draft-ietf-ldapbis-authmeth-02.txt   draft-ietf-ldapbis-authmeth-03.txt 
Individual Submission R. Harrison, Editor Individual Submission R. Harrison, Editor
Internet Draft Novell, Inc. Internet Draft Novell, Inc.
Document: draft-ietf-ldapbis-authmeth-02.txt November 14, 2001 Document: draft-ietf-ldapbis-authmeth-03.txt March 1, 2002
Intended Category: Draft Standard Intended Category: Draft Standard
Obsoletes: RFC 2829, RFC 2830
Authentication Methods LDAP: Authentication Methods
and and
Connection Level Security Mechanisms Connection Level Security Mechanisms
for LDAPv3
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
This document is intended to be, after appropriate review and This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor as a Standard Track document. revision, submitted to the RFC Editor as a Standard Track document.
Distribution of this memo is unlimited. Technical discussion of Distribution of this memo is unlimited. Technical discussion of
this document will take place on the IETF LDAP Extension Working this document will take place on the IETF LDAP Extension Working
skipping to change at page 2, line 5 skipping to change at page 1, line 51
This document describes LDAPv3 authentication methods and connection This document describes LDAPv3 authentication methods and connection
level security mechanisms that are required of all conforming LDAPv3 level security mechanisms that are required of all conforming LDAPv3
server implementations and makes recommendations for combinations of server implementations and makes recommendations for combinations of
these mechanisms to be used in various deployment circumstances. these mechanisms to be used in various deployment circumstances.
Among the mechanisms described are Among the mechanisms described are
- the LDAPv3 Bind operation used for authenticating LDAP clients - the LDAPv3 Bind operation used for authenticating LDAP clients
to LDAP servers. to LDAP servers.
Authentication Methods for LDAPv3 Nov. 14, 2001
- the Start TLS operation used to initiate Transport Layer - the Start TLS operation used to initiate Transport Layer
Security on an established connection between an LDAP client and Security on an established connection between an LDAP client and
server. server.
Authentication Methods for LDAPv3 Mar. 1, 2002
- various forms of authentication including anonymous - various forms of authentication including anonymous
authentication, password-based authentication, and certificate authentication, password-based authentication, and certificate
based authentication. based authentication.
1. Conventions Used in this Document 1. Conventions Used in this Document
1.1. Glossary of Terms 1.1. Glossary of Terms
The following terms are used in this document. To aid the reader, The following terms are used in this document. To aid the reader,
these terms are defined here. these terms are defined here.
skipping to change at page 2, line 49 skipping to change at page 2, line 45
1.3. Keywords 1.3. Keywords
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 document are to be interpreted as described in RFC 2119
[ReqsKeywords]. [ReqsKeywords].
2. Introduction 2. Introduction
This document is an integral part of the LDAP Technical
Specification [ROADMAP]. This document replaces RFC 2829 and RFC
2830. Changes to RFC 2829 are summarized in Appendix C and changes
to RFC 2830 are summared in Appendix D.
LDAPv3 is a powerful access protocol for directories. It offers LDAPv3 is a powerful access protocol for directories. It offers
means of searching, fetching and manipulating directory content, and means of searching, fetching and manipulating directory content, and
ways to access a rich set of security functions. ways to access a rich set of security functions.
It is vital that these security functions be interoperable among all It is vital that these security functions be interoperable among all
LDAP clients and servers on the Internet; therefore there has to be LDAP clients and servers on the Internet; therefore there has to be
a minimum subset of security functions that is common to all a minimum subset of security functions that is common to all
implementations that claim LDAPv3 conformance. implementations that claim LDAPv3 conformance.
Basic threats to an LDAP directory service include: Authentication Methods for LDAPv3 Mar. 1, 2002
Authentication Methods for LDAPv3 Nov. 14, 2001 Basic threats to an LDAP directory service include:
(1) Unauthorized access to directory data via data-fetching (1) Unauthorized access to directory data via data-fetching
operations, operations,
(2) Unauthorized access to reusable client authentication (2) Unauthorized access to reusable client authentication
information by monitoring others' access, information by monitoring others' access,
(3) Unauthorized access to directory data by monitoring others' (3) Unauthorized access to directory data by monitoring others'
access, access,
skipping to change at page 4, line 4 skipping to change at page 4, line 4
(5) Server resource usage limitation by means of administrative (5) Server resource usage limitation by means of administrative
service limits configured on the server, and service limits configured on the server, and
(6) Server authentication by means of the TLS protocol or SASL (6) Server authentication by means of the TLS protocol or SASL
mechanism. mechanism.
At the moment, imposition of access controls is done by means At the moment, imposition of access controls is done by means
outside the scope of the LDAP protocol. outside the scope of the LDAP protocol.
3. Required Security Mechanisms 3. Required Security Mechanisms
Authentication Methods for LDAPv3 Nov. 14, 2001 Authentication Methods for LDAPv3 Mar. 1, 2002
It is clear that allowing any implementation, faced with the above It is clear that allowing any implementation, faced with the above
requirements, to pick and choose among the possible alternatives is requirements, to pick and choose among the possible alternatives is
not a strategy that is likely to lead to interoperability. In the not a strategy that is likely to lead to interoperability. In the
absence of mandates, clients will be written that do not support any absence of mandates, clients will be written that do not support any
security function supported by the server, or worse, support only security function supported by the server, or worse, support only
mechanisms like cleartext passwords that provide clearly inadequate mechanisms like cleartext passwords that provide clearly inadequate
security. security.
Active intermediary attacks are the most difficult for an attacker Active intermediary attacks are the most difficult for an attacker
to perform, and for an implementation to protect against. Methods to perform, and for an implementation to protect against. Methods
that protect only against hostile client and passive eavesdropping that protect only against hostile client and passive eavesdropping
attacks are useful in situations where the cost of protection attacks are useful in situations where the cost of protection
against active intermediary attacks is not justified based on the against active intermediary attacks is not justified based on the
perceived risk of active intermediary attacks. perceived risk of active intermediary attacks.
Given the presence of the Directory, there is a strong desire to see Given the presence of the Directory, there is a strong desire to see
mechanisms where identities take the form of an LDAP distinguished mechanisms where identities take the form of an LDAP distinguished
name [LDAPDN] and authentication data can be stored in the name [LDAPDN] and authentication data can be stored in the
directory; this means that either this data is useless for faking directory. This means that this data must be updated outside the
authentication (like the Unix "/etc/passwd" file format used to be), protocol or only updated in sessions well protected against
or its content is never passed across the wire unprotected - that snooping. It is also desirable to allow authentication methods to
is, it's either updated outside the protocol or it is only updated carry authorization identities based on existing forms of user
in sessions well protected against snooping. It is also desirable to identities for backwards compatibility with non-LDAP-based
allow authentication methods to carry authorization identities based authentication services.
on existing forms of user identities for backwards compatibility
with non-LDAP-based authentication services.
Therefore, the following implementation conformance requirements are Therefore, the following implementation conformance requirements are
in place: in place:
(1) For a read-only, public directory, anonymous authentication, (1) For a read-only, public directory, anonymous authentication,
described in section 7, can be used. described in section 7, can be used.
(2) Implementations providing password-based authenticated access (2) Implementations providing password-based authenticated access
MUST support authentication using the DIGEST-MD5 SASL mechanism MUST support authentication using the DIGEST-MD5 SASL mechanism
[4], as described in section 8.2. This provides client [4], as described in section 8.2. This provides client
skipping to change at page 5, line 4 skipping to change at page 4, line 57
authentication choice or the SASL EXTERNAL mechanism, are to be authentication choice or the SASL EXTERNAL mechanism, are to be
used together. Implementations SHOULD support authentication used together. Implementations SHOULD support authentication
with a password as described in section 8.3, and SHOULD support with a password as described in section 8.3, and SHOULD support
authentication with a certificate as described in section 9.1. authentication with a certificate as described in section 9.1.
Together, these can provide integrity and disclosure protection Together, these can provide integrity and disclosure protection
of transmitted data, and authentication of client and server, of transmitted data, and authentication of client and server,
including protection against active intermediary attacks. including protection against active intermediary attacks.
If TLS is negotiated, the client MUST discard all information about If TLS is negotiated, the client MUST discard all information about
the server fetched prior to the initiation of the TLS negotiation. the server fetched prior to the initiation of the TLS negotiation.
Authentication Methods for LDAPv3 Nov. 14, 2001
In particular, the value of supportedSASLMechanisms MAY be different In particular, the value of supportedSASLMechanisms MAY be different
Authentication Methods for LDAPv3 Mar. 1, 2002
after TLS has been negotiated (specifically, the EXTERNAL mechanism after TLS has been negotiated (specifically, the EXTERNAL mechanism
or the proposed PLAIN mechanism are likely to only be listed after a or the proposed PLAIN mechanism are likely to only be listed after a
TLS negotiation has been performed). TLS negotiation has been performed).
If a SASL security layer is negotiated, the client MUST discard all If a SASL security layer is negotiated, the client MUST discard all
information about the server fetched prior to the initiation of the information about the server fetched prior to the initiation of the
SASL negotiation. If the client is configured to support multiple SASL negotiation. If the client is configured to support multiple
SASL mechanisms, it SHOULD fetch the supportedSASLmechanisms list SASL mechanisms, it SHOULD fetch the supportedSASLmechanisms list
both before and after the SASL security layer is negotiated. This both before and after the SASL security layer is negotiated. This
allows the client to detect active attacks that remove supported allows the client to detect active attacks that remove supported
skipping to change at page 5, line 31 skipping to change at page 5, line 29
environments where the supportedSASLMechanisms list is provided to environments where the supportedSASLMechanisms list is provided to
the client through a different trusted source, e.g. as part of a the client through a different trusted source, e.g. as part of a
digitally signed object.) digitally signed object.)
Appendix A contains example deployment scenarios that list the Appendix A contains example deployment scenarios that list the
mechanisms that might be used to achieve a reasonable level of mechanisms that might be used to achieve a reasonable level of
security in various circumstances. security in various circumstances.
4. Bind Operation 4. Bind Operation
The Bind operation allows authentication information to be exchanged The Bind operation defined in section 4.2 of [Protocol] allows
between the client and server. authentication information to be exchanged between the client and
server.
4.1. Bind Request
The Bind Request is defined in section 4.2 of [LDAPv3] as follows:
BindRequest ::= [APPLICATION 0] SEQUENCE {
version INTEGER (1 .. 127),
name LDAPDN,
authentication AuthenticationChoice }
AuthenticationChoice ::= CHOICE {
simple [0] OCTET STRING,
-- 1 and 2 reserved
sasl SaslCredentials }
SaslCredentials ::= SEQUENCE {
mechanism LDAPString,
credentials OCTET STRING OPTIONAL }
Parameters of the Bind Request are:
- version: A version number indicating the version of the protocol
to be used in this protocol session. This document describes
version 3 of the LDAP protocol. Note that there is no version
negotiation, and the client just sets this parameter to the
version it desires. If the client requests protocol version 2, a
Authentication Methods for LDAPv3 Nov. 14, 2001
server that supports the version 2 protocol as described in
[RFC1777] will not return any v3-specific protocol fields. (Note
that not all LDAP servers will support protocol version 2, since
they may be unable to generate the attribute syntaxes associated
with version 2.)
- name: The name of the directory object that the client wishes to
bind as. This field may take on a null value (a zero length
string) for the purposes of anonymous binds, when authentication
has been performed at a lower layer, or when using SASL
credentials with a mechanism that includes the name in the
credentials. Server behavior is undefined when the name is a
null value, simple authentication is used, and a password is
specified. Note that the server SHOULD NOT perform any alias
dereferencing in determining the object to bind as.
- authentication: information used to authenticate the name, if
any, provided in the Bind Request.
Upon receipt of a Bind Request, a protocol server will authenticate
the requesting client, if necessary. The server will then return a
Bind Response to the client indicating the status of the
authentication.
Authorization is the use of this authentication information when
performing operations. Authorization MAY be affected by factors
outside of the LDAP Bind request, such as lower layer security
services.
4.2. Bind Response
The Bind Response is defined in section 4.2 of [LDAPv3] as follows.
BindResponse ::= [APPLICATION 1] SEQUENCE {
COMPONENTS OF LDAPResult,
serverSaslCreds [ABNF] OCTET STRING OPTIONAL }
BindResponse consists simply of an indication from the server of the
status of the client's request for authentication.
If the bind was successful, the resultCode will be success.
Otherwise it will be one of:
- operationsError: server encountered an internal error.
- protocolError: unrecognized version number or incorrect PDU
structure.
- authMethodNotSupported: unrecognized SASL mechanism name.
- strongAuthRequired: the server requires authentication be
performed with a SASL mechanism.
Authentication Methods for LDAPv3 Nov. 14, 2001
- referral: this server cannot accept this bind and the client
should try another.
- saslBindInProgress: the server requires the client to send a new
bind request, with the same sasl mechanism, to continue the
authentication process.
- inappropriateAuthentication: the server requires the client
which had attempted to bind anonymously or without supplying
credentials to provide some form of credentials.
- invalidCredentials: the wrong password was supplied or the SASL
credentials could not be processed.
- unavailable: the server is shutting down.
If the server does not support the client's requested protocol
version it MUST set the resultCode to protocolError.
If the client receives a BindResponse response where the resultCode
was protocolError it MUST close the connection as the server will be
unwilling to accept further operations. (This is for compatibility
with earlier versions of LDAP, in which the bind was always the
first operation and there was no negotiation.)
The serverSaslCreds are used as part of a SASL-defined bind
mechanism to allow the client to authenticate the server to which it
is communicating, or to perform "challenge-response" authentication.
If the client bound with the password choice, or the SASL mechanism
does not require the server to return information to the client,
then this field is not to be included in the result.
