication Initiation and Protocol Exchange
1005 SASL authentication is initiated via an LDAP bind request
1006 ([Protocol] section 4.2) with the following parameters:
1010 - The AuthenticationChoice is sasl.
1011 - The mechanism element of the SaslCredentials sequence contains
1012 the value of the desired SASL mechanism.
1013 - The optional credentials field of the SaslCredentials sequence
1014 may be used to provide an initial client response for
1015 mechanisms that are defined to have the client send data first
1016 (see [SASL] sections 5 and 5.1).
1019 In general, a SASL authentication protocol exchange consists of a
1020 series of server challenges and client responses, the contents of
1021 which are specific to and defined by the SASL mechanism. Thus for
1022 some SASL authentication mechanisms, it may be necessary for the
1023 client to respond to one or more server challenges by invoking the
1024 BindRequest multiple times. A challenge is indicated by the server
1025 sending a BindResponse with the resultCode set to
1026 saslBindInProgress. This indicates that the server requires the
1027 client to send a new bind request with the same sasl mechanism to
1028 continue the authentication process.
1031 To the LDAP protocol, these challenges and responses are opaque
1032 binary tokens of arbitrary length. LDAP servers use the
1033 serverSaslCreds field, an OCTET STRING, in a bind response message
1034 to transmit each challenge. LDAP clients use the credentials field,
1035 an OCTET STRING, in the SaslCredentials sequence of a bind request
1036 message to transmit each response. Note that unlike some Internet
1037 protocols where SASL is used, LDAP is not text-based, thus no Base64
1038 transformations are performed on these challenge and response values.
1041 Clients sending a bind request with the sasl choice selected SHOULD
1042 send an zero-length value in the name field. Servers receiving a
1043 bind request with the sasl choice selected SHALL ignore any value in
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1052 A client may abort a SASL bind negotiation by sending a BindRequest
1053 with a different value in the mechanism field of SaslCredentials, or
1054 an AuthenticationChoice other than sasl.
1056 If the client sends a BindRequest with the sasl mechanism field as
1057 an empty string, the server MUST return a BindResponse with
1058 authMethodNotSupported as the resultCode. This will allow clients to
1059 abort a negotiation if it wishes to try again with the same SASL
1063 The server indicates completion of the SASL challenge-response
1064 exchange by responding with a bind response in which the resultCode
1065 is either success, or an error indication.
1068 The serverSaslCreds field in the BindResponse can be used to include
1069 an optional challenge with a success notification for mechanisms
1070 which are defined to have the server send additional data along with
1071 the indication of successful completion. If a server does not intend
1072 to send a challenge value in a BindResponse message, the server
1073 SHALL omit the serverSaslCreds field (rather than including the
1074 field with a zero-length value).
1077 9.3. Octet Where Negotiated Security Mechanisms Take Effect
1080 SASL security layers take effect following the transmission by the
1081 server and reception by the client of the final successful
1082 BindResponse in the exchange.
1085 Once a SASL security layer providing data integrity or
1086 confidentiality services takes effect, the layer remains in effect
1087 until a new layer is installed (i.e. at the first octet following
1088 the final BindResponse of the bind operation that caused the new
1089 layer to take effect). Thus, an established SASL security layer is
1090 not affected by a failed or non-SASL Bind.
1093 9.4. Determination of Supported SASL Mechanisms
1096 Clients may determine the SASL mechanisms a server supports by
1097 reading the supportedSASLMechanisms attribute from the root DSE
1098 (DSA-Specific Entry) ([Models] section 5.1). The values of this
1099 attribute, if any, list the mechanisms the server supports in the
1100 current LDAP session state. LDAP servers SHOULD allow an
1101 anonymously-bound client to retrieve the supportedSASLMechanisms
1102 attribute of the root DSE.
1105 Because SASL mechanisms provide critical security functions, clients
1106 and servers should be configurable to specify what mechanisms are
1107 acceptable and allow only those mechanisms to be used. Both clients
1108 and servers must confirm that the negotiated security level meets
1109 their requirements before proceeding to use the connection.
1112 9.5. Rules for Using SASL Security Layers
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1121 If a SASL security layer is negotiated, the client SHOULD discard
1122 information about the server it obtained prior to the initiation of
1123 the SASL negotiation and not obtained through secure mechanisms.
1126 If a lower level security layer (such as TLS) is negotiated, any
1127 SASL security services SHALL be layered on top of such security
1128 layers regardless of the order of their negotiation. In all other
1129 respects, SASL security services and other security layers act
1130 independently, e.g. if both TLS and SASL security service are in
1131 effect then removing the SASL security service does not affect the
1132 continuing service of TLS and vice versa.
1135 9.6 Support for Multiple Authentications
1138 LDAP supports multiple SASL authentications as defined in [SASL]
1142 10. SASL EXTERNAL Authentication Mechanism
1145 A client can use the SASL EXTERNAL [SASL] mechanism to request the
1146 LDAP server to authenticate and establish a resulting authorization
1147 identity using security credentials exchanged by a lower security
1148 layer (such as by TLS authentication or IP-level security
1152 The authorization identity used to determine the state of the
1153 association is derived from the security credentials in an
1154 implementation-specific manner. If the client's authentication
1155 credentials have not been established at a lower security layer, the
1156 SASL EXTERNAL bind MUST fail with a resultCode of
1157 inappropriateAuthentication. Although this situation has the effect
1158 of leaving the association in an anonymous state (section 5), the
1159 state of any established security layer is unaffected.
1162 A client may either implicitly request that its authorization
1163 identity be derived from its authentication credentials exchanged at
1164 a lower security layer or it may explicitly provide an authorization
1165 identity and assert that it be used in combination with those
1166 authentication credentials. The former is known as an implicit
1167 assertion, and the latter as an explicit assertion.
1170 10.1. Implicit Assertion
1173 An implicit authorization identity assertion is performed by
1174 invoking a Bind request of the SASL form using the EXTERNAL
1175 mechanism name that does not include the optional credentials octet
1176 string (found within the SaslCredentials sequence in the Bind
1177 Request). The server will derive the client's authorization identity
1178 from the authentication identity supplied by the security layer
1179 (e.g., a public key certificate used during TLS establishment)
1180 according to local policy. The underlying mechanics of how this is
1181 accomplished are implementation specific.
1184 10.2. Explicit Assertion
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1192 An explicit authorization identity assertion is performed by
1193 invoking a Bind request of the SASL form using the EXTERNAL
1194 mechanism name that includes the credentials octet string. This
1195 string MUST be constructed as documented in section 10.4.
