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rfc:rfc2829

Network Working Group M. Wahl Request for Comments: 2829 Sun Microsystems, Inc. Category: Standards Track H. Alvestrand

                                                           EDB Maxware
                                                             J. Hodges
                                                           Oblix, Inc.
                                                             R. Morgan
                                              University of Washington
                                                              May 2000
                  Authentication Methods for LDAP

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

 This document specifies particular combinations of security
 mechanisms which are required and recommended in LDAP [1]
 implementations.

1. Introduction

 LDAP version 3 is a powerful access protocol for directories.
 It offers means of searching, fetching and manipulating directory
 content, and ways to access a rich set of security functions.
 In order to function for the best of the Internet, it is vital that
 these security functions be interoperable; therefore there has to be
 a minimum subset of security functions that is common to all
 implementations that claim LDAPv3 conformance.
 Basic threats to an LDAP directory service include:
    (1)   Unauthorized access to data via data-fetching operations,

Wahl, et al. Standards Track [Page 1] RFC 2829 Authentication Methods for LDAP May 2000

    (2)   Unauthorized access to reusable client authentication
          information by monitoring others' access,
    (3)   Unauthorized access to data by monitoring others' access,
    (4)   Unauthorized modification of data,
    (5)   Unauthorized modification of configuration,
    (6)   Unauthorized or excessive use of resources (denial of
          service), and
    (7)   Spoofing of directory: Tricking a client into believing that
          information came from the directory when in fact it did not,
          either by modifying data in transit or misdirecting the
          client's connection.
 Threats (1), (4), (5) and (6) are due to hostile clients.  Threats
 (2), (3) and (7) are due to hostile agents on the path between client
 and server, or posing as a server.
 The LDAP protocol suite can be protected with the following security
 mechanisms:
    (1)   Client authentication by means of the SASL [2] mechanism
          set, possibly backed by the TLS credentials exchange
          mechanism,
    (2)   Client authorization by means of access control based on the
          requestor's authenticated identity,
    (3)   Data integrity protection by means of the TLS protocol or
          data-integrity SASL mechanisms,
    (4)   Protection against snooping by means of the TLS protocol or
          data-encrypting SASL mechanisms,
    (5)   Resource limitation by means of administrative limits on
          service controls, and
    (6)   Server authentication by means of the TLS protocol or SASL
          mechanism.
 At the moment, imposition of access controls is done by means outside
 the scope of the LDAP protocol.
 In this document, the term "user" represents any application which is
 an LDAP client using the directory to retrieve or store information.

Wahl, et al. Standards Track [Page 2] RFC 2829 Authentication Methods for LDAP May 2000

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [3].

2. Example deployment scenarios

 The following scenarios are typical for LDAP directories on the
 Internet, and have different security requirements. (In the
 following, "sensitive" means data that will cause real damage to the
 owner if revealed; there may be data that is protected but not
 sensitive).  This is not intended to be a comprehensive list, other
 scenarios are possible, especially on physically protected networks.
    (1)   A read-only directory, containing no sensitive data,
          accessible to "anyone", and TCP connection hijacking or IP
          spoofing is not a problem.  This directory requires no
          security functions except administrative service limits.
    (2)   A read-only directory containing no sensitive data; read
          access is granted based on identity.  TCP connection
          hijacking is not currently a problem. This scenario requires
          a secure authentication function.
    (3)   A read-only directory containing no sensitive data; and the
          client needs to ensure that the directory data is
          authenticated by the server and not modified while being
          returned from the server.
    (4)   A read-write directory, containing no sensitive data; read
          access is available to "anyone", update access to properly
          authorized persons.  TCP connection hijacking is not
          currently a problem.  This scenario requires a secure
          authentication function.
    (5)   A directory containing sensitive data.  This scenario
          requires session confidentiality protection AND secure
          authentication.

3. Authentication and Authorization: Definitions and Concepts

 This section defines basic terms, concepts, and interrelationships
 regarding authentication, authorization, credentials, and identity.
 These concepts are used in describing how various security approaches
 are utilized in client authentication and authorization.

