WDIFF

draft-ietf-ldapbis-authmeth-06.txt --> draft-ietf-ldapbis-authmeth-07.txt

INTERNET-DRAFT Editor: R. Harrison
draft-ietf-ldapbis-authmeth-06.txt
draft-ietf-ldapbis-authmeth-07.txt Novell, Inc.
Obsoletes: 2829, 2830 28 June 7 October 2003
Intended Category: Draft Standard

LDAP: Authentication Methods
and
Connection Level Security Mechanisms

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.

This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor as a Standard Track document.
Distribution of this memo is unlimited. Technical discussion of
this document will take place on the IETF LDAP Extension Working
Group mailing list <ietf-ldapbis@OpenLDAP.org>. Please send
editorial comments directly to the author
<roger_harrison@novell.com>.

Internet-Drafts are working documents of the Internet Engineering
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The list of current Internet-Drafts can be accessed at
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Abstract

This document describes LDAPv3 (Lightweight Directory Access
Protocol v3) authentication methods and connection level security
mechanisms that are required of all conforming LDAPv3 server
implementations and makes recommendations for combinations of these
mechanisms to be used in various deployment circumstances.

Among the mechanisms described are

- various forms of authentication including anonymous
authentication, password-based authentication, and certificate
based authentication
- the use of SASL mechanisms with LDAPv3

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- the use of TLS (Transport Layer Security) with LDAPv3

- the various authentication and authorization states through
which a connection to an LDAP server may pass and the actions
that trigger these state changes.

1. Introduction

This document is an integral part of the LDAP Technical
Specification [ROADMAP]. This document replaces RFC 2829 and
portions of RFC 2830. Changes to RFC 2829 are summarized in Appendix
C and changes to RFC 2830 are summarized in Appendix D.

LDAPv3 is a powerful access protocol for directories. It offers
means of searching, retrieving and manipulating directory content,
and ways to access a rich set of security functions.

It is vital that these security functions be interoperable among all
LDAP clients and servers on the Internet; therefore there has to be
a minimum subset of security functions that is common to all
implementations that claim LDAPv3 conformance.

Basic threats to an LDAP directory service include:

(1) Unauthorized access to directory data via data-retrieval
operations,

(2) Unauthorized access to reusable client authentication
information by monitoring others' access,

(3) Unauthorized access to directory data by monitoring others'
access,

(4) Unauthorized modification of directory data,

(5) Unauthorized modification of configuration information,

(6) Unauthorized or excessive use of resources (denial of service),
and

(7) Spoofing of directory: Tricking a client into believing that
information came from the directory when in fact it did not,
either by modifying data in transit or misdirecting the client's
connection. Also, tricking a client into sending privileged
information to a hostile entity that appears to be the directory
but is not.

Threats (1), (4), (5) and (6) are due to hostile clients. Threats
(2), (3) and (7) are due to hostile agents on the path between
client and server or hostile agents posing as a server.

The LDAP protocol suite can be protected with the following security
mechanisms:

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(1) Client authentication by means of the SASL [RFC2222] [SASL] mechanism set,
possibly backed by the TLS [RFC2246] credentials exchange
mechanism,

(2) Client authorization by means of access control based on the
requestor's authenticated identity,

(3) Data integrity protection by means of the TLS protocol or SASL
mechanisms that provide data integrity services,

(4) Data confidentiality protection against snooping by means of the
TLS protocol or SASL mechanisms that provide data
confidentiality services,

(5) Server resource usage limitation by means of administrative
service limits configured on the server, and

(6) Server authentication by means of the TLS protocol or SASL
mechanism.

At the moment, imposition of access controls is done by means
outside the scope of the LDAPv3 protocol.

It seems clear that allowing any implementation, faced with the
above requirements, to simply pick and choose among the possible
alternatives is not a strategy that is likely to lead to
interoperability. In the absence of mandates, clients will be
written that do not support any security function supported by the
server, or worse, they will support only mechanisms like the LDAPv3
simple bind using clear text passwords that provide inadequate
security for most circumstances.

Given the presence of the Directory, there is a strong desire to see
mechanisms where identities take the form of an LDAP distinguished
name [LDAPDN] and authentication data can be stored in the
directory. This means that this data must be updated outside the
protocol or only updated in sessions well protected against
snooping. It is also desirable to allow authentication methods to
carry authorization identities based on existing--non-LDAP DN--forms
of user identities for backwards compatibility with non-LDAP-based
authentication services.