4.3. Sequencing of the Bind Operation
4.3.1. Effect of Multiple Bind Requests
Subsequent to sending a bind request, A client MAY send a bind
request to change its identity. Such a bind request has the effect
of abandoning all operations outstanding on the connection. (This
simplifies server implementation.) Authentication from earlier binds
are subsequently ignored, and so if the bind fails, the connection
will be treated as anonymous (see section 4.3.3). If a SASL transfer
encryption or integrity mechanism has been negotiated, and that
mechanism does not support the changing of credentials from one
identity to another, then the client MUST instead establish a new
connection.
For some SASL authentication mechanisms, it may be necessary for the
client to invoke the BindRequest multiple times. If at any stage the
client wishes to abort the bind process it MAY unbind and then drop
the underlying connection. Clients MUST NOT invoke operations
between two Bind requests made as part of a multi-stage bind.
Authentication Methods for LDAPv3 Nov. 14, 2001
4.3.2. Aborting SASL Bind Negotiation
A client may abort a SASL bind negotiation by sending a BindRequest
with a different value in the mechanism field of SaslCredentials, or
an AuthenticationChoice other than sasl.
If the client sends a BindRequest with the sasl mechanism field as
an empty string, the server MUST return a BindResponse with
authMethodNotSupported as the resultCode. This will allow clients to
abort a negotiation if it wishes to try again with the same SASL
mechanism.
4.3.3. Unbound Connection Treated as Anonymous 4.1. Unbound Connection Treated as Anonymous
Unlike LDAP v2, the client need not send a Bind Request in the first Unlike LDAP v2, the client need not send a Bind Request in the first
PDU of the connection. The client may request any operations and the PDU of the connection. The client may request any operations and the
server MUST treat these as anonymous. If the server requires that server MUST treat these as anonymous. If the server requires that
the client bind before browsing or modifying the directory, the the client bind before browsing or modifying the directory, the
server MAY reject a request other than binding, unbinding or an server MAY reject a request other than binding, unbinding or an
extended request with the "operationsError" result. extended request with the "operationsError" result.
If the client did not bind before sending a request and receives an 4.2. Simple Authentication
operationsError, it may then send a Bind Request. If this also fails
or the client chooses not to bind on the existing connection, it
will close the connection, reopen it and begin again by first
sending a PDU with a Bind Request. This will aid in interoperating
with servers implementing other versions of LDAP.
4.4. Using SASL for Other Security Services
The simple authentication option provides minimal authentication The simple authentication option provides minimal authentication
facilities, with the contents of the authentication field consisting facilities, with the contents of the authentication field consisting
only of a cleartext password. Note that the use of cleartext only of a cleartext password. Note that the use of cleartext
passwords is not recommended over open networks when the underlying passwords is strongly discouraged over open networks when the
transport service cannot guarantee confidentiality; see the underlying transport service cannot guarantee confidentiality; see
"Security Considerations" section. the "Security Considerations" section.
4.3. SASL Authentication
The sasl choice allows for any mechanism defined for use with SASL The sasl choice allows for any mechanism defined for use with SASL
[RFC2222] not specifically prohibited by this document (see section [RFC2222] not specifically prohibited by this document (see section
4.4.1). The mechanism field contains the name of the mechanism. The 4.3.1).
credentials field contains the arbitrary data used for
authentication, inside an OCTET STRING wrapper. Note that unlike Authentication Methods for LDAPv3 Mar. 1, 2002
Clients sending a bind request with the sasl choice selected SHOULD
NOT send a value in the name field. Servers receiving a bind request
with the sasl choice selected SHALL ignore any value in the name
field.
The mechanism field in SaslCredentials contains the name of the
mechanism. The credentials field contains the arbitrary data used
for authentication, inside an OCTET STRING wrapper. Note that unlike
some Internet application protocols where SASL is used, LDAP is not some Internet application protocols where SASL is used, LDAP is not
text-based, thus no Base64 transformations are performed on the text-based, thus no Base64 transformations are performed on the
credentials. credentials.
If any SASL-based integrity or confidentiality services are enabled, If any SASL-based integrity or confidentiality services are enabled,
they take effect following the transmission by the server and they take effect following the transmission by the server and
reception by the client of the final BindResponse with resultCode reception by the client of the final BindResponse with resultCode
success. success.
Authentication Methods for LDAPv3 Nov. 14, 2001
The client can request that the server use authentication The client can request that the server use authentication
information from a lower layer protocol by using the SASL EXTERNAL information from a lower layer protocol by using the SASL EXTERNAL
mechanism (see section 5.5.1.2). mechanism (see section 5.5.1.2).
4.4.1. Use of ANONYMOUS and PLAIN SASL Mechanisms 4.3.1. Use of ANONYMOUS and PLAIN SASL Mechanisms
As LDAP includes native anonymous and plaintext authentication As LDAP includes native anonymous and plaintext authentication
methods, the "ANONYMOUS" and "PLAIN" SASL mechanisms are not used methods, the "ANONYMOUS" and "PLAIN" SASL mechanisms are not used
with LDAP. If an authorization identity of a form different from a with LDAP. If an authorization identity of a form different from a
DN is requested by the client, a mechanism that protects the DN is requested by the client, a mechanism that protects the
password in transit SHOULD be used. password in transit SHOULD be used.
4.4.2. Use of EXTERNAL SASL Mechanism 4.3.2. Use of EXTERNAL SASL Mechanism
The "EXTERNAL" SASL mechanism can be used to request the LDAP server The "EXTERNAL" SASL mechanism can be used to request the LDAP server
make use of security credentials exchanged by a lower layer. If a make use of security credentials exchanged by a lower layer. If a
TLS session has not been established between the client and server TLS session has not been established between the client and server
prior to making the SASL EXTERNAL Bind request and there is no other prior to making the SASL EXTERNAL Bind request and there is no other
external source of authentication credentials (e.g. IP-level external source of authentication credentials (e.g. IP-level
security [RFC2401]), or if, during the process of establishing the security [RFC2401]), or if, during the process of establishing the
TLS session, the server did not request the client's authentication TLS session, the server did not request the client's authentication
credentials, the SASL EXTERNAL bind MUST fail with a result code of credentials, the SASL EXTERNAL bind MUST fail with a result code of
inappropriateAuthentication. Any client authentication and inappropriateAuthentication. Any client authentication and
authorization state of the LDAP association is lost, so the LDAP authorization state of the LDAP association is lost, so the LDAP
association is in an anonymous state after the failure. association is in an anonymous state after the failure.
4.4.3. SASL Mechanisms not Considered in this Document 4.3.3. SASL Mechanisms not Considered in this Document
The following SASL-based mechanisms are not considered in this The following SASL-based mechanisms are not considered in this
document: KERBEROS_V4, GSSAPI and SKEY. document: KERBEROS_V4, GSSAPI and SKEY.
4.5. SASL Authorization Identity 4.4. SASL Authorization Identity
The authorization identity is carried as part of the SASL The authorization identity is carried as part of the SASL
credentials field in the LDAP Bind request and response. credentials field in the LDAP Bind request and response.
Authentication Methods for LDAPv3 Mar. 1, 2002
When the "EXTERNAL" SASL mechanism is being negotiated, if the When the "EXTERNAL" SASL mechanism is being negotiated, if the
credentials field is present, it contains an authorization identity credentials field is present, it contains an authorization identity
of the authzId form described below. of the authzId form described below.
Other mechanisms define the location of the authorization identity Other mechanisms define the location of the authorization identity
in the credentials field. in the credentials field.
4.5.1. Authorization Identity Syntax 4.4.1. Authorization Identity Syntax
The authorization identity is a string in the UTF-8 character set, The authorization identity is a string in the UTF-8 character set,
corresponding to the following ABNF grammar [ABNF]: corresponding to the following ABNF grammar [ABNF]:
; Specific predefined authorization (authz) id schemes are ; Specific predefined authorization (authz) id schemes are
; defined below -- new schemes may be defined in the future. ; defined below -- new schemes may be defined in the future.
authzId = dnAuthzId / uAuthzId authzId = dnAuthzId / uAuthzId
Authentication Methods for LDAPv3 Nov. 14, 2001
; distinguished-name-based authz id. ; distinguished-name-based authz id.
dnAuthzId = "dn:" dn dnAuthzId = "dn:" dn
dn = utf8string ; with syntax defined in [LDAPDN] section 3. dn = utf8string ; with syntax defined in [LDAPDN] section 3.
; unspecified authorization id, UTF-8 encoded. ; unspecified authorization id, UTF-8 encoded.
uAuthzId = "u:" userid uAuthzId = "u:" userid
userid = utf8string ; syntax unspecified userid = utf8string ; syntax unspecified
4.5.1.1. DN-based Authorization Identity 4.4.1.1. DN-based Authorization Identity
All servers that support the storage of authentication credentials, All servers that support the storage of authentication credentials,
such as passwords or certificates, in the directory MUST support the such as passwords or certificates, in the directory MUST support the
dnAuthzId choice. The format for distinguishedName is defined in dnAuthzId choice. The format for distinguishedName is defined in
section 3 of [LDAPDN]. section 3 of [LDAPDN].
4.5.1.2. Unspecified Authorization Identity 4.4.1.2. Unspecified Authorization Identity
The uAuthzId choice allows for compatibility with client The uAuthzId choice allows for compatibility with client
applications that wish to authenticate to a local directory but do applications that wish to authenticate to a local directory but do
not know their own distinguished name or that do not have a not know their own distinguished name or that do not have a
directory entry. The format of utf8string is defined as only a directory entry. The format of utf8string is defined as only a
sequence of UTF-8 encoded ISO 10646 characters, and further sequence of UTF-8 encoded ISO 10646 characters, and further
interpretation is subject to prior agreement between the client and interpretation is subject to prior agreement between the client and
server. server.
For example, the userid could identify a user of a specific 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 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 822 email address. In general a uAuthzId MUST NOT be assumed to be
globally unique. globally unique.
Additional authorization identity schemes MAY be defined in future Additional authorization identity schemes MAY be defined in future
versions of this document. versions of this document.
4.6. SASL Service Name for LDAP 4.5. SASL Service Name for LDAP
Authentication Methods for LDAPv3 Mar. 1, 2002
For use with SASL [SASL], a protocol must specify a service name to For use with SASL [SASL], a protocol must specify a service name to
be used with various SASL mechanisms, such as GSSAPI. For LDAP, the 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 service name is "ldap", which has been registered with the IANA as a
GSSAPI service name. GSSAPI service name.
4.7. SASL Integrity and Privacy Protections 4.6. SASL Integrity and Privacy Protections
Any negotiated SASL integrity and privacy protections SHALL start on Any negotiated SASL integrity and privacy protections SHALL start on
the first octet of the first LDAP PDU following successful the first octet of the first LDAP PDU following successful
completion of the SASL bind operation. If lower level security layer completion of the SASL bind operation. If lower level security layer
is negotiated, such as TLS, any SASL security services SHALL be is negotiated, such as TLS, any SASL security services SHALL be
layered on top of such security layers regardless of the order of layered on top of such security layers regardless of the order of
their negotiation. their negotiation.
5. Start TLS Operation 5. Start TLS Operation
Authentication Methods for LDAPv3 Nov. 14, 2001
The Start Transport Layer Security (StartTLS) operation provides the The Start Transport Layer Security (StartTLS) operation provides the
ability to establish Transport Layer Security [TLS] on an LDAP ability to establish Transport Layer Security [TLS] on an LDAP
association. association.
5.1. Start TLS Request 5.1. Start TLS Request
A client requests TLS establishment by transmitting a Start TLS A client requests TLS establishment by transmitting a Start TLS
request PDU to the server. The Start TLS request is defined in terms request PDU to the server. The Start TLS request is defined in terms
of the [LDAPv3] ExtendedRequest as follows: of the [Protocol] ExtendedRequest as follows:
ExtendedRequest ::= [APPLICATION 23] SEQUENCE { ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID, requestName [0] LDAPOID,
requestValue [LDAPv3] OCTET STRING OPTIONAL } requestValue [1] OCTET STRING OPTIONAL }
The requestName portion of the Start TLS request MUST be the OID The requestName portion of the Start TLS request MUST be the OID
"1.3.6.1.4.1.1466.20037". "1.3.6.1.4.1.1466.20037".
The requestValue field is absent. The requestValue field is absent.
The client MUST NOT send any PDUs on this connection following this The client MUST NOT send any PDUs on this connection following this
request until it receives a Start TLS extended response. request until it receives a Start TLS extended response.
5.2. Start TLS Response 5.2. Start TLS Response
When a Start TLS request is made, the server MUST return a Start TLS When a Start TLS request is made, the server MUST return a Start TLS
response PDU to the requestor. The Start TLS response id defined in response PDU to the requestor. The Start TLS response id defined in
terms of the [LDAPv3] ExtendedResponse as follows: terms of the [Protocol] ExtendedResponse as follows:
ExtendedResponse ::= [APPLICATION 24] SEQUENCE { ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
COMPONENTS OF LDAPResult, COMPONENTS OF LDAPResult,
responseName [10] LDAPOID OPTIONAL, responseName [10] LDAPOID OPTIONAL,
response [11] OCTET STRING OPTIONAL } response [11] OCTET STRING OPTIONAL }
The responseName portion of the Start TLS response MUST be the OID The responseName portion of the Start TLS response MUST be the OID
"1.3.6.1.4.1.1466.20037". (Note that this OID is the same OID value "1.3.6.1.4.1.1466.20037". (Note that this OID is the same OID value
used in the requestName of the Start TLS request.) used in the requestName of the Start TLS request.)
Authentication Methods for LDAPv3 Mar. 1, 2002
The response field is absent. The response field is absent.
