2 INTERNET-DRAFT Editor: R. Harrison
3 draft-ietf-ldapbis-authmeth-10.txt Novell, Inc.
4 Obsoletes: 2829, 2830 10 February 2003
5 Intended Category: Draft Standard
8 LDAP: Authentication Methods
10 Connection Level Security Mechanisms
14 This document is an Internet-Draft and is in full conformance with
15 all provisions of Section 10 of RFC2026.
17 This document is intended to be, after appropriate review and
18 revision, submitted to the RFC Editor as a Standard Track document.
19 Distribution of this memo is unlimited. Technical discussion of
20 this document will take place on the IETF LDAP Revision Working
21 Group mailing list <ietf-ldapbis@OpenLDAP.org>. Please send
22 editorial comments directly to the author
23 <roger_harrison@novell.com>.
25 Internet-Drafts are working documents of the Internet Engineering
26 Task Force (IETF), its areas, and its working groups. Note that
27 other groups may also distribute working documents as Internet-
28 Drafts. Internet-Drafts are draft documents valid for a maximum of
29 six months and may be updated, replaced, or obsoleted by other
30 documents at any time. It is inappropriate to use Internet-Drafts
31 as reference material or to cite them other than as "work in
34 The list of current Internet-Drafts can be accessed at
35 http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-
36 Draft Shadow Directories can be accessed at
37 http://www.ietf.org/shadow.html.
41 Copyright (C) The Internet Society (2003). All Rights Reserved.
45 This document describes authentication methods and connection level
46 security mechanisms of the Lightweight Directory Access Protocol
49 This document also details establishment of TLS (Transport Layer
50 Security) using the Start TLS operation.
52 This document also details the simple Bind authentication method
53 including anonymous, unauthenticated, and plain-text password
54 methods and the SASL (Simple Authentication and Security Layer) Bind
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60 authentication method including the use of DIGEST-MD5 and EXTERNAL
63 This document describes various authentication and authorization
64 states through which a connection to an LDAP server may pass and the
65 actions that trigger these state changes.
69 1. Introduction................................................3
70 1.1. Relationship to Other Documents...........................5
71 2. Conventions Used in this Document...........................5
72 2.1. Glossary of Terms.........................................5
73 2.2. Security Terms and Concepts...............................5
74 2.3. Keywords..................................................6
75 3. Start TLS Operation.........................................6
76 3.1. Sequencing of the Start TLS Operation ....................6
77 3.1.1. Start TLS Request.......................................6
78 3.1.2. Start TLS Response......................................7
79 3.1.3. TLS Version Negotiation.................................7
80 3.1.4. Discovery of Resultant Security Level...................7
81 3.1.5. Server Identity Check...................................7
82 3.1.6. Refresh of Server Capabilities Information..............8
83 3.2. Effects of TLS on a Client's Authorization Identity.......8
84 3.2.1. TLS Connection Establishment Effects....................9
85 3.2.2. Client Assertion of Authorization Identity..............9
86 3.2.3. TLS Connection Closure Effects..........................9
87 4. Bind Operation..............................................9
88 4.1. Simple Authentication.....................................9
89 4.2. SASL Authentication.......................................9
90 5. Anonymous LDAP Association on Unbound Connections......... 10
91 6. Anonymous Authentication ................................. 10
92 7. Simple Authentication..................................... 10
93 8. SASL Authentication Profile............................... 11
94 8.1. SASL Service Name for LDAP.............................. 11
95 8.2. SASL Authentication Initiation and Protocol Exchange.... 11
96 8.3. Octet Where Negotiated Security Mechanisms Take Effect.. 12
97 8.4. Determination of Supported SASL Mechanisms.............. 12
98 8.5. Rules for Using SASL Security Layers.................... 13
99 9. SASL EXTERNAL Mechanism................................... 13
100 9.1. Implicit Assertion...................................... 13
101 9.2. Explicit Assertion...................................... 14
102 9.3. SASL Authorization Identity............................. 14
103 9.4 Authorization Identity Syntax............................ 14
104 10. SASL DIGEST-MD5 Mechanism................................ 15
105 11. General Requirements for Password-based Authentication .. 15
106 12. Invalidated Associations................................. 16
107 13. TLS Ciphersuites......................................... 16
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114 13.1. TLS Ciphersuites Recommendations....................... 17
115 14. Security Considerations ................................. 18
116 14.1. Start TLS Security Considerations...................... 18
117 15. IANA Considerations...................................... 19
118 Acknowledgements............................................. 19
119 Normative References......................................... 19
120 Informative References....................................... 21
121 Author's Address............................................. 21
122 Appendix A. LDAP Association State Transition Tables......... 21
123 A.1. LDAP Association States................................. 21
124 A.2. Actions that Affect LDAP Association State.............. 22
125 A.3. Decisions Used in Making LDAP Association State Changes. 22
126 A.4. LDAP Association State Transition Table................. 22
127 Appendix B. Example Deployment Scenarios..................... 23
128 Appendix C. Authentication and Authorization Concepts........ 24
129 C.1. Access Control Policy................................... 24
130 C.2. Access Control Factors ................................. 24
131 C.3. Authentication, Credentials, Identity .................. 25
132 C.4. Authorization Identity ................................. 25
133 Appendix D. RFC 2829 Change History ......................... 25
134 Appendix E. RFC 2830 Change History ......................... 29
135 Appendix F. RFC 2251 Change History ......................... 30
136 Appendix G. Change History to Combined Document.............. 30
137 Appendix H. Issues to be Resolved............................ 41
142 The Lightweight Directory Access Protocol (LDAP) [Protocol] is a
143 powerful access protocol for directories. It offers means of
144 searching, retrieving and manipulating directory content, and ways
145 to access a rich set of security functions.
147 It is vital that these security functions be interoperable among all
148 LDAP clients and servers on the Internet; therefore there has to be
149 a minimum subset of security functions that is common to all
150 implementations that claim LDAP conformance.
152 Basic threats to an LDAP directory service include:
154 (1) Unauthorized access to directory data via data-retrieval
157 (2) Unauthorized access to directory data by monitoring others'
160 (3) Unauthorized access to reusable client authentication
161 information by monitoring others' access,
163 (4) Unauthorized modification of directory data,
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170 (5) Unauthorized modification of configuration information,
172 (6) Denial of Service: Use of resources (commonly in excess) in a
173 manner intended to deny service to others. and
175 (7) Spoofing: Tricking a user or client into believing that
176 information came from the directory when in fact it did not,
177 either by modifying data in transit or misdirecting the client's
178 connection. Tricking a user or client into sending privileged
179 information to a hostile entity that appears to be the directory
180 server but is not. Tricking a directory server into believing
181 that information came from a particular client when in fact it
182 came from a hostile entity.
184 (8) Hijacking of prototocol sessions.
186 Threats (1), (4), (5) and (6) are due to hostile clients. Threats
187 (2), (3) and (7) are due to hostile agents on the path between
188 client and server or hostile agents posing as a server, e.g. IP
191 LDAP offers the following security mechanisms:
193 (1) Authentication by means of the Bind operation. The Bind
194 operation provides a simple method which supports anonymous,
195 unauthenticated, and authenticated with password mechanisms, and
196 the Secure Authentication and Security Layer (SASL) method which
197 supports a wide variety of authentication mechanisms and which
198 may be extended to support additional methods of authentication.
200 (2) Client authorization by means of access control based on the
201 requestor's authenticated identity,
203 (3) Data integrity protection by means of TLS or SASL mechanisms
204 with security layers that provide data integrity services,
206 (4) Data confidentiality protection against snooping by means of the
207 TLS protocol or SASL mechanisms that provide data
208 confidentiality services,
210 (5) Server resource usage limitation by means of administrative
211 service limits configured on the server, and
213 (6) Server authentication by means of the TLS protocol or SASL
216 At the moment, imposition of access controls is done by means
217 outside the scope of LDAP.
219 It seems clear that allowing any implementation, faced with the
220 above requirements, to simply pick and choose among the possible
221 alternatives is not a strategy that is likely to lead to
222 interoperability. In the absence of mandates, clients will be
223 written that do not support any security function supported by the
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229 server, or worse, they will support only clear text passwords that
230 provide inadequate security for most circumstances.
232 Given the presence of the Directory, there is a strong desire to see
233 mechanisms where identities take the form of an LDAP distinguished
234 name [LDAPDN] and authentication data can be stored in the
235 directory. This means that this data must be updated outside the
236 protocol or only updated in sessions well protected against
237 snooping. It is also desirable to allow authentication methods to
238 carry identities not represented as LDAP DNs that are familiar to
239 the user or that are used in other systems.
241 The set of security mechanisms provided in LDAP and described in
242 this document is intended to meet the security needs for a wide
243 range of deployment scenarios and still provide a high degree of
244 interoperability among various LDAP implementations and deployments.
245 Appendix B contains example deployment scenarios that list the
246 mechanisms that might be used to achieve a reasonable level of
247 security in various circumstances.
249 1.1. Relationship to Other Documents
251 This document is an integral part of the LDAP Technical
252 Specification [Roadmap].
254 This document obsoletes RFC 2829.
256 Sections 2 and 4 of RFC 2830 are obsoleted by [Protocol]. The
257 remainder of RFC 2830 is obsoleted by this document.
259 2. Conventions Used in this Document
261 2.1. Glossary of Terms
263 The following terms are used in this document. To aid the reader,
264 these terms are defined here.
266 - "user" represents any human or application entity which is
267 accessing the directory using a directory client. A directory
268 client (or client) is also known as a directory user agent
271 - "connection" and "LDAP connection" both refer to the underlying
272 transport protocol connection between two protocol peers.
274 - "TLS connection" refers to a TLS-protected [TLS] LDAP
277 - "association" and "LDAP association" both refer to the
278 association of the LDAP connection and its current
279 authentication and authorization state.
281 2.2. Security Terms and Concepts
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288 In general, security terms in this document are used consistently
289 with the definitions provided in [Glossary]. In addition, several
290 terms and concepts relating to security, authentication, and
291 authorization are presented in Appendix C of this document. While
292 the formal definition of these terms and concepts is outside the
293 scope of this document, an understanding of them is prerequisite to
294 understanding much of the material in this document. Readers who are
295 unfamiliar with security-related concepts are encouraged to review
296 Appendix C before reading the remainder of this document.
300 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
301 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
302 document are to be interpreted as described in RFC 2119 [Keyword].
304 3. Start TLS Operation
306 The Start Transport Layer Security (Start TLS) operation defined in
307 section 4.13 of [Protocol] provides the ability to establish [TLS]
308 on an LDAP connection.
310 3.1. Sequencing of the Start TLS Operation
312 This section describes the overall procedures clients and servers
313 must follow for TLS establishment. These procedures take into
314 consideration various aspects of the overall security of the LDAP
315 association including discovery of resultant security level and
316 assertion of the client's authorization identity.
318 Note that the precise effects, on a client's authorization identity,
319 of establishing TLS on an LDAP connection are described in detail in
322 3.1.1. Start TLS Request
324 A client may send the Start TLS extended request at any time after
325 establishing an LDAP connection, except:
327 - when TLS is currently established on the connection,
328 - when a multi-stage SASL negotiation is in progress on the
330 - when there are outstanding LDAP operations on the connection.
332 The result of violating any of these requirements is a resultCode of
333 operationsError, as described in [Protocol] section 4.13.2.2. Client
334 implementers should note that it is possible to receive a resultCode
335 of success for a Start TLS operation that is sent on a connection
336 with outstanding LDAP operations if the server has sufficient time
337 to process them prior to its receiving the Start TLS request.
338 Implementors of clients should ensure that they do not inadvertently
339 depend upon this race condition.
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347 There is no requirement that the client have or have not already
348 performed a Bind operation (section 4) before sending a Start TLS
351 If the client did not establish a TLS connection before sending some
352 other request, and the server requires the client to establish a TLS
353 connection before performing that request, the server MUST reject
354 that request by sending a resultCode of confidentialityRequired or
357 An LDAP server which requests that clients provide their certificate
358 during TLS negotiation MAY use a local security policy to determine
359 whether to successfully complete TLS negotiation if the client did
360 not present a certificate which could be validated.
362 3.1.2. Start TLS Response
364 The server will return an extended response with the resultCode of
365 success if it is willing and able to negotiate TLS. It will return
366 other resultCode values (documented in [Protocol] section 4.13.2.2)
367 if it is unwilling or unable to do so.
369 In the successful case, the client (which has ceased to transfer
370 LDAP requests on the connection) MUST either begin a TLS negotiation
371 or close the connection. The client will send PDUs in the TLS Record
372 Protocol directly over the underlying transport connection to the
373 server to initiate [TLS] negotiation.
