3 INTERNET-DRAFT Editor: R. Harrison
4 draft-ietf-ldapbis-authmeth-12.txt Novell, Inc.
5 Obsoletes: 2829, 2830 August, 2004
6 Intended Category: Draft Standard
14 LDAP: Authentication Methods
16 Connection Level Security Mechanisms
20 By submitting this Internet-Draft, I accept the provisions of
21 Section 4 of RFC 3667. By submitting this Internet-Draft, I certify
22 that any applicable patent or other IPR claims of which I am aware
23 have been disclosed, and any of which I become aware will be
24 disclosed, in accordance with RFC 3668.
26 This document is intended to be, after appropriate review and
27 revision, submitted to the RFC Editor as a Standard Track document.
28 Distribution of this memo is unlimited. Technical discussion of
29 this document will take place on the IETF LDAP Revision Working
30 Group mailing list <ietf-ldapbis@OpenLDAP.org>. Please send
31 editorial comments directly to the author
32 <roger_harrison@novell.com>.
34 Internet-Drafts are working documents of the Internet Engineering
35 Task Force (IETF), its areas, and its working groups. Note that
36 other groups may also distribute working documents as Internet-
39 Internet-Drafts are draft documents valid for a maximum of six
40 months and may be updated, replaced, or obsoleted by other documents
41 at any time. It is inappropriate to use Internet-Drafts as
42 reference material or to cite them other than as "work in progress."
44 The list of current Internet-Drafts can be accessed at
45 http://www.ietf.org/ietf/1id-abstracts.txt
47 The list of Internet-Draft Shadow Directories can be accessed at
48 http://www.ietf.org/shadow.html.
52 Copyright (C) The Internet Society (2004). All Rights Reserved.
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61 This document describes authentication methods and connection level
62 security mechanisms of the Lightweight Directory Access Protocol
65 This document details establishment of TLS (Transport Layer
66 Security) using the StartTLS operation.
68 This document details the simple Bind authentication method
69 including anonymous, unauthenticated, and plain-text password
70 mechanisms and the SASL (Simple Authentication and Security Layer)
71 Bind authentication method including DIGEST-MD5 and EXTERNAL
74 This document discusses various authentication and authorization
75 states through which a connection to an LDAP server may pass and the
76 actions that trigger these state changes.
80 1. Introduction.....................................................3
81 1.1. Relationship to Other Documents................................5
82 1.2. Conventions Used in this Document..............................6
83 1.2.1. Glossary of Terms............................................6
84 1.2.2. Security Terms and Concepts..................................6
85 1.2.3. Keywords.....................................................6
86 2. Implementation Requirements......................................6
87 3. StartTLS Operation...............................................7
88 3.1. Sequencing of the StartTLS Operation...........................7
89 3.1.1. StartTLS Request ............................................7
90 3.1.2. StartTLS Response............................................8
91 3.1.3. TLS Version Negotiation......................................8
92 3.1.4. Client Certificate...........................................8
93 3.1.5. Discovery of Resultant Security Level........................8
94 3.1.6. Server Identity Check........................................9
95 3.1.7. Refresh of Server Capabilities Information...................9
96 3.2. Effects of TLS on a Client's Authorization Identity...........10
97 3.2.1. TLS Connection Establishment Effects........................10
98 3.2.2. Client Assertion of Authorization Identity..................10
99 3.2.3. TLS Connection Closure Effects..............................10
100 3.3. TLS Ciphersuites..............................................10
101 3.3.1. TLS Ciphersuites Recommendations............................11
102 4. LDAP Associations...............................................12
103 4.1. Anonymous LDAP Association on Unbound Connections.............12
104 4.2. Anonymous LDAP Association After Failed Bind..................12
105 4.3. Invalidated Associations......................................12
106 5. Bind Operation..................................................12
107 5.1. Simple Authentication Choice..................................13
108 5.2. SASL Authentication Choice....................................13
109 6. Anonymous Authentication Mechanism of Simple Bind...............13
110 7. Unauthenticated Authentication Mechanism of Simple Bind.........13
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117 8. Simple Authentication Mechanism of Simple Bind .................14
118 9. SASL Protocol Profile...........................................14
119 9.1. SASL Service Name for LDAP....................................14
120 9.2. SASL Authentication Initiation and Protocol Exchange..........15
121 9.3. Octet Where Negotiated Security Mechanisms Take Effect........16
122 9.4. Determination of Supported SASL Mechanisms....................16
123 9.5. Rules for Using SASL Security Layers..........................16
124 9.6 Support for Multiple Authentications...........................17
125 10. SASL EXTERNAL Mechanism........................................17
126 10.1. Implicit Assertion...........................................17
127 10.2. Explicit Assertion...........................................17
128 10.3. SASL Authorization Identity..................................17
129 10.4. SASL Authorization Identity Syntax...........................18
130 11. SASL DIGEST-MD5 Mechanism......................................19
131 12. Security Considerations........................................20
132 12.1. General LDAP Security Considerations.........................20
133 12.1.1.Password-related Security Considerations....................21
134 12.2. StartTLS Security Considerations.............................22
135 12.3. Unauthenticated Mechanism Security Considerations............22
136 12.4. Simple Mechanism Security Considerations.....................23
137 12.5. SASL DIGEST-MD5 Mechanism Security Considerations............23
138 12.6. Related Security Considerations..............................23
139 13. IANA Considerations............................................23
140 Acknowledgments....................................................23
141 Normative References...............................................24
142 Informative References.............................................25
143 Author's Address...................................................25
144 Appendix A. LDAP Association State Transition Tables...............25
145 A.1. LDAP Association States.......................................25
146 A.2. Actions that Affect LDAP Association State....................26
147 A.3. Decisions Used in Making LDAP Association State Changes.......26
148 A.4. LDAP Association State Transition Table.......................27
149 Appendix B. Authentication and Authorization Concepts..............27
150 B.1. Access Control Policy.........................................28
151 B.2. Access Control Factors........................................28
152 B.3. Authentication, Credentials, Identity.........................28
153 B.4. Authorization Identity........................................28
154 Appendix C. RFC 2829 Change History................................29
155 Appendix D. RFC 2830 Change History................................33
156 Appendix E. RFC 2251 Change History................................33
157 Appendix F. Change History to Combined Document....................33
158 Intellectual Property Rights.......................................52
163 The Lightweight Directory Access Protocol (LDAP) [Roadmap] is a
164 powerful protocol for accessing directories. It offers means of
165 searching, retrieving and manipulating directory content, and ways
166 to access a rich set of security functions.
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173 It is vital that these security functions be interoperable among all
174 LDAP clients and servers on the Internet; therefore there has to be
175 a minimum subset of security functions that is common to all
176 implementations that claim LDAP conformance.
178 Basic threats to an LDAP directory service include:
180 (1) Unauthorized access to directory data via data-retrieval
183 (2) Unauthorized access to directory data by monitoring others'
186 (3) Unauthorized access to reusable client authentication
187 information by monitoring others' access,
189 (4) Unauthorized modification of directory data,
191 (5) Unauthorized modification of configuration information,
193 (6) Denial of Service: Use of resources (commonly in excess) in a
194 manner intended to deny service to others,
196 (7) Spoofing: Tricking a user or client into believing that
197 information came from the directory when in fact it did not,
198 either by modifying data in transit or misdirecting the client's
199 connection. Tricking a user or client into sending privileged
200 information to a hostile entity that appears to be the directory
201 server but is not. Tricking a directory server into believing
202 that information came from a particular client when in fact it
203 came from a hostile entity, and
205 (8) Hijacking: An attacker seizes control of an established protocol
208 Threats (1), (4), (5), (6), (7) are (8) are active attacks. Threats
209 (2) and (3) are passive attacks.
211 Threats (1), (4), (5) and (6) are due to hostile clients. Threats
212 (2), (3), (7) and (8) are due to hostile agents on the path between
213 client and server or hostile agents posing as a server, e.g. IP
217 LDAP offers the following security mechanisms:
219 (1) Authentication by means of the Bind operation. The Bind
220 operation provides a simple method which supports anonymous,
221 unauthenticated, and authenticated with password mechanisms, and
222 the Secure Authentication and Security Layer (SASL) method which
223 supports a wide variety of authentication mechanisms,
225 (2) Mechanisms to support vendor-specific access control facilities
226 (LDAP does not offer a standard access control facility)
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233 (3) Data integrity protection by means of TLS or SASL mechanisms
234 with security layers that provide data integrity protection,
236 (4) Data confidentiality protection by means of the TLS protocol or
237 SASL mechanisms that provide data confidentiality protection,
239 (5) Server resource usage limitation by means of administrative
240 limits configured on the server, and
242 (6) Server authentication by means of the TLS protocol or SASL
245 LDAP may also be protected by means outside the LDAP protocol, e.g.
246 with IP-level security [RFC2401].
248 At the moment, imposition of access controls is done by means
249 outside the scope of LDAP.
251 It seems clear that allowing implementations, faced with the above
252 requirements, to simply pick and choose among the possible
253 alternatives is not a strategy that is likely to lead to
254 interoperability. In the absence of mandates, clients will be
255 written that do not support any security function supported by the
256 server, or worse, they will support only clear text passwords that
257 provide inadequate security for most circumstances.
259 It is desirable to allow clients to authenticate using a variety of
260 mechanisms including mechanisms where identities are represented as
261 distinguished names [X.501] [Models] in string form [LDAPDN] or are
262 used in different systems (e.g. user name in string form). Because
263 these authentication mechanisms transmit credentials in plain text
264 form and other authentication mechanisms do not provide data
265 security services, it is desirable to ensure secure interopability
266 by indentifying a mandatory-to-implement mechanism for establishing
267 transport-layer security services.
269 The set of security mechanisms provided in LDAP and described in
270 this document is intended to meet the security needs for a wide
271 range of deployment scenarios and still provide a high degree of
272 interoperability among various LDAP implementations and deployments.