The server MUST set the resultCode field to either success or one of The server MUST set the resultCode field to either success or one of
the other values outlined in section 5.2.2. the other values outlined in section 5.2.2.
5.2.1. "Success" Response 5.2.1. "Success" Response
If the ExtendedResponse contains a resultCode of success, this If the ExtendedResponse contains a resultCode of success, this
indicates that the server is willing and able to negotiate TLS. indicates that the server is willing and able to negotiate TLS.
Refer to section 5.3, below, for details. Refer to section 5.3, below, for details.
5.2.2. Response other than "success" 5.2.2. Response other than "success"
If the ExtendedResponse contains a resultCode other than success, If the ExtendedResponse contains a resultCode other than success,
this indicates that the server is unwilling or unable to negotiate this indicates that the server is unwilling or unable to negotiate
TLS. TLS.
Authentication Methods for LDAPv3 Nov. 14, 2001
If the Start TLS extended request was not successful, the resultCode If the Start TLS extended request was not successful, the resultCode
will be one of: will be one of:
operationsError (operations sequencing incorrect; e.g. TLS already operationsError (operations sequencing incorrect; e.g. TLS already
established) established)
protocolError (TLS not supported or incorrect PDU structure) protocolError (TLS not supported or incorrect PDU structure)
referral (this server doesn't do TLS, try this one) referral (this server doesn't do TLS, try this one)
unavailable (e.g. some major problem with TLS, or server is unavailable (e.g. some major problem with TLS, or server is
shutting down) shutting down)
The server MUST return operationsError if the client violates any of The server MUST return operationsError if the client violates any of
the Start TLS extended operation sequencing requirements described the Start TLS extended operation sequencing requirements described
in section 5.3, below. in section 5.3, below.
If the server does not support TLS (whether by design or by current If the server does not support TLS (whether by design or by current
configuration), it MUST set the resultCode to protocolError (see configuration), it MUST set the resultCode to protocolError (see
section 4.1.1 of [LDAPv3]), or to referral. The server MUST include section 4.1.1 of [Protocol]), or to referral. The server MUST
an actual referral value in the LDAP Result if it returns a include an actual referral value in the LDAP Result if it returns a
resultCode of referral. The client's current session is unaffected resultCode of referral. The client's current session is unaffected
if the server does not support TLS. The client MAY proceed with any if the server does not support TLS. The client MAY proceed with any
LDAP operation, or it MAY close the connection. LDAP operation, or it MAY close the connection.
The server MUST return unavailable if it supports TLS but cannot The server MUST return unavailable if it supports TLS but
establish a TLS connection for some reason, e.g. the certificate cannot establish a TLS connection for some reason, e.g. the
server not responding, it cannot contact its TLS implementation, or certificate server not responding, it cannot contact its TLS
if the server is in process of shutting down. The client MAY retry implementation, or if the server is in process of shutting
the StartTLS operation, or it MAY proceed with any other LDAP down. The client MAY retry the StartTLS operation, or it MAY
operation, or it MAY close the connection. proceed with any other LDAP operation, or it MAY close the
connection.
5.3. Sequencing of the Start TLS Operation 5.3. Sequencing of the Start TLS Operation
Authentication Methods for LDAPv3 Mar. 1, 2002
This section describes the overall procedures clients and servers This section describes the overall procedures clients and servers
MUST follow for TLS establishment. These procedures take into MUST follow for TLS establishment. These procedures take into
consideration various aspects of the overall security of the LDAP consideration various aspects of the overall security of the LDAP
association including discovery of resultant security level and association including discovery of resultant security level and
assertion of the client's authorization identity. assertion of the client's authorization identity.
Note that the precise effects, on a client's authorization identity, Note that the precise effects, on a client's authorization identity,
of establishing TLS on an LDAP association are described in detail of establishing TLS on an LDAP association are described in detail
in section 5.5. in section 5.5.
5.3.1. Requesting to Start TLS on an LDAP Association 5.3.1. Requesting to Start TLS on an LDAP Association
The client MAY send the Start TLS extended request at any time after The client MAY send the Start TLS extended request at any time after
establishing an LDAP association, except that in the following cases establishing an LDAP association, except that in the following cases
the client MUST NOT send a Start TLS extended request: the client MUST NOT send a Start TLS extended request:
- if TLS is currently established on the connection, or - if TLS is currently established on the connection, or
- during a multi-stage SASL negotiation, or - during a multi-stage SASL negotiation, or
Authentication Methods for LDAPv3 Nov. 14, 2001
- if there are any LDAP operations outstanding on the - if there are any LDAP operations outstanding on the
connection. connection.
The result of violating any of these requirements is a resultCode of The result of violating any of these requirements is a resultCode of
operationsError, as described above in section 5.2.2. operationsError, as described above in section 5.2.2.
The client MAY have already performed a Bind operation when it sends The client MAY have already performed a Bind operation when it sends
a Start TLS request, or the client might have not yet bound. a Start TLS request, or the client might have not yet bound.
If the client did not establish a TLS connection before sending any If the client did not establish a TLS connection before sending any
skipping to change at page 13, line 41 skipping to change at page 11, line 4
Protocol directly over the underlying transport connection to the Protocol directly over the underlying transport connection to the
server to initiate TLS negotiation [TLS]. server to initiate TLS negotiation [TLS].
5.3.3. TLS Version Negotiation 5.3.3. TLS Version Negotiation
Negotiating the version of TLS or SSL to be used is a part of the Negotiating the version of TLS or SSL to be used is a part of the
TLS Handshake Protocol, as documented in [TLS]. Please refer to that TLS Handshake Protocol, as documented in [TLS]. Please refer to that
document for details. document for details.
5.3.4. Discovery of Resultant Security Level 5.3.4. Discovery of Resultant Security Level
Authentication Methods for LDAPv3 Mar. 1, 2002
After a TLS connection is established on an LDAP association, both After a TLS connection is established on an LDAP association, both
parties MUST individually decide whether or not to continue based on parties MUST individually decide whether or not to continue based on
the privacy level achieved. Ascertaining the TLS connection's the privacy level achieved. Ascertaining the TLS connection's
privacy level is implementation dependent, and accomplished by privacy level is implementation dependent, and accomplished by
communicating with one's respective local TLS implementation. communicating with one's respective local TLS implementation.
If the client or server decides that the level of authentication or If the client or server decides that the level of authentication or
privacy is not high enough for it to continue, it SHOULD gracefully privacy is not high enough for it to continue, it SHOULD gracefully
close the TLS connection immediately after the TLS negotiation has close the TLS connection immediately after the TLS negotiation has
completed (see sections 5.4.1 and 5.5.2 below). If the client completed (see sections 5.4.1 and 5.5.2 below). If the client
decides to continue, it MAY attempt to Start TLS again, it MAY send decides to continue, it MAY attempt to Start TLS again, it MAY send
an unbind request, or it MAY send any other LDAP request. an unbind request, or it MAY send any other LDAP request.
5.3.5. Assertion of Client's Authorization Identity 5.3.5. Assertion of Client's Authorization Identity
The client MAY, upon receipt of a Start TLS response indicating The client MAY, upon receipt of a Start TLS response indicating
success, assert that a specific authorization identity be utilized success, assert that a specific authorization identity be utilized
Authentication Methods for LDAPv3 Nov. 14, 2001
in determining the client's authorization status. The client in determining the client's authorization status. The client
accomplishes this via an LDAP Bind request specifying a SASL accomplishes this via an LDAP Bind request specifying a SASL
mechanism of "EXTERNAL" [SASL] (see section 5.5.1.2 below). mechanism of "EXTERNAL" [SASL] (see section 5.5.1.2 below).
5.3.6. Server Identity Check 5.3.6. Server Identity Check
The client MUST check its understanding of the server's hostname The client MUST check its understanding of the server's hostname
against the server's identity as presented in the server's against the server's identity as presented in the server's
Certificate message, in order to prevent man-in-the-middle attacks. Certificate message, in order to prevent man-in-the-middle attacks.
skipping to change at page 14, line 41 skipping to change at page 12, line 4
only to the left-most name component. only to the left-most name component.
For example, *.bar.com would match a.bar.com and b.bar.com, but it For example, *.bar.com would match a.bar.com and b.bar.com, but it
would not match a.x.bar.com nor would it match bar.com. If more would not match a.x.bar.com nor would it match bar.com. If more
than one identity of a given type is present in the certificate than one identity of a given type is present in the certificate
(e.g. more than one dNSName name), a match in any one of the set is (e.g. more than one dNSName name), a match in any one of the set is
considered acceptable. considered acceptable.
If the hostname does not match the dNSName-based identity in the If the hostname does not match the dNSName-based identity in the
certificate per the above check, user-oriented clients SHOULD either certificate per the above check, user-oriented clients SHOULD either
Authentication Methods for LDAPv3 Mar. 1, 2002
notify the user (clients MAY give the user the opportunity to notify the user (clients MAY give the user the opportunity to
continue with the connection in any case) or terminate the continue with the connection in any case) or terminate the
connection and indicate that the server's identity is suspect. connection and indicate that the server's identity is suspect.
Automated clients SHOULD close the connection, returning and/or Automated clients SHOULD close the connection, returning and/or
logging an error indicating that the server's identity is suspect. logging an error indicating that the server's identity is suspect.
Beyond the server identity checks described in this section, clients Beyond the server identity checks described in this section, clients
SHOULD be prepared to do further checking to ensure that the server SHOULD be prepared to do further checking to ensure that the server
is authorized to provide the service it is observed to provide. The is authorized to provide the service it is observed to provide. The
client MAY need to make use of local policy information. client MAY need to make use of local policy information.
5.3.7. Refresh of Server Capabilities Information 5.3.7. Refresh of Server Capabilities Information
The client MUST refresh any cached server capabilities information The client MUST refresh any cached server capabilities information
(e.g. from the server's root DSE; see section 3.4 of [LDAPv3]) upon (e.g. from the server's root DSE; see section 3.4 of [Protocol])
TLS session establishment. This is necessary to protect against upon TLS session establishment. This is necessary to protect against
active-intermediary attacks that may have altered any server active-intermediary attacks that may have altered any server
Authentication Methods for LDAPv3 Nov. 14, 2001
capabilities information retrieved prior to TLS establishment. The capabilities information retrieved prior to TLS establishment. The
server MAY advertise different capabilities after TLS establishment. server MAY advertise different capabilities after TLS establishment.
5.4. Closing a TLS Connection 5.4. Closing a TLS Connection
Two forms of TLS connection closure--graceful and abrupt--are Two forms of TLS connection closure--graceful and abrupt--are
supported. supported.
5.4.1. Graceful Closure 5.4.1. Graceful Closure
Either the client or server MAY terminate the TLS connection on an Either the client or server MAY terminate the TLS connection on an
LDAP association by sending a TLS closure alert. This will leave the LDAP association by sending a TLS closure alert. This will leave the
LDAP association intact. LDAP association intact.
Before closing a TLS connection, the client MUST [RGH10]either wait Before closing a TLS connection, the client MUST [RGH9]either wait
for any outstanding LDAP operations to complete, or explicitly for any outstanding LDAP operations to complete, or explicitly
abandon them [LDAPv3]. abandon them [Protocol].
After the initiator of a close has sent a TLS closure alert, it MUST After the initiator of a close has sent a TLS closure alert, it MUST
discard any TLS messages until it has received a TLS closure alert discard any TLS messages until it has received a TLS closure alert
from the other party. It will cease to send TLS Record Protocol from the other party. It will cease to send TLS Record Protocol
PDUs, and following the receipt of the alert, MAY send and receive PDUs, and following the receipt of the alert, MAY send and receive
LDAP PDUs. LDAP PDUs.
The other party, if it receives a TLS closure alert, MUST The other party, if it receives a TLS closure alert, MUST
immediately transmit a TLS closure alert. It will subsequently immediately transmit a TLS closure alert. It will subsequently
cease to send TLS Record Protocol PDUs, and MAY send and receive cease to send TLS Record Protocol PDUs, and MAY send and receive
LDAP PDUs. LDAP PDUs.
5.4.2. Abrupt Closure 5.4.2. Abrupt Closure
Either the client or server MAY abruptly close the entire LDAP Either the client or server MAY abruptly close the entire LDAP
association and any TLS connection established on it by dropping the association and any TLS connection established on it by dropping the
underlying TCP connection. In this circumstance, a server MAY send underlying TCP connection. In this circumstance, a server MAY send
the client a Notice of Disconnection [LDAPv3] before dropping the the client a Notice of Disconnection [Protocol] before dropping the
TCP connection. TCP connection.
Authentication Methods for LDAPv3 Mar. 1, 2002
5.5. Effects of TLS on a Client's Authorization Identity 5.5. Effects of TLS on a Client's Authorization Identity
This section describes the effects on a client's authorization This section describes the effects on a client's authorization
identity brought about by establishing TLS on an LDAP association. identity brought about by establishing TLS on an LDAP association.
The default effects are described first, and next the facilities for The default effects are described first, and next the facilities for
client assertion of authorization identity are discussed including client assertion of authorization identity are discussed including
error conditions. Lastly, the effects of closing the TLS connection error conditions. Lastly, the effects of closing the TLS connection
are described. are described.
Authorization identities and related concepts are described in Authorization identities and related concepts are described in
Appendix B. Appendix B.
5.5.1. TLS Connection Establishment Effects 5.5.1. TLS Connection Establishment Effects
5.5.1.1. Default Effects 5.5.1.1. Default Effects
Authentication Methods for LDAPv3 Nov. 14, 2001
Upon establishment of the TLS connection onto the LDAP association, Upon establishment of the TLS connection onto the LDAP association,
any previously established authentication and authorization any previously established authentication and authorization
identities MUST remain in force, including anonymous state. This identities MUST remain in force, including anonymous state. This
holds even in the case where the server requests client holds even in the case where the server requests client
authentication via TLS -- e.g. requests the client to supply its authentication via TLS -- e.g. requests the client to supply its
certificate during TLS negotiation (see [TLS]). certificate during TLS negotiation (see [TLS]).