Wahl, et al. Standards Track [Page 3] RFC 2829 Authentication Methods for LDAP May 2000

3.1. Access Control Policy

 An access control policy is a set of rules defining the protection of
 resources, generally in terms of the capabilities of persons or other
 entities accessing those resources.  A common expression of an access
 control policy is an access control list.  Security objects and
 mechanisms, such as those described here, enable the expression of
 access control policies and their enforcement.  Access control
 policies are typically expressed in terms of access control
 attributes as described below.

3.2. Access Control Factors

 A request, when it is being processed by a server, may be associated
 with a wide variety of security-related factors (section 4.2 of [1]).
 The server uses these factors to determine whether and how to process
 the request.  These are called access control factors (ACFs).  They
 might include source IP address, encryption strength, the type of
 operation being requested, time of day, etc.  Some factors may be
 specific to the request itself, others may be associated with the
 connection via which the request is transmitted, others (e.g. time of
 day) may be "environmental".
 Access control policies are expressed in terms of access control
 factors.  E.g., a request having ACFs i,j,k can perform operation Y
 on resource Z. The set of ACFs that a server makes available for such
 expressions is implementation-specific.

3.3. Authentication, Credentials, Identity

 Authentication credentials are the evidence supplied by one party to
 another, asserting the identity of the supplying party (e.g. a user)
 who is attempting to establish an association with the other party
 (typically a server).  Authentication is the process of generating,
 transmitting, and verifying these credentials and thus the identity
 they assert.  An authentication identity is the name presented in a
 credential.
 There are many forms of authentication credentials -- the form used
 depends upon the particular authentication mechanism negotiated by
 the parties.  For example: X.509 certificates, Kerberos tickets,
 simple identity and password pairs.  Note that an authentication
 mechanism may constrain the form of authentication identities used
 with it.

Wahl, et al. Standards Track [Page 4] RFC 2829 Authentication Methods for LDAP May 2000

3.4. Authorization Identity

 An authorization identity is one kind of access control factor.  It
 is the name of the user or other entity that requests that operations
 be performed.  Access control policies are often expressed in terms
 of authorization identities; e.g., entity X can perform operation Y
 on resource Z.
 The authorization identity bound to an association is often exactly
 the same as the authentication identity presented by the client, but
 it may be different.  SASL allows clients to specify an authorization
 identity distinct from the authentication identity asserted by the
 client's credentials.  This permits agents such as proxy servers to
 authenticate using their own credentials, yet request the access
 privileges of the identity for which they are proxying [2].  Also,
 the form of authentication identity supplied by a service like TLS
 may not correspond to the authorization identities used to express a
 server's access control  policy, requiring a server-specific mapping
 to be done.  The method by which a server composes and validates an
 authorization identity from the authentication credentials supplied
 by a client is implementation-specific.

4. Required security mechanisms

 It is clear that allowing any implementation, faced with the above
 requirements, to pick and choose among the possible alternatives is
 not a strategy that is likely to lead to interoperability. In the
 absence of mandates, clients will be written that do not support any
 security function supported by the server, or worse, support only
 mechanisms like cleartext passwords that provide clearly inadequate
 security.
 Active intermediary attacks are the most difficult for an attacker to
 perform, and for an implementation to protect against.  Methods that
 protect only against hostile client and passive eavesdropping attacks
 are useful in situations where the cost of protection against active
 intermediary attacks is not justified based on the perceived risk of
 active intermediary attacks.
 Given the presence of the Directory, there is a strong desire to see
 mechanisms where identities take the form of a Distinguished Name and
 authentication data can be stored in the directory; this means that
 either this data is useless for faking authentication (like the Unix
 "/etc/passwd" file format used to be), or its content is never passed
 across the wire unprotected - that is, it's either updated outside
 the protocol or it is only updated in sessions well protected against
 snooping.  It is also desirable to allow authentication methods to