273 Appendix B contains example deployment scenarios that list the
274 mechanisms that might be used to achieve a reasonable level of
275 security in various circumstances.
277 1.1. Relationship to Other Documents
279 This document is an integral part of the LDAP Technical
280 Specification [Roadmap].
282 This document obsoletes RFC 2829.
284 Sections 2 and 4 of RFC 2830 are obsoleted by [Protocol]. The
285 remainder of RFC 2830 is obsoleted by this document.
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292 1.2. Conventions Used in this Document
294 1.2.1. Glossary of Terms
296 The following terms are used in this document. To aid the reader,
297 these terms are defined here.
299 - "user" represents any human or application entity which is
300 accessing the directory using a directory client. A directory
301 client (or client) is also known as a directory user agent (DUA).
303 - "connection" and "LDAP connection" both refer to the underlying
304 transport protocol connection between two protocol peers.
306 - "TLS connection" refers to an LDAP connection with TLS
309 - "association" and "LDAP association" both refer to the
310 association of the LDAP connection and its current
311 authentication and authorization state.
313 1.2.2. Security Terms and Concepts
315 In general, security terms in this document are used consistently
316 with the definitions provided in [RFC2828]. In addition, several
317 terms and concepts relating to security, authentication, and
318 authorization are presented in Appendix C of this document. While
319 the formal definition of these terms and concepts is outside the
320 scope of this document, an understanding of them is prerequisite to
321 understanding much of the material in this document. Readers who are
322 unfamiliar with security-related concepts are encouraged to review
323 Appendix C before reading the remainder of this document.
327 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
328 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
329 document are to be interpreted as described in RFC 2119 [RFC2119].
331 2. Implementation Requirements
333 LDAP server implementations MUST support the anonymous
334 authentication mechanism of simple bind (as discussed in Section 6).
336 LDAP implementations that support any authentication mechanism other
337 than the anonymous authentication mechanism of simple bind MUST
338 support the DIGEST-MD5 [DIGEST-MD5] mechanism of SASL bind (as
339 detailed in section 11). DIGEST-MD5 is a reasonably strong
340 authentication mechanism that provides (mandatory-to-implement) data
341 security (data integrity and data confidentiality) services.
343 LDAP impementations SHOULD support the simple (DN and password)
344 authentication mechanism of simple bind (as detailed in section 8).
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350 Implementations that support this mechanism MUST be capable of
351 protecting it by establishment of TLS (as discussed in section 3) or
352 other suitable suitable data confidentiality and data integrity
353 protection (e.g. IPSec).
355 Implementations MAY support additional mechanisms of the simple and
356 SASL bind choices. Some of these mechanisms are discussed below.
358 LDAP server implementations SHOULD support client assertion of
359 authorization identity via the SASL EXTERNAL mechanism (sections
362 LDAP server implementations SHOULD support the StartTLS operation,
363 and server implementations that do support the StartTLS operation
364 MUST support the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA ciphersuite.
366 3. StartTLS Operation
368 The Start Transport Layer Security (StartTLS) operation defined in
369 section 4.14 of [Protocol] provides the ability to establish TLS
370 [TLS] on an LDAP connection.
372 3.1. Sequencing of the StartTLS Operation
374 This section describes the overall procedures clients and servers
375 must follow for TLS establishment. These procedures take into
376 consideration various aspects of the overall security of the LDAP
377 association including discovery of resultant security level and
378 assertion of the client's authorization identity.
380 Note that the precise effects, on a client's authorization identity,
381 of establishing TLS on an LDAP connection are described in detail in
384 3.1.1. StartTLS Request
386 A client may send the StartTLS extended request at any time after
387 establishing an LDAP connection, except:
389 - when TLS is currently established on the connection,
390 - when a multi-stage SASL negotiation is in progress on the
392 - when it has not yet received responses for all operation
393 requests previously issued on the connection.
395 As described in [Protocol] Section 4.14.2.2, a (detected) violation
396 of any of these requirements results in a return of the
397 operationsError resultCode.
399 Client implementers should ensure that they strictly follow these
400 operation sequencing requirements to prevent interoperability
401 issues. Operational experience has shown that violating these
402 requirements causes interoperability issues because there are race
403 conditions that prevent servers from detecting some violations of
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409 these requirements due to server hardware speed, network latencies,
412 There is no general requirement that the client have or have not
413 already performed a Bind operation (section 4) before sending a
414 StartTLS operation request.
416 If the client did not establish a TLS connection before sending a
417 request and the server requires the client to establish a TLS
418 connection before performing that request, the server MUST reject
419 that request by sending a resultCode of confidentialityRequired.
421 3.1.2. StartTLS Response
423 The server will return an extended response with the resultCode of
424 success if it is willing and able to negotiate TLS.
426 It will return a resultCode other than success (documented in
427 [Protocol] section 4.13.2.2) if it is unwilling or unable to do so.
428 The client's current association is unaffected if a non-success
429 resultCode is returned.
431 In the successful case, the client (which has ceased to transfer
432 LDAP requests on the connection) MUST either begin a TLS negotiation
433 or close the connection. The client will send PDUs in the TLS Record
434 Protocol directly over the underlying transport connection to the
435 server to initiate [TLS] negotiation.
437 3.1.3. TLS Version Negotiation
439 Negotiating the version of TLS to be used is a part of the TLS
440 Handshake Protocol [TLS]. Please refer to that document for details.
442 3.1.4. Client Certificate
444 In an LDAP server requests a client to provide its certificate
445 during TLS negotiation and the client does not present a suitablle
446 certifcate (e.g. one that can be validated), the server MAY use a
447 local security policy to determine whether to successfully complete
450 If the client provides a certificate that can be validated,
451 information in the certificate may be used by the server in
452 establishing the client's authorization identity by use of the SASL
453 external mechanism as discussed in Section 9.
455 3.1.5. Discovery of Resultant Security Level
457 After a TLS connection is established on an LDAP connection, both
458 parties must individually decide whether or not to continue based on
459 the security level achieved. The procedure for ascertaining the TLS
460 connection's security level is implementation dependent.
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468 If the client or server decides that the security level is not high
469 enough for it to continue, it SHOULD gracefully close the TLS
470 connection immediately after the TLS negotiation has completed (see
471 [Protocol] section 4.13.3.1 and section 3.2.3 below). The client
472 may then close the connection, attempt to StartTLS again, send an
473 unbind request, or send any other LDAP request.
475 3.1.6. Server Identity Check
477 The client MUST check its understanding of the server's hostname
478 against the server's identity as presented in the server's
479 Certificate message in order to prevent man-in-the-middle attacks.
481 Matching is performed according to these rules:
483 - The client MUST use the server name provided by the user (or
484 other trusted entity) as the value to compare against the server
485 name as expressed in the server's certificate. A hostname
486 derived from user input is to be considered provided by the user
487 only if derived in a secure fashion (e.g., DNSSEC).
489 - If a subjectAltName extension of type dNSName is present in the
490 certificate, it SHOULD be used as the source of the server's
493 - The string values to be compared MUST be prepared according to
494 the rules described in [Matching].
496 - The "*" wildcard character is allowed. If present, it applies
497 only to the left-most name component.
499 For example, *.bar.com would match a.bar.com and b.bar.com, but
500 it would not match a.x.bar.com nor would it match bar.com. If
501 more than one identity of a given type is present in the
502 certificate (e.g. more than one dNSName name), a match in any
503 one of the set is considered acceptable.
505 If the hostname does not match the dNSName-based identity in the
506 certificate per the above check, user-oriented clients SHOULD either
507 notify the user (clients may give the user the opportunity to
508 continue with the connection in any case) or terminate the
509 connection and indicate that the server's identity is suspect.
510 Automated clients SHOULD close the connection, returning and/or
511 logging an error indicating that the server's identity is suspect.
513 Beyond the server identity checks described in this section, clients
514 SHOULD be prepared to do further checking to ensure that the server
515 is authorized to provide the service it is observed to provide. The
516 client may need to make use of local policy information in making
519 3.1.7. Refresh of Server Capabilities Information
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527 Upon TLS session establishment, the client SHOULD discard or refresh
528 all information about the server it obtained prior to the initiation
529 of the TLS negotiation and not obtained through secure mechanisms.
530 This protects against man-in-the-middle attacks that may have
531 altered any server capabilities information retrieved prior to TLS
534 The server may advertise different capabilities after TLS
535 establishment. In particular, the value of supportedSASLMechanisms
536 may be different after TLS has been negotiated (specifically, the
537 EXTERNAL and PLAIN [PLAIN] mechanisms are likely to be listed only
538 after a TLS negotiation has been performed).
540 3.2. Effects of TLS on a Client's Authorization Identity
542 This section describes the effects on a client's authorization
543 identity brought about by establishing TLS on an LDAP connection.
544 The default effects are described first, and next the facilities for
545 client assertion of authorization identity are discussed including
546 error conditions. Finally, the effects of closing the TLS connection
549 Authorization identities and related concepts are described in
552 3.2.1. TLS Connection Establishment Effects
554 The decision to keep or invalidate the established LDAP association
555 (section 12) after TLS connection establishment is a matter of local
558 3.2.2. Client Assertion of Authorization Identity
560 After successfully establishing a TLS session, a client may request
561 that its certificate exchanged during the TLS establishment be
562 utilized to determine the authorization identity of the LDAP
563 association. The client accomplishes this via an LDAP Bind request
564 specifying a SASL mechanism of EXTERNAL [SASL] (section 9).
566 3.2.3. TLS Connection Closure Effects
568 The decision to keep or invalidate the established LDAP association
569 after TLS closure is a matter of local server policy.