5.5.1.2. Client Assertion of Authorization Identity 5.5.1.2. Client Assertion of Authorization Identity
skipping to change at page 16, line 42 skipping to change at page 14, line 5
mechanics of how this is accomplished are implementation specific. mechanics of how this is accomplished are implementation specific.
5.5.1.2.2. Explicit Assertion 5.5.1.2.2. Explicit Assertion
An explicit authorization identity assertion is accomplished after An explicit authorization identity assertion is accomplished after
TLS establishment by invoking a Bind request of the SASL form using TLS establishment by invoking a Bind request of the SASL form using
the "EXTERNAL" mechanism name [SASL, LDAPv3] that SHALL include the the "EXTERNAL" mechanism name [SASL, LDAPv3] that SHALL include the
credentials octet string. This string MUST be constructed as credentials octet string. This string MUST be constructed as
documented in section 4.5. documented in section 4.5.
Authentication Methods for LDAPv3 Mar. 1, 2002
5.5.1.2.3. Error Conditions 5.5.1.2.3. Error Conditions
For either form of assertion, the server MUST verify that the For either form of assertion, the server MUST verify that the
client's authentication identity as supplied in its TLS credentials client's authentication identity as supplied in its TLS credentials
is permitted to be mapped to the asserted authorization identity. is permitted to be mapped to the asserted authorization identity.
The server MUST reject the Bind operation with an invalidCredentials The server MUST reject the Bind operation with an invalidCredentials
resultCode in the Bind response if the client is not so authorized. resultCode in the Bind response if the client is not so authorized.
Additionally, with either form of assertion, if a TLS session has Additionally, with either form of assertion, if a TLS session has
not been established between the client and server prior to making not been established between the client and server prior to making
the SASL EXTERNAL Bind request and there is no other external source the SASL EXTERNAL Bind request and there is no other external source
of authentication credentials (e.g. IP-level security [IPSEC]), or of authentication credentials (e.g. IP-level security [IPSEC]), or
if, during the process of establishing the TLS session, the server if, during the process of establishing the TLS session, the server
did not request the client's authentication credentials, the SASL did not request the client's authentication credentials, the SASL
EXTERNAL bind MUST fail with a result code of EXTERNAL bind MUST fail with a result code of
inappropriateAuthentication. inappropriateAuthentication.
Authentication Methods for LDAPv3 Nov. 14, 2001
After the above Bind operation failures, any client authentication After the above Bind operation failures, any client authentication
and authorization state of the LDAP association is lost, so the LDAP and authorization state of the LDAP association is lost, so the LDAP
association is in an anonymous state after the failure. TLS association is in an anonymous state after the failure. TLS
connection state is unaffected, though a server MAY end the TLS connection state is unaffected, though a server MAY end the TLS
connection, via a TLS close_notify message, based on the Bind connection, via a TLS close_notify message, based on the Bind
failure (as it MAY at any time). failure (as it MAY at any time).
5.5.2. TLS Connection Closure Effects 5.5.2. TLS Connection Closure Effects
Closure of the TLS connection MUST cause the LDAP association to Closure of the TLS connection MUST cause the LDAP association to
skipping to change at page 17, line 42 skipping to change at page 15, line 4
The following table lists the valid LDAP association states and The following table lists the valid LDAP association states and
provides a description of each state. The ID for each state is used provides a description of each state. The ID for each state is used
in the state transition table in section 6.4. in the state transition table in section 6.4.
ID State Description ID State Description
-- -------------------------------------------------------------- -- --------------------------------------------------------------
S1 no Auth ID S1 no Auth ID
no AuthZ ID no AuthZ ID
TLS: no Creds OFF TLS: no Creds OFF
S2 no Auth ID S2 no Auth ID
Authentication Methods for LDAPv3 Mar. 1, 2002
no AuthZ ID no AuthZ ID
TLS: no Creds ON TLS: no Creds ON
S3 no Auth ID S3 no Auth ID
no AuthZ ID no AuthZ ID
TLS: Creds Auth ID "I", ON. TLS: Creds Auth ID "I", ON.
S4 Auth ID = Xn S4 Auth ID = Xn
AuthZ ID= Yn AuthZ ID= Yn
[TLS: no Creds, Off] [TLS: no Creds, Off]
S5 Auth ID = Xn S5 Auth ID = Xn
AuthZ ID= Yn AuthZ ID= Yn
[TLS: no Creds, On] [TLS: no Creds, On]
S6 Auth ID = Xn S6 Auth ID = Xn
AuthZ ID= Yn AuthZ ID= Yn
[TLS: Creds Auth ID "I", On] [TLS: Creds Auth ID "I", On]
S7 Auth ID = I S7 Auth ID = I
AuthZ ID= Jn AuthZ ID= Jn
Authentication Methods for LDAPv3 Nov. 14, 2001
[TLS: Creds Auth ID "I", On] [TLS: Creds Auth ID "I", On]
S8 Auth ID = I S8 Auth ID = I
AuthZ ID= is based on "I" AuthZ ID= is based on "I"
[TLS: Creds Auth ID "I", On] [TLS: Creds Auth ID "I", On]
6.2. Actions that Affect LDAP Association State 6.2. Actions that Affect LDAP Association State
The following table lists the actions that can affect the state of The following table lists the actions that can affect the state of
an LDAP association. The ID for each action is used in the state an LDAP association. The ID for each action is used in the state
transition table in section 6.4. transition table in section 6.4.
skipping to change at page 18, line 29 skipping to change at page 15, line 45
A1 Client binds anonymously A1 Client binds anonymously
A2 Error: Inappropriate authentication A2 Error: Inappropriate authentication
A3 Client or Server: close TLS connection (section 5.5.2) A3 Client or Server: close TLS connection (section 5.5.2)
A4 Client StartTLS A4 Client StartTLS
Server: client auth NOT required Server: client auth NOT required
A5 Client: StartTLS A5 Client: StartTLS
Server: client creds requested Server: client creds requested
Client: {TLS creds: Auth ID "I"] Client: {TLS creds: Auth ID "I"]
A6 Client: Bind w/simple password or SASL mechanism (e.g. DIGEST- A6 Client: Bind w/simple password or SASL mechanism (e.g. DIGEST-
MD5 password, Kerberos, etc. ű except EXTERNAL [Auth ID "X" MD5 password, Kerberos, etc. - except EXTERNAL [Auth ID "X"
maps to AuthZ ID "Y"] maps to AuthZ ID "Y"]
A7 Client Binds SASL EXTERNAL w/ credentials: AuthZ ID "J" A7 Client Binds SASL EXTERNAL w/ credentials: AuthZ ID "J"
[Explicit Assertion (section 5.5.1.2.2)] [Explicit Assertion (section 5.5.1.2.2)]
A8 Client Bind SASL EXTERNAL w/saslcredentials: NULL [Implicit A8 Client Bind SASL EXTERNAL w/saslcredentials: NULL [Implicit
Assertion (section 5.5.1.2.1)] Assertion (section 5.5.1.2.1)]
6.3. Decisions Used in Making LDAP Association State Changes 6.3. Decisions Used in Making LDAP Association State Changes
Certain changes in the state of an LDAP association are only allowed Certain changes in the state of an LDAP association are only allowed
if the server can affirmatively answer a question. These questions if the server can affirmatively answer a question. These questions
are applied as part of the criteria for allowing or disallowing a are applied as part of the criteria for allowing or disallowing a
state change in the state transition table in section 6.4. state change in the state transition table in section 6.4.
Authentication Methods for LDAPv3 Mar. 1, 2002
ID Decision Question ID Decision Question
-- -------------------------------------------------------------- -- --------------------------------------------------------------
D1 Can TLS Credentials Auth ID "I" be mapped to AuthZ ID "J"? D1 Can TLS Credentials Auth ID "I" be mapped to AuthZ ID "J"?
D2 Can a valid AuthZ ID "J" be derived from TLS Credentials Auth D2 Can a valid AuthZ ID "J" be derived from TLS Credentials Auth
ID "I"? ID "I"?
6.4. LDAP Association State Transition Table 6.4. LDAP Association State Transition Table
The LDAP Association table below lists the valid states for an LDAP The LDAP Association table below lists the valid states for an LDAP
association and the actions that could affect them. For any given association and the actions that could affect them. For any given
row in the table, the Current State column gives the state of an row in the table, the Current State column gives the state of an
LDAP association, the Action column gives an action that could LDAP association, the Action column gives an action that could
affect the state of an LDAP assocation, and the Next State column affect the state of an LDAP assocation, and the Next State column
gives the resulting state of an LDAP association after the action gives the resulting state of an LDAP association after the action
occurs. occurs.
Authentication Methods for LDAPv3 Nov. 14, 2001
The initial state for the state machine described in this table is The initial state for the state machine described in this table is
S1. S1.
Current Next Current Next
State Action State Comment State Action State Comment
------- ------------- ----- ----------------------------------- ------- ------------- ----- -----------------------------------
S1 A1 S1 S1 A1 S1
S1 A2 S1 Error: Inappropriate authentication S1 A2 S1 Error: Inappropriate authentication
S1 A4 S2 S1 A4 S2
S1 A5 S3 S1 A5 S3
skipping to change at page 19, line 41 skipping to change at page 17, line 4
S4 A3 S1 S4 A3 S1
S4 A4 S5 S4 A4 S5
S4 A5 S6 S4 A5 S6
S5 A6 S5 S5 A6 S5
S5 A2 S5 Error: Inappropriate Authentication S5 A2 S5 Error: Inappropriate Authentication
S5 A3 S1 S5 A3 S1
S5 A1 S2 S5 A1 S2
S6 A6 S6 S6 A6 S6
S6 A3 S1 S6 A3 S1
S6 A1 S3 S6 A1 S3
Authentication Methods for LDAPv3 Mar. 1, 2002
S6 A7 and D1=NO S6 Error: InvalidCredentials S6 A7 and D1=NO S6 Error: InvalidCredentials
S6 A7 and D1=YES S10 S6 A7 and D1=YES S10
S6 A8 and D2=NO S6 Error: InvalidCredentials S6 A8 and D2=NO S6 Error: InvalidCredentials
S6 A8 and D2=YES S8 S6 A8 and D2=YES S8
S7 A1 S3 S7 A1 S3
S7 A3 S1 S7 A3 S1
S7 A6 S6 S7 A6 S6
S7 A7 S7 S7 A7 S7
S7 A8 and D2=NO S3 Error: InvalidCredentials S7 A8 and D2=NO S3 Error: InvalidCredentials
S7 A8 and D2=YES S8 S7 A8 and D2=YES S8
S8 A1 S3 S8 A1 S3
S8 A3 S1 S8 A3 S1
S8 A8 S8 S8 A8 S8
S8 A7 and D1=NO S6 Error: InvalidCredentials S8 A7 and D1=NO S6 Error: InvalidCredentials
S8 A7 and D1=YES S7 S8 A7 and D1=YES S7
S8 A6 S6 S8 A6 S6
Authentication Methods for LDAPv3 Nov. 14, 2001
7. Anonymous Authentication 7. Anonymous Authentication
Directory operations that modify entries or access protected Directory operations that modify entries or access protected
attributes or entries generally require client authentication. attributes or entries generally require client authentication.
Clients that do not intend to perform any of these operations Clients that do not intend to perform any of these operations
typically use anonymous authentication. Servers SHOULD NOT allow typically use anonymous authentication. Servers SHOULD NOT allow
clients with anonymous authentication to modify directory entries or clients with anonymous authentication to modify directory entries or
access sensitive information in directory entries. access sensitive information in directory entries.
skipping to change at page 20, line 39 skipping to change at page 18, line 4
7.1. Anonymous Authentication Procedure 7.1. Anonymous Authentication Procedure
An LDAPv3 client that has not successfully completed a bind An LDAPv3 client that has not successfully completed a bind
operation on a connection is anonymously authenticated. See section operation on a connection is anonymously authenticated. See section
4.3.3. 4.3.3.
An LDAP client MAY also choose to explicitly bind anonymously. A An LDAP client MAY also choose to explicitly bind anonymously. A
client that wishes to do so MUST choose the simple authentication client that wishes to do so MUST choose the simple authentication
option in the Bind Request (see section 4.1) and set the password to option in the Bind Request (see section 4.1) and set the password to
Authentication Methods for LDAPv3 Mar. 1, 2002
be of zero length. (This is often done by LDAPv2 clients.) Typically be of zero length. (This is often done by LDAPv2 clients.) Typically
the name is also of zero length. the name is also of zero length.
7.2. Anonymous Authentication and TLS 7.2. Anonymous Authentication and TLS
An LDAP client MAY use the Start TLS operation (section 5) to An LDAP client MAY use the Start TLS operation (section 5) to
negotiate the use of TLS security [TLS]. If the client has not bound negotiate the use of TLS security [TLS]. If the client has not bound
beforehand, then until the client uses the EXTERNAL SASL mechanism beforehand, then until the client uses the EXTERNAL SASL mechanism
to negotiate the recognition of the client's certificate, the client to negotiate the recognition of the client's certificate, the client
is anonymously authenticated. is anonymously authenticated.
Recommendations on TLS ciphersuites are given in section 11. Recommendations on TLS ciphersuites are given in section 11.