Wahl, et al. Standards Track [Page 5] RFC 2829 Authentication Methods for LDAP May 2000

 carry authorization identities based on existing forms of user
 identities for backwards compatibility with non-LDAP-based
 authentication services.
 Therefore, the following implementation conformance requirements are
 in place:
    (1)   For a read-only, public directory, anonymous authentication,
          described in section 5, can be used.
    (2)   Implementations providing password-based authenticated
          access MUST support authentication using the DIGEST-MD5 SASL
          mechanism [4], as described in section 6.1.  This provides
          client authentication with protection against passive
          eavesdropping attacks, but does not provide protection
          against active intermediary attacks.
    (3)   For a directory needing session protection and
          authentication, the Start TLS extended operation [5], and
          either the simple authentication choice or the SASL EXTERNAL
          mechanism, are to be used together.  Implementations SHOULD
          support authentication with a password as described in
          section 6.2, and SHOULD support authentication with a
          certificate as described in section 7.1.  Together, these
          can provide integrity and disclosure protection of
          transmitted data, and authentication of client and server,
          including protection against active intermediary attacks.
 If TLS is negotiated, the client MUST discard all information about
 the server fetched prior to the TLS negotiation.  In particular, the
 value of supportedSASLMechanisms MAY be different after TLS has been
 negotiated (specifically, the EXTERNAL mechanism or the proposed
 PLAIN mechanism are likely to only be listed after a TLS negotiation
 has been performed).
 If a SASL security layer is negotiated, the client MUST discard all
 information about the server fetched prior to SASL.  In particular,
 if the client is configured to support multiple SASL mechanisms, it
 SHOULD fetch supportedSASLMechanisms both before and after the SASL
 security layer is negotiated and verify that the value has not
 changed after the SASL security layer was negotiated.  This detects
 active attacks which remove supported SASL mechanisms from the
 supportedSASLMechanisms list, and allows the client to ensure that it
 is using the best mechanism supported by both client and server
 (additionally, this is a SHOULD to allow for environments where the
 supported SASL mechanisms list is provided to the client through a
 different trusted source, e.g. as part of a digitally signed object).

Wahl, et al. Standards Track [Page 6] RFC 2829 Authentication Methods for LDAP May 2000

5. Anonymous authentication

 Directory operations which modify entries or access protected
 attributes or entries generally require client authentication.
 Clients which do not intend to perform any of these operations
 typically use anonymous authentication.
 LDAP implementations MUST support anonymous authentication, as
 defined in section 5.1.
 LDAP implementations MAY support anonymous authentication with TLS,
 as defined in section 5.2.
 While there MAY be access control restrictions to prevent access to
 directory entries, an LDAP server SHOULD allow an anonymously-bound
 client to retrieve the supportedSASLMechanisms attribute of the root
 DSE.
 An LDAP server MAY use other information about the client provided by
 the lower layers or external means to grant or deny access even to
 anonymously authenticated clients.

5.1. Anonymous authentication procedure

 An LDAP client which has not successfully completed a bind operation
 on a connection is anonymously authenticated.
 An LDAP client MAY also specify anonymous authentication in a bind
 request by using a zero-length OCTET STRING with the simple
 authentication choice.

5.2. Anonymous authentication and TLS

 An LDAP client MAY use the Start TLS operation [5] to negotiate the
 use of TLS security [6].  If the client has not bound beforehand,
 then until the client uses the EXTERNAL SASL mechanism to negotiate
 the recognition of the client's certificate, the client is
 anonymously authenticated.
 Recommendations on TLS ciphersuites are given in section 10.
 An LDAP server which requests that clients provide their certificate
 during TLS negotiation MAY use a local security policy to determine
 whether to successfully complete TLS negotiation if the client did
 not present a certificate which could be validated.

Wahl, et al. Standards Track [Page 7] RFC 2829 Authentication Methods for LDAP May 2000

6. Password-based authentication

 LDAP implementations MUST support authentication with a password
 using the DIGEST-MD5 SASL mechanism for password protection, as
 defined in section 6.1.
 LDAP implementations SHOULD support authentication with the "simple"
 password choice when the connection is protected against
 eavesdropping using TLS, as defined in section 6.2.