571 3.3. TLS Ciphersuites
573 Several issues should be considered when selecting TLS ciphersuites
574 that are appropriate for use in a given circumstance. These issues
575 include the following:
577 - The ciphersuite's ability to provide adequate confidentiality
578 protection for passwords and other data sent over the LDAP
579 connection. Client and server implementers should recognize that
580 some TLS ciphersuites provide no confidentiality protection
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586 while other ciphersuites that do provide confidentiality
587 protection may be vulnerable to being cracked using brute force
588 methods, especially in light of ever-increasing CPU speeds that
589 reduce the time needed to successfully mount such attacks.
591 Client and server implementers should carefully consider the
592 value of the password or data being protected versus the level
593 of confidentially protection provided by the ciphersuite to
594 ensure that the level of protection afforded by the ciphersuite
597 - The ciphersuite's vulnerability (or lack thereof) to man-in-the-
598 middle attacks. Ciphersuites vulnerable to man-in-the-middle
599 attacks SHOULD NOT be used to protect passwords or sensitive
600 data, unless the network configuration is such that the danger
601 of a man-in-the-middle attack is tolerable.
603 3.3.1. TLS Ciphersuites Recommendations
605 [[TODO: Kurt will have someone from security to look at this and
606 will propose how to handle discussion of specific TLS ciphersuites
609 As of the writing of this document, the following recommendations
610 regarding TLS ciphersuites are applicable. Because circumstances are
611 constantly changing, this list must not be considered exhaustive,
612 but is hoped that it will serve as a useful starting point for
615 The following ciphersuites defined in [TLS] MUST NOT be used for
616 confidentiality protection of passwords or data:
618 TLS_NULL_WITH_NULL_NULL
619 TLS_RSA_WITH_NULL_MD5
620 TLS_RSA_WITH_NULL_SHA
622 The following ciphersuites defined in [TLS] can be cracked easily
623 (less than a day of CPU time on a standard CPU in 2000) and are NOT
624 RECOMMENDED for use in confidentiality protection of passwords or
627 TLS_RSA_EXPORT_WITH_RC4_40_MD5
628 TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5
629 TLS_RSA_EXPORT_WITH_DES40_CBC_SHA
630 TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA
631 TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA
632 TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
633 TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA
634 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
635 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
637 The following ciphersuites are vulnerable to man-in-the-middle
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645 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
646 TLS_DH_anon_WITH_RC4_128_MD5
647 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
648 TLS_DH_anon_WITH_DES_CBC_SHA
649 TLS_DH_anon_WITH_3DES_EDE_CBC_SHA
653 Every LDAP connection has an associated authentication and
654 authorization state referred to as the "LDAP association". The Bind
655 operation defined in section 4.2 of [Protocol] and discussed further
656 in section 5 below allows authentication information to be exchanged
657 between the client and server to set the authentication and
658 authorization state and thus establish a new LDAP association.
660 4.1. Anonymous LDAP Association on Unbound Connections
662 Prior to the successful completion of a Bind operation and during
663 any subsequent authentication exchange, the session has an anonymous
664 LDAP association. Among other things this implies that the client
665 need not send a Bind Request in the first PDU of the connection. The
666 client may send any operation request prior to binding, and the
667 server MUST treat it as if it had been performed after an anonymous
668 bind operation (section 6). This authentication state on an LDAP
669 association is sometimes referred to as an implied anonymous bind.
671 4.2. Anonymous LDAP Association After Failed Bind
673 Upon receipt of a Bind request, the LDAP association is moved to an
674 anonymous state and only upon successful completion of the
675 authentication exchange (and the Bind operation) is the association
676 moved to an authenticated state. Thus, a failed Bind operation
677 produces an anonymous LDAP association on the session.
679 4.3. Invalidated Associations
681 The server may invalidate the LDAP association at any time, e.g. if
682 the established security association between the client and server
683 has unexpectedly failed or been compromised. The association
684 remains invalidated until the next bind request. While the
685 association is invalidated, the server may reject any operation
686 request other than Bind, Unbind, and StartTLS by responding with a
687 resultCode of strongAuthRequired to indicate that the client needs
688 to bind to reestablish its authentication state before the server
689 will attempt to perform the requested operation. This behavior is
690 explained here to help client implementers properly understand and
691 react to this situation.
695 The Bind operation ([Protocol] section 4.2) allows authentication
696 information to be exchanged between the client and server to
697 establish a new LDAP association.
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704 The Bind request typically specifies the desired authentication
705 identity. Some Bind mechanisms also allow the client to specify the
706 authorization identity. If the authorization identity is not
707 specified, the server derives it from the authentication identity in
708 an implementation-specific manner.
710 If the authorization identity is specified the server MUST verify
711 that the client's authentication identity is permitted to assume
712 (e.g. proxy for) the asserted authorization identity. The server
713 MUST reject the Bind operation with an invalidCredentials resultCode
714 in the Bind response if the client is not so authorized.
716 5.1. Simple Authentication Choice
718 The simple authentication choice of the Bind Operation provides
719 three authentication mechanisms:
721 1. an anonymous authentication mechanism (section 6),
723 2. an unauthenticated authentication mechanism (section 7), and
725 3. a simple authentication mechanism using credentials consisting
726 of a name (in the form of an LDAP distinguished name [LDAPDN])
727 and a password (section X).
729 5.2. SASL Authentication Choice
731 The sasl authentication choice of the Bind Operation provides
732 facilities for using any SASL mechanism (sections 9-11) including
733 authentication mechanisms and other services (e.g. data security
736 6. Anonymous Authentication Mechanism of Simple Bind
738 An LDAP client may use the anonymous authentication mechanism of the
739 simple Bind choice to explicitly establish an anonymous LDAP
740 association by sending a Bind request with a name value of zero
741 length and with the simple authentication choice containing a
742 password value of zero length.
744 7. Unauthenticated Authentication Mechanism of Simple Bind
746 An LDAP client may use the unauthenticated authentication mechanism
747 of the simple Bind choice to establish an anonymous LDAP association
748 by sending a Bind request with a name value, a distinguished name in
749 LDAP string form [LDAPDN], of non-zero length, and specifying the
750 the simple authentication choice containing a password value of zero
753 Unauthenticated binds can have significant security issues (see
754 section 14). Servers SHOULD by default reject unauthenticated bind
755 requests with a resultCode of invalidCredentials, and clients may
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762 need to actively detect situations where they would unintentionally
763 make an unauthenticated bind request.
765 8. Simple Authentication Mechanism of Simple Bind
767 An LDAP client may use the simple authentication mechanism of the
768 simple Bind choice to establish an authenticated LDAP association by
769 sending a Bind request with a name value, a distinguished name in
770 LDAP string form [LDAPDN], and specifying the simple authentication
771 choice containing an OCTET STRING password value of non-zero length.
773 Servers that map the DN sent in the bind request to a directory
774 entry with an associated set of one or more passwords, will compare
775 the presented password to the set of passwords associated with that
776 entry. The presented password is considered valid if it matches any
779 If the DN is not valid, or the password is not valid for the DN, or
780 the server otherwise considers the credentials to be invalid, the
781 server is to return the invalidCredentials result code. The server
782 is only to return success result code when the credentials are valid
783 and the server is willing to provide service to the entity these
784 credentials identify.
786 Server behavior is undefined for Bind requests with a zero-length
787 name value and specifying the simple authentication choice with a
788 value of non-zero length.
790 The simple authentication mechanism of simple bind is not suitable
791 for authentication in environments where there is no network or
792 transport layer confidentiality. LDAP implementations MUST be
793 capable of protecting it by establish::qment of TLS (as discussed in
794 section 3) or other suitable data confidentiality and data integrity
795 protection(e.g. IPSec). LDAP implementations
796 SHOULD support authentication with the "simple" authentication
797 choice when the connection is protected against eavesdropping using
798 TLS, as defined in section 4. LDAP implementations SHOULD NOT
799 support authentication with the "simple" authentication choice
800 unless the data on the connection is protected using TLS or other
801 data confidentiality and data integrity protection.
803 9. SASL Protocol Profile
805 LDAP allows authentication via any SASL mechanism [SASL]. As LDAP
806 includes native anonymous and simple (plain text) authentication
807 methods, the ANONYMOUS [ANONYMOUS] and PLAIN [PLAIN] SASL mechanisms
808 are typically not used with LDAP.
810 Each protocol that utilizes SASL services is required to supply
811 certain information profiling the way they are exposed through the
812 protocol ([SASL] section 5). This section explains how each of these
813 profiling requirements are met by LDAP.
815 9.1. SASL Service Name for LDAP
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822 The SASL service name for LDAP is "ldap", which has been registered
823 with the IANA as a GSSAPI service name.
825 9.2. SASL Authentication Initiation and Protocol Exchange
827 SASL authentication is initiated via an LDAP bind request
828 ([Protocol] section 4.2) with the following parameters:
831 - The AuthenticationChoice is sasl.
832 - The mechanism element of the SaslCredentials sequence contains
833 the value of the desired SASL mechanism.
834 - The optional credentials field of the SaslCredentials sequence
835 may be used to provide an initial client response for
836 mechanisms that are defined to have the client send data first
837 (see [SASL] sections 5 and 5.1).
839 In general, a SASL authentication protocol exchange consists of a
840 series of server challenges and client responses, the contents of
841 which are specific to and defined by the SASL mechanism. Thus for
842 some SASL authentication mechanisms, it may be necessary for the
843 client to respond to one or more server challenges by invoking the
844 BindRequest multiple times. A challenge is indicated by the server
845 sending a BindResponse with the resultCode set to
846 saslBindInProgress. This indicates that the server requires the
847 client to send a new bind request with the same sasl mechanism to
848 continue the authentication process.
850 To the LDAP protocol, these challenges and responses are opaque
851 binary tokens of arbitrary length. LDAP servers use the
852 serverSaslCreds field, an OCTET STRING, in a bind response message
853 to transmit each challenge. LDAP clients use the credentials field,
854 an OCTET STRING, in the SaslCredentials sequence of a bind request
855 message to transmit each response. Note that unlike some Internet
856 protocols where SASL is used, LDAP is not text-based, thus no Base64
857 transformations are performed on these challenge and response values.