An LDAP server which requests that clients provide their certificate An LDAP server which requests that clients provide their certificate
during TLS negotiation MAY use a local security policy to determine during TLS negotiation MAY use a local security policy to determine
whether to successfully complete TLS negotiation if the client did whether to successfully complete TLS negotiation if the client did
not present a certificate which could be validated. not present a certificate which could be validated.
Authentication Methods for LDAPv3 Nov. 14, 2001
8. Password-based authentication 8. Password-based authentication
8.1. Simple authentication 8.1. Simple authentication
The LDAP "simple" authentication choice is not suitable for The LDAP "simple" authentication choice is not suitable for
authentication in environments where there is no network or authentication in environments where there is no network or
transport layer confidentiality. LDAP implementations SHOULD support transport layer confidentiality. LDAP implementations SHOULD support
authentication with the "simple" authentication choice when the authentication with the "simple" authentication choice when the
connection is protected against eavesdropping using TLS, as defined connection is protected against eavesdropping using TLS, as defined
in section 7.3. LDAP implementations SHOULD NOT support in section 7.3. LDAP implementations SHOULD NOT support
authentication with the "simple" authentication choice unless the authentication with the "simple" authentication choice unless the
data on the connection is protected using TLS or other privacy and data on the connection is protected using TLS or other privacy and
data-integrity protection. data-integrity protection.
8.2. Digest Authentication 8.2. Digest Authentication
LDAP implementations MUST support authentication with a password LDAP server implementations MUST support authentication with a
using the DIGEST-MD5 SASL mechanism for password protection. password using the DIGEST-MD5 SASL mechanism for password
protection.
An LDAP client MAY determine whether the server supports this An LDAP client MAY determine whether the server supports this
mechanism by performing a search request on the root DSE, requesting mechanism by performing a search request on the root DSE, requesting
the supportedSASLMechanisms attribute, and checking whether the the supportedSASLMechanisms attribute, and checking whether the
string "DIGEST-MD5" is present as a value of this attribute. string "DIGEST-MD5" is present as a value of this attribute.
In the first stage of authentication, when the client is performing In the first stage of authentication, when the client is performing
an "initial authentication" as defined in section 2.1 of [RFC2831], an "initial authentication" as defined in section 2.1 of [RFC2831],
the client sends a bind request in which the version number is 3, the client sends a bind request in which the version number is 3,
the authentication choice is sasl, the sasl mechanism name is the authentication choice is sasl, the sasl mechanism name is
"DIGEST- MD5", and the credentials are absent. The client then waits DIGEST- MD5, and the credentials are absent. The client then waits
for a response from the server to this request. for a response from the server to this request.
The server will respond with a bind response in which the resultCode The server will respond with a bind response in which the resultCode
is saslBindInProgress, and the serverSaslCreds field is present. The is saslBindInProgress, and the serverSaslCreds field is present. The
contents of this field is a string defined by "digest-challenge" in contents of this field is a string defined by "digest-challenge" in
Authentication Methods for LDAPv3 Mar. 1, 2002
section 2.1.1 of [RFC2831]. The server SHOULD include a realm section 2.1.1 of [RFC2831]. The server SHOULD include a realm
indication and MUST indicate support for UTF-8. indication and MUST indicate support for UTF-8.
The client will send a bind request with a distinct message id, in The client will send a bind request with a distinct message id, in
which the version number is 3, the authentication choice is sasl, which the version number is 3, the authentication choice is sasl,
the sasl mechanism name is "DIGEST-MD5", and the credentials contain the sasl mechanism name is "DIGEST-MD5", and the credentials contain
the string defined by "digest-response" in section 2.1.2 of the string defined by "digest-response" in section 2.1.2 of
[RFC2831]. The serv-type is "ldap". [RFC2831]. The serv-type is "ldap".
The server will respond with a bind response in which the resultCode The server will respond with a bind response in which the resultCode
is either success, or an error indication. If the authentication is is either success, or an error indication. If the authentication is
successful and the server does not support subsequent successful and the server does not support subsequent
authentication, then the credentials field is absent. If the authentication, then the credentials field is absent. If the
authentication is successful and the server supports subsequent authentication is successful and the server supports subsequent
authentication, then the credentials field contains the string authentication, then the credentials field contains the string
defined by "response-auth" in section 2.1.3 of [4]. Support for defined by "response-auth" in section 2.1.3 of [4]. Support for
subsequent authentication is OPTIONAL in clients and servers. subsequent authentication is OPTIONAL in clients and servers.
8.3. "simple" authentication choice under TLS encryption 8.3. "simple" authentication choice under TLS encryption
Authentication Methods for LDAPv3 Nov. 14, 2001
Following the negotiation of an appropriate TLS ciphersuite Following the negotiation of an appropriate TLS ciphersuite
providing connection confidentiality [6], a client MAY authenticate providing connection confidentiality [6], a client MAY authenticate
to a directory that supports the simple authentication choice by to a directory that supports the simple authentication choice by
performing a simple bind operation. performing a simple bind operation.
The client will use the Start TLS operation [5] to negotiate the use 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 of TLS security [6] on the connection to the LDAP server. The client
need not have bound to the directory beforehand. need not have bound to the directory beforehand.
skipping to change at page 22, line 28 skipping to change at page 19, line 48
are given in section 11. are given in section 11.
Following the successful completion of TLS negotiation, the client Following the successful completion of TLS negotiation, the client
MUST send an LDAP bind request with the version number of 3, the MUST send an LDAP bind request with the version number of 3, the
name field containing a DN , and the "simple" authentication choice, name field containing a DN , and the "simple" authentication choice,
containing a password. containing a password.
8.3.1. "simple" Authentication Choice 8.3.1. "simple" Authentication Choice
DSAs that map the DN sent in the bind request to a directory entry DSAs that map the DN sent in the bind request to a directory entry
with a userPassword attribute will, for each value of the with an associated set of one or more passwords will compare the
userPassword attribute in the named user's entry, compare these for presented password to the set of passwords associated with that
case-sensitive equality with the client's presented password. If entry. If there is a match, then the server will respond with
there is a match, then the server will respond with resultCode resultCode success, otherwise the server will respond with
success, otherwise the server will respond with resultCode resultCode invalidCredentials.
invalidCredentials.
8.4. Other authentication choices with TLS 8.4. Other authentication choices with TLS
It is also possible, following the negotiation of TLS, to perform a It is also possible, following the negotiation of TLS, to perform a
SASL authentication that does not involve the exchange of plaintext SASL authentication that does not involve the exchange of plaintext
reusable passwords. In this case the client and server need not reusable passwords. In this case the client and server need not
Authentication Methods for LDAPv3 Mar. 1, 2002
negotiate a ciphersuite that provides confidentiality if the only negotiate a ciphersuite that provides confidentiality if the only
service required is data integrity. service required is data integrity.
9. Certificate-based authentication 9. Certificate-based authentication
LDAP implementations SHOULD support authentication via a client LDAP implementations SHOULD support authentication via a client
certificate in TLS, as defined in section 8.1. certificate in TLS, as defined in section 8.1.
9.1. Certificate-based authentication with TLS 9.1. Certificate-based authentication with TLS
A user who has a public/private key pair in which the public key has 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 been signed by a Certification Authority may use this key pair to
authenticate to the directory server if the user's certificate is authenticate to the directory server if the user's certificate is
requested by the server. The user's certificate subject field SHOULD requested by the server. The user's certificate subject field SHOULD
be the name of the user's directory entry, and the Certification be the name of the user's directory entry, and the Certification
Authority that issued the userĂs certificate must be sufficiently Authority that issued the user's certificate must be sufficiently
trusted by the directory server in order for the server to process trusted by the directory server in order for the server to process
Authentication Methods for LDAPv3 Nov. 14, 2001
the certificate. The means by which servers validate certificate the certificate. The means by which servers validate certificate
paths is outside the scope of this document. paths is outside the scope of this document.
A server MAY support mappings for certificates in which the subject A server MAY support mappings for certificates in which the subject
field name is different from the name of the user's directory entry. 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 A server which supports mappings of names MUST be capable of being
configured to support certificates for which no mapping is required. configured to support certificates for which no mapping is required.
The client will use the Start TLS operation [5] to negotiate the use 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 of TLS security [6] on the connection to the LDAP server. The client
skipping to change at page 23, line 42 skipping to change at page 21, line 5
the server can perform these checks. the server can perform these checks.
Following the successful completion of TLS negotiation, the client Following the successful completion of TLS negotiation, the client
will send an LDAP bind request with the SASL "EXTERNAL" mechanism. will send an LDAP bind request with the SASL "EXTERNAL" mechanism.
10. TLS Ciphersuites 10. TLS Ciphersuites
The following ciphersuites defined in [6] MUST NOT be used for The following ciphersuites defined in [6] MUST NOT be used for
confidentiality protection of passwords or data: confidentiality protection of passwords or data:
Authentication Methods for LDAPv3 Mar. 1, 2002
TLS_NULL_WITH_NULL_NULL TLS_NULL_WITH_NULL_NULL
TLS_RSA_WITH_NULL_MD5 TLS_RSA_WITH_NULL_MD5
TLS_RSA_WITH_NULL_SHA TLS_RSA_WITH_NULL_SHA
The following ciphersuites defined in [6] can be cracked easily The following ciphersuites defined in [6] can be cracked easily
(less than a day of CPU time on a standard CPU in 2000). These (less than a day of CPU time on a standard CPU in 2000). These
ciphersuites are NOT RECOMMENDED for use in confidentiality ciphersuites are NOT RECOMMENDED for use in confidentiality
protection of passwords or data. Client and server implementers protection of passwords or data. Client and server implementers
SHOULD carefully consider the value of the password or data being SHOULD carefully consider the value of the password or data being
protected before using these ciphersuites: protected before using these ciphersuites:
TLS_RSA_EXPORT_WITH_RC4_40_MD5 TLS_RSA_EXPORT_WITH_RC4_40_MD5
TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5 TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5
TLS_RSA_EXPORT_WITH_DES40_CBC_SHA TLS_RSA_EXPORT_WITH_DES40_CBC_SHA
TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA
TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA
TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
Authentication Methods for LDAPv3 Nov. 14, 2001
TLS_DHE_RSA_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_RC4_40_MD5
TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
The following ciphersuites are vulnerable to man-in-the-middle The following ciphersuites are vulnerable to man-in-the-middle
attacks, and SHOULD NOT be used to protect passwords or sensitive attacks, and SHOULD NOT be used to protect passwords or sensitive
data, unless the network configuration is such that the danger of a data, unless the network configuration is such that the danger of a
man-in-the-middle attack is tolerable: man-in-the-middle attack is tolerable:
TLS_DH_anon_EXPORT_WITH_RC4_40_MD5 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
skipping to change at page 24, line 37 skipping to change at page 21, line 55
Security issues are discussed throughout this memo; the Security issues are discussed throughout this memo; the
(unsurprising) conclusion is that mandatory security is important, (unsurprising) conclusion is that mandatory security is important,
and that session encryption is required when snooping is a problem. and that session encryption is required when snooping is a problem.
Servers are encouraged to prevent modifications by anonymous users. Servers are encouraged to prevent modifications by anonymous users.
Servers may also wish to minimize denial of service attacks by Servers may also wish to minimize denial of service attacks by
timing out idle connections, and returning the unwillingToPerform timing out idle connections, and returning the unwillingToPerform
result code rather than performing computationally expensive result code rather than performing computationally expensive
operations requested by unauthorized clients. operations requested by unauthorized clients.
Operational experience shows that clients can misuse unauthenticated
access (simple bind with name but no password). For this reason,
aervers SHOULD by default reject authentication requests that have a
DN with an empty password with an error of invalidCredentials.
Authentication Methods for LDAPv3 Mar. 1, 2002
Access control MUST only be applied to authenticated clients and
SHOULD be applied when reading sensitive information or updating
directory information.
A connection on which the client has not performed the Start TLS A connection on which the client has not performed the Start TLS
operation or negotiated a suitable SASL mechanism for connection operation or negotiated a suitable SASL mechanism for connection
integrity and encryption services is subject to man-in-the-middle integrity and encryption services is subject to man-in-the-middle
attacks to view and modify information in transit. attacks to view and modify information in transit.
11.1. Start TLS Security Considerations 11.1. Start TLS Security Considerations
The goals of using the TLS protocol with LDAP are to ensure The goals of using the TLS protocol with LDAP are to ensure
connection confidentiality and integrity, and to optionally provide connection confidentiality and integrity, and to optionally provide
for authentication. TLS expressly provides these capabilities, as for authentication. TLS expressly provides these capabilities, as
skipping to change at page 25, line 4 skipping to change at page 22, line 32
All security gained via use of the Start TLS operation is gained by All security gained via use of the Start TLS operation is gained by
the use of TLS itself. The Start TLS operation, on its own, does not the use of TLS itself. The Start TLS operation, on its own, does not
provide any additional security. provide any additional security.
The use of TLS does not provide or ensure for confidentiality and/or The use of TLS does not provide or ensure for confidentiality and/or
non-repudiation of the data housed by an LDAP-based directory non-repudiation of the data housed by an LDAP-based directory
server. Nor does it secure the data from inspection by the server server. Nor does it secure the data from inspection by the server
administrators. Once established, TLS only provides for and ensures administrators. Once established, TLS only provides for and ensures
confidentiality and integrity of the operations and data in transit confidentiality and integrity of the operations and data in transit
Authentication Methods for LDAPv3 Nov. 14, 2001
over the LDAP association, and only if the implementations on the over the LDAP association, and only if the implementations on the
client and server support and negotiate it. client and server support and negotiate it.