375 3.1.3. TLS Version Negotiation
377 Negotiating the version of TLS to be used is a part of the TLS
378 Handshake Protocol [TLS]. Please refer to that document for details.
380 3.1.4. Discovery of Resultant Security Level
382 After a TLS connection is established on an LDAP connection, both
383 parties must individually decide whether or not to continue based on
384 the security level achieved. Ascertaining the TLS connection's
385 security level is implementation dependent and accomplished by
386 communicating with one's respective local TLS implementation.
388 If the client or server decides that the level of authentication or
389 security is not high enough for it to continue, it SHOULD gracefully
390 close the TLS connection immediately after the TLS negotiation has
391 completed (see [Protocol] section 4.13.3.1 and section 3.2.3 below).
392 If the client decides to continue, it may gracefully close the TLS
393 connection and attempt to Start TLS again, it may send an unbind
394 request, or it may send any other LDAP request.
396 3.1.5. Server Identity Check
398 The client MUST check its understanding of the server's hostname
399 against the server's identity as presented in the server's
400 Certificate message in order to prevent man-in-the-middle attacks.
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407 Matching is performed according to these rules:
409 - The client MUST use the server provided by the user (or other
410 trusted entity) as the value to compare against the server name
411 as expressed in the server's certificate. A hostname derived
412 from the user input is to be considered provided by the user
413 only if derived in a secure fashion (e.g., DNSSEC).
415 - If a subjectAltName extension of type dNSName is present in the
416 certificate, it SHOULD be used as the source of the server's
419 - Matching is case-insensitive.
421 - The "*" wildcard character is allowed. If present, it applies
422 only to the left-most name component.
424 For example, *.bar.com would match a.bar.com and b.bar.com, but
425 it would not match a.x.bar.com nor would it match bar.com. If
426 more than one identity of a given type is present in the
427 certificate (e.g. more than one dNSName name), a match in any
428 one of the set is considered acceptable.
430 If the hostname does not match the dNSName-based identity in the
431 certificate per the above check, user-oriented clients SHOULD either
432 notify the user (clients may give the user the opportunity to
433 continue with the connection in any case) or terminate the
434 connection and indicate that the server's identity is suspect.
435 Automated clients SHOULD close the connection, returning and/or
436 logging an error indicating that the server's identity is suspect.
438 Beyond the server identity checks described in this section, clients
439 SHOULD be prepared to do further checking to ensure that the server
440 is authorized to provide the service it is observed to provide. The
441 client may need to make use of local policy information in making
444 3.1.6. Refresh of Server Capabilities Information
446 Upon TLS session establishment, the client SHOULD discard or refresh
447 all information about the server it obtained prior to the initiation
448 of the TLS negotiation and not obtained through secure mechanisms.
449 This protects against active-intermediary attacks that may have
450 altered any server capabilities information retrieved prior to TLS
453 The server may advertise different capabilities after TLS
454 establishment. In particular, the value of supportedSASLMechanisms
455 may be different after TLS has been negotiated (specifically, the
456 EXTERNAL and PLAIN [PLAIN] mechanisms are likely to be listed only
457 after a TLS negotiation has been performed).
459 3.2. Effects of TLS on a Client's Authorization Identity
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466 This section describes the effects on a client's authorization
467 identity brought about by establishing TLS on an LDAP connection.
468 The default effects are described first, and next the facilities for
469 client assertion of authorization identity are discussed including
470 error conditions. Finally, the effects of closing the TLS connection
473 Authorization identities and related concepts are described in
476 3.2.1. TLS Connection Establishment Effects
478 The decision to keep or invalidate the established authentication
479 and authorization identities in place after TLS closure is a matter
480 of local server policy.
482 3.2.2. Client Assertion of Authorization Identity
484 After successfully establishing a TLS session, a client may request
485 that its credentials exchanged during the TLS establishment be
486 utilized to authenticate the LDAP association and thus determine the
487 client's authorization status. The client accomplishes this via an
488 LDAP Bind request specifying a SASL mechanism of EXTERNAL [SASL]
489 (section 9). LDAP server implementations SHOULD support this
490 authentication method.
492 3.2.3. TLS Connection Closure Effects
494 The decision to keep or invalidate the established authentication
495 and authorization identities in place after TLS closure is a matter
496 of local server policy.
500 The Bind operation defined in section 4.2 of [Protocol] allows
501 authentication information to be exchanged between the client and
502 server to establish a new LDAP association.
504 Upon receipt of a Bind request, the LDAP association is moved to an
505 anonymous state and only upon successful completion of the
506 authentication exchange (and the Bind operation) is the association
507 moved to an authenticated state.
509 4.1. Simple Authentication
511 The simple authentication choice of the Bind Operation provides
512 minimal facilities for establishing an anonymous association
513 (section 6) or for establishing an LDAP association based upon
514 credentials consisting of a name (in the form of an LDAP
515 distinguished name [LDAPDN]) and a password (section 7).
517 4.2. SASL Authentication
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524 The sasl authentication choice of the Bind Operation provides
525 facilities for authenticating via SASL mechanisms (sections 8-10).
527 5. Anonymous LDAP Association on Unbound Connections
529 Prior to the successful completion of a Bind operation and during
530 any subsequent authentication exchange, the session has an anonymous
531 LDAP association. Among other things this implies that the client
532 need not send a Bind Request in the first PDU of the connection. The
533 client may send any operation request prior to binding, and the
534 server MUST treat it as if it had been performed after an anonymous
535 bind operation. This authentication state on an LDAP association is
536 sometimes referred to as an implied anonymous bind.
538 6. Anonymous Authentication
540 Directory operations that modify entries or access protected
541 attributes or entries generally require client authentication.
542 Clients that do not intend to perform any of these operations
543 typically use anonymous authentication.
545 An LDAP client may explicitly establish an anonymous association by
546 sending a Bind Request with the simple authentication choice
547 containing a value--construed as the password--of zero length. A
548 bind request where both the name and password are of zero length is
549 said to be an anonymous bind. A bind request where the name, a DN,
550 is of non-zero length, and the password is of zero length is said to
551 be an unauthenticated bind. Both variations produce an anonymous
554 Unauthenticated binds can have significant security issues (see
555 section 14). Servers SHOULD by default reject unauthenticated bind
556 requests with a resultCode of invalidCredentials, and clients may
557 need to actively detect situations where they would make an
558 unauthenticated bind request.
560 An LDAP server may use other information about the client provided
561 by the lower layers or external means to grant or deny access even
562 to anonymously authenticated clients.
564 LDAP implementations MUST support anonymous authentication.
566 7. Simple Authentication
568 An LDAP client may establish an LDAP association by sending a Bind
569 Request with a name value consisting of an LDAP distinguished name
570 [LDAPDN] and specifying the simple authentication choice with a
573 DSAs that map the DN sent in the bind request to a directory entry
574 with an associated set of one or more passwords will compare the
575 presented password to the set of passwords associated with that
576 entry. If the presented password matches any member of that set,
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583 then the server will respond with a success resultCode, otherwise
584 the server will respond with an invalidCredentials resultCode.
586 The simple authentication choice is not suitable for authentication
587 in environments where there is no network or transport layer
588 confidentiality. LDAP implementations SHOULD support authentication
589 with the "simple" authentication choice when the connection is
590 protected against eavesdropping using TLS, as defined in section 4.
591 LDAP implementations SHOULD NOT support authentication with the
592 "simple" authentication choice unless the data on the connection is
593 protected using TLS or other data confidentiality and data integrity
596 8. SASL Authentication Profile
598 LDAP allows authentication via any SASL mechanism [SASL]. As LDAP
599 includes native anonymous and plaintext authentication methods, the
600 ANONYMOUS [ANONYMOUS] and PLAIN [PLAIN] SASL mechanisms are
601 typically not used with LDAP.
603 Each protocol that utilizes SASL services is required to supply
604 certain information profiling the way they are exposed through the
605 protocol ([SASL] section 5). This section explains how each of these
606 profiling requirements are met by LDAP.
608 8.1. SASL Service Name for LDAP
610 The SASL service name for LDAP is "ldap", which has been registered
611 with the IANA as a GSSAPI service name.
613 8.2. SASL Authentication Initiation and Protocol Exchange
615 SASL authentication is initiated via an LDAP bind request
616 ([Protocol] section 4.2) with the following parameters:
619 - The AuthenticationChoice is sasl.
620 - The mechanism element of the SaslCredentials sequence contains
621 the value of the desired SASL mechanism.
622 - The optional credentials field of the SaslCredentials sequence
623 may be used to provide an initial client response for
624 mechanisms that are defined to have the client send data first
625 (see [SASL] sections 5 and 5.1).
627 In general, a SASL authentication protocol exchange consists of a
628 series of server challenges and client responses, the contents of
629 which are specific to and defined by the SASL mechanism. Thus for
630 some SASL authentication mechanisms, it may be necessary for the
631 client to respond to one or more server challenges by invoking the
632 BindRequest multiple times. A challenge is indicated by the server
633 sending a BindResponse with the resultCode set to
634 saslBindInProgress. This indicates that the server requires the
635 client to send a new bind request with the same sasl mechanism to
636 continue the authentication process.
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643 To the encapsulating protocol, these challenges and responses are
644 opaque binary tokens of arbitrary length. LDAP servers use the
645 serverSaslCreds field, an OCTET STRING, in a bind response message
646 to transmit each challenge. LDAP clients use the credentials field,
647 an OCTET STRING, in the SaslCredentials sequence of a bind request
648 message to transmit each response. Note that unlike some Internet
649 protocols where SASL is used, LDAP is not text-based, thus no Base64
650 transformations are performed on these challenge and response
653 Clients sending a bind request with the sasl choice selected SHOULD
654 NOT send a value in the name field. Servers receiving a bind request
655 with the sasl choice selected SHALL ignore any value in the name
658 A client may abort a SASL bind negotiation by sending a BindRequest
659 with a different value in the mechanism field of SaslCredentials, or
660 an AuthenticationChoice other than sasl.
662 If the client sends a BindRequest with the sasl mechanism field as
663 an empty string, the server MUST return a BindResponse with
664 authMethodNotSupported as the resultCode. This will allow clients to
665 abort a negotiation if it wishes to try again with the same SASL
668 The server indicates completion of the SASL challenge-response
669 exchange by responding with a bind response in which the resultCode
670 is either success, or an error indication.
672 The serverSaslCreds field in the bind response can be used to
673 include an optional challenge with a success notification for
674 mechanisms which are defined to have the server send additional data
675 along with the indication of successful completion.
677 8.3. Octet Where Negotiated Security Mechanisms Take Effect
679 SASL security layers take effect following the transmission by the
680 server and reception by the client of the final successful
681 BindResponse in the exchange.
683 Once a SASL security layer providing integrity or confidentiality
684 services takes effect, the layer remains in effect until a new layer
685 is installed (i.e. at the first octet following the final
686 BindResponse of the bind operation that caused the new layer to take
689 8.4. Determination of Supported SASL Mechanisms
691 Clients may determine the SASL mechanisms a server supports by
692 reading the 'supportedSASLMechanisms ' attribute from the root DSE
693 (DSA-Specific Entry) ([Models] section 5.1). The values of this
694 attribute, if any, list the mechanisms the server supports in the
695 current LDAP session state.
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702 LDAP servers SHOULD allow an anonymously-bound client to retrieve
703 the supportedSASLMechanisms attribute of the root DSE.
705 8.5. Rules for Using SASL Security Layers
707 If a SASL security layer is negotiated, the client SHOULD discard
708 information about the server it obtained prior to the initiation of
709 the SASL negotiation and not obtained through secure mechanisms.
711 If a lower level security layer (such as TLS) is negotiated, any
712 SASL security services SHALL be layered on top of such security
713 layers regardless of the order of their negotiation. In all other
714 respects, SASL security services and other security layers act
715 independently, e.g. if both TLS and SASL security service are in
716 effect removing the SASL security service does not affect the
717 continuing service of TLS and vice versa.
719 Because SASL mechanisms provide critical security functions, clients
720 and servers should allow the user to specify what mechanisms are
721 acceptable and allow only those mechanisms to be used.
723 9. SASL EXTERNAL Mechanism
725 A client can use the EXTERNAL SASL [SASL] mechanism to request the
726 LDAP server to make use of security credentials exchanged by a lower
727 security layer (such as by TLS authentication or IP-level security
730 If the client's authentication credentials have not been established
731 at a lower security layer, the SASL EXTERNAL bind MUST fail with a
732 resultCode of inappropriateAuthentication. Any client
733 authentication and authorization state of the LDAP association is
734 lost, so the LDAP association is in an anonymous state after the
735 failure (see [Protocol] section 4.2.1). In such a situation, the
736 state of any established security layer is unaffected.