859 Clients sending a bind request with the sasl choice selected SHOULD
860 send an zero-length value in the name field. Servers receiving a
861 bind request with the sasl choice selected SHALL ignore any value in
864 A client may abort a SASL bind negotiation by sending a BindRequest
865 with a different value in the mechanism field of SaslCredentials, or
866 an AuthenticationChoice other than sasl.
868 If the client sends a BindRequest with the sasl mechanism field as
869 an empty string, the server MUST return a BindResponse with
870 authMethodNotSupported as the resultCode. This will allow clients to
871 abort a negotiation if it wishes to try again with the same SASL
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880 The server indicates completion of the SASL challenge-response
881 exchange by responding with a bind response in which the resultCode
882 is either success, or an error indication.
884 The serverSaslCreds field in the BindResponse can be used to include
885 an optional challenge with a success notification for mechanisms
886 which are defined to have the server send additional data along with
887 the indication of successful completion. If a server does not intend
888 to send a challenge value in a BindResponse message, the server
889 SHALL omit the serverSaslCreds field (rather than including the
890 field with a zero-length value).
892 9.3. Octet Where Negotiated Security Mechanisms Take Effect
894 SASL security layers take effect following the transmission by the
895 server and reception by the client of the final successful
896 BindResponse in the exchange.
898 Once a SASL security layer providing integrity or confidentiality
899 services takes effect, the layer remains in effect until a new layer
900 is installed (i.e. at the first octet following the final
901 BindResponse of the bind operation that caused the new layer to take
902 effect). Thus, an established SASL security layer is not affected
903 by a failed or non-SASL Bind.
905 9.4. Determination of Supported SASL Mechanisms
907 Clients may determine the SASL mechanisms a server supports by
908 reading the supportedSASLMechanisms attribute from the root DSE
909 (DSA-Specific Entry) ([Models] section 5.1). The values of this
910 attribute, if any, list the mechanisms the server supports in the
911 current LDAP session state. LDAP servers SHOULD allow an
912 anonymously-bound client to retrieve the supportedSASLMechanisms
913 attribute of the root DSE.
915 Because SASL mechanisms provide critical security functions, clients
916 and servers should be configurable to specify what mechanisms are
917 acceptable and allow only those mechanisms to be used. Both clients
918 and servers must confirm that the negotiated security level meets
919 their requirements before proceeding to use the connection.
921 9.5. Rules for Using SASL Security Layers
923 If a SASL security layer is negotiated, the client SHOULD discard
924 information about the server it obtained prior to the initiation of
925 the SASL negotiation and not obtained through secure mechanisms.
927 If a lower level security layer (such as TLS) is negotiated, any
928 SASL security services SHALL be layered on top of such security
929 layers regardless of the order of their negotiation. In all other
930 respects, SASL security services and other security layers act
931 independently, e.g. if both TLS and SASL security service are in
932 effect then removing the SASL security service does not affect the
933 continuing service of TLS and vice versa.
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940 9.6 Support for Multiple Authentications
942 LDAP supports multiple SASL authentications as defined in [SASL]
945 10. SASL EXTERNAL Mechanism
947 A client can use the EXTERNAL SASL [SASL] mechanism to request the
948 LDAP server to authenticate and establish a resulting authorization
949 identity using security credentials exchanged by a lower security
950 layer (such as by TLS authentication or IP-level security
953 The resulting authentication identity of the LDAP association is
954 derived from the security credentials in an implementation-specific
955 manner. If the client's authentication credentials have not been
956 established at a lower security layer, the SASL EXTERNAL bind MUST
957 fail with a resultCode of inappropriateAuthentication. Although
958 this situation has the effect of leaving the LDAP association in an
959 anonymous state (section 5), the state of any established security
962 A client may either implicitly request that its LDAP authorization
963 identity be derived from its authentication credentials exchanged at
964 a lower security layer or it may explicitly provide an authorization
965 identity and assert that it be used in combination with those
966 authentication credentials. The former is known as an implicit
967 assertion, and the latter as an explicit assertion.
969 10.1. Implicit Assertion
971 An implicit authorization identity assertion is performed by
972 invoking a Bind request of the SASL form using the EXTERNAL
973 mechanism name that does not include the optional credentials octet
974 string (found within the SaslCredentials sequence in the Bind
975 Request). The server will derive the client's authorization identity
976 from the authentication identity supplied by the security layer
977 (e.g., a public key certificate used during TLS establishment)
978 according to local policy. The underlying mechanics of how this is
979 accomplished are implementation specific.
981 10.2. Explicit Assertion
983 An explicit authorization identity assertion is performed by
984 invoking a Bind request of the SASL form using the EXTERNAL
985 mechanism name that includes the credentials octet string. This
986 string MUST be constructed as documented in section 3.4.1.
988 10.3. SASL Authorization Identity
990 When the EXTERNAL SASL mechanism is being negotiated, if the
991 SaslCredentials credentials field is present, it contains an
992 authorization identity. Other mechanisms define the location of the
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998 authorization identity in the credentials field. In either case, the
999 authorization identity is represented in the authzId form described
1002 10.4. SASL Authorization Identity Syntax
1004 The authorization identity is a string of UTF-8 [RFC3629] encoded
1005 [Unicode] characters corresponding to the following ABNF [RFC2234]
1008 authzId = dnAuthzId / uAuthzId
1010 DNCOLON = %x64 %x6e %x3a ; "dn:"
1011 UCOLON = %x75 %x3a ; "u:"
1013 ; distinguished-name-based authz id.
1014 dnAuthzId = DNCOLON distinguishedName
1016 ; unspecified authorization id, UTF-8 encoded.
1017 uAuthzId = UCOLON userid
1018 userid = *UTF8 ; syntax unspecified
1020 where the <distinguishedName> production is defined in section 3 of
1021 [LDAPDN] and <UTF8> production is defined in section 1.3 of [Models].
1023 In order to support additional specific authorization identity
1024 forms, future updates to this specification may add new choices
1025 supporting other forms of the authzId production.
1027 The dnAuthzId choice is used to assert authorization identities in
1028 the form of a distinguished name to be matched in accordance with
1029 the distinguishedNameMatch matching rule [Syntaxes]. The decision to
1030 allow or disallow an authentication identity to have access to the
1031 requested authorization identity is a matter of local policy ([SASL]
1032 section 4.2). For this reason there is no requirement that the
1033 asserted dn be that of an entry in the directory.
1035 The uAuthzId choice allows clients to assert an authorization
1036 identity that is not in distinguished name form. The format of
1037 userid is defined as only a sequence of UTF-8 [RFC3629] encoded
1038 [Unicode] characters, and any further interpretation is a local
1039 matter. To compare uAuthzID values, each uAuthzID value MUST be
1040 prepared using [SASLPrep] and then the two values are compared
1043 For example, the userid could identify a user of a specific
1044 directory service, be a login name, or be an email address. A
1045 uAuthzId SHOULD NOT be assumed to be globally unique.
1047 11. SASL DIGEST-MD5 Mechanism
1049 LDAP servers that implement any authentication method or mechanism
1050 other than simple anonymous bind MUST implement the SASL
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1057 DIGEST-MD5 mechanism [DIGEST-MD5]. This provides client
1058 authentication with protection against passive eavesdropping attacks
1059 but does not provide protection against man-in-the-middle attacks.
1060 DIGEST-MD5 also provides data integrity and data confidentiality
1063 Support for subsequent authentication ([DIGEST-MD5] section 2.2) is
1064 OPTIONAL in clients and servers.
1066 Implementers must take care to ensure that they maintain the
1067 semantics of the DIGEST-MD5 specification even when handling data
1068 that has different semantics in the LDAP protocol.
1069 For example, the SASL DIGEST-MD5 authentication mechanism utilizes
1070 realm and username values ([DIGEST-MD5] section 2.1) which are
1071 syntactically simple strings and semantically simple realm and
1072 username values. These values are not LDAP DNs, and there is no
1073 requirement that they be represented or treated as such. Username
1074 and realm values that look like LDAP DNs in form, e.g. <cn=bob,
1075 dc=example,dc=com>, are syntactically allowed, however DIGEST-MD5
1076 treats them as simple strings for comparison purposes. To illustrate
1077 further, the two DNs <cn=Bob,dc=example,dc=com> (upper case "B") and
1078 <cn=bob,dc=example,dc=com> (lower case "b") are equivalent when
1079 being compared semantically as LDAP DNs because the cn attribute is
1080 defined to be case insensitive, however the two values are not
1081 equivalent if they represent username values in DIGEST-MD5 because
1082 [SASLPrep] semantics are used by DIGEST-MD5.
1084 12. Security Considerations
1086 Security issues are discussed throughout this document. The
1087 unsurprising conclusion is that security is an integral and
1088 necessary part of LDAP. This section discusses a number of LDAP-
1089 related security considerations.
1091 12.1. General LDAP Security Considerations
1093 LDAP itself provides no security or protection from accessing or
1094 updating the directory by other means than through the LDAP
1095 protocol, e.g. from inspection by database administrators. Access
1096 control SHOULD always be applied when reading sensitive information
1097 or updating directory information.
1099 Servers can minimize denial of service attacks by timing out idle
1100 connections, and returning the unwillingToPerform resultCode rather
1101 than performing computationally expensive operations requested by
1102 unauthorized clients.
1104 A connection on which the client has not established connection
1105 integrity and privacy services (e.g via StartTLS, IPSec or a
1106 suitable SASL mechanism) is subject to man-in-the-middle attacks to
1107 view and modify information in transit. Client and server
1108 implementors SHOULD take measures to protect confidential data from
1109 these attacks by using data protection services as discussed in this
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1117 12.1.1.Password-related Security Considerations
1119 LDAP allows multi-valued password attributes. In systems where
1120 entries are expected to have one and only one password,
1121 administrative controls should be provided to enforce this behavior.