6.1. Digest authentication

 An LDAP client MAY determine whether the server supports this
 mechanism by performing a search request on the root DSE, requesting
 the supportedSASLMechanisms attribute, and checking whether the
 string "DIGEST-MD5" is present as a value of this attribute.
 In the first stage of authentication, when the client is performing
 an "initial authentication" as defined in section 2.1 of [4], the
 client sends a bind request in which the version number is 3, the
 authentication choice is sasl, the sasl mechanism name is "DIGEST-
 MD5", and the credentials are absent.  The client then waits for a
 response from the server to this request.
 The server will respond with a bind response in which the resultCode
 is saslBindInProgress, and the serverSaslCreds field is present.  The
 contents of this field is a string defined by "digest-challenge" in
 section 2.1.1 of [4].  The server SHOULD include a realm indication
 and MUST indicate support for UTF-8.
 The client will send a bind request with a distinct message id, in
 which the version number is 3, the authentication choice is sasl, the
 sasl mechanism name is "DIGEST-MD5", and the credentials contain the
 string defined by "digest-response" in section 2.1.2 of [4].  The
 serv-type is "ldap".
 The server will respond with a bind response in which the resultCode
 is either success, or an error indication.  If the authentication is
 successful and the server does not support subsequent authentication,
 then the credentials field is absent.  If the authentication is
 successful and the server supports subsequent authentication, then
 the credentials field contains the string defined by "response-auth"
 in section 2.1.3 of [4].   Support for subsequent authentication is
 OPTIONAL in clients and servers.

Wahl, et al. Standards Track [Page 8] RFC 2829 Authentication Methods for LDAP May 2000

6.2. "simple" authentication choice under TLS encryption

 A user who has a directory entry containing a userPassword attribute
 MAY authenticate to the directory by performing a simple password
 bind sequence following the negotiation of a TLS ciphersuite
 providing connection confidentiality [6].
 The client will use the Start TLS operation [5] to negotiate the use
 of TLS security [6] on the connection to the LDAP server.  The client
 need not have bound to the directory beforehand.
 For this authentication procedure to be successful, the client and
 server MUST negotiate a ciphersuite which contains a bulk encryption
 algorithm of appropriate strength.  Recommendations on cipher suites
 are given in section 10.
 Following the successful completion of TLS negotiation, the client
 MUST send an LDAP bind request with the version number of 3, the name
 field containing the name of the user's entry, and the "simple"
 authentication choice, containing a password.
 The server will, for each value of the userPassword attribute in the
 named user's entry, compare these for case-sensitive equality with
 the client's presented password.  If there is a match, then the
 server will respond with resultCode success, otherwise the server
 will respond with resultCode invalidCredentials.

6.3. Other authentication choices with TLS

 It is also possible, following the negotiation of TLS, to perform a
 SASL authentication which does not involve the exchange of plaintext
 reusable passwords.  In this case the client and server need not
 negotiate a ciphersuite which provides confidentiality if the only
 service required is data integrity.

7. Certificate-based authentication

 LDAP implementations SHOULD support authentication via a client
 certificate in TLS, as defined in section 7.1.

7.1. Certificate-based authentication with TLS

 A user who has a public/private key pair in which the public key has
 been signed by a Certification Authority may use this key pair to
 authenticate to the directory server if the user's certificate is
 requested by the server.  The user's certificate subject field SHOULD
 be the name of the user's directory entry, and the Certification
 Authority must be sufficiently trusted by the directory server to

Wahl, et al. Standards Track [Page 9] RFC 2829 Authentication Methods for LDAP May 2000

 have issued the certificate in order that the server can process the
 certificate.  The means by which servers validate certificate paths
 is outside the scope of this document.
 A server MAY support mappings for certificates in which the subject
 field name is different from the name of the user's directory entry.
 A server which supports mappings of names MUST be capable of being
 configured to support certificates for which no mapping is required.
 The client will use the Start TLS operation [5] to negotiate the use
 of TLS security [6] on the connection to the LDAP server.  The client
 need not have bound to the directory beforehand.
 In the TLS negotiation, the server MUST request a certificate.  The
 client will provide its certificate to the server, and MUST perform a
 private key-based encryption, proving it has the private key
 associated with the certificate.
 As deployments will require protection of sensitive data in transit,
 the client and server MUST negotiate a ciphersuite which contains a
 bulk encryption algorithm of appropriate strength.  Recommendations
 of cipher suites are given in section 10.
 The server MUST verify that the client's certificate is valid. The
 server will normally check that the certificate is issued by a known
 CA, and that none of the certificates on the client's certificate
 chain are invalid or revoked.  There are several procedures by which
 the server can perform these checks.
 Following the successful completion of TLS negotiation, the client
 will send an LDAP bind request with the SASL "EXTERNAL" mechanism.