738 A client may either implicitly request that its LDAP authorization
739 identity be derived from a lower layer or it may explicitly provide
740 an authorization identity and assert that it be used in combination
741 with its authenticated TLS credentials. The former is known as an
742 implicit assertion, and the latter as an explicit assertion.
744 9.1. Implicit Assertion
746 An implicit authorization identity assertion is performed by
747 invoking a Bind request of the SASL form using the EXTERNAL
748 mechanism name that does not include the optional credentials octet
749 string (found within the SaslCredentials sequence in the Bind
750 Request). The server will derive the client's authorization identity
751 from the authentication identity supplied by the security layer
752 (e.g., a public key certificate used during TLS establishment)
753 according to local policy. The underlying mechanics of how this is
754 accomplished are implementation specific.
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761 9.2. Explicit Assertion
763 An explicit authorization identity assertion is performed by
764 invoking a Bind request of the SASL form using the EXTERNAL
765 mechanism name that includes the credentials octet string. This
766 string MUST be constructed as documented in section 3.4.1.
768 The server MUST verify that the client's authentication identity as
769 supplied in its TLS credentials is permitted to be mapped to the
770 asserted authorization identity. The server MUST reject the Bind
771 operation with an invalidCredentials resultCode in the Bind response
772 if the client is not so authorized.
774 9.3. SASL Authorization Identity
776 When the EXTERNAL SASL mechanism is being negotiated, if the
777 SaslCredentials credentials field is present, it contains an
778 authorization identity. Other mechanisms define the location of the
779 authorization identity in the credentials field. In either case, the
780 authorization identity is represented in the authzId form described
783 9.4 Authorization Identity Syntax
785 The authorization identity is a string of [UTF-8] encoded [Unicode]
786 characters corresponding to the following [ABNF] grammar:
788 authzId = dnAuthzId / uAuthzId
790 DNCOLON = %x64 %x6e %x3a ; "dn:"
791 UCOLON = %x75 %x3a ; "u:"
793 ; distinguished-name-based authz id.
794 dnAuthzId = DNCOLON distinguishedName
796 ; unspecified authorization id, UTF-8 encoded.
797 uAuthzId = UCOLON userid
798 userid = *UTF8 ; syntax unspecified
800 where the <distinguishedName> production is defined in section 3 of
801 [LDAPDN] and <UTF8> production is defined in section 1.3 of
804 In order to support additional specific authorization identity
805 forms, future updates to this specification may add new choices
806 supporting other forms may be added to the authzId production.
808 The dnAuthzId choice allows clients to assert authorization
809 identities in the form of a distinguished name to be matched in
810 accordance with the distinguishedNameMatch matching rule [Syntaxes].
811 The decision to allow or disallow an authentication identity to have
812 access to the requested authorization identity is a matter of local
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817 Internet-Draft LDAP Authentication Methods 5 December 2003
819 policy ([SASL] section 4.2). For this reason there is no requirement
820 that the asserted dn be that of an entry in directory.
822 The uAuthzId choice allows for compatibility with clients that wish
823 to assert an authorization identity to a local directory but do not
824 have that identity in distinguished name form. The value contained
825 within a uAuthzId MUST be prepared using [SASLPrep] before being
826 compared octet-wise. The format of userid is defined as only a
827 sequence of [UTF-8] encoded [Unicode] characters, and further
828 interpretation is subject to prior agreement between the client and
831 For example, the userid could identify a user of a specific
832 directory service or be a login name or the local-part of an RFC 822
833 email address. A uAuthzId SHOULD NOT be assumed to be globally
836 10. SASL DIGEST-MD5 Mechanism
838 LDAP servers that implement any authentication method or mechanism
839 other than simple anonymous bind MUST implement the SASL
840 DIGEST-MD5 mechanism [DIGEST-MD5]. This provides client
841 authentication with protection against passive eavesdropping attacks
842 but does not provide protection against active intermediary attacks.
843 DIGEST-MD5 also provides data integrity and data confidentiality
847 Support for subsequent authentication ([DIGEST-MD5] section 2.2) is
848 OPTIONAL in clients and servers.
850 Implementers must take care to ensure that they maintain the
851 semantics of the DIGEST-MD5 specification even when handling data
852 that has different semantics in the LDAP protocol.
853 For example, the SASL DIGEST-MD5 authentication mechanism utilizes
854 realm and username values ([DIGEST-MD5] section 2.1) which are
855 syntactically simple strings and semantically simple realm and
856 username values. These values are not LDAP DNs, and there is no
857 requirement that they be represented or treated as such. Username
858 and realm values that look like LDAP DNs in form, e.g. <cn=bob,
859 dc=example,dc=com>, are syntactically allowed, however DIGEST-MD5
860 treats them as simple strings for comparison purposes. To illustrate
861 further, the two DNs <cn=Bob,dc=example,dc=com> (upper case "B") and
862 <cn=bob,dc=example,dc=com> (lower case "b") are equivalent when
863 being compared semantically as LDAP DNs because the cn attribute is
864 defined to be case insensitive, however the two values are not
865 equivalent if they represent username values in DIGEST-MD5 because
866 [SASLPrep] semantics are used by DIGEST-MD5.
868 11. General Requirements for Password-based Authentication
870 The transmission of passwords in the clear--typically for
871 authentication or modification--poses a significant security risk.
872 This risk can be avoided by using SASL authentication [SASL]
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878 mechanisms that do not transmit passwords in the clear or by
879 negotiating transport or session layer confidentiality services
880 before transmitting password values.
882 To mitigate the security risks associated with the use of passwords,
883 a server implementation MUST implement a configuration that at the
884 time of authentication or password modification, requires:
886 1) A Start TLS encryption layer has been successfully negotiated.
890 2) Some other confidentiality mechanism that protects the password
891 value from snooping has been provided.
895 3) The server returns a resultCode of confidentialityRequired for
896 the operation (i.e. simple bind with password value, SASL bind
897 transmitting a password value in the clear, add or modify
898 including a userPassword value, etc.), even if the password
901 12. Invalidated Associations
903 The server may, at any time, invalidate the association, e.g. if the
904 established security association between the client and server has
905 unexpectedly failed or been compromised. The association remains
906 invalidated until the next successful bind request. While the
907 association is invalidated, the server may reject any operation
908 request other than Bind, Unbind, and Start TLS by responding with a
909 resultCode of strongAuthRequired to indicate that the client needs
910 to bind to reestablish its authentication state before performing
911 the requested operation.
915 A client or server that supports TLS MUST support
916 TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA. Servers SHOULD NOT support
917 weaker ciphersuites unless other data integrity and
918 confidentiality protection (such as a SASL security layer) is
921 Several issues should be considered when selecting TLS ciphersuites
922 that are appropriate for use in a given circumstance. These issues
923 include the following:
925 - The ciphersuite's ability to provide adequate confidentiality
926 protection for passwords and other data sent over the LDAP
927 connection. Client and server implementers should recognize that
928 some TLS ciphersuites provide no confidentiality protection
929 while other ciphersuites that do provide confidentiality
930 protection may be vulnerable to being cracked using brute force
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937 methods, especially in light of ever-increasing CPU speeds that
938 reduce the time needed to successfully mount such attacks.
940 Client and server implementers SHOULD carefully consider the
941 value of the password or data being protected versus the level
942 of confidentially protection provided by the ciphersuite to
943 ensure that the level of protection afforded by the ciphersuite
946 - The ciphersuite's vulnerability (or lack thereof) to man-in-the-
947 middle attacks. Ciphersuites vulnerable to man-in-the-middle
948 attacks SHOULD NOT be used to protect passwords or sensitive
949 data, unless the network configuration is such that the danger
950 of a man-in-the-middle attack is tolerable.
952 13.1. TLS Ciphersuites Recommendations
954 As of the writing of this document, the following recommendations
955 regarding TLS ciphersuites are applicable. Because circumstances are
956 constantly changing, this list must not be considered exhaustive,
957 but is hoped that it will serve as a useful starting point for
960 The following ciphersuites defined in [TLS] MUST NOT be used for
961 confidentiality protection of passwords or data:
963 TLS_NULL_WITH_NULL_NULL
964 TLS_RSA_WITH_NULL_MD5
965 TLS_RSA_WITH_NULL_SHA
967 The following ciphersuites defined in [TLS] can be cracked easily
968 (less than a day of CPU time on a standard CPU in 2000) and are NOT
969 RECOMMENDED for use in confidentiality protection of passwords or
972 TLS_RSA_EXPORT_WITH_RC4_40_MD5
973 TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5
974 TLS_RSA_EXPORT_WITH_DES40_CBC_SHA
975 TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA
976 TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA
977 TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
978 TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA
979 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
980 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
982 The following ciphersuites are vulnerable to man-in-the-middle
985 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
986 TLS_DH_anon_WITH_RC4_128_MD5
987 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
988 TLS_DH_anon_WITH_DES_CBC_SHA
989 TLS_DH_anon_WITH_3DES_EDE_CBC_SHA
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998 14. Security Considerations
1000 Security issues are discussed throughout this memo; the unsurprising
1001 conclusion is that mandatory security is important and that session
1002 confidentiality protection is required when snooping is a problem.
1004 Servers can minimize denial of service attacks by timing out idle
1005 connections, and returning the unwillingToPerform resultCode rather
1006 than performing computationally expensive operations requested by
1007 unauthorized clients.
1009 The use of cleartext passwords and other unprotected authentication
1010 credentials is strongly discouraged over open networks when the
1011 underlying transport service cannot guarantee confidentiality.
1013 Operational experience shows that clients can (and frequently do)
1014 misuse unauthenticated bind (see section 5.1). For example, a
1015 client program might make a decision to grant access to non-
1016 directory information on the basis of completing a successful bind
1017 operation. Some LDAP server implementations will return a success
1018 response to an unauthenticated bind thus leaving the client with the
1019 impression that the server has successfully authenticated the
1020 identity represented by the user name, when in effect, an anonymous
1021 LDAP association has been created. Clients that use the results from
1022 a simple bind operation to make authorization decisions should
1023 actively detect unauthenticated bind requests (via the empty
1024 password value) and react appropriately.
1026 Access control SHOULD always be applied when reading sensitive
1027 information or updating directory information.
1029 A connection on which the client has not established connection
1030 integrity and privacy services (e.g via Start TLS, IPSec or a
1031 suitable SASL mechanism) is subject to man-in-the-middle attacks to
1032 view and modify information in transit.
1034 14.1. Start TLS Security Considerations
1036 The goals of using the TLS protocol with LDAP are to ensure
1037 connection confidentiality and integrity, and to optionally provide
1038 for authentication. [TLS] expressly provides these capabilities.
1040 All security gained via use of the Start TLS operation is gained by
1041 the use of TLS itself. The Start TLS operation, on its own, does not
1042 provide any additional security.
1044 Once established, TLS only provides for and ensures confidentiality
1045 and integrity of the operations and data in transit over the LDAP
1046 connection--and only if the implementations on the client and server
1047 support and negotiate it. The use of TLS does not provide or ensure
1048 for confidentiality and/or non-repudiation of the data housed by an
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1055 LDAP-based directory server. Nor does it secure the data from
1056 inspection by the server administrators.
1058 The level of security provided though the use of TLS depends
1059 directly on both the quality of the TLS implementation used and the
1060 style of usage of that implementation. Additionally, an active-
1061 intermediary attacker can remove the Start TLS extended operation
1062 from the supported attribute of the root DSE. Therefore, both
1063 parties SHOULD independently ascertain and consent to the security
1064 level achieved once TLS is established and before beginning use of
1065 the TLS connection. For example, the security level of the TLS
1066 connection might have been negotiated down to plaintext.
1068 Clients SHOULD either warn the user when the security level achieved
1069 does not provide data confidentiality and/or integrity protection,
1070 or be configurable to refuse to proceed without an acceptable level
1073 Client and server implementors SHOULD take measures to ensure proper
1074 protection of credentials and other confidential data where such
1075 measures are not otherwise provided by the TLS implementation.
1077 Server implementors SHOULD allow for server administrators to elect
1078 whether and when connection confidentiality and/or integrity is
1079 required, as well as elect whether and when client authentication
1080 via TLS is required.
1082 Additional security considerations relating to the EXTERNAL
1083 mechanism to negotiate TLS can be found in [SASL] and [TLS].