1198 10.3. SASL Authorization Identity
1201 When the EXTERNAL SASL mechanism is being negotiated, if the
1202 SaslCredentials credentials field is present, it contains an
1203 authorization identity. Other mechanisms define the location of the
1204 authorization identity in the credentials field. In either case, the
1205 authorization identity is represented in the authzId form described
1209 10.4. SASL Authorization Identity Syntax
1212 The authorization identity is a string of UTF-8 [RFC3629] encoded
1213 [Unicode] characters corresponding to the following ABNF [RFC2234]
1217 authzId ::= dnAuthzId / uAuthzId
1220 DNCOLON ::= %x64 %x6e %x3a ; "dn:"
1221 UCOLON ::= %x75 %x3a ; "u:"
1224 ; distinguished-name-based authz id.
1225 dnAuthzId ::= DNCOLON distinguishedName
1228 ; unspecified authorization id, UTF-8 encoded.
1229 uAuthzId ::= UCOLON userid
1230 userid ::= *UTF8 ; syntax unspecified
1233 where the <distinguishedName> production is defined in section 3 of
1234 [LDAPDN] and <UTF8> production is defined in section 1.3 of [Models].
1237 In order to support additional specific authorization identity
1238 forms, future updates to this specification may add new choices
1239 supporting other forms of the authzId production.
1242 The dnAuthzId choice is used to assert authorization identities in
1243 the form of a distinguished name to be matched in accordance with
1244 the distinguishedNameMatch matching rule [Syntaxes]. The decision to
1245 allow or disallow an authentication identity to have access to the
1246 requested authorization identity is a matter of local policy ([SASL]
1247 section 4.2). For this reason there is no requirement that the
1248 asserted dn be that of an entry in the directory.
1251 The uAuthzId choice allows clients to assert an authorization
1252 identity that is not in distinguished name form. The format of
1253 userid is defined as only a sequence of UTF-8 [RFC3629] encoded
1254 [Unicode] characters, and any further interpretation is a local
1255 matter. To compare uAuthzID values, each uAuthzID value MUST be
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1263 prepared using [SASLPrep] and then the two values are compared
1267 For example, the userid could identify a user of a specific
1268 directory service, be a login name, or be an email address. A
1269 uAuthzId SHOULD NOT be assumed to be globally unique.
1272 11. SASL DIGEST-MD5 Authentication Mechanism
1275 LDAP servers that implement any authentication method or mechanism
1276 other than simple anonymous bind MUST implement the SASL
1277 DIGEST-MD5 mechanism [DIGEST-MD5]. This provides client
1278 authentication with protection against passive eavesdropping attacks
1279 but does not provide protection against man-in-the-middle attacks.
1280 DIGEST-MD5 also provides data integrity and data confidentiality
1284 Support for subsequent authentication ([DIGEST-MD5] section 2.2) is
1285 OPTIONAL in clients and servers.
1288 Implementers must take care to ensure that they maintain the
1289 semantics of the DIGEST-MD5 specification even when handling data
1290 that has different semantics in the LDAP protocol.
1291 For example, the SASL DIGEST-MD5 authentication mechanism utilizes
1292 realm and username values ([DIGEST-MD5] section 2.1) which are
1293 syntactically simple strings and semantically simple realm and
1294 username values. These values are not LDAP DNs, and there is no
1295 requirement that they be represented or treated as such. Username
1296 and realm values that look like LDAP DNs in form, e.g. <cn=bob,
1297 dc=example,dc=com>, are syntactically allowed, however DIGEST-MD5
1298 treats them as simple strings for comparison purposes. To illustrate
1299 further, the two DNs <cn=Bob,dc=example,dc=com> (upper case "B") and
1300 <cn=bob,dc=example,dc=com> (lower case "b") are equivalent when
1301 being compared semantically as LDAP DNs because the cn attribute is
1302 defined to be case insensitive, however the two values are not
1303 equivalent if they represent username values in DIGEST-MD5 because
1304 [SASLPrep] semantics are used by DIGEST-MD5.
1307 12. Security Considerations
1310 Security issues are discussed throughout this document. The
1311 unsurprising conclusion is that security is an integral and
1312 necessary part of LDAP. This section discusses a number of LDAP-
1313 related security considerations.
1316 12.1. General LDAP Security Considerations
1319 LDAP itself provides no security or protection from accessing or
1320 updating the directory by other means than through the LDAP
1321 protocol, e.g. from inspection by database administrators. Access
1322 control SHOULD always be applied when reading sensitive information
1323 or updating directory information.
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1332 Servers can minimize denial of service attacks by providing the
1333 ability to configure and enforce administrative limits on
1334 operations, timing out idle connections and returning the
1335 unwillingToPerform resultCode rather than performing computationally
1336 expensive operations requested by unauthorized clients.
1339 A connection on which the client has not established connection
1340 integrity and privacy services (e.g via StartTLS, IPSec or a
1341 suitable SASL mechanism) is subject to man-in-the-middle attacks to
1342 view and modify information in transit. Client and server
1343 implementors SHOULD take measures to protect confidential data from
1344 these attacks by using data protection services as discussed in this
1348 12.1.1. Password-related Security Considerations
1351 LDAP allows multi-valued password attributes. In systems where
1352 entries are expected to have one and only one password,
1353 administrative controls should be provided to enforce this behavior.
1356 The use of clear text passwords and other unprotected authentication
1357 credentials is strongly discouraged over open networks when the
1358 underlying transport service cannot guarantee confidentiality.
1361 The transmission of passwords in the clear--typically for
1362 authentication or modification--poses a significant security risk.
1363 This risk can be avoided by using SASL authentication [SASL]
1364 mechanisms that do not transmit passwords in the clear or by
1365 negotiating transport or session layer data confidentiality services
1366 before transmitting password values.
1369 To mitigate the security risks associated with the transfer of
1370 passwords, a server implementation that supports any password-based
1371 authentication mechanism that transmits passwords in the clear MUST
1372 support a policy mechanism that at the time of authentication or
1373 password modification, requires:
1376 A StartTLS encryption layer has been successfully negotiated.
1382 Some other data confidentiality mechanism that protects the
1383 password value from snooping has been provided.
1389 The server returns a resultCode of confidentialityRequired for
1390 the operation (i.e. simple bind with password value, SASL bind
1391 transmitting a password value in the clear, add or modify
1392 including a userPassword value, etc.), even if the password
1396 12.2. StartTLS Security Considerations
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1406 All security gained via use of the StartTLS operation is gained by
1407 the use of TLS itself. The StartTLS operation, on its own, does not
1408 provide any additional security.
1411 The level of security provided though the use of TLS depends
1412 directly on both the quality of the TLS implementation used and the
1413 style of usage of that implementation. Additionally, a man-in-the-
1414 middle attacker can remove the StartTLS extended operation from the
1415 supportedExtension attribute of the root DSE. Both parties SHOULD
1416 independently ascertain and consent to the security level achieved
1417 once TLS is established and before beginning use of the TLS
1418 connection. For example, the security level of the TLS connection
1419 might have been negotiated down to plaintext.