The level of security provided though the use of TLS depends The level of security provided though the use of TLS depends
directly on both the quality of the TLS implementation used and the directly on both the quality of the TLS implementation used and the
style of usage of that implementation. Additionally, an active- style of usage of that implementation. Additionally, an active-
intermediary attacker can remove the Start TLS extended operation intermediary attacker can remove the Start TLS extended operation
from the supportedExtension attribute of the root DSE. Therefore, from the supportedExtension attribute of the root DSE. Therefore,
both parties SHOULD independently ascertain and consent to the both parties SHOULD independently ascertain and consent to the
security level achieved once TLS is established and before beginning security level achieved once TLS is established and before beginning
skipping to change at page 25, line 33 skipping to change at page 23, line 5
Client and server implementors SHOULD take measures to ensure proper Client and server implementors SHOULD take measures to ensure proper
protection of credentials and other confidential data where such protection of credentials and other confidential data where such
measures are not otherwise provided by the TLS implementation. measures are not otherwise provided by the TLS implementation.
Server implementors SHOULD allow for server administrators to elect Server implementors SHOULD allow for server administrators to elect
whether and when connection confidentiality and/or integrity is whether and when connection confidentiality and/or integrity is
required, as well as elect whether and when client authentication required, as well as elect whether and when client authentication
via TLS is required. via TLS is required.
Authentication Methods for LDAPv3 Mar. 1, 2002
Additional security considerations relating to the EXTERNAL Additional security considerations relating to the EXTERNAL
mechanism to negotiate TLS can be found in [SASL] and [6]. mechanism to negotiate TLS can be found in [SASL] and [6].
12. Acknowledgements 12. Acknowledgements
This document combines information originally contained in RFC 2829, This document combines information originally contained in RFC 2829,
RFC 2830 and portions of RFC 2251. The author acknowledges the work RFC 2830 and portions of RFC 2251. The author acknowledges the work
of Harald Tveit Alvestrand, Jeff Hodges, Tim Howes, Steve Kille, RL of Harald Tveit Alvestrand, Jeff Hodges, Tim Howes, Steve Kille, RL
"Bob" Morgan , and Mark Wahl, each of whom authored one or more of "Bob" Morgan , and Mark Wahl, each of whom authored one or more of
these documents. RFC 2829 and RFC 2830 were products of the IETF these documents. RFC 2829 and RFC 2830 were products of the IETF
skipping to change at page 26, line 5 skipping to change at page 23, line 31
group. The contributions of its members is greatly appreciated. group. The contributions of its members is greatly appreciated.
13. Bibliography 13. Bibliography
[ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997. Specifications: ABNF", RFC 2234, November 1997.
[IPSEC] Kent, S. and R. Atkinson, "Security Architecture for the [IPSEC] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998. Internet Protocol", RFC 2401, November 1998.
Authentication Methods for LDAPv3 Nov. 14, 2001
[LDAPDN] Zeilenga, Kurt D., "Lightweight Directory Access Protocol [LDAPDN] Zeilenga, Kurt D., "Lightweight Directory Access Protocol
(v3): UTF-8 String Representation of Distinguished Names", (v3): UTF-8 String Representation of Distinguished Names",
draft-ietf-ldapbis-dn-06.txt, July, 2001. draft-ietf-ldapbis-dn-06.txt, July, 2001.
[LDAPv3] Wahl, M., Kille S. and T. Howes, "Lightweight Directory [Protocol] Wahl, M., Kille S. and T. Howes, "Lightweight Directory
Access Protocol (v3)", RFC 2251, December 1997. Access Protocol (v3)", RFC 2251, December 1997.
[RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828, May [RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828, May
2000. 2000.
[RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the [RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998. Internet Protocol", RFC 2401, November 1998.
[RFC2831] Leach, P. and C. Newman, "Using Digest Authentication as a [RFC2831] Leach, P. and C. Newman, "Using Digest Authentication as a
SASL Mechanism", RFC 2831, May 2000. SASL Mechanism", RFC 2831, May 2000.
[ReqsKeywords] Bradner, S., "Key Words for use in RFCs to Indicate [ReqsKeywords] Bradner, S., "Key Words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[ROADMAP] K. Zeilenga (editor), "LDAP: Technical Specification Road
Map", draft-ietf-ldapbis-roadmap-xx.txt (a work in progress).
[SASL] Myers, J., "Simple Authentication and Security Layer (SASL)", [SASL] Myers, J., "Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997. RFC 2222, October 1997.
[TLS] Dierks, T. and C. Allen. "The TLS Protocol Version 1.0", RFC [TLS] Dierks, T. and C. Allen. "The TLS Protocol Version 1.0", RFC
2246, January 1999. 2246, January 1999.
Authentication Methods for LDAPv3 Mar. 1, 2002
14. Author's Address 14. Author's Address
Roger Harrison Roger Harrison
Novell, Inc. Novell, Inc.
1800 S. Novell Place 1800 S. Novell Place
Provo, UT 84606 Provo, UT 84606
+1 801 861 2642 +1 801 861 2642
roger_harrison@novell.com roger_harrison@novell.com
15. Full Copyright Statement 15. Full Copyright Statement
skipping to change at page 27, line 5 skipping to change at page 24, line 34
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than followed, or as required to translate it into languages other than
English. English.
Authentication Methods for LDAPv3 Nov. 14, 2001
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
skipping to change at page 27, line 30 skipping to change at page 25, line 4
Internet, and have different security requirements. (In the Internet, and have different security requirements. (In the
following discussion, "sensitive data" refers to information whose following discussion, "sensitive data" refers to information whose
disclosure, alteration, destruction, or loss would adversely affect disclosure, alteration, destruction, or loss would adversely affect
the interests or business of its owner or user. Also note that there the interests or business of its owner or user. Also note that there
may be data that is protected but not sensitive.) This is not may be data that is protected but not sensitive.) This is not
intended to be a comprehensive list; other scenarios are possible, intended to be a comprehensive list; other scenarios are possible,
especially on physically protected networks. especially on physically protected networks.
(1) A read-only directory, containing no sensitive data, accessible (1) A read-only directory, containing no sensitive data, accessible
to "anyone", and TCP connection hijacking or IP spoofing is not to "anyone", and TCP connection hijacking or IP spoofing is not
Authentication Methods for LDAPv3 Mar. 1, 2002
a problem. This directory requires no security functions except a problem. This directory requires no security functions except
administrative service limits. administrative service limits.
(2) A read-only directory containing no sensitive data; read access (2) A read-only directory containing no sensitive data; read access
is granted based on identity. TCP connection hijacking is not is granted based on identity. TCP connection hijacking is not
currently a problem. This scenario requires data confidentiality currently a problem. This scenario requires data confidentiality
for sensitive authentication information AND data integrity for for sensitive authentication information AND data integrity for
all authentication information. all authentication information.
(3) A read-only directory containing no sensitive data; and the (3) A read-only directory containing no sensitive data; and the
skipping to change at page 28, line 4 skipping to change at page 25, line 35
sensitive authentication information AND data integrity for all sensitive authentication information AND data integrity for all
authentication information. authentication information.
(5) A directory containing sensitive data. This scenario requires (5) A directory containing sensitive data. This scenario requires
data confidentiality protection AND secure authentication. data confidentiality protection AND secure authentication.
Appendix B. Authentication and Authorization: Definitions and Concepts Appendix B. Authentication and Authorization: Definitions and Concepts
This appendix defines basic terms, concepts, and interrelationships This appendix defines basic terms, concepts, and interrelationships
regarding authentication, authorization, credentials, and identity. regarding authentication, authorization, credentials, and identity.
Authentication Methods for LDAPv3 Nov. 14, 2001
These concepts are used in describing how various security These concepts are used in describing how various security
approaches are utilized in client authentication and authorization. approaches are utilized in client authentication and authorization.
B.1. Access Control Policy B.1. Access Control Policy
An access control policy is a set of rules defining the protection An access control policy is a set of rules defining the protection
of resources, generally in terms of the capabilities of persons or of resources, generally in terms of the capabilities of persons or
other entities accessing those resources. A common expression of an other entities accessing those resources. A common expression of an
access control policy is an access control list. Security objects access control policy is an access control list. Security objects
and mechanisms, such as those described here, enable the expression and mechanisms, such as those described here, enable the expression
of access control policies and their enforcement. Access control of access control policies and their enforcement. Access control
policies are typically expressed in terms of access control policies are typically expressed in terms of access control
attributes as described below. attributes as described below.
B.2. Access Control Factors B.2. Access Control Factors
A request, when it is being processed by a server, may be associated 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 with a wide variety of security-related factors (section 4.2 of
[LDAPv3]). The server uses these factors to determine whether and [Protocol]). The server uses these factors to determine whether and
how to process the request. These are called access control factors how to process the request. These are called access control factors
(ACFs). They might include source IP address, encryption strength, (ACFs). They might include source IP address, encryption strength,
the type of operation being requested, time of day, etc. Some the type of operation being requested, time of day, etc. Some
factors may be specific to the request itself, others may be factors may be specific to the request itself, others may be
Authentication Methods for LDAPv3 Mar. 1, 2002
associated with the connection via which the request is transmitted, associated with the connection via which the request is transmitted,
others (e.g. time of day) may be "environmental". others (e.g. time of day) may be "environmental".
Access control policies are expressed in terms of access control Access control policies are expressed in terms of access control
factors. E.g., a request having ACFs i,j,k can perform operation Y 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 on resource Z. The set of ACFs that a server makes available for
such expressions is implementation-specific. such expressions is implementation-specific.
B.3. Authentication, Credentials, Identity B.3. Authentication, Credentials, Identity
skipping to change at page 29, line 4 skipping to change at page 26, line 36
the parties. For example: X.509 certificates, Kerberos tickets, the parties. For example: X.509 certificates, Kerberos tickets,
simple identity and password pairs. Note that an authentication simple identity and password pairs. Note that an authentication
mechanism may constrain the form of authentication identities used mechanism may constrain the form of authentication identities used
with it. with it.
B.4. Authorization Identity B.4. Authorization Identity
An authorization identity is one kind of access control factor. It An authorization identity is one kind of access control factor. It
is the name of the user or other entity that requests that is the name of the user or other entity that requests that
operations be performed. Access control policies are often expressed operations be performed. Access control policies are often expressed
Authentication Methods for LDAPv3 Nov. 14, 2001
in terms of authorization identities; e.g., entity X can perform in terms of authorization identities; e.g., entity X can perform
operation Y on resource Z. operation Y on resource Z.
The authorization identity bound to an association is often exactly The authorization identity bound to an association is often exactly
the same as the authentication identity presented by the client, but the same as the authentication identity presented by the client, but
it may be different. SASL allows clients to specify an authorization it may be different. SASL allows clients to specify an authorization
identity distinct from the authentication identity asserted by the identity distinct from the authentication identity asserted by the
client's credentials. This permits agents such as proxy servers to client's credentials. This permits agents such as proxy servers to
authenticate using their own credentials, yet request the access authenticate using their own credentials, yet request the access
privileges of the identity for which they are proxying [SASL]. Also, privileges of the identity for which they are proxying [SASL]. Also,
skipping to change at page 29, line 29 skipping to change at page 27, line 4
to be done. The method by which a server composes and validates an to be done. The method by which a server composes and validates an
authorization identity from the authentication credentials supplied authorization identity from the authentication credentials supplied
by a client is implementation-specific. by a client is implementation-specific.
Appendix C. RFC 2829 Change History Appendix C. RFC 2829 Change History
This appendix lists the changes made to the text of RFC 2829 in This appendix lists the changes made to the text of RFC 2829 in
preparing this document. preparing this document.
C.0. General Editorial Changes C.0. General Editorial Changes
Authentication Methods for LDAPv3 Mar. 1, 2002
Version -00 Version -00
- Changed other instances of the term LDAP to LDAPv3 where v3 of - Changed other instances of the term LDAP to LDAPv3 where v3 of
the protocol is implied. Also made all references to LDAPv3 use the protocol is implied. Also made all references to LDAPv3 use
the same wording. the same wording.
- Miscellaneous grammatical changes to improve readability. - Miscellaneous grammatical changes to improve readability.
- Made capitalization in section headings consistent. - Made capitalization in section headings consistent.
skipping to change at page 30, line 4 skipping to change at page 27, line 36
C.2. Changes to Section 2 C.2. Changes to Section 2
Version -01 Version -01
- Moved section to an appendix. - Moved section to an appendix.
C.3. Changes to Section 3 C.3. Changes to Section 3
Version -01 Version -01
Authentication Methods for LDAPv3 Nov. 14, 2001
- Moved section to an appendix. - Moved section to an appendix.
C.4 Changes to Section 4 C.4 Changes to Section 4
Version -00 Version -00
- Changed "Distinguished Name" to "LDAP distinguished name". - Changed "Distinguished Name" to "LDAP distinguished name".
C.5. Changes to Section 5 C.5. Changes to Section 5
Version -00 Version -00
- Added the following sentence: "Servers SHOULD NOT allow clients - Added the following sentence: "Servers SHOULD NOT allow clients
with anonymous authentication to modify directory entries or with anonymous authentication to modify directory entries or
access sensitive information in directory entries." access sensitive information in directory entries."
C.5.1. Changes to Section 5.1 C.5.1. Changes to Section 5.1
Version -00 Version -00
Authentication Methods for LDAPv3 Mar. 1, 2002
- Replaced the text describing the procedure for performing an - Replaced the text describing the procedure for performing an
anonymous bind (protocol) with a reference to section 4.2 of RFC anonymous bind (protocol) with a reference to section 4.2 of RFC
2251 (the protocol spec). 2251 (the protocol spec).