1085 15. IANA Considerations
1087 The following IANA considerations apply to this document:
1089 Please update the GSSAPI service name registry to point to [Roadmap]
1096 This document combines information originally contained in RFC 2829
1097 and RFC 2830. The editor acknowledges the work of Harald Tveit
1098 Alvestrand, Jeff Hodges, Tim Howes, Steve Kille, RL "Bob" Morgan ,
1099 and Mark Wahl, each of whom authored one or more of these documents.
1101 This document is based upon input of the IETF LDAP Revision working
1102 group. The contributions and suggestions made by its members in
1103 shaping the contents and technical accuracy of this document is
1104 greatly appreciated.
1106 Normative References
1110 Harrison Expires July 2004 [Page 19]
1112 Internet-Draft LDAP Authentication Methods 5 December 2003
1114 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for
1115 Syntax Specifications: ABNF", RFC 2234, November 1997.
1117 [DIGEST-MD5] Leach, P. C. Newman, and A. Melnikov, "Using Digest
1118 Authentication as a SASL Mechanism", draft-ietf-sasl-
1119 rfc2831bis-xx.txt, a work in progress.
1121 [Keyword] Bradner, S., "Key Words for use in RFCs to Indicate
1122 Requirement Levels", BCP 14, RFC 2119, March 1997.
1124 [LDAPDN] Zeilenga, Kurt D. (editor), "LDAP: String
1125 Representation of Distinguished Names", draft-ietf-
1126 ldapbis-dn-xx.txt, a work in progress.
1128 [Models] Zeilenga, Kurt D. (editor), "LDAP: Directory
1129 Information Models", draft-ietf-ldapbis-models-xx.txt,
1132 [Protocol] Sermersheim, J., "LDAP: The Protocol", draft-ietf-
1133 ldapbis-protocol-xx.txt, a work in progress.
1135 [Roadmap] K. Zeilenga, "LDAP: Technical Specification Road Map",
1136 draft-ietf-ldapbis-roadmap-xx.txt, a work in progress.
1138 [SASL] Melnikov, A. (editor), "Simple Authentication and
1139 Security Layer (SASL)", draft-ietf-sasl-rfc2222bis-
1140 xx.txt, a work in progress.
1142 [SASLPrep] Zeilenga, K., "Stringprep profile for user names and
1143 passwords", draft-ietf-sasl-saslprep-xx.txt, (a work in
1146 [StringPrep] Hoffman P. and M. Blanchet, "Preparation of
1147 Internationalized Strings ('stringprep')", draft-
1148 hoffman-rfc3454bis-xx.txt, a work in progress.
1150 [Syntaxes] Legg, S. (editor), "LDAP: Syntaxes and Matching Rules",
1151 draft-ietf-ldapbis-syntaxes-xx.txt, a work in progress.
1153 [TLS] Dierks, T. and C. Allen. "The TLS Protocol Version
1154 1.1", draft-ietf-tls-rfc2246-bis-xx.txt, a work in
1157 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO
1158 10646", RFC 3629, STD 63, November 2003.
1160 [Unicode] The Unicode Consortium, "The Unicode Standard, Version
1161 3.2.0" is defined by "The Unicode Standard, Version
1162 3.0" (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-
1163 61633-5), as amended by the "Unicode Standard Annex
1165 (http://www.unicode.org/reports/tr27/) and by the
1166 "Unicode Standard Annex #28: Unicode 3.2"
1167 (http://www.unicode.org/reports/tr28/).
1169 Harrison Expires July 2004 [Page 20]
1171 Internet-Draft LDAP Authentication Methods 5 December 2003
1174 Informative References
1176 [ANONYMOUS] Zeilenga, K.,"Anonymous SASL Mechanism", draft-
1177 zeilenga-sasl-anon-xx.txt, a work in progress.
1179 [Glossary] Shirey, R., "Internet Security Glossary", RFC 2828, May
1182 [PLAIN] Zeilenga, K.,"Plain SASL Mechanism", draft-zeilenga-
1183 sasl-plain-xx.txt, a work in progress.
1185 [SecArch] Kent, S. and R. Atkinson, "Security Architecture for
1186 the Internet Protocol", RFC 2401, November 1998.
1193 1800 S. Novell Place
1197 roger_harrison@novell.com
1199 Appendix A. LDAP Association State Transition Tables
1201 This section provides a state transition table to represent a state
1202 diagram for the various authentication and TLS states through which
1203 an LDAP association may pass during the course of its existence and
1204 the actions that cause these changes in state.
1206 This section is based entirely on information found in this document
1207 and other documents that are part of the LDAP Technical
1208 Specification [Roadmap]. As such, it is strictly informational in
1211 A.1. LDAP Association States
1213 The following table lists the valid LDAP association states and
1214 provides a description of each state. The ID for each state is used
1215 in the state transition table in section A.4.
1217 ID State Description
1218 -- --------------------------------------------------------------
1220 no Authentication ID is associated with the LDAP connection
1221 no Authorization ID is in force
1223 Authentication ID = I
1224 Authorization ID = X
1225 S3 Authenticated SASL EXTERNAL, implicit authorization ID
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1231 Authentication ID = J
1232 Authorization ID = Y
1233 S4 Authenticated SASL EXTERNAL, explicit authorization ID
1234 Authentication ID = J
1235 Authorization ID = Z
1237 A.2. Actions that Affect LDAP Association State
1239 The following table lists the actions that can affect the
1240 authentication and authorization state of an LDAP association. The
1241 ID for each action is used in the state transition table in section
1245 -- --------------------------------------------------------------
1246 A1 Client bind request fails
1247 A2 Client successfully performs anonymous simple bind
1248 A3 Client successfully performs unauthenticated simple bind
1249 A4 Client successfully performs simple bind with name and
1250 password OR SASL bind with any mechanism except EXTERNAL using
1251 an authentication ID = I that maps to authorization ID X
1252 A5 Client Binds SASL EXTERNAL with implicit assertion of
1253 authorization ID (section 3.3.6.1)]. The current
1254 authentication ID maps to authorization ID = Y.
1255 A6 Client Binds SASL EXTERNAL with explicit assertion of
1256 authorization ID = Z (section 3.3.6.2)]
1257 A7 Client abandons a bind operation, and server processes the
1259 A8 Client abandons a bind operation, and server does not process
1261 A9 Client Start TLS request fails
1262 A10 Client Start TLS request succeeds
1263 A11 Client or Server: graceful TLS closure ([Protocol] section
1266 A.3. Decisions Used in Making LDAP Association State Changes
1268 Certain changes in the authentication and authorization state of an
1269 LDAP association are only allowed if the server can affirmatively
1270 answer a question. These questions are applied as part of the
1271 criteria for allowing or disallowing a state transition in the state
1272 transition table in section A.4.
1274 ID Decision Question
1275 -- --------------------------------------------------------------
1276 D1 Are lower-layer credentials available?
1277 D2 Can lower-layer credentials for Auth ID "K" be mapped to
1278 asserted AuthZID "L"?
1280 A.4. LDAP Association State Transition Table
1282 The LDAP Association table below lists the valid authentication and
1283 authorization states for an LDAP association and the actions that
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1289 could affect them. For any given row in the table, the Current State
1290 column gives the state of an LDAP association, the Action column
1291 gives an action that could affect the state of an LDAP assocation,
1292 and the Next State column gives the resulting state of an LDAP
1293 association after the action occurs.
1295 S1, the initial state for the state machine described in this table,
1296 is the authentication state when an LDAP connection is initially
1300 State Action State Comment
1301 ------- ------- ----- ---------------------------------------
1302 Any A1 S1 [Protocol] section 4.2.1
1305 Any A4 S2 Sections 6.1, 6.2
1306 Any A5, S1 Failed bind, section 3.3.6
1310 Any A6, S1 failed bind, section 3.3.6
1312 Any A6, S1 failed bind, section 3.3.6.2
1318 Any A7 S1 [Protocol] section 4.2.1. Clients
1319 cannot detect this state.
1320 Any A8 no [Protocol] section 4.2.1. Clients
1321 change cannot detect this state.
1322 Any A9 no [Protocol] section 4.13.2.2
1324 Any A10 no Section 4.2.1
1326 Any A11 S1 Section 4.2.3
1328 Appendix B. Example Deployment Scenarios
1330 The following scenarios are typical for LDAP directories on the
1331 Internet, and have different security requirements. (In the
1332 following discussion, "sensitive data" refers to information whose
1333 disclosure, alteration, destruction, or loss would adversely affect
1334 the interests or business of its owner or user. Also note that there
1335 may be data that is protected but not sensitive.) This is not
1336 intended to be a comprehensive list; other scenarios are possible,
1337 especially on physically protected networks.
1339 (1) A read-only directory, containing no sensitive data, accessible
1340 to "anyone", and TCP connection hijacking or IP spoofing is not
1341 a problem. Anonymous authentication, described in section 7, is
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1347 suitable for this type of deployment, and requires no additional
1348 security functions except administrative service limits.
1350 (2) A read-only directory containing no sensitive data; read access
1351 is granted based on identity. TCP connection hijacking is not
1352 currently a problem. This scenario requires data confidentiality
1353 for sensitive authentication information AND data integrity for
1354 all authentication information.
1356 (3) A read-only directory containing no sensitive data; and the
1357 client needs to ensure the identity of the directory server and
1358 that the directory data is not modified while being returned
1359 from the server. A data origin authentication service AND data
1360 integrity service are required.
1362 (4) A read-write directory, containing no sensitive data; read
1363 access is available to "anyone", update access to properly
1364 authorized persons. TCP connection hijacking is not currently a
1365 problem. This scenario requires data confidentiality for
1366 sensitive authentication information AND data integrity for all
1367 authentication information.
1369 (5) A directory containing sensitive data. This scenario requires
1370 data confidentiality protection AND secure authentication.
1372 Appendix C. Authentication and Authorization Concepts
1374 This appendix defines basic terms, concepts, and interrelationships
1375 regarding authentication, authorization, credentials, and identity.
1376 These concepts are used in describing how various security
1377 approaches are utilized in client authentication and authorization.
1379 C.1. Access Control Policy
1381 An access control policy is a set of rules defining the protection
1382 of resources, generally in terms of the capabilities of persons or
1383 other entities accessing those resources. Security objects and
1384 mechanisms, such as those described here, enable the expression of
1385 access control policies and their enforcement.
1387 C.2. Access Control Factors
1389 A request, when it is being processed by a server, may be associated
1390 with a wide variety of security-related factors (section 4.2 of
1391 [Protocol]). The server uses these factors to determine whether and
1392 how to process the request. These are called access control factors
1393 (ACFs). They might include source IP address, encryption strength,
1394 the type of operation being requested, time of day, etc. Some
1395 factors may be specific to the request itself, others may be
1396 associated with the connection via which the request is transmitted,
1397 others (e.g. time of day) may be "environmental".
1399 Access control policies are expressed in terms of access control
1400 factors. E.g., a request having ACFs i,j,k can perform operation Y
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1406 on resource Z. The set of ACFs that a server makes available for
1407 such expressions is implementation-specific.
1409 C.3. Authentication, Credentials, Identity
1411 Authentication credentials are the evidence supplied by one party to
1412 another, asserting the identity of the supplying party (e.g. a user)
1413 who is attempting to establish an association with the other party
1414 (typically a server). Authentication is the process of generating,
1415 transmitting, and verifying these credentials and thus the identity
1416 they assert. An authentication identity is the name presented in a
1419 There are many forms of authentication credentials -- the form used
1420 depends upon the particular authentication mechanism negotiated by
1421 the parties. For example: X.509 certificates, Kerberos tickets,
1422 simple identity and password pairs. Note that an authentication
1423 mechanism may constrain the form of authentication identities used
1426 C.4. Authorization Identity
1428 An authorization identity is one kind of access control factor. It
1429 is the name of the user or other entity that requests that
1430 operations be performed. Access control policies are often expressed
1431 in terms of authorization identities; e.g., entity X can perform
1432 operation Y on resource Z.
1434 The authorization identity bound to an association is often exactly
1435 the same as the authentication identity presented by the client, but
1436 it may be different. SASL allows clients to specify an authorization
1437 identity distinct from the authentication identity asserted by the
1438 client's credentials. This permits agents such as proxy servers to
1439 authenticate using their own credentials, yet request the access
1440 privileges of the identity for which they are proxying [SASL]. Also,
1441 the form of authentication identity supplied by a service like TLS
1442 may not correspond to the authorization identities used to express a
1443 server's access control policy, requiring a server-specific mapping
1444 to be done. The method by which a server composes and validates an
1445 authorization identity from the authentication credentials supplied
1446 by a client is implementation-specific.