1123 The use of clear text passwords and other unprotected authentication
1124 credentials is strongly discouraged over open networks when the
1125 underlying transport service cannot guarantee confidentiality.
1127 The transmission of passwords in the clear--typically for
1128 authentication or modification--poses a significant security risk.
1129 This risk can be avoided by using SASL authentication [SASL]
1130 mechanisms that do not transmit passwords in the clear or by
1131 negotiating transport or session layer confidentiality services
1132 before transmitting password values.
1134 To mitigate the security risks associated with the transfer of
1135 passwords, a server implementation that supports any password-based
1136 authentication mechanism that transmits passwords in the clear MUST
1137 support a policy mechanism that at the time of authentication or
1138 password modification, requires:
1140 A StartTLS encryption layer has been successfully negotiated.
1144 Some other confidentiality mechanism that protects the password
1145 value from snooping has been provided.
1149 The server returns a resultCode of confidentialityRequired for
1150 the operation (i.e. simple bind with password value, SASL bind
1151 transmitting a password value in the clear, add or modify
1152 including a userPassword value, etc.), even if the password
1155 12.2. StartTLS Security Considerations
1157 The goals of using the TLS [TLS] protocol with LDAP are to ensure
1158 connection confidentiality and integrity, and to optionally provide
1159 for authentication. TLS expressly provides these capabilities
1160 (although the authentication services of TLS are available to LDAP
1161 only in combination with the SASL EXTERNAL authentication method,
1162 and then only if the SASL EXTERNAL implementation chooses to make
1163 use of the TLS credentials).
1165 All security gained via use of the StartTLS operation is gained by
1166 the use of TLS itself. The StartTLS operation, on its own, does not
1167 provide any additional security.
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1175 The level of security provided though the use of TLS depends
1176 directly on both the quality of the TLS implementation used and the
1177 style of usage of that implementation. Additionally, a man-in-the-
1178 middle attacker can remove the StartTLS extended operation from the
1179 supportedExtension attribute of the root DSE. Both parties SHOULD
1180 independently ascertain and consent to the security level achieved
1181 once TLS is established and before beginning use of the TLS
1182 connection. For example, the security level of the TLS connection
1183 might have been negotiated down to plaintext.
1185 Clients SHOULD either warn the user when the security level
1186 achieved does not provide data confidentiality and/or integrity
1187 protection, or be configurable to refuse to proceed without an
1188 acceptable level of security.
1190 Server implementors SHOULD allow server administrators to elect
1191 whether and when data confidentiality and integrity are required, as
1192 well as elect whether TLS authentication of the client is required.
1194 Implementers should be aware of and understand TLS security
1195 considerations as discussed in the TLS specification [TLS].
1197 12.3. Unauthenticated Mechanism Security Considerations
1199 Operational experience shows that clients can (and frequently do)
1200 misuse the unauthenticated authentication mechanism of simple bind
1201 (see section 7). For example, a client program might make a
1202 decision to grant access to non-directory information on the basis
1203 of completing a successful bind operation. LDAP server
1204 implementations will return a success response to an unauthenticated
1205 bind request thus leaving the client with the impression that the
1206 server has successfully authenticated the identity represented by
1207 the user name, when in effect, an anonymous LDAP association has
1208 been established. Clients that use the results from a simple bind
1209 operation to make authorization decisions should actively detect
1210 unauthenticated bind requests (by verifying that the supplied
1211 password is not empty) and react appropriately.
1213 12.4. Simple Mechanism Security Considerations
1215 The simple authentication mechanism of simple bind discloses the
1216 password to server, which is an inherent security risk. There are
1217 other mechanisms such as DIGEST-MD5 that do not disclose password to
1220 12.5. SASL DIGEST-MD5 Mechanism Security Considerations
1222 The SASL DIGEST-MD5 mechanism is prone to the qop substitution
1223 attack, as discussed in 6.2 of RFC 2831. The qop substitution
1224 attack can be mitigated (as discussed in 6.2 of RFC 2831).
1226 The SASL DIGEST-MD5 mechanism [DIGEST-MD5] provides client
1227 authentication with protection against passive eavesdropping attacks
1228 but does not provide protection against man-in-the-middle attacks.
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1235 Implementers should be aware of and understand DIGEST-MD5 security
1236 considerations as discussed in the DIGEST-MD5 specification [DIGEST-
1239 12.6. Related Security Considerations
1240 Additional security considerations relating to the various
1241 authentication methods and mechanisms discussed in this document
1242 apply and can be found in [SASL], [SASLPrep], [StringPrep] and
1245 13. IANA Considerations
1247 The following IANA considerations apply to this document:
1249 Please update the GSSAPI service name registry to point to [Roadmap]
1252 [[TODO: add any missing IANA Considerations.]]
1256 This document combines information originally contained in RFC 2829
1257 and RFC 2830. The editor acknowledges the work of Harald Tveit
1258 Alvestrand, Jeff Hodges, Tim Howes, Steve Kille, RL "Bob" Morgan ,
1259 and Mark Wahl, each of whom authored one or more of these documents.
1261 This document is based upon input of the IETF LDAP Revision working
1262 group. The contributions and suggestions made by its members in
1263 shaping the contents and technical accuracy of this document is
1264 greatly appreciated.
1266 Normative References
1268 [[Note to the RFC Editor: please replace the citation tags used in
1269 referencing Internet-Drafts with tags of the form RFCnnnn.]]
1271 [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
1272 Syntax Specifications: ABNF", RFC 2234, November 1997.
1274 [DIGEST-MD5] Leach, P. C. Newman, and A. Melnikov, "Using Digest
1275 Authentication as a SASL Mechanism", draft-ietf-sasl-
1276 rfc2831bis-xx.txt, a work in progress.
1278 [RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
1279 Requirement Levels", BCP 14, RFC 2119, March 1997.
1281 [LDAPDN] Zeilenga, Kurt D. (editor), "LDAP: String
1282 Representation of Distinguished Names", draft-ietf-
1283 ldapbis-dn-xx.txt, a work in progress.
1285 [Matching] Hoffman, Paul and Steve Hanna, "Matching Text Strings
1286 in PKIX Certificates", draft-hoffman-pkix-stringmatch-
1287 xx.txt, a work in progress.
1289 Harrison Expires February 2005 [Page 22]
1291 Internet-Draft LDAP Authentication Methods 16 July 2004
1294 [Models] Zeilenga, Kurt D. (editor), "LDAP: Directory
1295 Information Models", draft-ietf-ldapbis-models-xx.txt,
1298 [Protocol] Sermersheim, J., "LDAP: The Protocol", draft-ietf-
1299 ldapbis-protocol-xx.txt, a work in progress.
1301 [Roadmap] K. Zeilenga, "LDAP: Technical Specification Road Map",
1302 draft-ietf-ldapbis-roadmap-xx.txt, a work in progress.
1304 [SASL] Melnikov, A. (editor), "Simple Authentication and
1305 Security Layer (SASL)", draft-ietf-sasl-rfc2222bis-
1306 xx.txt, a work in progress.
1308 [SASLPrep] Zeilenga, K., "Stringprep profile for user names and
1309 passwords", draft-ietf-sasl-saslprep-xx.txt, (a work in
1312 [StringPrep] M. Blanchet, "Preparation of Internationalized
1313 Strings ('stringprep')", draft-hoffman-rfc3454bis-
1314 xx.txt, a work in progress.
1316 [Syntaxes] Legg, S. (editor), "LDAP: Syntaxes and Matching Rules",
1317 draft-ietf-ldapbis-syntaxes-xx.txt, a work in progress.
1319 [TLS] Dierks, T. and C. Allen. "The TLS Protocol Version
1320 1.1", draft-ietf-tls-rfc2246-bis-xx.txt, a work in
1323 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
1324 10646", RFC 3629, STD 63, November 2003.
1326 [Unicode] The Unicode Consortium, "The Unicode Standard, Version
1327 3.2.0" is defined by "The Unicode Standard, Version
1328 3.0" (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-
1329 61633-5), as amended by the "Unicode Standard Annex
1331 (http://www.unicode.org/reports/tr27/) and by the
1332 "Unicode Standard Annex #28: Unicode 3.2"
1333 (http://www.unicode.org/reports/tr28/).
1335 Informative References
1337 [ANONYMOUS] Zeilenga, K.,"Anonymous SASL Mechanism", draft-
1338 zeilenga-sasl-anon-xx.txt, a work in progress.
1340 [RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828, May
1343 [PLAIN] Zeilenga, K.,"Plain SASL Mechanism", draft-zeilenga-
1344 sasl-plain-xx.txt, a work in progress.
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1352 [RFC2401] Kent, S. and R. Atkinson, "Security Architecture for
1353 the Internet Protocol", RFC 2401, November 1998.
1359 1800 S. Novell Place
1363 roger_harrison@novell.com
1365 Appendix A. LDAP Association State Transition Tables
1367 This section provides a state transition table to represent a state
1368 diagram for the various authentication and TLS states through which
1369 an LDAP association may pass during the course of its existence and
1370 the actions that cause these changes in state.
1372 This section is based entirely on information found in this document
1373 and other documents that are part of the LDAP Technical
1374 Specification [Roadmap]. As such, it is strictly informational in
1377 A.1. LDAP Association States
1379 The following table lists the valid LDAP association states and
1380 provides a description of each state. The ID for each state is used
1381 in the state transition table in section A.4.