Version -01 Version -01
- Brought text describing procedure for performing an anonymous - Brought text describing procedure for performing an anonymous
bind from section 4.2 of RFC 2251 bis. This text will be bind from section 4.2 of RFC 2251 bis. This text will be
removed from the draft standard version of that document. removed from the draft standard version of that document.
skipping to change at page 30, line 54 skipping to change at page 28, line 34
section 6.1. Added sentences to the paragraph indicating: section 6.1. Added sentences to the paragraph indicating:
a. simple authentication is not suitable for environments where a. simple authentication is not suitable for environments where
confidentiality is not available. confidentiality is not available.
b. LDAP implementations SHOULD NOT support simple b. LDAP implementations SHOULD NOT support simple
authentication unless confidentiality and data integrity authentication unless confidentiality and data integrity
mechanisms are in force. mechanisms are in force.
2. Moved first paragraph of section 6 (beginning with "LDAP 2. Moved first paragraph of section 6 (beginning with "LDAP
implementations MUST support authentication with a passwordÓ") to implementations MUST support authentication with a passwordÓ")
section on Digest Authentication (Now section 6.2). to section on Digest Authentication (Now section 6.2).
C.6.1. Changes to Section 6.1. C.6.1. Changes to Section 6.1.
Authentication Methods for LDAPv3 Nov. 14, 2001
Version -00 Renamed section to 6.2 Version -00 Renamed section to 6.2
- Added sentence from original section 6 indicating that the - Added sentence from original section 6 indicating that the
DIGEST-MD5 SASL mechanism is required for all conforming LDAPv3 DIGEST-MD5 SASL mechanism is required for all conforming LDAPv3
implementations implementations
C.6.2. Changes to Section 6.2 C.6.2. Changes to Section 6.2
Version -00 Version -00
- Renamed section to 6.3 - Renamed section to 6.3
- Reworded first paragraph to remove reference to user and the - Reworded first paragraph to remove reference to user and the
userPassword password attribute Made the first paragraph more userPassword password attribute Made the first paragraph more
general by simply saying that if a directory supports simple general by simply saying that if a directory supports simple
authentication that the simple bind operation MAY performed authentication that the simple bind operation MAY performed
following negotiation of a TLS ciphersuite that supports following negotiation of a TLS ciphersuite that supports
confidentiality. confidentiality.
Authentication Methods for LDAPv3 Mar. 1, 2002
- Replaced "the name of the user's entry" with "a DN" since not - Replaced "the name of the user's entry" with "a DN" since not
all bind operations are performed on behalf of a "user." all bind operations are performed on behalf of a "user."
- Added Section 6.3.1 heading just prior to paragraph 5. - Added Section 6.3.1 heading just prior to paragraph 5.
- Paragraph 5: replaced "The server" with "DSAs that map the DN - Paragraph 5: replaced "The server" with "DSAs that map the DN
sent in the bind request to a directory entry with a sent in the bind request to a directory entry with a
userPassword attribute." userPassword attribute."
C.6.3. Changes to section 6.3. C.6.3. Changes to section 6.3.
skipping to change at page 32, line 5 skipping to change at page 29, line 41
"to have issued the certificate" immediately after "to have issued the certificate" immediately after
"Certification Authority." "Certification Authority."
C.8. Changes to section 8. C.8. Changes to section 8.
Version -00 Version -00
- Removed the first paragraph because simple authentication is - Removed the first paragraph because simple authentication is
covered explicitly in section 6. covered explicitly in section 6.
Authentication Methods for LDAPv3 Nov. 14, 2001
- Added section 8.1. heading just prior to second paragraph. - Added section 8.1. heading just prior to second paragraph.
- Added section 8.2. heading just prior to third paragraph. - Added section 8.2. heading just prior to third paragraph.
- Added section 8.3. heading just prior to fourth paragraph. - Added section 8.3. heading just prior to fourth paragraph.
Version -01 Version -01
- Moved entire section 8 of RFC 2829 into section 3.4 (Using SASL - Moved entire section 8 of RFC 2829 into section 3.4 (Using SASL
for Other Security Services) to bring material on SASL for Other Security Services) to bring material on SASL
mechanisms together into one location. mechanisms together into one location.
C.9. Changes to section 9. C.9. Changes to section 9.
Version -00 Version -00
- Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL - Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL
mechanism." mechanism."
Authentication Methods for LDAPv3 Mar. 1, 2002
- Added section 9.1. heading. - Added section 9.1. heading.
- Modified a comment in the ABNF from "unspecified userid" to - Modified a comment in the ABNF from "unspecified userid" to
"unspecified authz id". "unspecified authz id".
- Deleted sentence, "A utf8string is defined to be the UTF-8 - Deleted sentence, "A utf8string is defined to be the UTF-8
encoding of one or more ISO 10646 characters," because it is encoding of one or more ISO 10646 characters," because it is
redundant. redundant.
skipping to change at page 33, line 5 skipping to change at page 30, line 39
be a day of CPU time in 2000. be a day of CPU time in 2000.
- Added text: "These ciphersuites are NOT RECOMMENDED for use... - Added text: "These ciphersuites are NOT RECOMMENDED for use...
and server implementers SHOULD" to sentence just prior the and server implementers SHOULD" to sentence just prior the
second list of ciphersuites. second list of ciphersuites.
- Added text: "and MAY support other ciphersuites offering - Added text: "and MAY support other ciphersuites offering
equivalent or better protection," to the last paragraph of the equivalent or better protection," to the last paragraph of the
section. section.
Authentication Methods for LDAPv3 Nov. 14, 2001
C.11. Changes to Section 11. C.11. Changes to Section 11.
Version -01 Version -01
- Moved to section 3.6 to be with other SASL material. - Moved to section 3.6 to be with other SASL material.
C.12. Changes to Section 12. C.12. Changes to Section 12.
Version -00 Version -00
- Inserted new section 12 that specifies when SASL protections - Inserted new section 12 that specifies when SASL protections
begin following SASL negotiation, etc. The original section 12 begin following SASL negotiation, etc. The original section 12
is renumbered to become section 13. is renumbered to become section 13.
Version -01 Version -01
- Moved to section 3.7 to be with other SASL material. - Moved to section 3.7 to be with other SASL material.
C.13. Changes to Section 13 (original section 12). C.13. Changes to Section 13 (original section 12).
Authentication Methods for LDAPv3 Mar. 1, 2002
None None
Appendix D. RFC 2830 Change History Appendix D. RFC 2830 Change History
This appendix lists the changes made to the text of RFC 2830 in This appendix lists the changes made to the text of RFC 2830 in
preparing this document. preparing this document.
D.0. General Editorial Changes D.0. General Editorial Changes
- Material showing the PDUs for the Start TLS response was broken - Material showing the PDUs for the Start TLS response was broken
skipping to change at page 34, line 4 skipping to change at page 31, line 38
This appendix lists the changes made to the text of RFC 2251 in This appendix lists the changes made to the text of RFC 2251 in
preparing this document. preparing this document.
E.0. General Editorial Changes E.0. General Editorial Changes
- All material from section 4.2 of RFC 2251 was moved into this - All material from section 4.2 of RFC 2251 was moved into this
document. document.
- A new section was created for the Bind Request - A new section was created for the Bind Request
Authentication Methods for LDAPv3 Nov. 14, 2001
- Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved - Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved
after the section on the Bind Response for parallelism with the after the section on the Bind Response for parallelism with the
presentation of the Start TLS operations. The section was also presentation of the Start TLS operations. The section was also
subdivided to explicitly call out the various effects being subdivided to explicitly call out the various effects being
described within it. described within it.
- All SASL profile information from RFC 2829 was brought within - All SASL profile information from RFC 2829 was brought within
the discussion of the Bind operation (primarily sections 4.4 - the discussion of the Bind operation (primarily sections 4.4 -
4.7). 4.7).
Appendix F. Change History to Combined Document Appendix F. Change History to Combined Document
F.1. Changes for draft-ldap-bis-authmeth-02.doc F.1. Changes for draft-ldap-bis-authmeth-02.doc
General
- Added references to other LDAP standard documents, to sections
within the document, and fixed broken references.
- General editorial changes¨punctuation, spelling, formatting,
etc.
Authentication Methods for LDAPv3 Mar. 1, 2002
Section 1. Section 1.
- Added glossary of terms and added sub-section headings - Added glossary of terms and added sub-section headings
Section 2. Section 2.
- Clarified security mechanisms 3, 4, & 5 and brought language in - Clarified security mechanisms 3, 4, & 5 and brought language in
line with IETF security glossary. line with IETF security glossary.
Section 3. Section 3.
- Brought language in requirement (3) in line with security - Brought language in requirement (3) in line with security
glossary. glossary.
- Clarified that information fetched prior to initiation of TLS - Clarified that information fetched prior to initiation of TLS
negotiation must be discarded negotiation must be discarded
-Clarified that information fetched prior to initiation of SASL -Clarified that information fetched prior to initiation of SASL
negotiation must be discarded negotiation must be discarded
- Rewrote paragraph on SASL negotiation requirements to clarify - Rewrote paragraph on SASL negotiation requirements to clarify
skipping to change at page 34, line 41 skipping to change at page 32, line 31
- Clarified that information fetched prior to initiation of TLS - Clarified that information fetched prior to initiation of TLS
negotiation must be discarded negotiation must be discarded
-Clarified that information fetched prior to initiation of SASL -Clarified that information fetched prior to initiation of SASL
negotiation must be discarded negotiation must be discarded
- Rewrote paragraph on SASL negotiation requirements to clarify - Rewrote paragraph on SASL negotiation requirements to clarify
intent intent
Section 4.4. Section 4.4.
- Added stipulation that sasl choice allows for any SASL mechanism - Added stipulation that sasl choice allows for any SASL mechanism
not prohibited by this document. (Resolved conflict between this not prohibited by this document. (Resolved conflict between this
statement and one that prohibited use of ANONYMOUS and PLAIN statement and one that prohibited use of ANONYMOUS and PLAIN
SASL mechanisms.) SASL mechanisms.)
Section 5.3.6 Section 5.3.6
- Added a.x.bar.com to wildcard matching example on hostname - Added a.x.bar.com to wildcard matching example on hostname
check. check.
Section 6 Section 6
- Added LDAP Association State Transition Tables to show the - Added LDAP Association State Transition Tables to show the
various states through which an LDAP association may pass along various states through which an LDAP association may pass along
with the actions and decisions required to traverse from state with the actions and decisions required to traverse from state
to state. to state.
Appendix A Appendix A
- Brought security terminology in line with IETF security glossary - Brought security terminology in line with IETF security glossary
throughout the appendix. throughout the appendix.
Authentication Methods for LDAPv3 Nov. 14, 2001 F.2. Changes for draft-ldap-bis-authmeth-03.doc
General General
- Added references to other LDAP standard documents, to sections Authentication Methods for LDAPv3 Mar. 1, 2002
within the document, and fixed broken references.
- General editorial changes¨punctuation, spelling, formatting, - Added introductory notes and changed title of document and
etc. references to conform to WG chair suggestions for the overall
technical specification.
- Several issues--G.13, G.14, G.16, G.17--were resolved without
requiring changes to the document.
Section 3
- Removed reference to /etc/passwd file and associated text.
Section 4
- Removed sections 4.1, 4.2 and parts of section 4.3. This
information was being duplicated in the protocol specification
and will now reside there permanently.
Section 4.2
- changed words, "not recommended" to "strongly discouraged"
Section 4.3
- Based on ldapbis WG discussion at IETF52 two sentences were
added indicating that clients SHOULD NOT send a DN value when
binding with the sasl choice and servers SHALL ignore any value
received in this circumstance.
-
Section 8.3.1
- Generalized the language of this section to not refer to any
specific password attribute or to refer to the directory entry
as a "user" entry.
Section 11
- Added security consideration regarding misuse of unauthenticated
access.
- Added security consideration requiring access control to be
applied only to authenticated users and recommending it be
applied when reading sensitive information or updating directory
information.
Appendix G. Issues to be Resolved Appendix G. Issues to be Resolved
This appendix lists open questions and issues that need to be This appendix lists open questions and issues that need to be
resolved before work on this document is deemed complete. resolved before work on this document is deemed complete.
G.1. G.1.
Authentication Methods for LDAPv3 Mar. 1, 2002
Section 1 lists 6 security mechanisms that can be used by LDAP Section 1 lists 6 security mechanisms that can be used by LDAP
servers. I'm not sure what mechanism 5, "Resource limitation by servers. I'm not sure what mechanism 5, "Resource limitation by
means of administrative limits on service controls" means. means of administrative limits on service controls" means.
Status: resolved. Changed wording to "administrative service limits" Status: resolved. Changed wording to "administrative service limits"
to clarify meaning. to clarify meaning.
G.2. G.2.
Section 2 paragraph 1 defines the term, "sensitive." Do we want to Section 2 paragraph 1 defines the term, "sensitive." Do we want to
skipping to change at page 36, line 5 skipping to change at page 34, line 44
Section 3, deployment scenario 3: What is meant by the phrase, Section 3, deployment scenario 3: What is meant by the phrase,
"directory data is authenticated by the server?" "directory data is authenticated by the server?"
Status: resolved. I interpreted this to mean the ability to ensure Status: resolved. I interpreted this to mean the ability to ensure
the identity of the directory server and the integrity of the data the identity of the directory server and the integrity of the data
sent from that server to the client, and explictly stated such. sent from that server to the client, and explictly stated such.
G.5. G.5.
Authentication Methods for LDAPv3 Nov. 14, 2001
Section 4 paragraph 3: What is meant by the phrase, "this means that Section 4 paragraph 3: What is meant by the phrase, "this means that
either this data is useless for faking authentication (like the Unix either this data is useless for faking authentication (like the Unix
"/etc/passwd" file format used to be)?" "/etc/passwd" file format used to be)?"
Status: resolved. Discussion at IETF 52 along with discussions with
the original authors of this material have convinced us that this
reference is simply too arcane to be left in place. In -03 the text
has been modified to focus on the need to either update password
information in a protected fashion outside of the protocol or to
update it in session well protected against snooping, and the
reference to /etc/passwd has been removed.