The set of security mechanisms provided in LDAPv3 and described in
this document is intended to meet the security needs for a wide
range of deployment scenarios and still provide a high degree of
interoperability among various LDAPv3 implementations and
deployments. Appendix A contains example deployment scenarios that
list the mechanisms that might be used to achieve a reasonable level
of security in various circumstances.

2. Conventions Used in this Document

2.1. Glossary of Terms

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The following terms are used in this document. To aid the reader,
these terms are defined here.

- "user" represents any application which is an LDAP client using
the directory to retrieve or store information.

- "connection" and "LDAP connection" both refer to the underlying
transport protocol connection between two protocol peers.

- "TLS connection" refers to a TLS-protected LDAP connection.

- "association" and "LDAP association" both refer to the
association of the LDAP connection and its current
authentication and authorization state.

2.2. Security Terms and Concepts

In general, security terms in this document are used consistently
with the definitions provided in [RFC2828]. In addition, several
terms and concepts relating to security, authentication, and
authorization are presented in Appendix B of this document. While
the formal definition of these terms and concepts is outside the
scope of this document, an understanding of them is prerequisite to
understanding much of the material in this document. Readers who are
unfamiliar with security-related concepts are encouraged to review
Appendix B before reading the remainder of this document.

2.3. Keywords

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].

3. Bind Operation

The Bind operation defined in section 4.2 of [PROTOCOL] [Protocol] allows
authentication information to be exchanged between the client and
server.

3.1. Unbound Connection Treated as Anonymous ("Implied Anonymous Bind")

Unlike LDAP version 2, the client need not send a Bind Request in
the first PDU of the connection. The client may send any operation
request prior to binding, and the server MUST treat it as if it had
been performed after an anonymous bind operation. If the server
requires that the client bind before browsing or modifying the
directory, the server MAY reject a request other than binding,
unbinding or an extended request with the "operationsError" result.

3.2. Simple Authentication

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The simple authentication option provides minimal authentication
facilities, with the contents of the authentication field consisting
only of a cleartext password. Note that the use of cleartext
passwords is strongly discouraged over open networks when the
underlying transport service cannot guarantee confidentiality (see
section 8).

3.3. SASL Authentication

The sasl authentication option Profile

LDAP allows for authentication via any SASL mechanism defined for
use with [SASL]. As LDAP
includes native anonymous and plaintext authentication methods, the
"ANONYMOUS" [ANONYMOUS] and "PLAIN" [PLAIN] SASL [RFC2222] mechanisms are
typically not specifically prohibited by this document
(see section 3.3.1).

Clients sending a bind request used with LDAP.

Each protocol that utilizes SASL services is required to supply
certain information profiling the sasl choice selected SHOULD
NOT send a value in way they are exposed through the
protocol ([SASL] section 5). This section explains how each of these
profiling requirements are met by LDAPv3.

3.3.1. SASL Service Name for LDAP

The SASL service name field. Servers receiving for LDAPv3 is "ldap", which has been
registered with the IANA as a GSSAPI service name.

3.3.2. SASL authentication initiation and protocol exchange

SASL authentication is initiated via an LDAP bind request
([Protocol] section 4.2) with the sasl choice selected SHALL ignore any value in the name
field. following parameters:

- The version is 3.
- The AuthenticationChoice is sasl.
- The mechanism field in element of the SaslCredentials sequence contains
the name value of the desired SASL mechanism.
- The optional credentials field contains of of the arbitrary data SaslCredentials
sequence may be used
for authentication, inside to provide an OCTET STRING wrapper. Note initial client response for
mechanisms that unlike
some Internet application protocols where SASL is used, LDAP is not
text-based, thus no Base64 transformations are performed on the
credentials.

If any SASL-based integrity or confidentiality services are enabled,
they take effect following the transmission by defined to have the client send data first
(see [SASL] sections 5 and 6.1).

In general, a SASL authentication protocol exchange consists of a
series of server challenges and
reception by the client of responses, the final BindResponse with a resultCode contents of success.

If a SASL security layer is negotiated, the client MUST discard all
information about the server fetched prior
which are specific to the initiation of and defined by the SASL negotiation. If the client is configured to support multiple mechanism. Thus for
some SASL authentication mechanisms, it SHOULD fetch the supportedSASLmechanisms list
both before and after the SASL security layer is negotiated. This
allows may be necessary for the
client to detect active attacks that remove supported
SASL mechanisms from the supportedSASLMechanisms list and allows the
client respond to ensure that it is using the best mechanism supported one or more server challenges by
both client and server. (This requirement is a SHOULD to allow for
environments where invoking the supportedSASLMechanisms list
BindRequest multiple times. A challenge is provided to indicated by the client through a different trusted source, e.g. as part of server
sending a
digitally signed object.)