1448 Appendix D. RFC 2829 Change History
1450 This appendix lists the changes made to the text of RFC 2829 in
1451 preparing this document.
1453 D.0. General Editorial Changes
1456 - Changed other instances of the term LDAP to LDAP where v3 of the
1457 protocol is implied. Also made all references to LDAP use the
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1465 - Miscellaneous grammatical changes to improve readability.
1467 - Made capitalization in section headings consistent.
1471 - Changed title to reflect inclusion of material from RFC 2830 and
1474 D.1. Changes to Section 1
1478 - Moved conventions used in document to a separate section.
1480 D.2. Changes to Section 2
1484 - Moved section to an appendix.
1486 D.3. Changes to Section 3
1490 - Moved section to an appendix.
1492 D.4 Changes to Section 4
1496 - Changed "Distinguished Name" to "LDAP distinguished name".
1498 D.5. Changes to Section 5
1502 - Added the following sentence: "Servers SHOULD NOT allow clients
1503 with anonymous authentication to modify directory entries or
1504 access sensitive information in directory entries."
1506 D.5.1. Changes to Section 5.1
1510 - Replaced the text describing the procedure for performing an
1511 anonymous bind (protocol) with a reference to section 4.2 of RFC
1512 2251 (the protocol spec).
1516 - Brought text describing procedure for performing an anonymous
1517 bind from section 4.2 of RFC 2251 bis. This text will be
1518 removed from the draft standard version of that document.
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1525 D.6. Changes to Section 6.
1529 Reorganized text in section 6.1 as follows:
1531 1. Added a new section (6.1) titled "Simple Authentication" and
1532 moved one of two introductory paragraphs for section 6 into
1533 section 6.1. Added sentences to the paragraph indicating:
1535 a. simple authentication is not suitable for environments where
1536 confidentiality is not available.
1538 b. LDAP implementations SHOULD NOT support simple
1539 authentication unless confidentiality and data integrity
1540 mechanisms are in force.
1542 2. Moved first paragraph of section 6 (beginning with "LDAP
1543 implementations MUST support authentication with a password...")
1544 to section on Digest Authentication (Now section 6.2).
1546 D.6.1. Changes to Section 6.1.
1548 Version -00 Renamed section to 6.2
1550 - Added sentence from original section 6 indicating that the
1551 DIGEST-MD5 SASL mechanism is required for all conforming LDAP
1554 D.6.2. Changes to Section 6.2
1558 - Renamed section to 6.3
1560 - Reworded first paragraph to remove reference to user and the
1561 userPassword password attribute Made the first paragraph more
1562 general by simply saying that if a directory supports simple
1563 authentication that the simple bind operation MAY performed
1564 following negotiation of a TLS ciphersuite that supports
1567 - Replaced "the name of the user's entry" with "a DN" since not
1568 all bind operations are performed on behalf of a "user."
1570 - Added Section 6.3.1 heading just prior to paragraph 5.
1572 - Paragraph 5: replaced "The server" with "DSAs that map the DN
1573 sent in the bind request to a directory entry with a
1574 userPassword attribute."
1576 D.6.3. Changes to section 6.3.
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1585 - Renamed to section 6.4.
1587 D.7. Changes to section 7.
1591 D.7.1. Changes to section 7.1.
1595 - Clarified the entity issuing a certificate by moving the phrase
1596 "to have issued the certificate" immediately after
1597 "Certification Authority."
1599 D.8. Changes to section 8.
1603 - Removed the first paragraph because simple authentication is
1604 covered explicitly in section 6.
1606 - Added section 8.1. heading just prior to second paragraph.
1608 - Added section 8.2. heading just prior to third paragraph.
1610 - Added section 8.3. heading just prior to fourth paragraph.
1614 - Moved entire section 8 of RFC 2829 into section 3.4 (Using SASL
1615 for Other Security Services) to bring material on SASL
1616 mechanisms together into one location.
1618 D.9. Changes to section 9.
1622 - Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL
1625 - Added section 9.1. heading.
1627 - Modified a comment in the ABNF from "unspecified userid" to
1628 "unspecified authz id".
1630 - Deleted sentence, "A utf8string is defined to be the UTF-8
1631 encoding of one or more ISO 10646 characters," because it is
1634 - Added section 9.1.1. heading.
1636 - Added section 9.1.2. heading.
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1640 Internet-Draft LDAP Authentication Methods 5 December 2003
1645 - Moved entire section 9 to become section 3.5 so that it would be
1646 with other SASL material.
1648 D.10. Changes to Section 10.
1652 - Updated reference to cracking from a week of CPU time in 1997 to
1653 be a day of CPU time in 2000.
1655 - Added text: "These ciphersuites are NOT RECOMMENDED for use...
1656 and server implementers SHOULD" to sentence just prior the
1657 second list of ciphersuites.
1659 - Added text: "and MAY support other ciphersuites offering
1660 equivalent or better protection," to the last paragraph of the
1663 D.11. Changes to Section 11.
1667 - Moved to section 3.6 to be with other SASL material.
1669 D.12. Changes to Section 12.
1673 - Inserted new section 12 that specifies when SASL protections
1674 begin following SASL negotiation, etc. The original section 12
1675 is renumbered to become section 13.
1679 - Moved to section 3.7 to be with other SASL material.
1681 D.13. Changes to Section 13 (original section 12).
1685 Appendix E. RFC 2830 Change History
1687 This appendix lists the changes made to the text of RFC 2830 in
1688 preparing this document.
1690 E.0. General Editorial Changes
1692 - Material showing the PDUs for the Start TLS response was broken
1693 out into a new section.
1697 Harrison Expires July 2004 [Page 29]
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1701 - The wording of the definition of the Start TLS request and Start
1702 TLS response was changed to make them parallel. NO changes were
1703 made to the ASN.1 definition or the associated values of the
1706 - A separate section heading for graceful TLS closure was added
1707 for parallelism with section on abrupt TLS closure.
1709 Appendix F. RFC 2251 Change History
1711 This appendix lists the changes made to the text of RFC 2251 in
1712 preparing this document.
1714 F.0. General Editorial Changes
1716 - All material from section 4.2 of RFC 2251 was moved into this
1719 - A new section was created for the Bind Request
1721 - Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved
1722 after the section on the Bind Response for parallelism with the
1723 presentation of the Start TLS operations. The section was also
1724 subdivided to explicitly call out the various effects being
1725 described within it.
1727 - All SASL profile information from RFC 2829 was brought within
1728 the discussion of the Bind operation (primarily sections 4.4 -
1731 Appendix G. Change History to Combined Document
1733 G.1. Changes for draft-ldap-bis-authmeth-02
1737 - Added references to other LDAP standard documents, to sections
1738 within the document, and fixed broken references.
1740 - General editorial changes--punctuation, spelling, formatting,
1745 - Added glossary of terms and added sub-section headings
1749 - Clarified security mechanisms 3, 4, & 5 and brought language in
1750 line with IETF security glossary.
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1760 - Brought language in requirement (3) in line with security
1763 - Clarified that information fetched prior to initiation of TLS
1764 negotiation must be discarded
1766 -Clarified that information fetched prior to initiation of SASL
1767 negotiation must be discarded
1769 - Rewrote paragraph on SASL negotiation requirements to clarify
1774 - Added stipulation that sasl choice allows for any SASL mechanism
1775 not prohibited by this document. (Resolved conflict between this
1776 statement and one that prohibited use of ANONYMOUS and PLAIN
1781 - Added a.x.bar.com to wildcard matching example on hostname
1786 - Added LDAP Association State Transition Tables to show the
1787 various states through which an LDAP association may pass along
1788 with the actions and decisions required to traverse from state
1793 - Brought security terminology in line with IETF security glossary
1794 throughout the appendix.
1796 G.2. Changes for draft-ldap-bis-authmeth-03
1800 - Added introductory notes and changed title of document and
1801 references to conform to WG chair suggestions for the overall
1802 technical specification.
1804 - Several issues--H.13, H.14, H.16, H.17--were resolved without
1805 requiring changes to the document.
1809 - Removed reference to /etc/passwd file and associated text.
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1819 - Removed sections 4.1, 4.2 and parts of section 4.3. This
1820 information was being duplicated in the protocol specification
1821 and will now reside there permanently.
1824 - changed words, "not recommended" to "strongly discouraged"
1828 - Based on ldapbis WG discussion at IETF52 two sentences were
1829 added indicating that clients SHOULD NOT send a DN value when
1830 binding with the sasl choice and servers SHALL ignore any value
1831 received in this circumstance.
1836 - Generalized the language of this section to not refer to any
1837 specific password attribute or to refer to the directory entry
1842 - Added security consideration regarding misuse of unauthenticated
1845 - Added security consideration requiring access control to be
1846 applied only to authenticated users and recommending it be
1847 applied when reading sensitive information or updating directory
1851 G.3. Changes for draft-ldap-bis-authmeth-04
1855 - Changed references to use [RFCnnnn] format wherever possible.
1856 (References to works in progress still use [name] format.)
1857 - Various edits to correct typos and bring field names, etc. in
1858 line with specification in [Protocol] draft.
1860 - Several issues--H.13, H.14, H.16, H.17--were resolved without
1861 requiring changes to the document.
1865 - Changed ABNF grammar to use productions that are like those in
1870 - Removed sections 5.1, 5.2, and 5.4 that will be added to
1871 [Protocol]. Renumbered sections to accommodate this change.
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1881 - Reviewed LDAP Association State table for completeness and
1882 accuracy. Renumbered actions A3, A4, and A5 to be A5, A3, and A4
1883 respectively. Re-ordered several lines in the table to ensure
1884 that actions are in ascending order (makes analyzing the table
1885 much more logical). Added action A2 to several states where it
1886 was missing and valid. Added actions A7 and A8 placeholders to
1887 states S1, S2, S4 and S5 pending resolution of issue H.28.
1891 - Modified security consideration (originally added in -03)
1892 requiring access control to be applied only to authenticated
1893 users. This seems nonsensical because anonymous users may have
1894 access control applied to limit permissible actions.
1898 - Verified all normative references and moved informative
1899 references to a new section 14.
1901 G.4. Changes for draft-ldap-bis-authmeth-05
1905 - General editory changes to fix punctuation, spelling, line
1907 - Verified and updated intra- and inter-document references
1909 - Document-wide review for proper usage of RFC 2119 keywords with
1910 several changes to correct improper usage.
1913 - Updated to match current contents of documents. This was needed
1914 due to movement of material on Bind and Start TLS operations to
1915 [Protocol] in this revision.
1919 - Renamed section to "Rationale for LDAP Security Mechanisms" and
1920 removed text that did not support this theme. Part of the
1921 motivation for this change was to remove the implication of the
1922 previous section title, "Required Security Mechanisms", and
1923 other text found in the section that everything in the section
1926 - Information from several removed paragraphs that describe
1927 deployment scenarios will be added Appendix A in the next
1928 revision of the draft.
1933 Harrison Expires July 2004 [Page 33]
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1937 - Paragraph beginning, " If TLS is negotiated, the client MUST
1938 discard all information..." was moved to section 5.1.7 and
1939 integrated with related material there.
1941 - Paragraph beginning, "If a SASL security layer is negotiated..."
1942 was moved to section 4.2
1946 - Changed wording of first paragraph to clarify meaning.
1949 - Added paragraph from section 3 of -04 beginning, "If a SASL
1950 security layer is negotiated..."
1953 - Renamed to "Other SASL Mechanisms" and completely rewrote the
1954 section (one sentence) to generalize the treatment of SASL
1955 mechanisms not explicitly mentioned in this document.
1959 - Added paragraph beginning, "The dnAuthzID choice allows client
1960 applications..." to clarify whether DN form authorization
1961 identities have to also have a corresponding directory entry.
1962 This change was based on editor's perception of WG consensus.
1964 - Made minor clarifying edits in the paragraph beginning, "The
1965 uAuthzID choice allows for compatibility..."
1969 - Made minor clarifying edits in the last paragraph of the
1974 - Wording from section 3 paragraph beginning " If TLS is
1975 negotiated, the client MUST discard all information..." was
1976 moved to this section and integrated with existing text.
1980 - Changed usage of "TLS connection" to "TLS session" throughout.
1982 - Removed empty section 5.2.1 and renumbered sections it had
1983 previously contained.
1987 - Added introductory paragraph at beginning of section.
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1994 Internet-Draft LDAP Authentication Methods 5 December 2003
1996 - Changed term "data privacy" to "data confidentiality" to be
1997 consistent with usage in rest of document.
2001 - Changed first paragraph to require implementations that
2002 implement *password-based* authentication to implement and
2003 support DIGEST-MD5 SASL authentication.