8. Other mechanisms

 The LDAP "simple" authentication choice is not suitable for
 authentication on the Internet where there is no network or transport
 layer confidentiality.
 As LDAP includes native anonymous and plaintext authentication
 methods, the "ANONYMOUS" and "PLAIN" SASL mechanisms are not used
 with LDAP.  If an authorization identity of a form different from a
 DN is requested by the client, a mechanism that protects the password
 in transit SHOULD be used.
 The following SASL-based mechanisms are not considered in this
 document: KERBEROS_V4, GSSAPI and SKEY.

Wahl, et al. Standards Track [Page 10] RFC 2829 Authentication Methods for LDAP May 2000

 The "EXTERNAL" SASL mechanism can be used to request the LDAP server
 make use of security credentials exchanged by a lower layer. If a TLS
 session has not been established between the client and server prior
 to making the SASL EXTERNAL Bind request and there is no other
 external source of authentication credentials (e.g.  IP-level
 security [8]), or if, during the process of establishing the TLS
 session, the server did not request the client's authentication
 credentials, the SASL EXTERNAL bind MUST fail with a result code of
 inappropriateAuthentication.  Any client authentication and
 authorization state of the LDAP association is lost, so the LDAP
 association is in an anonymous state after the failure.

9. Authorization Identity

 The authorization identity is carried as part of the SASL credentials
 field in the LDAP Bind request and response.
 When the "EXTERNAL" mechanism is being negotiated, if the credentials
 field is present, it contains an authorization identity of the
 authzId form described below.
 Other mechanisms define the location of the authorization identity in
 the credentials field.
 The authorization identity is a string in the UTF-8 character set,
 corresponding to the following ABNF [7]:
 ; Specific predefined authorization (authz) id schemes are
 ; defined below -- new schemes may be defined in the future.
 authzId    = dnAuthzId / uAuthzId
 ; distinguished-name-based authz id.
 dnAuthzId  = "dn:" dn
 dn         = utf8string    ; with syntax defined in RFC 2253
 ; unspecified userid, UTF-8 encoded.
 uAuthzId   = "u:" userid
 userid     = utf8string    ; syntax unspecified
 A utf8string is defined to be the UTF-8 encoding of one or more ISO
 10646 characters.
 All servers which support the storage of authentication credentials,
 such as passwords or certificates, in the directory MUST support the
 dnAuthzId choice.

Wahl, et al. Standards Track [Page 11] RFC 2829 Authentication Methods for LDAP May 2000

 The uAuthzId choice allows for compatibility with client applications
 which wish to authenticate to a local directory but do not know their
 own Distinguished Name or have a directory entry.  The format of the
 string is defined as only a sequence of UTF-8 encoded ISO 10646
 characters, and further interpretation is subject to prior agreement
 between the client and server.
 For example, the userid could identify a user of a specific directory
 service, or be a login name or the local-part of an RFC 822 email
 address. In general a uAuthzId MUST NOT be assumed to be globally
 unique.
 Additional authorization identity schemes MAY be defined in future
 versions of this document.