1422 Clients SHOULD by default either warn the user when the security
1423 level achieved does not provide an acceptable level of data
1424 confidentiality and/or data integrity protection, or be configured
1425 to refuse to proceed without an acceptable level of security.
1428 Server implementors SHOULD allow server administrators to elect
1429 whether and when data confidentiality and integrity are required, as
1430 well as elect whether authentication of the client during the TLS
1431 handshake is required.
1434 Implementers should be aware of and understand TLS security
1435 considerations as discussed in the TLS specification [TLS].
1438 12.3. Unauthenticated Mechanism Security Considerations
1441 Operational experience shows that clients can (and frequently do)
1442 misuse the unauthenticated authentication mechanism of simple bind
1443 (see section 7). For example, a client program might make a
1444 decision to grant access to non-directory information on the basis
1445 of completing a successful bind operation. LDAP server
1446 implementations may return a success response to an unauthenticated
1447 bind request thus leaving the client with the impression that the
1448 server has successfully authenticated the identity represented by
1449 the user name, when in effect, an anonymous association has been
1450 established. Clients that use the results from a simple bind
1451 operation to make authorization decisions should actively detect
1452 unauthenticated bind requests (by verifying that the supplied
1453 password is not empty) and react appropriately.
1456 12.4. Simple Mechanism Security Considerations
1459 The simple authentication mechanism of simple bind discloses the
1460 password to the server, which is an inherent security risk. There
1461 are other mechanisms such as DIGEST-MD5 that do not disclose
1465 12.5. SASL DIGEST-MD5 Mechanism Security Considerations
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1470 Internet-Draft LDAP Authentication Methods 25 October 2004
1473 The SASL DIGEST-MD5 mechanism is prone to the qop substitution
1474 attack, as discussed in 3.6 of [DIGEST-MD5]. The qop substitution
1475 attack can be mitigated (as discussed in 3.6 of [DIGEST-MD5]).
1478 The SASL DIGEST-MD5 mechanism [DIGEST-MD5] provides client
1479 authentication with protection against passive eavesdropping attacks
1480 but does not provide protection against man-in-the-middle attacks.
1483 Implementers should be aware of and understand DIGEST-MD5 security
1484 considerations as discussed in the DIGEST-MD5 specification [DIGEST-
1488 12.6. Related Security Considerations
1491 Additional security considerations relating to the various
1492 authentication methods and mechanisms discussed in this document
1493 apply and can be found in [SASL], [SASLPrep], [StringPrep] and
1497 13. IANA Considerations
1500 The following IANA considerations apply to this document:
1503 It is requested that the IANA update the LDAP Protocol Mechanism
1504 registry to indicate that this document and [Protocol] provide the
1505 definitive technical specification for the StartTLS
1506 (1.3.6.1.4.1.1466.20037) extended operation.
1509 [[TODO: add any missing IANA Considerations.]]
1515 This document combines information originally contained in RFC 2829
1516 and RFC 2830. The editor acknowledges the work of Harald Tveit
1517 Alvestrand, Jeff Hodges, Tim Howes, Steve Kille, RL "Bob" Morgan ,
1518 and Mark Wahl, each of whom authored one or more of these documents.
1521 This document is based upon input of the IETF LDAP Revision working
1522 group. The contributions and suggestions made by its members in
1523 shaping the contents and technical accuracy of this document is
1524 greatly appreciated.
1527 Normative References
1530 [[Note to the RFC Editor: please replace the citation tags used in
1531 referencing Internet-Drafts with tags of the form RFCnnnn.]]
1534 [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
1535 Syntax Specifications: ABNF", RFC 2234, November 1997.
1538 [DIGEST-MD5] Leach, P. C. Newman, and A. Melnikov, "Using Digest
1539 Authentication as a SASL Mechanism", draft-ietf-sasl-
1540 rfc2831bis-xx.txt, a work in progress.
1544 Harrison Expires April 2005 [Page 22]
1545 Internet-Draft LDAP Authentication Methods 25 October 2004
1548 [RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
1549 Requirement Levels", BCP 14, RFC 2119, March 1997.
1552 [LDAPDN] Zeilenga, Kurt D. (editor), "LDAP: String
1553 Representation of Distinguished Names", draft-ietf-
1554 ldapbis-dn-xx.txt, a work in progress.
1557 [Matching] Hoffman, Paul and Steve Hanna, "Matching Text Strings
1558 in PKIX Certificates", draft-hoffman-pkix-stringmatch-
1559 xx.txt, a work in progress.
1562 [Models] Zeilenga, Kurt D. (editor), "LDAP: Directory
1563 Information Models", draft-ietf-ldapbis-models-xx.txt,
1567 [Protocol] Sermersheim, J., "LDAP: The Protocol", draft-ietf-
1568 ldapbis-protocol-xx.txt, a work in progress.
1571 [Roadmap] K. Zeilenga, "LDAP: Technical Specification Road Map",
1572 draft-ietf-ldapbis-roadmap-xx.txt, a work in progress.
1575 [SASL] Melnikov, A. (editor), "Simple Authentication and
1576 Security Layer (SASL)", draft-ietf-sasl-rfc2222bis-
1577 xx.txt, a work in progress.
1580 [SASLPrep] Zeilenga, K., "Stringprep profile for user names and
1581 passwords", draft-ietf-sasl-saslprep-xx.txt, (a work in
1585 [StringPrep] M. Blanchet, "Preparation of Internationalized Strings
1586 ('stringprep')", draft-hoffman-rfc3454bis-xx.txt, a
1590 [Syntaxes] Legg, S. (editor), "LDAP: Syntaxes and Matching Rules",
1591 draft-ietf-ldapbis-syntaxes-xx.txt, a work in progress.
1594 [TLS] Dierks, T. and C. Allen. "The TLS Protocol Version
1595 1.1", draft-ietf-tls-rfc2246-bis-xx.txt, a work in
1599 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
1600 10646", RFC 3629, STD 63, November 2003.
1603 [Unicode] The Unicode Consortium, "The Unicode Standard, Version
1604 3.2.0" is defined by "The Unicode Standard, Version
1605 3.0" (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-
1606 61633-5), as amended by the "Unicode Standard Annex
1608 (http://www.unicode.org/reports/tr27/) and by the
1609 "Unicode Standard Annex #28: Unicode 3.2"
1610 (http://www.unicode.org/reports/tr28/).
1613 Informative References
1617 Harrison Expires April 2005 [Page 23]
1618 Internet-Draft LDAP Authentication Methods 25 October 2004
1621 [ANONYMOUS] Zeilenga, K.,"Anonymous SASL Mechanism", draft-
1622 zeilenga-sasl-anon-xx.txt, a work in progress.