2007 - First paragraph: changed "session encryption" to "session
2008 confidentiality protection" to be consistent with usage in rest
2013 - Began changes to incorporate information on deployment scenarios
2014 removed from section 3.
2016 G.5. Changes for draft-ldap-bis-authmeth-06
2021 - Combined Section 2 (Introduction) and Section 3 (Motivation) and
2022 moved Introduction to section 1. All following sections numbers
2023 were decremented by one as result.
2025 - Edits to fix typos, I-D nits, etc.
2027 - Opened several new issues in Appendix G based on feedback from
2028 WG. Some of these have been resolved. Others require further
2033 - Added additional example of spoofing under threat (7).
2037 - Changed definition of "LDAP association" and added terms,
2038 "connection" and "TLS connection" to bring usage in line with
2043 - Clarified sentence stating that the client MUST NOT use derived
2048 - Began edits to LDAP Association state table to clarify meaning
2049 of various states and actions.
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2056 - Added action A9 to cover abandoned bind operation and added
2057 appropriate transitions to the state transition table to
2062 - Replaced first paragraph to clarify that the "DIGEST-MD5" SASL
2063 mechanism is required to implement.
2067 - Rewrote the section to make the advice more applicable over the
2068 long term, i.e. more "timeless." The intent of content in the
2069 original section was preserved.
2073 - Added a clarifying example to the consideration regarding misuse
2074 of unauthenticated access.
2076 G.6. Changes for draft-ldap-bis-authmeth-07
2081 - Updated external and internal references to accommodate changes
2084 - Opened several new issues in Appendix G based on feedback from
2085 WG. Some of these have been resolved. Others require further
2090 - Rewrote much of section 3.3 to meet the SASL profile
2091 requirements of draft-ietf-sasl-rfc2222bis-xx.txt section 5.
2093 - Changed treatement of SASL ANONYMOUS and PLAIN mechanisms to
2094 bring in line with WG consensus.
2098 - Note to implementers in section 4.1.1 based on operational
2101 - Clarification on client continuing by performing a Start TLS
2102 with TLS already established in section 4.1.4.
2104 - Moved verification of mapping of client's authentication ID to
2105 asserted authorization ID to apply only to explicit assertion.
2106 The local policy in place for implicit assertion is adequate.
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2115 - Removed most of section 7.2 as the information is now covered
2116 adequately via the new SASL profile in section 3.3. Added note
2117 to implementors regarding the treatment of username and realm
2118 values in DIGEST-MD5.
2120 - Section 7.3. Minor clarifications in wording.
2122 - Section 7.3.1. Clarification that a match of the presented value
2123 to any member of the set of stored passwords constitutes a
2124 successful authentication.
2126 G.7. Changes for draft-ldap-bis-authmeth-08
2131 - Changed usage from LDAPv3 to LDAP for usage consistency across
2132 LDAP technical specification.
2134 - Fixed a number of usage nits for consistency and to bring doc in
2135 conformance with publication guidelines.
2139 - Significant cleanup and rewording of abstract based on WG
2144 - New definition of user.
2148 - Added 1.5 sentences at end of introductory paragraph indicating
2149 the effect of the Bind op on the LDAP association.
2153 - Retitled section and clarified wording
2157 - Clarified that simple authentication choice provides three types
2158 of authentication: anonymous, unauthenticated, and simple
2163 - New wording clarifying when negotiated security mechanisms take
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2173 - Changed requirement to discard information about server fetched
2174 prior to SASL negotiation from MUST to SHOULD to allow for
2175 information obtained through secure mechanisms.
2179 - Simplified wording of first paragraph based on suggestion from
2184 - Minor clarifications in wording.
2188 - Minor clarifications in wording in first sentence.
2189 - Explicitly called out that the DN value in the dnAuthzID form is
2190 to be matched using DN matching rules.
2191 - Called out that the uAuthzID MUST be prepared using SASLprep
2192 rules before being compared.
2193 - Clarified requirement on assuming global uniqueness by changing
2194 a "generally... MUST" wording to "SHOULD".
2198 - Simplified wording describing conditions when Start TLS cannot
2200 - Simplified wording in note to implementers regarding race
2201 condition with outstanding LDAP operations on connection.
2205 - Removed section and moved relevant text to section 4.2.2.
2209 - Renumbered to 4.1.5.
2210 - Updated server identity check rules for server's name based on
2215 - Renumbered to 4.1.6
2216 - Changed requirement to discard information about server fetched
2217 prior to TLS negotion from MUST to SHOULD to allow for
2218 information obtained through secure mechanisms.
2222 - Clarified wording.
2223 - Added definition of anonymous and unauthenticated binds.
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2232 - Added security consideration (moved from elsewhere) discouraging
2233 use of cleartext passwords on unprotected communication
2238 - Added an IANA consideration to update GSSAPI service name
2239 registry to point to [Roadmap] and [Authmeth]
2241 G.8. Changes for draft-ldap-bis-authmeth-09
2246 - Updated section references within document
2247 - Changed reference tags to match other docs in LDAP TS
2248 - Used non-quoted names for all SAL mechanisms
2252 - Inspected keyword usage and removed several improper usages.
2254 - Removed sentence saying DIGEST-MD5 is LDAP's mandatory-to-
2255 implement mechanism. This is covered elsewhere in document.
2257 - Moved section 5, authentication state table, of -08 draft to
2258 section 8 of -09 and completely rewrote it.
2262 - Reworded sentence beginning, "It is also desireable to allow
2263 authentication methods to carry identities based on existingù
2264 non-LDAP DN-forms..."
2265 - Clarified relationship of this document to other documents in
2270 - Removed paragraph beginning,"If the client is configured to
2271 support multiple SASL mechanisms..." because the actions
2272 specified in the paragraph do not provide the protections
2273 indicated. Added a new paragraph indicating that clients and
2274 server should allow specification of acceptable mechanisms and
2275 only allow those mechanisms to be used.
2277 - Clarified independent behavior when TLS and SASL security layers
2278 are both in force (e.g. one being removed doesn't affect the
2283 - Moved most of section 4.2.2, Client Assertion of Authorization
2284 Identity, to sections 3.3.6, 3.3.6.1, and 3.3.6.2.
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2293 - Moved some normative comments into text body.
2297 - Non success resultCode values are valid if server is *unwilling*
2298 or unable to negotiate TLS.
2302 - Rewrote entire section based on WG feedback.
2306 - Moved most of this section to 3.3.6 for better document flow.
2310 - Rewrote entire section based on WG feedback.
2314 - Moved imperative language regarding unauthenticated access from
2315 security considerations to here.
2319 - Added several paragraphs regarding the risks of transmitting
2320 passwords in the clear and requiring server implementations to
2321 provide a specific configuration that reduces these risks.
2325 - Added sentence describing protections provided by DIGEST-MD5
2327 - Changed DNs in exmple to be dc=example,dc=com.
2331 - Updated consideration on use of cleartext passwords to include
2332 other unprotected authentication credentials
2333 - Substantial rework of consideration on misuse of unauthenticated
2336 G.9. Changes for draft-ldap-bis-authmeth-10
2339 - Reorganized content of sections 3-9 to improve document flow and
2341 - Resolved issue of effect of Start TLS and TLS closure on LDAP
2343 - Made numerous minor wording changes based on WG feedback.
2344 - Updated list of threats for Section 1.
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2350 - Recommendation that servers should not support weaker TLS
2351 ciphersuites unless other protection is in place.
2352 - Moved authentication state table to appendix and relettered
2355 Appendix H. Issues to be Resolved
2357 This appendix lists open questions and issues that need to be
2358 resolved before work on this document is deemed complete.
2362 Section 1 lists 6 security mechanisms that can be used by LDAP
2363 servers. I'm not sure what mechanism 5, "Resource limitation by
2364 means of administrative limits on service controls" means.
2366 Status: resolved. Changed wording to "administrative service limits"
2371 Section 2 paragraph 1 defines the term, "sensitive." Do we want to
2372 bring this term and other security-related terms in alignment with
2373 usage with the IETF security glossary (RFC 2828)?
2375 Status: resolved. WG input at IETF 51 was that we should do this, so
2376 the appropriate changes have been made.
2380 Section 2, deployment scenario 2: What is meant by the term "secure
2381 authentication function?"
2383 Status: resolved. Based on the idea that a "secure authentication
2384 function" could be provided by TLS, I changed the wording to require
2385 data confidentiality for sensitive authentication information and
2386 data integrity for all authentication information.
2390 Section 3, deployment scenario 3: What is meant by the phrase,
2391 "directory data is authenticated by the server?"
2393 Status: resolved. I interpreted this to mean the ability to ensure
2394 the identity of the directory server and the integrity of the data
2395 sent from that server to the client, and explictly stated such.
2399 Section 4 paragraph 3: What is meant by the phrase, "this means that
2400 either this data is useless for faking authentication (like the Unix
2401 "/etc/passwd" file format used to be)?"
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2407 Internet-Draft LDAP Authentication Methods 5 December 2003
2409 Status: resolved. Discussion at IETF 52 along with discussions with
2410 the original authors of this material have convinced us that this
2411 reference is simply too arcane to be left in place. In -03 the text
2412 has been modified to focus on the need to either update password
2413 information in a protected fashion outside of the protocol or to
2414 update it in session well protected against snooping, and the
2415 reference to /etc/passwd has been removed.
2419 Section 4 paragraph 7 begins: "For a directory needing session
2420 protection..." Is this referring to data confidentiality or data
2423 Status: resolved. Changed wording to say, "For a directory needing
2424 data security (both data integrity and data confidentiality)..."
2428 Section 4 paragraph 8 indicates that "information about the server
2429 fetched prior to the TLS negotiation" must be discarded. Do we want
2430 to explicitly state that this applies to information fetched prior
2431 to the *completion* of the TLS negotiation or is this going too far?
2433 Status: resolved. Based on comments in the IETF 51 LDAPBIS WG
2434 meeting, this has been changed to explicitly state, "fetched prior
2435 to the initiation of the TLS negotiation..."
2439 Section 4 paragraph 9 indicates that clients SHOULD check the
2440 supportedSASLMechanisms list both before and after a SASL security
2441 layer is negotiated to ensure that they are using the best available
2442 security mechanism supported mutually by the client and server. A
2443 note at the end of the paragraph indicates that this is a SHOULD
2444 since there are environments where the client might get a list of
2445 supported SASL mechanisms from a different trusted source.
2447 I wonder if the intent of this could be restated more plainly using
2448 one of these two approaches (I've paraphrased for the sake of
2451 Approach 1: Clients SHOULD check the supportedSASLMechanisms
2452 list both before and after SASL negotiation or clients SHOULD
2453 use a different trusted source to determine available supported
2456 Approach 2: Clients MUST check the supportedSASLMechanisms list
2457 both before and after SASL negotiation UNLESS they use a
2458 different trusted source to determine available supported SASL
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2466 Internet-Draft LDAP Authentication Methods 5 December 2003
2468 Status: resolved. WG input at IETF 51 was that Approach 1 was
2469 probably best. I ended up keeping the basic structure similar to the
2470 original to meet this intent.
2474 Section 6.3.1 states: "DSAs that map the DN sent in the bind request
2475 to a directory entry with a userPassword attribute will... compare
2476 [each value in the named user's entry]... with the presented
2477 password." This implies that this applies only to user entries with
2478 userPassword attributes. What about other types of entries that
2479 might allow passwords and might store in the password information in
2480 other attributes? Do we want to make this text more general?
2482 Status: resolved in -03 draft by generalizing section 8.3.1 to not
2483 refer to any specific password attribute and by removing the term
2484 "user" in referring to the directory entry specified by the DN in
2487 H.10 userPassword and simple bind
2489 We need to be sure that we don't require userPassword to be the only
2490 attribute used for authenticating via simple bind. (See 2251 sec 4.2
2491 and authmeth 6.3.1. Work with Jim Sermersheim on resolution to this.
2492 On publication state something like: "This is the specific
2493 implementation of what we discussed in our general reorg
2494 conversation on the list." (Source: Kurt Zeilenga)
2496 Status: resolved in -03 draft by generalizing section 8.3.1 to not
2497 refer to any specific password attribute and by removing the term
2498 "user" in referring to the directory entry specified by the DN in
2501 H.11. Meaning of LDAP Association
2503 The original RFC 2830 uses the term "LDAP association" in describing
2504 a connection between an LDAP client and server regardless of the
2505 state of TLS on that connection. This term needs to be defined or
2508 Status: resolved. at IETF 51 Bob Morgan indicated that the term
2509 "LDAP association" was intended to distinguish the LDAP-level
2510 connection from the TLS-level connection. This still needs to be
2511 clarified somewhere in the draft. Added "LDAP association" to a
2512 glossary in section 1.