1383 ID State Description
1384 -- --------------------------------------------------------------
1386 no Authentication ID is associated with the LDAP connection
1387 no Authorization ID is in force
1389 Authentication ID = I
1390 Authorization ID = X
1391 S3 Authenticated SASL EXTERNAL, implicit authorization ID
1392 Authentication ID = J
1393 Authorization ID = Y
1394 S4 Authenticated SASL EXTERNAL, explicit authorization ID Z
1395 Authentication ID = J
1396 Authorization ID = Z
1398 A.2. Actions that Affect LDAP Association State
1400 The following table lists the actions that can affect the
1401 authentication and authorization state of an LDAP association. The
1402 ID for each action is used in the state transition table in section
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1411 -- --------------------------------------------------------------
1412 A1 Client bind request fails
1413 A2 Client successfully performs anonymous simple bind
1414 A3 Client successfully performs unauthenticated simple bind
1415 A4 Client successfully performs simple bind with name and password
1416 OR SASL bind with any mechanism except EXTERNAL using an
1417 authentication ID = I that maps to authorization ID X
1418 A5 Client Binds SASL EXTERNAL with implicit assertion of
1419 authorization ID (section 9.1)]. The current authentication ID
1420 maps to authorization ID = Y.
1421 A6 Client Binds SASL EXTERNAL with explicit assertion of
1422 authorization ID = Z (section 9.2)]
1423 A7 Client StartTLS request fails
1424 A8 Client StartTLS request succeeds
1425 A9 Client or Server: graceful TLS removal
1427 A.3. Decisions Used in Making LDAP Association State Changes
1429 Certain changes in the authentication and authorization state of an
1430 LDAP association are only allowed if the server can affirmatively
1431 answer a question. These questions are applied as part of the
1432 criteria for allowing or disallowing a state transition in the state
1433 transition table in section A.4.
1435 ID Decision Question
1436 -- --------------------------------------------------------------
1437 D1 Are lower-layer credentials available?
1438 D2 Can lower-layer credentials for Auth ID "K" be mapped to
1439 asserted AuthZID "L"?
1441 A.4. LDAP Association State Transition Table
1443 The LDAP Association table below lists the the actions that could
1444 affect authentication and authorization state of an LDAP association
1445 and the resulting state of an LDAP association after a given action
1448 S1, the initial state for the state machine described in this table,
1449 is the authentication state when an LDAP connection is initially
1453 Action State Comment
1454 ------- ----- -------------------------------------------------
1459 A5, S1 Failed bind, section 10.1
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1469 A6, S1 Failed bind, section 10.2
1471 A6, S1 Failed bind, section 10.2
1477 A7 no [Protocol] section 4.14.2.2
1479 A8 no [Protocol] section 4.14.2.1
1481 A9 S1 [Protocol] section 4.14.3.1
1483 Appendix B. Authentication and Authorization Concepts
1485 This appendix defines basic terms, concepts, and interrelationships
1486 regarding authentication, authorization, credentials, and identity.
1487 These concepts are used in describing how various security
1488 approaches are utilized in client authentication and authorization.
1490 B.1. Access Control Policy
1492 An access control policy is a set of rules defining the protection
1493 of resources, generally in terms of the capabilities of persons or
1494 other entities accessing those resources. Security objects and
1495 mechanisms, such as those described here, enable the expression of
1496 access control policies and their enforcement.
1498 B.2. Access Control Factors
1500 A request, when it is being processed by a server, may be associated
1501 with a wide variety of security-related factors (section 4.2 of
1502 [Protocol]). The server uses these factors to determine whether and
1503 how to process the request. These are called access control factors
1504 (ACFs). They might include source IP address, encryption strength,
1505 the type of operation being requested, time of day, etc. Some
1506 factors may be specific to the request itself, others may be
1507 associated with the connection via which the request is transmitted,
1508 others (e.g. time of day) may be "environmental".
1510 Access control policies are expressed in terms of access control
1511 factors. E.g., a request having ACFs i,j,k can perform operation Y
1512 on resource Z. The set of ACFs that a server makes available for
1513 such expressions is implementation-specific.
1515 B.3. Authentication, Credentials, Identity
1517 Authentication credentials are the evidence supplied by one party to
1518 another, asserting the identity of the supplying party (e.g. a user)
1519 who is attempting to establish an association with the other party
1520 (typically a server). Authentication is the process of generating,
1521 transmitting, and verifying these credentials and thus the identity
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1529 they assert. An authentication identity is the name presented in a
1532 There are many forms of authentication credentials -- the form used
1533 depends upon the particular authentication mechanism negotiated by
1534 the parties. For example: X.509 certificates, Kerberos tickets,
1535 simple identity and password pairs. Note that an authentication
1536 mechanism may constrain the form of authentication identities used
1539 B.4. Authorization Identity
1541 An authorization identity is one kind of access control factor. It
1542 is the name of the user or other entity that requests that
1543 operations be performed. Access control policies are often expressed
1544 in terms of authorization identities; e.g., entity X can perform
1545 operation Y on resource Z.
1547 The authorization identity bound to an association is often exactly
1548 the same as the authentication identity presented by the client, but
1549 it may be different. SASL allows clients to specify an authorization
1550 identity distinct from the authentication identity asserted by the
1551 client's credentials. This permits agents such as proxy servers to
1552 authenticate using their own credentials, yet request the access
1553 privileges of the identity for which they are proxying [SASL]. Also,
1554 the form of authentication identity supplied by a service like TLS
1555 may not correspond to the authorization identities used to express a
1556 server's access control policy, requiring a server-specific mapping
1557 to be done. The method by which a server composes and validates an
1558 authorization identity from the authentication credentials supplied
1559 by a client is implementation-specific.
1561 Appendix C. RFC 2829 Change History
1563 This appendix lists the changes made to the text of RFC 2829 in
1564 preparing this document.
1566 C.0. General Editorial Changes
1569 - Changed other instances of the term LDAP to LDAP where v3 of the
1570 protocol is implied. Also made all references to LDAP use the
1573 - Miscellaneous grammatical changes to improve readability.
1575 - Made capitalization in section headings consistent.
1579 - Changed title to reflect inclusion of material from RFC 2830 and
1582 C.1. Changes to Section 1
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1586 Internet-Draft LDAP Authentication Methods 16 July 2004
1591 - Moved conventions used in document to a separate section.
1593 C.2. Changes to Section 2
1597 - Moved section to an appendix.
1599 C.3. Changes to Section 3
1603 - Moved section to an appendix.
1605 C.4 Changes to Section 4
1609 - Changed "Distinguished Name" to "LDAP distinguished name".
1611 C.5. Changes to Section 5
1615 - Added the following sentence: "Servers SHOULD NOT allow clients
1616 with anonymous authentication to modify directory entries or
1617 access sensitive information in directory entries."
1619 C.5.1. Changes to Section 5.1
1623 - Replaced the text describing the procedure for performing an
1624 anonymous bind (protocol) with a reference to section 4.2 of RFC
1625 2251 (the protocol spec).
1629 - Brought text describing procedure for performing an anonymous
1630 bind from section 4.2 of RFC 2251 bis. This text will be
1631 removed from the draft standard version of that document.
1633 C.6. Changes to Section 6.
1637 Reorganized text in section 6.1 as follows:
1639 1. Added a new section (6.1) titled "Simple Authentication" and
1640 moved one of two introductory paragra phs for section 6 into
1641 section 6.1. Added sentences to the paragraph indicating:
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1645 Internet-Draft LDAP Authentication Methods 16 July 2004
1648 a. simple authentication is not suitable for environments where
1649 confidentiality is not available.
1651 b. LDAP implementations SHOULD NOT support simple
1652 authentication unless confidentiality and data integrity
1653 mechanisms are in force.
1655 2. Moved first paragraph of section 6 (beginning with "LDAP
1656 implementations MUST support authentication with a password...")
1657 to section on Digest Authentication (Now section 6.2).
1659 C.6.1. Changes to Section 6.1.
1661 Version -00 Renamed section to 6.2
1663 - Added sentence from original section 6 indicating that the
1664 DIGEST-MD5 SASL mechanism is required for all conforming LDAP
1667 C.6.2. Changes to Section 6.2
1671 - Renamed section to 6.3
1673 - Reworded first paragraph to remove reference to user and the
1674 userPassword password attribute Made the first paragraph more
1675 general by simply saying that if a directory supports simple
1676 authentication that the simple bind operation MAY performed
1677 following negotiation of a TLS ciphersuite that supports
1680 - Replaced "the name of the user's entry" with "a DN" since not
1681 all bind operations are performed on behalf of a "user."
1683 - Added Section 6.3.1 heading just prior to paragraph 5.
1685 - Paragraph 5: replaced "The server" with "DSAs that map the DN
1686 sent in the bind request to a directory entry with a
1687 userPassword attribute."
1689 C.6.3. Changes to section 6.3.
1693 - Renamed to section 6.4.
1695 C.7. Changes to section 7.
1699 C.7.1. Changes to section 7.1.
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1704 Internet-Draft LDAP Authentication Methods 16 July 2004
1708 - Clarified the entity issuing a certificate by moving the phrase
1709 "to have issued the certificate" immediately after
1710 "Certification Authority."
1712 C.8. Changes to section 8.
1716 - Removed the first paragraph because simple authentication is
1717 covered explicitly in section 6.
1719 - Added section 8.1. heading just prior to second paragraph.
1721 - Added section 8.2. heading just prior to third paragraph.
1723 - Added section 8.3. heading just prior to fourth paragraph.
1727 - Moved entire section 8 of RFC 2829 into section 3.4 (Using SASL
1728 for Other Security Services) to bring material on SASL
1729 mechanisms together into one location.
1731 C.9. Changes to section 9.
1735 - Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL
1738 - Added section 9.1. heading.
1740 - Modified a comment in the ABNF from "unspecified userid" to
1741 "unspecified authz id".
1743 - Deleted sentence, "A utf8string is defined to be the UTF-8
1744 encoding of one or more ISO 10646 characters," because it is
1747 - Added section 9.1.1. heading.
1749 - Added section 9.1.2. heading.