1625 [RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828, May
1629 [PLAIN] Zeilenga, K.,"Plain SASL Mechanism", draft-zeilenga-
1630 sasl-plain-xx.txt, a work in progress.
1633 [RFC2401] Kent, S. and R. Atkinson, "Security Architecture for
1634 the Internet Protocol", RFC 2401, November 1998.
1642 1800 S. Novell Place
1646 roger_harrison@novell.com
1649 Appendix A. Association State Transition Tables
1652 This section provides a state transition table to represent a state
1653 diagram for the various authentication states through which an
1654 association may pass during the course of its existence and the
1655 actions that cause these changes in state.
1658 This section is based entirely on information found in this document
1659 and other documents that are part of the LDAP Technical
1660 Specification [Roadmap]. As such, it is strictly informational in
1664 A.1. Association States
1667 The following table lists the valid association states and provides
1668 a description of each state. The ID for each state is used in the
1669 state transition table in section A.4.
1672 ID State Description
1673 -- --------------------------------------------------------------
1675 no Authentication ID is associated with the LDAP connection
1676 no Authorization ID is in force
1678 Authentication ID = I
1679 Authorization ID = X
1680 S3 Authenticated SASL EXTERNAL, implicit authorization ID
1681 Authentication ID = J
1682 Authorization ID = Y
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1691 S4 Authenticated SASL EXTERNAL, explicit authorization ID Z
1692 Authentication ID = J
1693 Authorization ID = Z
1697 A.2. Actions that Affect Association State
1700 The following table lists the actions that can affect the
1701 authentication and authorization state of an association. The ID for
1702 each action is used in the state transition table in section A.4.
1706 -- --------------------------------------------------------------
1707 A1 Client bind request fails
1708 A2 Client successfully performs anonymous simple bind or
1709 unauthenticated simple bind
1710 A3 Client successfully performs simple bind with name and password
1711 OR SASL bind with any mechanism except EXTERNAL using an
1712 authentication ID = I that maps to authorization ID X
1713 A4 Client Binds SASL EXTERNAL with implicit assertion of
1714 authorization ID (section 9.1). The current authentication ID
1715 maps to authorization ID = Y.
1716 A5 Client Binds SASL EXTERNAL with explicit assertion of
1717 authorization ID = Z (section 9.2).
1718 A6 Client StartTLS request fails
1719 A7 Client StartTLS request succeeds
1720 A8 Client or Server: graceful TLS removal
1721 A9 Server decides to invalidate current association state
1724 A.3. Decisions Used in Making Association State Changes
1727 Certain changes in the authentication and authorization state of an
1728 association are only allowed if the server can affirmatively answer
1729 a question. These questions are applied as part of the criteria for
1730 allowing or disallowing a state transition in the state transition
1731 table in section A.4.
1734 ID Decision Question
1735 -- --------------------------------------------------------------
1736 D1 Are lower-layer credentials available?
1737 D2 Can lower-layer credentials for Auth ID "K" be mapped to
1738 asserted AuthZID "L"?
1741 A.4. Association State Transition Table
1744 The Association table below lists the the actions that could affect
1745 the authorization state of an association and the resulting state of
1746 an association after a given action occurs.
1749 S1, the initial state for the state machine described in this table,
1750 is the association state when an LDAP connection is initially
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1762 ------------------ ----------- --------------------------------
1764 A2 S1 Sections 6 & 7
1766 A4, S1 Failed bind, section 10.1
1770 A5, S1 Failed bind, section 10.2
1772 A5, S1 Failed bind, section 10.2
1777 A6 no change* [Protocol] section 4.14.2.2
1778 A7 no change* [Protocol] section 4.14.2.1
1779 A8 S1 [Protocol] section 4.14.3.1
1783 * The server may invalidate the association after TLS
1784 establishment or closure (section 3.2).
1787 Appendix B. Authentication and Authorization Concepts
1790 This appendix defines basic terms, concepts, and interrelationships
1791 regarding authentication, authorization, credentials, and identity.
1792 These concepts are used in describing how various security
1793 approaches are utilized in client authentication and authorization.
1796 B.1. Access Control Policy
1799 An access control policy is a set of rules defining the protection
1800 of resources, generally in terms of the capabilities of persons or
1801 other entities accessing those resources. Security objects and
1802 mechanisms, such as those described here, enable the expression of
1803 access control policies and their enforcement.
1806 B.2. Access Control Factors
1809 A request, when it is being processed by a server, may be associated
1810 with a wide variety of security-related factors (section 4.2 of
1811 [Protocol]). The server uses these factors to determine whether and
1812 how to process the request. These are called access control factors
1813 (ACFs). They might include source IP address, encryption strength,
1814 the type of operation being requested, time of day, etc. Some
1815 factors may be specific to the request itself, others may be
1816 associated with the connection via which the request is transmitted,
1817 others (e.g. time of day) may be "environmental".
1820 Access control policies are expressed in terms of access control
1821 factors. E.g., a request having ACFs i,j,k can perform operation Y
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1828 on resource Z. The set of ACFs that a server makes available for
1829 such expressions is implementation-specific.
1832 B.3. Authentication, Credentials, Identity
1835 Authentication credentials are the evidence supplied by one party to
1836 another, asserting the identity of the supplying party (e.g. a user)
1837 who is attempting to establish a new association state with the
1838 other party (typically a server). Authentication is the process of
1839 generating, transmitting, and verifying these credentials and thus
1840 the identity they assert. An authentication identity is the name
1841 presented in a credential.
1844 There are many forms of authentication credentials -- the form used
1845 depends upon the particular authentication mechanism negotiated by
1846 the parties. For example: X.509 certificates, Kerberos tickets,
1847 simple identity and password pairs. Note that an authentication
1848 mechanism may constrain the form of authentication identities used
1852 B.4. Authorization Identity
1855 An authorization identity is one kind of access control factor. It
1856 is the name of the user or other entity that requests that
1857 operations be performed. Access control policies are often expressed
1858 in terms of authorization identities; e.g., entity X can perform
1859 operation Y on resource Z.
1862 The authorization identity bound to an association is often exactly
1863 the same as the authentication identity presented by the client, but
1864 it may be different. SASL allows clients to specify an authorization
1865 identity distinct from the authentication identity asserted by the
1866 client's credentials. This permits agents such as proxy servers to
1867 authenticate using their own credentials, yet request the access
1868 privileges of the identity for which they are proxying [SASL]. Also,
1869 the form of authentication identity supplied by a service like TLS
1870 may not correspond to the authorization identities used to express a
1871 server's access control policy, requiring a server-specific mapping
1872 to be done. The method by which a server composes and validates an
1873 authorization identity from the authentication credentials supplied
1874 by a client is performed in an implementation-specific manner.