10. TLS Ciphersuites

 The following ciphersuites defined in [6] MUST NOT be used for
 confidentiality protection of passwords or data:
       TLS_NULL_WITH_NULL_NULL
       TLS_RSA_WITH_NULL_MD5
       TLS_RSA_WITH_NULL_SHA
 The following ciphersuites defined in [6] can be cracked easily (less
 than a week of CPU time on a standard CPU in 1997).  The client and
 server SHOULD carefully consider the value of the password or data
 being protected before using these ciphersuites:
       TLS_RSA_EXPORT_WITH_RC4_40_MD5
       TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5
       TLS_RSA_EXPORT_WITH_DES40_CBC_SHA
       TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA
       TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA
       TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
       TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA
       TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
       TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
 The following ciphersuites are vulnerable to man-in-the-middle
 attacks, and SHOULD NOT be used to protect passwords or sensitive
 data, unless the network configuration is such that the danger of a
 man-in-the-middle attack is tolerable:

Wahl, et al. Standards Track [Page 12] RFC 2829 Authentication Methods for LDAP May 2000

       TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
       TLS_DH_anon_WITH_RC4_128_MD5
       TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
       TLS_DH_anon_WITH_DES_CBC_SHA
       TLS_DH_anon_WITH_3DES_EDE_CBC_SHA
 A client or server that supports TLS MUST support at least
 TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA.

11. SASL service name for LDAP

 For use with SASL [2], a protocol must specify a service name to be
 used with various SASL mechanisms, such as GSSAPI.  For LDAP, the
 service name is "ldap", which has been registered with the IANA as a
 GSSAPI service name.

12. Security Considerations

 Security issues are discussed throughout this memo; the
 (unsurprising) conclusion is that mandatory security is important,
 and that session encryption is required when snooping is a problem.
 Servers are encouraged to prevent modifications by anonymous users.
 Servers may also wish to minimize denial of service attacks by timing
 out idle connections, and returning the unwillingToPerform result
 code rather than performing computationally expensive operations
 requested by unauthorized clients.
 A connection on which the client has not performed the Start TLS
 operation or negotiated a suitable SASL mechanism for connection
 integrity and encryption services is subject to man-in-the-middle
 attacks to view and modify information in transit.
 Additional security considerations relating to the EXTERNAL mechanism
 to negotiate TLS can be found in [2], [5] and [6].

13. Acknowledgements

 This document is a product of the LDAPEXT Working Group of the IETF.
 The contributions of its members is greatly appreciated.

Wahl, et al. Standards Track [Page 13] RFC 2829 Authentication Methods for LDAP May 2000

14. Bibliography

 [1] Wahl, M., Howes, T. and S. Kille, "Lightweight Directory Access
     Protocol (v3)", RFC 2251, December 1997.
 [2] Myers, J., "Simple Authentication and Security Layer (SASL)", RFC
     2222, October 1997.
 [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
     Levels", BCP 14, RFC 2119, March 1997.
 [4] Leach, P. and C. Newman, "Using Digest Authentication as a SASL
     Mechanism", RFC 2831, May 2000.
 [5] Hodges, J., Morgan, R. and M. Wahl, "Lightweight Directory Access
     Protocol (v3): Extension for Transport Layer Security", RFC 2830,
     May 2000.
 [6] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC
     2246, January 1999.
 [7] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
     Specifications: ABNF", RFC 2234, November 1997.
 [8] Kent, S. and R. Atkinson, "Security Architecture for the Internet
     Protocol", RFC 2401, November 1998.

Wahl, et al. Standards Track [Page 14] RFC 2829 Authentication Methods for LDAP May 2000

15. Authors' Addresses

 Mark Wahl
 Sun Microsystems, Inc.
 8911 Capital of Texas Hwy #4140
 Austin TX 78759
 USA
 EMail: M.Wahl@innosoft.com
 Harald Tveit Alvestrand
 EDB Maxware
 Pirsenteret
 N-7462 Trondheim, Norway
 Phone: +47 73 54 57 97
 EMail: Harald@Alvestrand.no
 Jeff Hodges
 Oblix, Inc.
 18922 Forge Drive
 Cupertino, CA 95014
 USA
 Phone: +1-408-861-6656
 EMail: JHodges@oblix.com
 RL "Bob" Morgan
 Computing and Communications
 University of Washington
 Seattle, WA 98105
 USA
 Phone: +1-206-221-3307
 EMail: rlmorgan@washington.edu

Wahl, et al. Standards Track [Page 15] RFC 2829 Authentication Methods for LDAP May 2000

16. Full Copyright Statement

 Copyright (C) The Internet Society (2000).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

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

Wahl, et al. Standards Track [Page 16]

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