1753 - Moved entire section 9 to become section 3.5 so that it would be
1754 with other SASL material.
1756 C.10. Changes to Section 10.
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1765 - Updated reference to cracking from a week of CPU time in 1997 to
1766 be a day of CPU time in 2000.
1768 - Added text: "These ciphersuites are NOT RECOMMENDED for use...
1769 and server implementers SHOULD" to sentence just prior the
1770 second list of ciphersuites.
1772 - Added text: "and MAY support other ciphersuites offering
1773 equivalent or better protection," to the last paragraph of the
1776 C.11. Changes to Section 11.
1780 - Moved to section 3.6 to be with other SASL material.
1782 C.12. Changes to Section 12.
1786 - Inserted new section 12 that specifies when SASL protections
1787 begin following SASL negotiation, etc. The original section 12
1788 is renumbered to become section 13.
1792 - Moved to section 3.7 to be with other SASL material.
1794 C.13. Changes to Section 13 (original section 12).
1798 Appendix D. RFC 2830 Change History
1800 This appendix lists the changes made to the text of RFC 2830 in
1801 preparing this document.
1803 D.0. General Editorial Changes
1805 - Material showing the PDUs for the StartTLS response was broken
1806 out into a new section.
1808 - The wording of the definition of the StartTLS request and
1809 StartTLS response was changed to make them parallel. NO changes
1810 were made to the ASN.1 definition or the associated values of
1813 - A separate section heading for graceful TLS closure was added
1814 for parallelism with section on abrupt TLS closure.
1816 Appendix E. RFC 2251 Change History
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1824 This appendix lists the changes made to the text of RFC 2251 in
1825 preparing this document.
1827 E.0. General Editorial Changes
1829 - All material from section 4.2 of RFC 2251 was moved into this
1832 - A new section was created for the Bind Request
1834 - Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved
1835 after the section on the Bind Response for parallelism with the
1836 presentation of the StartTLS operations. The section was also
1837 subdivided to explicitly call out the various effects being
1838 described within it.
1840 - All SASL profile information from RFC 2829 was brought within
1841 the discussion of the Bind operation (primarily sections 4.4 -
1844 Appendix F. Change History to Combined Document
1846 F.1. Changes for draft-ldap-bis-authmeth-02
1850 - Added references to other LDAP standard documents, to sections
1851 within the document, and fixed broken references.
1853 - General editorial changes--punctuation, spelling, formatting,
1858 - Added glossary of terms and added sub-section headings
1862 - Clarified security mechanisms 3, 4, & 5 and brought language in
1863 line with IETF security glossary.
1867 - Brought language in requirement (3) in line with security
1870 - Clarified that information fetched prior to initiation of TLS
1871 negotiation must be discarded
1873 -Clarified that information fetched prior to initiation of SASL
1874 negotiation must be discarded
1876 - Rewrote paragraph on SASL negotiation requirements to clarify
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1886 - Added stipulation that sasl choice allows for any SASL mechanism
1887 not prohibited by this document. (Resolved conflict between this
1888 statement and one that prohibited use of ANONYMOUS and PLAIN
1893 - Added a.x.bar.com to wildcard matching example on hostname check.
1897 - Added LDAP Association State Transition Tables to show the
1898 various states through which an LDAP association may pass along
1899 with the actions and decisions required to traverse from state
1904 - Brought security terminology in line with IETF security glossary
1905 throughout the appendix.
1907 F.2. Changes for draft-ldapbis-authmeth-03
1911 - Added introductory notes and changed title of document and
1912 references to conform to WG chair suggestions for the overall
1913 technical specification.
1915 - Several issues--H.13, H.14, H.16, H.17--were resolved without
1916 requiring changes to the document.
1920 - Removed reference to /etc/passwd file and associated text.
1924 - Removed sections 4.1, 4.2 and parts of section 4.3. This
1925 information was being duplicated in the protocol specification
1926 and will now reside there permanently.
1929 - changed words, "not recommended" to "strongly discouraged"
1933 - Based on ldapbis WG discussion at IETF52 two sentences were
1934 added indicating that clients SHOULD NOT send a DN value when
1935 binding with the sasl choice and servers SHALL ignore any value
1936 received in this circumstance.
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1946 - Generalized the language of this section to not refer to any
1947 specific password attribute or to refer to the directory entry
1952 - Added security consideration regarding misuse of unauthenticated
1955 - Added security consideration requiring access control to be
1956 applied only to authenticated users and recommending it be
1957 applied when reading sensitive information or updating directory
1960 F.3. Changes for draft-ldapbis-authmeth-04
1964 - Changed references to use [RFCnnnn] format wherever possible.
1965 (References to works in progress still use [name] format.)
1966 - Various edits to correct typos and bring field names, etc. in
1967 line with specification in [Protocol] draft.
1969 - Several issues--H.13, H.14, H.16, H.17--were resolved without
1970 requiring changes to the document.
1974 - Changed ABNF grammar to use productions that are like those in
1979 - Removed sections 5.1, 5.2, and 5.4 that will be added to
1980 [Protocol]. Renumbered sections to accommodate this change.
1985 - Reviewed LDAP Association State table for completeness and
1986 accuracy. Renumbered actions A3, A4, and A5 to be A5, A3, and A4
1987 respectively. Re-ordered several lines in the table to ensure
1988 that actions are in ascending order (makes analyzing the table
1989 much more logical). Added action A2 to several states where it
1990 was missing and valid. Added actions A7 and A8 placeholders to
1991 states S1, S2, S4 and S5 pending resolution of issue H.28.
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1999 Internet-Draft LDAP Authentication Methods 16 July 2004
2001 - Modified security consideration (originally added in -03)
2002 requiring access control to be applied only to authenticated
2003 users. This seems nonsensical because anonymous users may have
2004 access control applied to limit permissible actions.
2008 - Verified all normative references and moved informative
2009 references to a new section 14.
2011 F.4. Changes for draft-ldapbis-authmeth-05
2015 - General editory changes to fix punctuation, spelling, line
2017 - Verified and updated intra- and inter-document references
2019 - Document-wide review for proper usage of RFC 2119 keywords with
2020 several changes to correct improper usage.
2023 - Updated to match current contents of documents. This was needed
2024 due to movement of material on Bind and StartTLS operations to
2025 [Protocol] in this revision.
2029 - Renamed section to "Rationale for LDAP Security Mechanisms" and
2030 removed text that did not support this theme. Part of the
2031 motivation for this change was to remove the implication of the
2032 previous section title, "Required Security Mechanisms", and
2033 other text found in the section that everything in the section
2036 - Information from several removed paragraphs that describe
2037 deployment scenarios will be added Appendix A in the next
2038 revision of the draft.
2041 - Paragraph beginning, " If TLS is negotiated, the client MUST
2042 discard all information..." was moved to section 5.1.7 and
2043 integrated with related material there.
2045 - Paragraph beginning, "If a SASL security layer is negotiated..."
2046 was moved to section 4.2
2050 - Changed wording of first paragraph to clarify meaning.
2053 - Added paragraph from section 3 of -04 beginning, "If a SASL
2054 security layer is negotiated..."
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2058 Internet-Draft LDAP Authentication Methods 16 July 2004
2062 - Renamed to "Other SASL Mechanisms" and completely rewrote the
2063 section (one sentence) to generalize the treatment of SASL
2064 mechanisms not explicitly mentioned in this document.
2068 - Added paragraph beginning, "The dnAuthzID choice allows client
2069 applications..." to clarify whether DN form authorization
2070 identities have to also have a corresponding directory entry.
2071 This change was based on editor's perception of WG consensus.
2073 - Made minor clarifying edits in the paragraph beginning, "The
2074 uAuthzID choice allows for compatibility..."
2078 - Made minor clarifying edits in the last paragraph of the
2083 - Wording from section 3 paragraph beginning " If TLS is
2084 negotiated, the client MUST discard all information..." was
2085 moved to this section and integrated with existing text.
2089 - Changed usage of "TLS connection" to "TLS session" throughout.
2091 - Removed empty section 5.2.1 and renumbered sections it had
2092 previously contained.
2096 - Added introductory paragraph at beginning of section.
2100 - Changed term "data privacy" to "data confidentiality" to be
2101 consistent with usage in rest of document.
2105 - Changed first paragraph to require implementations that
2106 implement *password-based* authentication to implement and
2107 support DIGEST-MD5 SASL authentication.
2111 - First paragraph: changed "session encryption" to "session
2112 confidentiality protection" to be consistent with usage in rest
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2122 - Began changes to incorporate information on deployment scenarios
2123 removed from section 3.
2125 F.5. Changes for draft-ldapbis-authmeth-06
2129 - Combined Section 2 (Introduction) and Section 3 (Motivation) and
2130 moved Introduction to section 1. All following sections numbers
2131 were decremented by one as result.
2133 - Edits to fix typos, I-D nits, etc.
2135 - Opened several new issues in Appendix G based on feedback from
2136 WG. Some of these have been resolved. Others require further
2141 - Added additional example of spoofing under threat (7).
2145 - Changed definition of "LDAP association" and added terms,
2146 "connection" and "TLS connection" to bring usage in line with
2151 - Clarified sentence stating that the client MUST NOT use derived
2156 - Began edits to LDAP Association state table to clarify meaning
2157 of various states and actions.
2159 - Added action A9 to cover abandoned bind operation and added
2160 appropriate transitions to the state transition table to
2165 - Replaced first paragraph to clarify that the "DIGEST-MD5" SASL
2166 mechanism is required to implement.
2170 - Rewrote the section to make the advice more applicable over the
2171 long term, i.e. more "timeless." The intent of content in the
2172 original section was preserved.
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2181 - Added a clarifying example to the consideration regarding misuse
2182 of unauthenticated access.