1877 Appendix C. RFC 2829 Change History
1880 This appendix lists the changes made to the text of RFC 2829 in
1881 preparing this document.
1884 C.0. General Editorial Changes
1888 - Changed other instances of the term LDAP to LDAP where v3 of the
1889 protocol is implied. Also made all references to LDAP use the
1894 Harrison Expires April 2005 [Page 27]
1895 Internet-Draft LDAP Authentication Methods 25 October 2004
1898 - Miscellaneous grammatical changes to improve readability.
1901 - Made capitalization in section headings consistent.
1907 - Changed title to reflect inclusion of material from RFC 2830 and
1911 C.1. Changes to Section 1
1917 - Moved conventions used in document to a separate section.
1920 C.2. Changes to Section 2
1926 - Moved section to an appendix.
1929 C.3. Changes to Section 3
1935 - Moved section to an appendix.
1938 C.4 Changes to Section 4
1944 - Changed "Distinguished Name" to "LDAP distinguished name".
1947 C.5. Changes to Section 5
1953 - Added the following sentence: "Servers SHOULD NOT allow clients
1954 with anonymous authentication to modify directory entries or
1955 access sensitive information in directory entries."
1958 C.5.1. Changes to Section 5.1
1964 - Replaced the text describing the procedure for performing an
1965 anonymous bind (protocol) with a reference to section 4.2 of RFC
1966 2251 (the protocol spec).
1972 - Brought text describing procedure for performing an anonymous
1973 bind from section 4.2 of RFC 2251 bis. This text will be
1974 removed from the draft standard version of that document.
1977 Harrison Expires April 2005 [Page 28]
1978 Internet-Draft LDAP Authentication Methods 25 October 2004
1982 C.6. Changes to Section 6.
1988 Reorganized text in section 6.1 as follows:
1991 1. Added a new section (6.1) titled "Simple Authentication" and
1992 moved one of two introductory paragraphs for section 6 into
1993 section 6.1. Added sentences to the paragraph indicating:
1996 a. simple authentication is not suitable for environments where
1997 confidentiality is not available.
2000 b. LDAP implementations SHOULD NOT support simple
2001 authentication unless confidentiality and data integrity
2002 mechanisms are in force.
2005 2. Moved first paragraph of section 6 (beginning with "LDAP
2006 implementations MUST support authentication with a password...")
2007 to section on Digest Authentication (Now section 6.2).
2010 C.6.1. Changes to Section 6.1.
2013 Version -00 Renamed section to 6.2
2016 - Added sentence from original section 6 indicating that the
2017 DIGEST-MD5 SASL mechanism is required for all conforming LDAP
2021 C.6.2. Changes to Section 6.2
2027 - Renamed section to 6.3
2030 - Reworded first paragraph to remove reference to user and the
2031 userPassword password attribute Made the first paragraph more
2032 general by simply saying that if a directory supports simple
2033 authentication that the simple bind operation MAY performed
2034 following negotiation of a TLS ciphersuite that supports
2038 - Replaced "the name of the user's entry" with "a DN" since not
2039 all bind operations are performed on behalf of a "user."
2042 - Added Section 6.3.1 heading just prior to paragraph 5.
2045 - Paragraph 5: replaced "The server" with "DSAs that map the DN
2046 sent in the bind request to a directory entry with a
2047 userPassword attribute."
2050 C.6.3. Changes to section 6.3.
2054 Harrison Expires April 2005 [Page 29]
2055 Internet-Draft LDAP Authentication Methods 25 October 2004
2061 - Renamed to section 6.4.
2064 C.7. Changes to section 7.
2070 C.7.1. Changes to section 7.1.
2076 - Clarified the entity issuing a certificate by moving the phrase
2077 "to have issued the certificate" immediately after
2078 "Certification Authority."
2081 C.8. Changes to section 8.
2087 - Removed the first paragraph because simple authentication is
2088 covered explicitly in section 6.
2091 - Added section 8.1. heading just prior to second paragraph.
2094 - Added section 8.2. heading just prior to third paragraph.
2097 - Added section 8.3. heading just prior to fourth paragraph.
2103 - Moved entire section 8 of RFC 2829 into section 3.4 (Using SASL
2104 for Other Security Services) to bring material on SASL
2105 mechanisms together into one location.
2108 C.9. Changes to section 9.
2114 - Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL
2118 - Added section 9.1. heading.
2121 - Modified a comment in the ABNF from "unspecified userid" to
2122 "unspecified authz id".
2125 - Deleted sentence, "A utf8string is defined to be the UTF-8
2126 encoding of one or more ISO 10646 characters," because it is
2130 - Added section 9.1.1. heading.
2133 - Added section 9.1.2. heading.
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2137 Internet-Draft LDAP Authentication Methods 25 October 2004
2144 - Moved entire section 9 to become section 3.5 so that it would be
2145 with other SASL material.
2148 C.10. Changes to Section 10.
2154 - Updated reference to cracking from a week of CPU time in 1997 to
2155 be a day of CPU time in 2000.
2158 - Added text: "These ciphersuites are NOT RECOMMENDED for use...
2159 and server implementers SHOULD" to sentence just prior the
2160 second list of ciphersuites.
2163 - Added text: "and MAY support other ciphersuites offering
2164 equivalent or better protection," to the last paragraph of the
2168 C.11. Changes to Section 11.
2174 - Moved to section 3.6 to be with other SASL material.
2177 C.12. Changes to Section 12.
2183 - Inserted new section 12 that specifies when SASL protections
2184 begin following SASL negotiation, etc. The original section 12
2185 is renumbered to become section 13.
2191 - Moved to section 3.7 to be with other SASL material.
2194 C.13. Changes to Section 13 (original section 12).
2200 Appendix D. RFC 2830 Change History
2203 This appendix lists the changes made to the text of RFC 2830 in
2204 preparing this document.
2207 D.0. General Editorial Changes
2210 - Material showing the PDUs for the StartTLS response was broken
2211 out into a new section.
2216 Harrison Expires April 2005 [Page 31]
2217 Internet-Draft LDAP Authentication Methods 25 October 2004
2220 - The wording of the definition of the StartTLS request and
2221 StartTLS response was changed to make them parallel. NO changes
2222 were made to the ASN.1 definition or the associated values of
2226 - A separate section heading for graceful TLS closure was added
2227 for parallelism with section on abrupt TLS closure.
2230 Appendix E. RFC 2251 Change History
2233 This appendix lists the changes made to the text of RFC 2251 in
2234 preparing this document.
2237 E.0. General Editorial Changes
2240 - All material from section 4.2 of RFC 2251 was moved into this
2244 - A new section was created for the Bind Request
2247 - Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved
2248 after the section on the Bind Response for parallelism with the
2249 presentation of the StartTLS operations. The section was also
2250 subdivided to explicitly call out the various effects being
2251 described within it.