2514 H.12. Is DIGEST-MD5 mandatory for all implementations?
2516 Reading 2829bis I think DIGEST-MD5 is mandatory ONLY IF your server
2517 supports password based authentication...but the following makes it
2518 sound mandatory to provide BOTH password authentication AND DIGEST-
2521 "6.2. Digest authentication
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2525 Internet-Draft LDAP Authentication Methods 5 December 2003
2528 LDAP implementations MUST support authentication with a password
2529 using the DIGEST-MD5 SASL mechanism for password protection, as
2530 defined in section 6.1."
2532 The thing is for acl it would be nice (though not critical) to be
2533 able to default the required authentication level for a subject to a
2534 single "fairly secure" mechanism--if there is no such mandatory
2535 authentication scheme then you cannot do that. (Source: Rob Byrne)
2537 Status: resolved. -00 version of the draft added a sentence at the
2538 beginning of section 8.2 stating that LDAP server implementations
2539 must support this method.
2541 H.13. Ordering of authentication levels requested
2543 Again on the subject of authentication level, is it possible to
2544 define an ordering on authentication levels which defines their
2545 relative "strengths" ? This would be useful in acl as you could say
2546 things like"a given aci grants access to a given subject at this
2547 authentication level AND ABOVE". David Chadwick raised this before
2548 in the context of denying access to a subject at a given
2549 authentication level, in which case he wanted to express "deny
2550 access to this subject at this authentication level AND TO ALL
2551 IDENTITIES AUTHENTICATED BELOW THAT LEVEL". (Source: Rob Byrne)
2553 Status: out of scope. This is outside the scope of this document and
2554 will not be addressed.
2556 H.14. Document vulnerabilities of various mechanisms
2558 While I'm here...in 2829, I think it would be good to have some
2559 comments or explicit reference to a place where the security
2560 properties of the particular mandatory authentication schemes are
2561 outlined. When I say "security properties" I mean stuff like "This
2562 scheme is vulnerable to such and such attacks, is only safe if the
2563 key size is > 50, this hash is widely considered the best, etc...".
2564 I think an LDAP implementor is likely to be interested in that
2565 information, without having to wade through the security RFCs.
2568 Status: out of scope. This is outside the scope of this document and
2569 will not be addressed.
2571 H.15. Include a Start TLS state transition table
2573 The pictoral representation it is nominally based on is here (URL
2576 http://www.stanford.edu/~hodges/doc/LDAPAssociationStateDiagram-
2579 (Source: Jeff Hodges)
2582 Harrison Expires July 2004 [Page 44]
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2588 Table provided in -03. Review of content for accuracy in -04.
2589 Additional review is needed, plus comments from WG members indicate
2590 that additional description of each state's meaning would be
2593 Did a significant revision of state transition table in -09. Changes
2594 were based on suggestions from WG and greatly simplified overall
2597 H.16. Empty sasl credentials question
2599 I spent some more time looking microscopically at ldap-auth-methods
2600 and ldap-ext-tls drafts. The drafts say that the credential must
2601 have the form dn:xxx or u:xxx or be absent, and although they don't
2602 say what to do in the case of an empty octet string I would say that
2603 we could send protocolError (claim it is a bad PDU).
2605 There is still the question of what to do if the credential is 'dn:'
2606 (or 'u:') followed by the empty string. (Source: ariel@columbia.edu
2609 Status: resolved. Kurt Zeilenga indicated during ldapbis WG
2610 discussion at IETF 52 that SASL AuthzID credentials empty and absent
2611 are equivalent in the latest SASL ID. This resolves the issue.
2613 H.17. Hostname check from MUST to SHOULD?
2615 I am uneasy about the hostname check. My experience from PKI with
2616 HTTP probably is a contributing factor; we have people using the
2617 short hostname to get to a server which naturally has the FQDN in
2618 the certificate, no end of problems. I have a certificate on my
2619 laptop which has the FQDN for the casse when the system is on our
2620 Columbia network with a fixed IP; when I dial in however, I have
2621 some horrible dialup name, and using the local https server becomes
2622 annoying. Issuing a certificate in the name 'localhost' is not a
2623 solution! Wildcard match does not solve this problem. For these
2624 reasons I am inclined to argue for 'SHOULD' instead of
2625 'MUST' in paragraph...
2627 Also, The hostname check against the name in the certificate is a
2628 very weak means of preventing man-in-the-middle attacks; the proper
2629 solution is not here yet (SecureDNS or some equivalent). Faking out
2630 DNS is not so hard, and we see this sort of thing in the press on a
2631 pretty regular basis, where site A hijacks the DNS server for site B
2632 and gets all their requests. Some mention of this should be made in
2633 the draft. (Source: ariel@columbia.edu via Jeff Hodges)
2635 Status: resolved. Based on discussion at IETF 52 ldapbis WG meeting,
2636 this text will stand as it is. The check is a MUST, but the behavior
2637 afterward is a SHOULD. This gives server implementations the room to
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2645 H.18. Must SASL DN exist in the directory?
2647 If the 'dn:' form of sasl creds is used, is it the intention of the
2648 draft(ers) that this DN must exist in the directory and the client
2649 will have the privileges associated with that entry, or can the
2650 server map the sasl DN to perhaps some other DN in the directory,
2651 in an implementation-dependent fashion?
2653 We already know that if *no* sasl credentials are presented, the DN
2654 or altname in the client certificate may be mapped to a DN in an
2655 implementation-dependent fashion, or indeed to something not in the
2656 directory at all. (Right?) (Source: ariel@columbia.edu via Jeff
2659 Status: resolved. (11/12/02)Based on my research I propose that the
2660 DN MUST exist in the directory when the DN form of sasl creds is
2661 used. I have made this proposal to the ldapbis mailing list.
2663 (11/21/02) Feedback from mailing list has proposed removing this
2664 paragraph entirely because (1) explicit assertion of authorization
2665 identity should only be done when proxying (2) mapping of the
2666 asserted authorization identity is implementation specific and
2667 policy driven [SASL] section 4.2, and (3) keeping this paragraph is
2668 not required for interoperability.
2670 H.19. DN used in conjunction with SASL mechanism
2672 We need to specify whether the DN field in Bind operation can/cannot
2673 be used when SASL mechanism is specified. (source: RL Bob)
2675 Status: resolved. (-03) Based on ldapbis WG discussion at IETF52 two
2676 sentences were added to section 4.3 indicating that clients SHOULD
2677 NOT send a DN value when binding with the sasl choice and servers
2678 SHALL ignore any value received in this circumstance. During edits
2679 for -04 version of draft it was noted that [Protocol] section 4.2
2680 conflicts with this draft. The editor of [Protocol] has been
2681 notified of the discrepancy, and they have been handled.
2685 Differences between unauthenticated and anonymous. There are four
2686 states you can get into. One is completely undefined (this is now
2687 explicitly called out in [Protocol]). This text needs to be moved
2688 from [Protocol] to this draft. (source: Jim Sermersheim)
2690 Status: Resolved. There are four states: (1) no name, no password
2691 (anon); (2) name, no password (anon); (3) no name, password
2692 (invalid); (4) name, password (simple bind). States 1, 2, and 4 are
2693 called out in [AuthMeth]. State 3 is called out in [Protocol]; this
2694 seems appropriate based on review of alternatives.
2696 H.21. Misuse of unauthenticated access
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2702 Internet-Draft LDAP Authentication Methods 5 December 2003
2704 Add a security consideration that operational experience shows that
2705 clients can misuse unauthenticated access (simple bind with name but
2706 no password). Servers SHOULD by default reject authentication
2707 requests that have a DN with an empty password with an error of
2708 invalidCredentials. (Source: Kurt Zeilenga and Chris Newman (Sun))
2710 Status: Resolved. Added to security considerations in -03.
2712 H.22. Need to move Start TLS protocol information to [Protocol]
2714 Status: Resolved. Removed Sections 5.1, 5.2, and 5.4 for -04 and
2715 they are [Protocol] -11.
2717 H.23. Split Normative and Non-normative references into separate
2720 Status: Resolved. Changes made in -04
2722 H.24. What is the authentication state if a Bind operation is
2727 (3/24/03) This following text appears in section 4.2.1 of [Protocol]
2728 revision -13 to cover what happens if a bind operation is abandoned:
2730 A failed or abandoned Bind Operation has the effect of leaving the
2731 connection in an anonymous state. To arrive at a known
2732 authentication state after abandoning a bind operation, clients may
2733 unbind, rebind, or make use of the BindResponse.
2735 (6/28/03): The state table in section 6 of [AuthMeth] has been
2736 updated to reflect this wording.
2738 H.25. Difference between checking server hostname and server's
2739 canonical DNS name in Server Identity Check?
2741 Section 4.1.6: I now understand the intent of the check (prevent
2742 man-in-the-middle attacks). But what is the subtle difference
2743 between the "server hostname" and the "server's canonical DNS name"?
2748 (11/12/02) Sent suggested wording change to this paragraph to the
2749 ldapbis mail list and also asked for opinion as to whether we should
2750 discuss the distinction between server DNS hostname and server
2751 canonical DNS hostname in [AuthMeth].
2753 (11/21/02): RL Bob Morgan will provide wording that allows
2754 derivations of the name that are provided securely.
2756 (6/28/03): posted to the WG list asking Bob or any other WG member
2757 who is knowledgeable about the issues involved to help me with
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2763 wording or other information I can use to make this change and close
2766 (10/08/03): Based on WG list feedback, I've updated this text to
2767 read what I judge to be the WG consensus, "The client MUST use the
2768 server provided by the user (or other trusted entity) as the value
2769 to compare against the server name as expressed in the server's
2770 certificate. A hostname derived from the user input is to be
2771 considered provided by the user only if derived in a secure fashion
2775 H.26. Server Identity Check using servers located via SRV records
2777 Section 4.1.6: What should be done if the server was found using SRV
2778 records based on the "locate" draft/RFC? (Source: Tim Hahn).
2780 Status: Resolved. Section 5 of draft-ietf-ldapext-locate-08
2781 specifically calls out how the server identity should be performed
2782 if the server is located using the method defined in that draft.
2783 This is the right location for this information, and the coverage
2784 appears to be adequate.
2786 H.27 Inconsistency in effect of TLS closure on LDAP association.
2788 Section 4.4.1 of authmeth -03 (section 4.1 of RFC2830) states that
2789 TLS closure alert will leave the LDAP association intact. Contrast
2790 this with Section 4.5.2 (section 5.2 of RFC2830) that says that the
2791 closure of the TLS connection MUST cause the LDAP association to
2792 move to an anonymous authentication.
2794 Status: Resolved. (11/12/02) This is actually a [Protocol] issue
2795 because these sections have now been moved to [Protocol] -11. I have
2796 proposed the following text for Section 4.4.1 of [AuthMeth] -03
2797 (section 4.13.3.1 of [Protocol]) to resolve this apparent
2800 "Either the client or server MAY terminate the TLS connection on an
2801 LDAP association by sending a TLS closure alert. The LDAP
2802 connection remains open for further communication after TLS closure
2803 occurs although the authentication state of the LDAP connection is
2804 affected (see [AuthMeth] section 4.2.2).
2806 (11/21/02): resolution to this is expected in [Protocol] -12
2808 (06/28/03): [Protocol]-15 clarifies that a TLS closure alert
2809 terminates the TLS connection while leaving the LDAP connection
2810 intact. The authentication state table in [AuthMeth] specifies the
2811 effect on the LDAP association.
2813 H.28 Ordering of external sources of authorization identities
2815 Section 4.3.2 implies that external sources of authorization
2816 identities other than TLS are permitted. What is the behavior when
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2820 Internet-Draft LDAP Authentication Methods 5 December 2003
2822 two external sources of authentication credentials are available
2823 (e.g. TLS and IPsec are both present (is this possible?)) and a SASL
2824 EXTERNAL Bind operation is performed?
2826 Status: resolved. 11/20/02: Resolved by Section 4.2 of [SASL] which
2827 states that the decision to allow or disallow the asserted identity
2828 is based on an implementation defined policy.
2830 H.29 Rewrite of Section 9, TLS Ciphersuites
2832 This section contains anachronistic references and needs to be
2833 updated/rewritten in a way that provides useful guidance for future
2834 readers in a way that will transcend the passage of time.
2836 Status: Resolved. (6/28/03): Rewrote the section to cover the
2837 general issues and considerations involved in selecting TLS
2840 H.30 Update to Appendix A, Example Deployment Scenarios
2842 This section needs to be updated to indicate which security
2843 mechanisms and/or combinations of security mechanisms described
2844 elsewhere in the document can provide the types of protections
2845 suggested in this appendix.