2184 F.6. Changes for draft-ldapbis-authmeth-07
2188 - Updated external and internal references to accommodate changes
2191 - Opened several new issues in Appendix G based on feedback from
2192 WG. Some of these have been resolved. Others require further
2197 - Rewrote much of section 3.3 to meet the SASL profile
2198 requirements of draft-ietf-sasl-rfc2222bis-xx.txt section 5.
2200 - Changed treatement of SASL ANONYMOUS and PLAIN mechanisms to
2201 bring in line with WG consensus.
2205 - Note to implementers in section 4.1.1 based on operational
2208 - Clarification on client continuing by performing a StartTLS with
2209 TLS already established in section 4.1.4.
2211 - Moved verification of mapping of client's authentication ID to
2212 asserted authorization ID to apply only to explicit assertion.
2213 The local policy in place for implicit assertion is adequate.
2217 - Removed most of section 7.2 as the information is now covered
2218 adequately via the new SASL profile in section 3.3. Added note
2219 to implementors regarding the treatment of username and realm
2220 values in DIGEST-MD5.
2222 - Section 7.3. Minor clarifications in wording.
2224 - Section 7.3.1. Clarification that a match of the presented value
2225 to any member of the set of stored passwords constitutes a
2226 successful authentication.
2228 F.7. Changes for draft-ldapbis-authmeth-08
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2235 Internet-Draft LDAP Authentication Methods 16 July 2004
2237 - Changed usage from LDAPv3 to LDAP for usage consistency across
2238 LDAP technical specification.
2240 - Fixed a number of usage nits for consistency and to bring doc in
2241 conformance with publication guidelines.
2245 - Significant cleanup and rewording of abstract based on WG
2250 - New definition of user.
2254 - Added 1.5 sentences at end of introductory paragraph indicating
2255 the effect of the Bind op on the LDAP association.
2259 - Retitled section and clarified wording
2263 - Clarified that simple authentication choice provides three types
2264 of authentication: anonymous, unauthenticated, and simple
2269 - New wording clarifying when negotiated security mechanisms take
2274 - Changed requirement to discard information about server fetched
2275 prior to SASL negotiation from MUST to SHOULD to allow for
2276 information obtained through secure mechanisms.
2280 - Simplified wording of first paragraph based on suggestion from
2285 - Minor clarifications in wording.
2289 - Minor clarifications in wording in first sentence.
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2294 Internet-Draft LDAP Authentication Methods 16 July 2004
2296 - Explicitly called out that the DN value in the dnAuthzID form is
2297 to be matched using DN matching rules.
2298 - Called out that the uAuthzID MUST be prepared using SASLprep
2299 rules before being compared.
2300 - Clarified requirement on assuming global uniqueness by changing
2301 a "generally... MUST" wording to "SHOULD".
2305 - Simplified wording describing conditions when StartTLS cannot be
2307 - Simplified wording in note to implementers regarding race
2308 condition with outstanding LDAP operations on connection.
2312 - Removed section and moved relevant text to section 4.2.2.
2316 - Renumbered to 4.1.5.
2317 - Updated server identity check rules for server's name based on
2322 - Renumbered to 4.1.6
2323 - Changed requirement to discard information about server fetched
2324 prior to TLS negotion from MUST to SHOULD to allow for
2325 information obtained through secure mechanisms.
2329 - Clarified wording.
2330 - Added definition of anonymous and unauthenticated binds.
2334 - Added security consideration (moved from elsewhere) discouraging
2335 use of cleartext passwords on unprotected communication
2340 - Added an IANA consideration to update GSSAPI service name
2341 registry to point to [Roadmap] and [Authmeth]
2343 F.8. Changes for draft-ldapbis-authmeth-09
2347 - Updated section references within document
2348 - Changed reference tags to match other docs in LDAP TS
2349 - Used non-quoted names for all SASL mechanisms
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2353 Internet-Draft LDAP Authentication Methods 16 July 2004
2358 - Inspected keyword usage and removed several improper usages.
2360 - Removed sentence saying DIGEST-MD5 is LDAP's mandatory-to-
2361 implement mechanism. This is covered elsewhere in document.
2363 - Moved section 5, authentication state table, of -08 draft to
2364 section 8 of -09 and completely rewrote it.
2368 - Reworded sentence beginning, "It is also desirable to allow
2369 authentication methods to carry identities based on existingù
2370 non-LDAP DN-forms..."
2371 - Clarified relationship of this document to other documents in
2376 - Removed paragraph beginning,"If the client is configured to
2377 support multiple SASL mechanisms..." because the actions
2378 specified in the paragraph do not provide the protections
2379 indicated. Added a new paragraph indicating that clients and
2380 server should allow specification of acceptable mechanisms and
2381 only allow those mechanisms to be used.
2383 - Clarified independent behavior when TLS and SASL security layers
2384 are both in force (e.g. one being removed doesn't affect the
2389 - Moved most of section 4.2.2, Client Assertion of Authorization
2390 Identity, to sections 3.3.6, 3.3.6.1, and 3.3.6.2.
2394 - Moved some normative comments into text body.
2398 - Non success resultCode values are valid if server is *unwilling*
2399 or unable to negotiate TLS.
2403 - Rewrote entire section based on WG feedback.
2407 - Moved most of this section to 3.3.6 for better document flow.
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2412 Internet-Draft LDAP Authentication Methods 16 July 2004
2416 - Rewrote entire section based on WG feedback.
2420 - Moved imperative language regarding unauthenticated access from
2421 security considerations to here.
2425 - Added several paragraphs regarding the risks of transmitting
2426 passwords in the clear and requiring server implementations to
2427 provide a specific configuration that reduces these risks.
2431 - Added sentence describing protections provided by DIGEST-MD5
2433 - Changed DNs in exmple to be dc=example,dc=com.
2437 - Updated consideration on use of cleartext passwords to include
2438 other unprotected authentication credentials
2439 - Substantial rework of consideration on misuse of unauthenticated
2442 F.9. Changes for draft-ldapbis-authmeth-10
2444 - Reorganized content of sections 3-9 to improve document flow and
2446 - Resolved issue of effect of Start TLS and TLS closure on LDAP
2448 - Made numerous minor wording changes based on WG feedback.
2449 - Updated list of threats for Section 1.
2450 - Recommendation that servers should not support weaker TLS
2451 ciphersuites unless other protection is in place.
2452 - Moved authentication state table to appendix and relettered
2455 F.10. Changes for draft-ldapbis-authmeth-11
2459 - Many editorial changes throughout to clarify wording and better
2460 express intent, primarily based on suggestions from WG mail
2462 - More standard naming of authentication mechanisms throughout
2463 document, e.g. "Anonymous Authentication Mechanism of the Simple
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2471 Internet-Draft LDAP Authentication Methods 16 July 2004
2473 - Editorial changes to add clarity.
2474 - Moved section 2 of authmeth -09 into section 1
2478 - New section outlining implementation requirements.
2482 - Editorial clarification on need for following operation
2483 sequencing requirements.
2487 - New section added to describe use of client certificates with
2488 StartTLS. Incorporates material moved from other sections of
2492 - New section added to discuss LDAP Associations. Related material
2493 was moved from various other sections of authmeth -09 and
2494 incorporated into this new section.
2498 - Added several paragraphs regarding transmission and derivation
2499 of authentication and authorization identities using the Bind
2504 - Clarified rules for determining valid credentials and situations
2505 where invalidCredentials result is to be returned.
2509 - Added three security considerations based on WG feedback.
2513 - Simplfied state tables by removing two unnecessary actions from
2514 the actions table, and removing the current state column of the
2515 state transition table. Updated references to authmeth and
2518 F.11. Changes for draft-ldapbis-authmeth-12
2522 - Changed refererences from Start TLS to StartTLS.
2523 - Removed Appendix B: Example Deployment Scenarios
2524 - Removed Appendix H as all issues listed in the appendix are now
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2534 - Added implementation requirement that server implementations
2535 that SUPPORT StartTLS MUST support the
2536 TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA ciphersuite.
2540 - Added wording clarifying that a client's association is
2541 unaffected if a non-success resultCode is returned in the
2546 - Final paragraph of this section details requirements for
2547 serverSaslCreds field when no challenge value is sent.
2551 - Clarified language on uAuthzID usage.
2555 - Moved entire section into security considerations. New section
2557 - Reorganized security considerations by topic.
2558 - Added several security considerations based on WG feedback.
2562 - Moved section to become section 3.3.
2564 Intellectual Property Rights
2566 The IETF takes no position regarding the validity or scope of any
2567 Intellectual Property Rights or other rights that might be claimed
2568 to pertain to the implementation or use of the technology described
2569 in this document or the extent to which any license under such
2570 rights might or might not be available; nor does it represent that
2571 it has made any independent effort to identify any such rights.
2572 Information on the procedures with respect to rights in RFC
2573 documents can be found in BCP 78 and BCP 79.
2575 Copies of IPR disclosures made to the IETF Secretariat and any
2576 assurances of licenses to be made available, or the result of an
2577 attempt made to obtain a general license or permission for the use
2578 of such proprietary rights by implementers or users of this
2579 specification can be obtained from the IETF on-line IPR repository
2580 at http://www.ietf.org/ipr.
2582 The IETF invites any interested party to bring to its attention any
2583 copyrights, patents or patent applications, or other proprietary
2584 rights that may cover technology that may be required to implement
2587 Harrison Expires February 2005 [Page 44]
2589 Internet-Draft LDAP Authentication Methods 16 July 2004
2591 this standard. Please address the information to the IETF at ietf-
2594 Full Copyright Statement
2596 Copyright (C) The Internet Society (2004). This document is subject
2597 to the rights, licenses and restrictions contained in BCP 78, and
2598 except as set forth therein, the authors retain all their rights.
2600 This document and the information contained herein are provided on
2601 an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
2602 REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
2603 INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
2604 IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
2605 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
2606 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
2646 Harrison Expires February 2005 [Page 45]