2253 - All SASL profile information from RFC 2829 was brought within
2254 the discussion of the Bind operation (primarily sections 4.4 -
2258 Appendix F. Change History to Combined Document
2261 F.1. Changes for draft-ldap-bis-authmeth-02
2267 - Added references to other LDAP standard documents, to sections
2268 within the document, and fixed broken references.
2271 - General editorial changes--punctuation, spelling, formatting,
2278 - Added glossary of terms and added sub-section headings
2284 - Clarified security mechanisms 3, 4, & 5 and brought language in
2285 line with IETF security glossary.
2293 Harrison Expires April 2005 [Page 32]
2294 Internet-Draft LDAP Authentication Methods 25 October 2004
2297 - Brought language in requirement (3) in line with security
2301 - Clarified that information fetched prior to initiation of TLS
2302 negotiation must be discarded
2305 -Clarified that information fetched prior to initiation of SASL
2306 negotiation must be discarded
2309 - Rewrote paragraph on SASL negotiation requirements to clarify
2316 - Added stipulation that sasl choice allows for any SASL mechanism
2317 not prohibited by this document. (Resolved conflict between this
2318 statement and one that prohibited use of ANONYMOUS and PLAIN
2325 - Added a.x.bar.com to wildcard matching example on hostname check.
2331 - Added Association State Transition Tables to show the various
2332 states through which an association may pass along with the
2333 actions and decisions required to traverse from state to state.
2339 - Brought security terminology in line with IETF security glossary
2340 throughout the appendix.
2343 F.2. Changes for draft-ldapbis-authmeth-03
2349 - Added introductory notes and changed title of document and
2350 references to conform to WG chair suggestions for the overall
2351 technical specification.
2354 - Several issues--H.13, H.14, H.16, H.17--were resolved without
2355 requiring changes to the document.
2361 - Removed reference to /etc/passwd file and associated text.
2367 - Removed sections 4.1, 4.2 and parts of section 4.3. This
2368 information was being duplicated in the protocol specification
2369 and will now reside there permanently.
2372 Harrison Expires April 2005 [Page 33]
2373 Internet-Draft LDAP Authentication Methods 25 October 2004
2379 - changed words, "not recommended" to "strongly discouraged"
2385 - Based on ldapbis WG discussion at IETF52 two sentences were
2386 added indicating that clients SHOULD NOT send a DN value when
2387 binding with the sasl choice and servers SHALL ignore any value
2388 received in this circumstance.
2395 - Generalized the language of this section to not refer to any
2396 specific password attribute or to refer to the directory entry
2403 - Added security consideration regarding misuse of unauthenticated
2407 - Added security consideration requiring access control to be
2408 applied only to authenticated users and recommending it be
2409 applied when reading sensitive information or updating directory
2413 F.3. Changes for draft-ldapbis-authmeth-04
2419 - Changed references to use [RFCnnnn] format wherever possible.
2420 (References to works in progress still use [name] format.)
2421 - Various edits to correct typos and bring field names, etc. in
2422 line with specification in [Protocol] draft.
2425 - Several issues--H.13, H.14, H.16, H.17--were resolved without
2426 requiring changes to the document.
2432 - Changed ABNF grammar to use productions that are like those in
2439 - Removed sections 5.1, 5.2, and 5.4 that will be added to
2440 [Protocol]. Renumbered sections to accommodate this change.
2449 Harrison Expires April 2005 [Page 34]
2450 Internet-Draft LDAP Authentication Methods 25 October 2004
2453 - Reviewed Association State table for completeness and accuracy.
2454 Renumbered actions A3, , and A5 to be A5, A3, and A4
2455 respectively. Re-ordered several lines in the table to ensure
2456 that actions are in ascending order (makes analyzing the table
2457 much more logical). Added action A2 to several states where it
2458 was missing and valid. Added actions A7 and A8 placeholders to
2459 states S1, S2, S4 and S5 pending resolution of issue H.28.
2465 - Modified security consideration (originally added in -03)
2466 requiring access control to be applied only to authenticated
2467 users. This seems nonsensical because anonymous users may have
2468 access control applied to limit permissible actions.
2473 - Verified all normative references and moved informative
2474 references to a new section 14.
2477 F.4. Changes for draft-ldapbis-authmeth-05
2483 - General editory changes to fix punctuation, spelling, line
2485 - Verified and updated intra- and inter-document references
2487 - Document-wide review for proper usage of RFC 2119 keywords with
2488 several changes to correct improper usage.
2492 - Updated to match current contents of documents. This was needed
2493 due to movement of material on Bind and StartTLS operations to
2494 [Protocol] in this revision.
2500 - Renamed section to "Rationale for LDAP Security Mechanisms" and
2501 removed text that did not support this theme. Part of the
2502 motivation for this change was to remove the implication of the
2503 previous section title, "Required Security Mechanisms", and
2504 other text found in the section that everything in the section
2508 - Information from several removed paragraphs that describe
2509 deployment scenarios will be added Appendix A in the next
2510 revision of the draft.
2514 - Paragraph beginning, " If TLS is negotiated, the client MUST
2515 discard all information..." was moved to section 5.1.7 and
2516 integrated with related material there.
2520 Harrison Expires April 2005 [Page 35]
2521 Internet-Draft LDAP Authentication Methods 25 October 2004
2524 - Paragraph beginning, "If a SASL security layer is negotiated..."
2525 was moved to section 4.2
2531 - Changed wording of first paragraph to clarify meaning.
2535 - Added paragraph from section 3 of -04 beginning, "If a SASL
2536 security layer is negotiated..."
2540 - Renamed to "Other SASL Mechanisms" and completely rewrote the
2541 section (one sentence) to generalize the treatment of SASL
2542 mechanisms not explicitly mentioned in this document.
2548 - Added paragraph beginning, "The dnAuthzID choice allows client
2549 applications..." to clarify whether DN form authorization
2550 identities have to also have a corresponding directory entry.
2551 This change was based on editor's perception of WG consensus.
2554 - Made minor clarifying edits in the paragraph beginning, "The
2555 uAuthzID choice allows for compatibility..."
2561 - Made minor clarifying edits in the last paragraph of the
2568 - Wording from section 3 paragraph beginning " If TLS is
2569 negotiated, the client MUST discard all information..." was
2570 moved to this section and integrated with existing text.
2576 - Changed usage of "TLS connection" to "TLS session" throughout.
2579 - Removed empty section 5.2.1 and renumbered sections it had
2580 previously contained.
2586 - Added introductory paragraph at beginning of section.
2592 - Changed term "data privacy" to "data confidentiality" to be
2593 consistent with usage in rest of document.