2847 H.31 Use of PLAIN SASL Mechanism
2849 At least one LDAP server implementer has found the SASL "PLAIN"
2850 mechanism useful in authenticating to legacy systems that do not
2851 represent authentication identities as DNs. Section 3.3.1 appears to
2852 implicitly disallow the use of the SASL "PLAIN" mechanism with LDAP.
2853 Should we allow the use of this mechanism? I.e. is this "SASL"
2854 "PLAIN" MUST NOT be used with LDAP, or is it simply that LDAP
2855 doesn't define bindings for these mechanism. If SASL "PLAIN" is
2856 allowed, the following adjustments will be needed to section 3.3.1:
2857 (a) change section heading, (b) remove reference to "PLAIN" in the
2858 section, (c) ensure wording of last sentence regarding non-DN
2859 AuthZIDs is consistent with rest of the section.
2863 (6/28/03): email to WG list stating issue and asking if we should
2864 remove the reference to SASL "PLAIN".
2866 For -07 draft I've generalized the SASL profile in section 3.3 to
2867 allow any SASL mechanism.
2870 H.32 Clarification on use of SASL mechanisms
2872 Section 3.3.1: BTW, what _are_ the "ANONYMOUS" and "PLAIN" SASL
2873 mechanisms? They are not defined in RFC2222. If you refer to other
2874 SASL mechanisms than those in rfc2222, Maybe you should only list
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2879 Internet-Draft LDAP Authentication Methods 5 December 2003
2881 which mechanisms _are_used, instead of which ones are _not. (Source:
2884 I (Kurt Zeilenga) note[s] as well that the ANONYMOUS/PLAIN section
2886 be deleted. ANONYMOUS and PLAIN, like in other mechanism,
2887 can be used in LDAP if a) supported and b) enabled. I note
2888 that they each offer capabilities not found in their simple
2889 bind equivalents (and hence are used in some deployments).
2890 For example, PLAIN (over TLS) is quite useful when interacting
2891 with legacy authentication subsystems. (Source: Kurt Zeilenga)
2895 For -07 draft I've generalized the SASL profile in section 3.3 to
2896 allow any SASL mechanism.
2900 H.33 Clarification on use of password protection based on AuthZID form
2902 Section 3.3.1: "If an authorization identity of a form different
2903 from a DN is requested by the client, a mechanism that protects the
2904 password in transit SHOULD be used." What has that to do with DNs?
2905 A mechanism that protects the password in transit should be used in
2906 any case, shouldn't it?
2910 In -08 draft this text was removed. There is already a general
2911 security consideration that covers this issue.
2914 H.34 Clarification on use of matching rules in Server Identity Check
2916 The text in section 4.1.6 isn't explicit on whether all rules apply
2917 to both CN and dNSName values. The text should be clear as to which
2918 rules apply to which values.... in particular, the wildcard
2919 rules. (Source: Kurt Zeilenga)
2922 H.35 Requested Additions to Security Considerations
2924 Requested to mention hostile servers which the user might have been
2925 fooled to into contacting. Which mechanisms that are standardized by
2926 the LDAP standard do/do not disclose the user's password to the
2927 server? (Or to servers doing man-in-the-middle attack? Or is that a
2930 Requested to mention denial of service attacks.
2932 Requested list of methods that need/don't need the server to know
2933 the user's plaintext password. (I say 'know' instead of 'store'
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2938 Internet-Draft LDAP Authentication Methods 5 December 2003
2940 because it could still store the password encrypted, but in a way
2941 which it knows how to decrypt.)
2943 (Source: Hallvard Furuseth)
2945 H.36 Add reference to definition of DIGEST-MD5
2947 Need a reference to the definition of DIGEST-MD5 SASL mechanism in
2948 section 7.2 (Source: Hallvard Furuseth)
2950 Status: Resolved. A reference to to the DIGEST-MD5 SASL mechanism,
2951 [DigestAuth], is included in the -07 revision.
2953 H.37 Clarification on procedure for certificate-based authentication
2956 8.1. Certificate-based authentication with TLS states: "Following
2957 the successful completion of TLS negotiation, the client will send
2958 an LDAP bind request with the SASL "EXTERNAL" mechanism." Is this
2959 immediately following, or just some time later? Should the wording,
2960 "the client will send..." actually read, "the client MUST send..."?
2962 Status: Resolved. In -10 this text has been absorbed into the SASL
2963 EXTERNAL mechanism section.
2965 H.38 Effect of Start TLS on authentication state
2967 Should the server drop all knowledge of connection, i.e. return to
2968 anonymous state, if it gets a Start TLS request on a connection that
2969 has successfully bound using the simple method?
2971 Status: Resolved. In -09 the effect on an LDAP association by a
2972 Start TLS operation is made a matter of local policy. This is based
2973 on editorÆs perception of WG consensus gaged by conversations at
2974 IETF 58 and subsequent discussion on the WG mail list.
2976 H.39 Be sure that there is a consideration in [SCHEMA] that discusses
2977 multiple password values in userPassword
2979 Allowing multiple values obviously does raise a number of security
2980 considerations and these need to be discussed in the document.
2982 Certainly applications which intend to replace the userPassword with
2983 new value(s) should use modify/replaceValues (or
2984 modify/deleteAttribute+addAttribute). Additionally, server
2985 implementations should be encouraged to provide administrative
2986 controls which, if enabled, restrict userPassword to one value.
2988 H.40. Clarify need to verify mapping between authentication identity
2989 and resulting authorization identity on implicit assertion of AuthZID.
2991 4.2.2.3. Error Conditions
2993 "For either form of assertion, the server MUST verify that the
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2997 Internet-Draft LDAP Authentication Methods 5 December 2003
2999 client's authentication identity as supplied in its TLS credentials
3000 is permitted to be mapped to the asserted authorization identity."
3002 This makes sense for the explicit assertion case, but seems to be
3003 ambiguous for the implicit case.
3004 IMHO, the mapping can be done as two steps:
3005 a). deriving LDAP authentication identity from TLS credentials; If t
3006 this steps fails, EXTERNAL mechanism returns failure.
3007 b). verify that the authorization identity is allowed for the
3008 derived authentication identity. This is always "noop" for the
3010 I am not sure that the text is saying this.
3011 (Source: Alexey Melnikov email 8/1/2003 5:30:43 PM)
3013 Status: Resolved in -07. After reading the comments and the text of
3014 the draft, I believe that this should be clarified. The local policy
3015 used to map the AuthNID to the AuthZID in the implicit case is
3016 sufficient and that no additional verification is useful or needed.
3017 This text has been moved to apply only to the explicit assertion
3020 H.41. Section 7.2 contains unnecessary and misleading detail.
3022 " I am not sure why this section is required in the document.
3023 DIGEST-MD5 is defined in a separate document and there should be
3024 nothing magical about its usage in LDAP. If DIGEST-MD5 description
3025 creates confusion for LDAP implementors, let's fix the DIGEST-MD5
3026 document! Also, this section tries to redefine DIGEST-MD5 behavior,
3027 which is explicitly prohibited by the SASL specification."
3028 (Source: Alexey Melnikov: email 8/1/2003 5:30:43 PM)
3032 After reading the comments and the text of the draft plus the
3033 related text in draft-ietf-sasl-rfc2831bis-02.txt plus
3034 http://www.ietf.org/internet-drafts/draft-ietf-sasl-rfc2222bis-
3035 02.txt, I am inclined to agree with Alexey. In -07 I rewrote section
3036 3.3 (SASL mechanisms) to match the profiling requirements
3037 rfc2831bis. I then dramatically reduced the material in section 7.2
3038 to a bare minimum and let the SASL profile stand on its own.
3040 H.42. Does change for H.41 cause interoperability issue?
3042 There is one issue with the way the authmeth draft is currently
3043 written that changes the SASL DIGEST-MD5 behavior on the way the
3044 server responds with the subsequent authentication information .
3045 This has been documented in this fashion since RFC 2829 (section
3046 6.1) was originally published and may cause an interoperability
3047 issue at this point if it changed to follow the DIGEST-MD5 spec (as
3048 it was in -07 of AuthMeth). Take this issue to the list.
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3058 (10/08/03) This item was discussed on the WG list between 5/2/03 and
3059 5/9/03. Consensus apppears to support the notion that RFC 2829 was
3060 in error and that the semantics of RFC 2831 are correct and should
3061 be reflected in authmeth. This is already the case as of the -07
3064 H.43. DIGEST-MD5 Realms recommendations for LDAP
3066 From http://www.ietf.org/internet-drafts/draft-ietf-sasl-rfc2222bis-
3067 02.txt: A protocol profile SHOULD provide a guidance how realms are
3068 to be constructed and used in the protocol and MAY further restrict
3069 its syntax and protocol-specific semantics."
3071 I don't believe that any such guidance exists within the LDAP TS.
3072 The most likely place for this to reside is in the authmeth draft.
3074 Related email from Alexey Melnikov (8/4/2003 1:08:40 PM):
3076 "The problem I have with the document is that it references realm
3077 without explaining what it is (or at least some examples of valid
3078 values). For LDAP, some recommendations should be given. For
3080 1). Use a hardcoded string as the realm (one of the implementations
3081 I worked on was doing that)
3082 2). Use hostname (realm==host) or domain/cluster name (realm
3083 includes multiple hosts).
3084 3). Use a node in DIT above user entry, for example for "cn=Barbara
3085 Jensen, ou=Accounting, o=Ace Industry, c=US"
3086 and "cn=John Doe, ou=Accounting, o=Ace Industry, c=US" realm can be
3087 "ou=Accounting, o=Ace Industry, c=US"
3088 (or "o=Ace Industry, c=US"); for "cn=Gern Jensen, ou=Product
3089 Testing,o=Ace Industry, c=US" realm can be "ou=Product Testing,
3090 o=Ace Industry, c=US".
3092 Of course other choices are possible.
3096 To summarize: I'd like authmeth to define a realm name for use with
3097 Digest-MD5 that corresponds to LDAP DNs known to this server.
3098 Authzid is okay, but perhaps could be better put into context.
3101 John McMeeking (5/12/2003)
3105 draft-ietf-sasl-rfc2222bis-03.txt no longer requires this
3106 information in a SASL protocol. In addition, the ldapbis WG chairs
3107 have ruled this work out of scope. Individuals are welcome to make
3108 submissions to provide guidance on the use of realm and realm values
3111 H.44. Use of DNs in usernames and realms in DIGEST-MD5
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3118 In reading the discussion on the mailing list, I reach the following
3121 DIGEST-MD5 username and realm are simple strings. The syntax of
3122 these strings allows strings that look like DNs in form, however,
3123 DIGEST-MD5 treats them a simple strings for comparision purposes.
3124 For example, the DNs cn=roger, o=US and cn=roger,o=us are equivalent
3125 when being compared semantically as DNs, however, these would be
3126 considered two different username values in DIGEST-MD5 because
3127 simple octet-wise semantics (rather than DN semantics) are used to
3128 compare username values in DIGEST-MD5. Ditto for realm values.
3132 In -07 revision I added notes to implementors expressing this issue
3135 H.45: Open Issue: Is Simple+TLS mandatory to implement?
3137 Going forward, it would be much better to clarify that simple
3138 +TLS is to be used for DN/password credentials and DIGEST-MD5
3139 (or PLAIN+TLS) be used for username/password credentials. (Kurt
3140 Zeilenga, 5/12/2003)
3142 I don't believe you can mandate simple/TLS! At the time RFC 2829 was
3143 debated, a large number on the WG wanted this. They did not get
3144 their way because of the complexity of the solution. It was argued
3145 that a password-based method would be better. I think they believed
3146 it would still be DN/password, though. (Ron Ramsay, 5/12/2003)
3148 This was officially opened as an issue by WG co-chair Kurt Zeilenga
3149 on 5/12/03. Little direct discussion has occurred since, however
3150 there has been significant discussion on the use of DN values as the
3151 username for DIGEST-MD5.
3155 Based on WG list discussion, Kurt Zeilenga has gaged a lack of WG
3156 consensus that Simple+TLS should be mandatory to implement. No
3157 further discussion is necessary.
3160 Intellectual Property Rights
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3169 standards-related documentation can be found in BCP-11. Copies of
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3172 Harrison Expires July 2004 [Page 54]
3174 Internet-Draft LDAP Authentication Methods 5 December 2003
3176 of licenses to be made available, or the result of an attempt made
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3231 Harrison Expires July 2004 [Page 55]