G.6. G.6.
Authentication Methods for LDAPv3 Mar. 1, 2002
Section 4 paragraph 7 begins: "For a directory needing session Section 4 paragraph 7 begins: "For a directory needing session
protection..." Is this referring to data confidentiality or data protection..." Is this referring to data confidentiality or data
integrity or both? integrity or both?
Status: resolved. Changed wording to say, "For a directory needing Status: resolved. Changed wording to say, "For a directory needing
data security (both data integrity and data confidentiality)..." data security (both data integrity and data confidentiality)..."
G.7. G.7.
Section 4 paragraph 8 indicates that "information about the server Section 4 paragraph 8 indicates that "information about the server
skipping to change at page 37, line 5 skipping to change at page 35, line 54
Approach 2: Clients MUST check the supportedSASLMechanisms list Approach 2: Clients MUST check the supportedSASLMechanisms list
both before and after SASL negotiation UNLESS they use a both before and after SASL negotiation UNLESS they use a
different trusted source to determine available supported SASL different trusted source to determine available supported SASL
mechanisms. mechanisms.
Status: Resolved. WG input at IETF 51 was that Approach 1 was Status: Resolved. WG input at IETF 51 was that Approach 1 was
probably best. I ended up keeping the basic structure similar to the probably best. I ended up keeping the basic structure similar to the
original to meet this intent. original to meet this intent.
Authentication Methods for LDAPv3 Nov. 14, 2001
G.9. G.9.
Section 6.3.1 states: "DSAs that map the DN sent in the bind request Section 6.3.1 states: "DSAs that map the DN sent in the bind request
to a directory entry with a userPassword attribute will... compare to a directory entry with a userPassword attribute will... compare
[each value in the named user's entry]... with the presented [each value in the named user's entry]... with the presented
password." This implies that this this applies only to user entries password." This implies that this this applies only to user entries
Authentication Methods for LDAPv3 Mar. 1, 2002
with userPassword attributes. What about other types of entries with userPassword attributes. What about other types of entries
that might allow passwords and might store in the password that might allow passwords and might store in the password
information in other attributes? Do we want to make this text more information in other attributes? Do we want to make this text more
general? general?
Status: Resolved in -03 draft by generalizing section 8.3.1 to not
refer to any specific password attribute and by removing the term
"user" in referring to the directory entry specified by the DN in
the bind request.
G.10 userPassword and simple bind G.10 userPassword and simple bind
We need to be sure that we don't require userPassword to be the only We need to be sure that we don't require userPassword to be the only
attribute used for authenticating via simple bind. (See 2251 sec 4.2 attribute used for authenticating via simple bind. (See 2251 sec 4.2
and authmeth 6.3.1. Work with Jim Sermersheim on resolution to this. and authmeth 6.3.1. Work with Jim Sermersheim on resolution to this.
On publication state something like: "This is the specific On publication state something like: "This is the specific
implementation of what we discussed in our general reorg implementation of what we discussed in our general reorg
conversation on the list." (Source: Kurt Zeilenga) conversation on the list." (Source: Kurt Zeilenga)
Status: Resolved in -03 draft by generalizing section 8.3.1 to not
refer to any specific password attribute and by removing the term
"user" in referring to the directory entry specified by the DN in
the bind request.
G.11. Meaning of LDAP Association G.11. Meaning of LDAP Association
The original RFC 2830 uses the term "LDAP association" in describing The original RFC 2830 uses the term "LDAP association" in describing
a connection between an LDAP client and server regardless of the a connection between an LDAP client and server regardless of the
state of TLS on that connection. This term needs to be defined or state of TLS on that connection. This term needs to be defined or
possibly changed. possibly changed.
Status: Resolved. at IETF 51 Bob Morgan indicated that the term Status: Resolved. at IETF 51 Bob Morgan indicated that the term
"LDAP association" was intended to distinguish the LDAP-level "LDAP association" was intended to distinguish the LDAP-level
connection from the TLS-level connection. This still needs to be connection from the TLS-level connection. This still needs to be
skipping to change at page 37, line 55 skipping to change at page 37, line 4
MD5: MD5:
"6.2. Digest authentication "6.2. Digest authentication
LDAP implementations MUST support authentication with a password LDAP implementations MUST support authentication with a password
using the DIGEST-MD5 SASL mechanism for password protection, as using the DIGEST-MD5 SASL mechanism for password protection, as
defined in section 6.1." defined in section 6.1."
The thing is for acl it would be nice (though not critical) to be The thing is for acl it would be nice (though not critical) to be
able to default the required authentication level for a subject to a able to default the required authentication level for a subject to a
Authentication Methods for LDAPv3 Mar. 1, 2002
single "fairly secure" mechanism--if there is no such mandatory single "fairly secure" mechanism--if there is no such mandatory
authentication scheme then you cannot do that. (Source: Rob Byrne) authentication scheme then you cannot do that. (Source: Rob Byrne)
Status: resolved. -00 version of the draft added a sentence at the
beginning of section 8.2 stating that LDAP server implementations
must support this method.
G.13. Ordering of authentication levels requested G.13. Ordering of authentication levels requested
Authentication Methods for LDAPv3 Nov. 14, 2001
Again on the subject of authentication level, is it possible to Again on the subject of authentication level, is it possible to
define an ordering on authentication levels which defines their define an ordering on authentication levels which defines their
relative "strengths" ? This would be useful in acl as you could say relative "strengths" ? This would be useful in acl as you could say
things like"a given aci grants access to a given subject at this things like"a given aci grants access to a given subject at this
authentication level AND ABOVE". David Chadwick raised this before authentication level AND ABOVE". David Chadwick raised this before
in the context of denying access to a subject at a given in the context of denying access to a subject at a given
authentication level, in which case he wanted to express "deny authentication level, in which case he wanted to express "deny
access to this subject at this authentication level AND TO ALL access to this subject at this authentication level AND TO ALL
IDENTITIES AUTHENTICATED BELOW THAT LEVEL". (Source: Rob Byrne) IDENTITIES AUTHENTICATED BELOW THAT LEVEL". (Source: Rob Byrne)
Status: out of scope. This is outside the scope of this document and
will not be addressed.
G.14. Document vulnerabilities of various mechanisms G.14. Document vulnerabilities of various mechanisms
While I'm here...in 2829, I think it would be good to have some While I'm here...in 2829, I think it would be good to have some
comments or explicit reference to a place where the security comments or explicit reference to a place where the security
properties of the particular mandatory authentication schemes are properties of the particular mandatory authentication schemes are
outlined. When I say "security properties" I mean stuff like "This outlined. When I say "security properties" I mean stuff like "This
scheme is vulnerable to such and such attacks, is only safe if the scheme is vulnerable to such and such attacks, is only safe if the
key size is > 50, this hash is widely considered the best, etc...". key size is > 50, this hash is widely considered the best, etc...".
I think an LDAP implementor is likely to be interested in that I think an LDAP implementor is likely to be interested in that
information, without having to wade through the security RFCs. information, without having to wade through the security RFCs.
(Source: Rob Byrne) (Source: Rob Byrne)
Status: out of scope. This is outside the scope of this document and
will not be addressed.
G.15. Include a StartTLS state transition table G.15. Include a StartTLS state transition table
The pictoral representation it is nominally based on is here (URL The pictoral representation it is nominally based on is here (URL
possibly folded): possibly folded):
http://www.stanford.edu/~hodges/doc/LDAPAssociationStateDiagram- http://www.stanford.edu/~hodges/doc/LDAPAssociationStateDiagram-
1999-12-14.html 1999-12-14.html
(Source: Jeff Hodges) (Source: Jeff Hodges)
Status: Table provided. Final review of content for accuracy is Status: Table provided. Final review of content for accuracy is
still needed. still needed.
G.16. Empty sasl credentials question G.16. Empty sasl credentials question
Authentication Methods for LDAPv3 Mar. 1, 2002
I spent some more time looking microscopically at ldap-auth-methods I spent some more time looking microscopically at ldap-auth-methods
and ldap-ext-tls drafts. The drafts say that the credential must and ldap-ext-tls drafts. The drafts say that the credential must
have the form dn:xxx or u:xxx or be absent, and although they don't have the form dn:xxx or u:xxx or be absent, and although they don't
say what to do in the case of an empty octet string I would say that say what to do in the case of an empty octet string I would say that
we could send protocolError (claim it is a bad PDU). we could send protocolError (claim it is a bad PDU).
There is still the question of what to do if the credential is 'dn:' There is still the question of what to do if the credential is 'dn:'
(or 'u:') followed by the empty string. (Source: ariel@columbia.edu (or 'u:') followed by the empty string. (Source: ariel@columbia.edu
via Jeff Hodges) via Jeff Hodges)
Status: resolved. Kurt Zeilenga indicated during ldapbis WG
discussion at IETF 52 that SASL AuthzID credentials empty and absent
are equivalent in the latest SASL ID. This resolves the issue.
G.17. Hostname check from MUST to SHOULD? G.17. Hostname check from MUST to SHOULD?
I am uneasy about the hostname check. My experience from PKI with I am uneasy about the hostname check. My experience from PKI with
HTTP probably is a contributing factor; we have people using the HTTP probably is a contributing factor; we have people using the
short hostname to get to a server which naturally has the FQDN in short hostname to get to a server which naturally has the FQDN in
the certificate, no end of problems. I have a certificate on my the certificate, no end of problems. I have a certificate on my
Authentication Methods for LDAPv3 Nov. 14, 2001
laptop which has the FQDN for the casse when the system is on our laptop which has the FQDN for the casse when the system is on our
Columbia network with a fixed IP; when I dial in however, I have Columbia network with a fixed IP; when I dial in however, I have
some horrible dialup name, and using the local https server becomes some horrible dialup name, and using the local https server becomes
annoying. Issuing a certificate in the name 'localhost' is not a annoying. Issuing a certificate in the name 'localhost' is not a
solution! Wildcard match does not solve this problem. For these solution! Wildcard match does not solve this problem. For these
reasons I am inclined to argue for 'SHOULD' instead of reasons I am inclined to argue for 'SHOULD' instead of
'MUST' in paragraph... 'MUST' in paragraph...
Also, The hostname check against the name in the certificate is a Also, The hostname check against the name in the certificate is a
very weak means of preventing man-in-the-middle attacks; the proper very weak means of preventing man-in-the-middle attacks; the proper
solution is not here yet (SecureDNS or some equivalent). Faking out solution is not here yet (SecureDNS or some equivalent). Faking out
DNS is not so hard, and we see this sort of thing in the press on a DNS is not so hard, and we see this sort of thing in the press on a
pretty regular basis, where site A hijacks the DNS server for site B pretty regular basis, where site A hijacks the DNS server for site B
and gets all their requests. Some mention of this should be made in and gets all their requests. Some mention of this should be made in
the draft. (Source: ariel@columbia.edu via Jeff Hodges) the draft. (Source: ariel@columbia.edu via Jeff Hodges)
Status: resolved. Based on discussion at IETF 52 ldapbis WG meeting,
this text will stand as it is. The check is a MUST, but the behavior
afterward is a SHOULD. This gives server implementations the room to
maneuver as needed.
G.18. Must SASL DN exist in the directory? G.18. Must SASL DN exist in the directory?
If the 'dn:' form of sasl creds is used, is it the intention of the If the 'dn:' form of sasl creds is used, is it the intention of the
draft(ers) that this DN must exist in the directory and the client draft(ers) that this DN must exist in the directory and the client
will have the privileges associated with that entry, or can the will have the privileges associated with that entry, or can the
server map the sasl DN to perhaps some other DN in the directory, server map the sasl DN to perhaps some other DN in the directory,
in an implementation-dependent fashion? in an implementation-dependent fashion?
We already know that if *no* sasl credentials are presented, the DN We already know that if *no* sasl credentials are presented, the DN
or altname in the client certificate may be mapped to a DN in an or altname in the client certificate may be mapped to a DN in an
implementation-dependent fashion, or indeed to something not in the implementation-dependent fashion, or indeed to something not in the
Authentication Methods for LDAPv3 Mar. 1, 2002
directory at all. (Right?) (Source: ariel@columbia.edu via Jeff directory at all. (Right?) (Source: ariel@columbia.edu via Jeff
Hodges) Hodges)
G.19. DN used in conjunction with SASL mechanism G.19. DN used in conjunction with SASL mechanism
We need to specify whether the DN field in Bind operation can/cannot We need to specify whether the DN field in Bind operation can/cannot
be used when SASL mechanism is specified. (source: RL Bob) be used when SASL mechanism is specified. (source: RL Bob)
Status: resolved. (-03) Based on ldapbis WG discussion at IETF52 two
sentences were added indicating that clients SHOULD NOT send a DN
value when binding with the sasl choice and servers SHALL ignore any
value received in this circumstance.
G.20. Bind states G.20. Bind states
Differences between unauthenticated and anonymous. four states you Differences between unauthenticated and anonymous. four states you
can get into. One is completely undefined (this is now explicitly can get into. One is completely undefined (this is now explicitly
called out in document). This text needs to be moved from called out in document). This text needs to be moved from
RFC2251bis to this draft. (source: Jim Sermersheim) RFC2251bis to this draft. (source: Jim Sermersheim)
G.21. Misuse of unauthenticated access
Add a security consideration that operational experience shows that
clients can misuse unauthenticated access (simple bind with name but
no password). Servers SHOULD by default reject authentication
requests that have a DN with an empty password with an error of
invalidCredentials. (Source: Kurt Zeilenga and Chris Newman (Sun))
Status: Resolved. Added to security considerations in ű03.
G.22. Need to move StartTLS protocol information to [Protocol]
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/