2599 Harrison Expires April 2005 [Page 36]
2600 Internet-Draft LDAP Authentication Methods 25 October 2004
2604 - Changed first paragraph to require implementations that
2605 implement *password-based* authentication to implement and
2606 support DIGEST-MD5 SASL authentication.
2612 - First paragraph: changed "session encryption" to "session
2613 confidentiality protection" to be consistent with usage in rest
2620 - Began changes to incorporate information on deployment scenarios
2621 removed from section 3.
2624 F.5. Changes for draft-ldapbis-authmeth-06
2630 - Combined Section 2 (Introduction) and Section 3 (Motivation) and
2631 moved Introduction to section 1. All following sections numbers
2632 were decremented by one as result.
2635 - Edits to fix typos, I-D nits, etc.
2638 - Opened several new issues in Appendix G based on feedback from
2639 WG. Some of these have been resolved. Others require further
2646 - Added additional example of spoofing under threat (7).
2652 - Changed definition of "association" and added terms,
2653 "connection" and "TLS connection" to bring usage in line with
2660 - Clarified sentence stating that the client MUST NOT use derived
2667 - Began edits to association state table to clarify meaning of
2668 various states and actions.
2671 - Added action A9 to cover abandoned bind operation and added
2672 appropriate transitions to the state transition table to
2677 Harrison Expires April 2005 [Page 37]
2678 Internet-Draft LDAP Authentication Methods 25 October 2004
2684 - Replaced first paragraph to clarify that the "DIGEST-MD5" SASL
2685 mechanism is required to implement.
2691 - Rewrote the section to make the advice more applicable over the
2692 long term, i.e. more "timeless." The intent of content in the
2693 original section was preserved.
2699 - Added a clarifying example to the consideration regarding misuse
2700 of unauthenticated access.
2703 F.6. Changes for draft-ldapbis-authmeth-07
2709 - Updated external and internal references to accommodate changes
2713 - Opened several new issues in Appendix G based on feedback from
2714 WG. Some of these have been resolved. Others require further
2721 - Rewrote much of section 3.3 to meet the SASL profile
2722 requirements of draft-ietf-sasl-rfc2222bis-xx.txt section 5.
2725 - Changed treatement of SASL ANONYMOUS and PLAIN mechanisms to
2726 bring in line with WG consensus.
2732 - Note to implementers in section 4.1.1 based on operational
2736 - Clarification on client continuing by performing a StartTLS with
2737 TLS already established in section 4.1.4.
2740 - Moved verification of mapping of client's authentication ID to
2741 asserted authorization ID to apply only to explicit assertion.
2742 The local policy in place for implicit assertion is adequate.
2748 - Removed most of section 7.2 as the information is now covered
2749 adequately via the new SASL profile in section 3.3. Added note
2750 to implementors regarding the treatment of username and realm
2751 values in DIGEST-MD5.
2755 Harrison Expires April 2005 [Page 38]
2756 Internet-Draft LDAP Authentication Methods 25 October 2004
2759 - Section 7.3. Minor clarifications in wording.
2762 - Section 7.3.1. Clarification that a match of the presented value
2763 to any member of the set of stored passwords constitutes a
2764 successful authentication.
2767 F.7. Changes for draft-ldapbis-authmeth-08
2773 - Changed usage from LDAPv3 to LDAP for usage consistency across
2774 LDAP technical specification.
2777 - Fixed a number of usage nits for consistency and to bring doc in
2778 conformance with publication guidelines.
2784 - Significant cleanup and rewording of abstract based on WG
2791 - New definition of user.
2797 - Added 1.5 sentences at end of introductory paragraph indicating
2798 the effect of the Bind op on the association.
2804 - Retitled section and clarified wording
2810 - Clarified that simple authentication choice provides three types
2811 of authentication: anonymous, unauthenticated, and simple
2818 - New wording clarifying when negotiated security mechanisms take
2825 - Changed requirement to discard information about server fetched
2826 prior to SASL negotiation from MUST to SHOULD to allow for
2827 information obtained through secure mechanisms.
2835 Harrison Expires April 2005 [Page 39]
2836 Internet-Draft LDAP Authentication Methods 25 October 2004
2839 - Simplified wording of first paragraph based on suggestion from
2846 - Minor clarifications in wording.
2852 - Minor clarifications in wording in first sentence.
2853 - Explicitly called out that the DN value in the dnAuthzID form is
2854 to be matched using DN matching rules.
2855 - Called out that the uAuthzID MUST be prepared using SASLprep
2856 rules before being compared.
2857 - Clarified requirement on assuming global uniqueness by changing
2858 a "generally... MUST" wording to "SHOULD".
2864 - Simplified wording describing conditions when StartTLS cannot be
2866 - Simplified wording in note to implementers regarding race
2867 condition with outstanding LDAP operations on connection.
2873 - Removed section and moved relevant text to section 4.2.2.
2879 - Renumbered to 4.1.5.
2880 - Updated server identity check rules for server's name based on
2887 - Renumbered to 4.1.6
2888 - Changed requirement to discard information about server fetched
2889 prior to TLS negotion from MUST to SHOULD to allow for
2890 information obtained through secure mechanisms.
2896 - Clarified wording.
2897 - Added definition of anonymous and unauthenticated binds.
2903 - Added security consideration (moved from elsewhere) discouraging
2904 use of cleartext passwords on unprotected communication
2912 Harrison Expires April 2005 [Page 40]
2913 Internet-Draft LDAP Authentication Methods 25 October 2004
2916 - Added an IANA consideration to update GSSAPI service name
2917 registry to point to [Roadmap] and [Authmeth]
2920 F.8. Changes for draft-ldapbis-authmeth-09
2926 - Updated section references within document
2927 - Changed reference tags to match other docs in LDAP TS
2928 - Used non-quoted names for all SASL mechanisms
2934 - Inspected keyword usage and removed several improper usages.
2937 - Removed sentence saying DIGEST-MD5 is LDAP's mandatory-to-
2938 implement mechanism. This is covered elsewhere in document.
2941 - Moved section 5, authentication state table, of -08 draft to
2942 section 8 of -09 and completely rewrote it.
2948 - Reworded sentence beginning, "It is also desirable to allow
2949 authentication methods to carry identities based on existing,
2950 non-LDAP DN-forms..."
2951 - Clarified relationship of this document to other documents in
2958 - Removed paragraph beginning,"If the client is configured to
2959 support multiple SASL mechanisms..." because the actions
2960 specified in the paragraph do not provide the protections
2961 indicated. Added a new paragraph indicating that clients and
2962 server should allow specification of acceptable mechanisms and
2963 only allow those mechanisms to be used.
2966 - Clarified independent behavior when TLS and SASL security layers
2967 are both in force (e.g. one being removed doesn't affect the
2974 - Moved most of section 4.2.2, Client Assertion of Authorization
2975 Identity, to sections 3.3.6, 3.3.6.1, and 3.3.6.2.
2981 - Moved some normative comments into text body.
2989 Harrison Expires April 2005 [Page 41]
2990 Internet-Draft LDAP Authentication Methods 25 October 2004
2993 - Non success resultCode values are valid if server is *unwilling*
2994 or unable to negotiate TLS.
3000 - Rewrote entire section based on WG feedback.
3006 - Moved most of this section to 3.3.6 for better document flow.
3012 - Rewrote entire section based on WG feedback.
3018 - Moved imperative language regarding unauthenticated access from
3019 security considerations to here.
3025 - Added several paragraphs regarding the risks of transmitting
3026 passwords in the clear and requiring server implementations to
3027 provide a specific configuration that reduces these risks.
3033 - Added sentence describing protections provided by DIGEST-MD5
3035 - Changed DNs in exmple to be dc=example,dc=com.
3041 - Updated consideration on use of cleartext passwords to include
3042 other unprotected authentication credentials
3043 - Substantial rework of consideration on misuse of unauthenticated
3047 F.9. Changes for draft-ldapbis-authmeth-10
3050 - Reorganized content of sections 3-9 to improve document flow and
3052 - Resolved issue of effect of Start TLS and TLS closure on
3054 - Made numerous minor wording changes based on WG feedback.
3055 - Updated list of threats for Section 1.
3056 - Recommendation that servers should not support weaker TLS
3057 ciphersuites unless other protection is in place.
3058 - Moved authentication state table to appendix and relettered
3062 F.10. Changes for draft-ldapbis-authmeth-11
3066 Harrison Expires April 2005 [Page 42]
3067 Internet-Draft LDAP Authentication Methods 25 October 2004
3073 - Many editorial changes throughout to clarify wording and better
3074 express intent, primarily based on suggestions from WG mail
3076 - More standard naming of authentication mechanisms throughout
3077 document, e.g. "Anonymous Authentication Mechanism of the Simple
3084 - Editorial changes to add clarity.
3085 - Moved section 2 of authmeth -09 into section 1
3091 - New section outlining implementation requirements.
3097 - Editorial clarification on need for following operation
3098 sequencing requirements.
3104 - New section added to describe use of client certificates with
3105 StartTLS. Incorporates material moved from other sections of
3110 - New section added to discuss associations. Related material was
3111 moved from various other sections of authmeth -09 and
3112 incorporated into this new section.
3118 - Added several paragraphs regarding transmission and derivation
3119 of authentication and authorization identities using the Bind
3126 - Clarified rules for determining valid credentials and situations
3127 where invalidCredentials result is to be returned.
3133 - Added three security considerations based on WG feedback.
3139 - Simplfied state tables by removing two unnecessary actions from
3140 the actions table, and removing the current state column of the
3144 Harrison Expires April 2005 [Page 43]
3145 Internet-Draft LDAP Authentication Methods 25 October 2004
3148 state transition table. Updated references to authmeth and
3152 F.11. Changes for draft-ldapbis-authmeth-12
3158 - Changed refererences from Start TLS to StartTLS.
3159 - Removed Appendix B: Example Deployment Scenarios
3160 - Removed Appendix H as all issues listed in the appendix are now
3167 - Added implementation requirement that server implementations
3168 that SUPPORT StartTLS MUST support the
3169 TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA ciphersuite.
3175 - Added wording clarifying that a client's association is
3176 unaffected if a non-success resultCode is returned in the
3183 - Final paragraph of this section details requirements for
3184 serverSaslCreds field when no challenge value is sent.
3190 - Clarified language on uAuthzID usage.
3196 - Moved entire section into security considerations. New section
3198 - Reorganized security considerations by topic.
3199 - Added several security considerations based on WG feedback.
3205 - Moved section to become section 3.3.
3208 F.12. Changes for draft-ldapbis-authmeth-13
3214 - General edits for clarity and to remove errors.
3215 - Reworded definition of association (section 1.2) and reworked
3216 usage of association throughout document. Current semantics:
3217 every connection has an association with the same lifetime as
3218 the connection, and that association passes through various
3219 authorization states.
3222 Harrison Expires April 2005 [Page 44]
3223 Internet-Draft LDAP Authentication Methods 25 October 2004
3226 - Made usage of data confidentiality consistent throughout
3231 - Reworded mechanisms 3 and 4 for more parallelism.
3232 - Changed language on rationale for required mechansisms from
3233 future to past tense.
3237 - Clarified that implementations may support any additional
3238 authentication mechanism, not just mechanisms associated with
3239 simple and SASL bind choices.
3243 - Moved paragraph explaining goals for using TLS with LDAP from
3244 security considerations to here.
3248 - Reworked text to better explain meaning of strongAuthRequired
3249 result code when for invalidated associations.
3253 - Clarified action when simple bind request has a DN with invalid
3258 - Added ability to configure and enforce administrative service
3259 limits as a way to protect against denial of service attacks.
3263 - Clarified that this security consideration relates to performing
3264 client authentication during the TLS handshake and not to
3265 subsequent SASL EXTERNAL authentication.
3269 - Updated tables by collapsing identical states and actions. Also
3270 added an invalidated association state and accompanying actions.
3273 Added implementation requirement that server implementations
3276 Intellectual Property Rights
3279 The IETF takes no position regarding the validity or scope of any
3280 Intellectual Property Rights or other rights that might be claimed
3281 to pertain to the implementation or use of the technology described
3282 in this document or the extent to which any license under such
3283 rights might or might not be available; nor does it represent that
3284 it has made any independent effort to identify any such rights.
3285 Information on the procedures with respect to rights in RFC
3286 documents can be found in BCP 78 and BCP 79.
3289 Copies of IPR disclosures made to the IETF Secretariat and any
3290 assurances of licenses to be made available, or the result of an
3291 attempt made to obtain a general license or permission for the use
3294 Harrison Expires April 2005 [Page 45]
3295 Internet-Draft LDAP Authentication Methods 25 October 2004
3298 of such proprietary rights by implementers or users of this
3299 specification can be obtained from the IETF on-line IPR repository
3300 at http://www.ietf.org/ipr.
3303 The IETF invites any interested party to bring to its attention any
3304 copyrights, patents or patent applications, or other proprietary
3305 rights that may cover technology that may be required to implement
3306 this standard. Please address the information to the IETF at ietf-
3310 Full Copyright Statement
3313 Copyright (C) The Internet Society (2004). This document is subject
3314 to the rights, licenses and restrictions contained in BCP 78, and
3315 except as set forth therein, the authors retain all their rights.
3318 This document and the information contained herein are provided on
3319 an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
3320 REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
3321 INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
3322 IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
3323 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
3324 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
3357 Harrison Expires April 2005 [Page 46]