The client can request BindResponse with the resultCode set to
saslBindInProgress. This indicates that the server use authentication
information from requires the
client to send a lower layer protocol by using new bind request, with the SASL EXTERNAL same sasl mechanism (see section 4.2.2.).

3.3.1. Use of ANONYMOUS and PLAIN SASL Mechanisms

As LDAP includes native anonymous and plaintext to
continue the authentication
methods, process.

To the "ANONYMOUS" encapsulating protocol, these challenges and "PLAIN" SASL mechanisms responses are not used
with LDAP. If an authorization identity
opaque binary tokens of a form different from a
DN is requested by arbitrary length. LDAP servers use the client,
serverSaslCreds field, an OCTET STRING, in a data confidentiality mechanism that
protects bind response message
to transmit each challenge. LDAP clients use the password credentials field,
an OCTET STRING, in transit should be used. the SaslCredentials sequence of a bind request

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3.3.2. Use of EXTERNAL SASL Mechanism

The "EXTERNAL" SASL mechanism can be used

message to request the transmit each response. Note that unlike some Internet
application protocols where SASL is used, LDAP server
make use of security credentials exchanged by a lower layer. If a
TLS session has is not been established between the client text-based,
thus no Base64 transformations are performed on these challenge and server
prior to making the SASL EXTERNAL Bind
response values.

Clients sending a bind request and there is no other
external source of authentication credentials (e.g. IP-level
security [RFC2401]), or if during the process of establishing with the
TLS session, sasl choice selected SHOULD
NOT send a value in the server did not name field. Servers receiving a bind request
with the client's authentication
credentials, sasl choice selected SHALL ignore any value in the name
field.

A client may abort a SASL EXTERNAL bind MUST fail negotiation by sending a BindRequest
with a resultCode of
inappropriateAuthentication. Any client authentication and
authorization state different value in the mechanism field of SaslCredentials, or
an AuthenticationChoice other than sasl.

If the LDAP association is lost, so client sends a BindRequest with the LDAP
association is in sasl mechanism field as
an anonymous state after empty string, the failure (see
[PROTOCOL] section 4.2.1).

3.3.3. Other SASL Mechanisms

Other SASL mechanisms may be used server MUST return a BindResponse with LDAP, but their usage is not
considered in this document.

3.4. SASL Authorization Identity

The authorization identity is carried
authMethodNotSuppored as part of the SaslCredentials
credentials field in resultCode. This will allow clients to
abort a negotiation if it wishes to try again with the Bind request and response.

When same SASL
mechanism.

The server indicates completion of the "EXTERNAL" SASL mechanism is being negotiated, if challenge-response
exchange by responding with a bind response in which the
credentials field resultCode
is present, it contains either success, or an authorization identity
of the authzId form described below.

Other mechanisms define the location of the authorization identity
in the credentials field.

3.4.1. Authorization Identity Syntax error indication.

The authorization identity is a string serverSaslCreds field in the UTF-8 character set,
corresponding bind response can be used to the following ABNF grammar [RFC2234]:

; Specific predefined authorization (authz) id schemes
include an optional challenge with a success notification for
mechanisms which are
; defined below -- new schemes may be defined in to have the future.

authzId = dnAuthzId / uAuthzId

DNCOLON = %x64 %x6e %x3a ; "dn:"
UCOLON = %x75 %x3a ; "u:"

; distinguished-name-based authz id.
dnAuthzId = DNCOLON dn
dn = utf8string ; server send additional data
along with syntax defined in [LDAPDN] section 3.

; unspecified authorization id, UTF-8 encoded.
uAuthzId = UCOLON userid
userid = utf8string ; syntax unspecified

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The dnAuthzId choice allows client applications to assert
authorization identities in the form indication of a distinguished name. The
decision to allow successful completion.

3.3.3. Octet where negotiated security mechanisms take effect

If any SASL-based integrity or disallow an authentication identity to have
access to confidentiality services are enabled,
they take effect following the requested authorization identity is a matter of local
policy ([SASL] section 4.2). For this reason there is no requirement
that transmission by the asserted dn be that server and
reception by the client of an entry in directory.

The uAuthzId choice allows for compatibility the final BindResponse with client
applications that wish to assert an authorization identity to a
local directory but do not have that identity in distinguished name
form. The format resultCode
of utf8string is defined as only a sequence success.

3.3.4. Determination of UTF-
8 encoded ISO 10646 characters, and further interpretation is
subject to prior agreement between the supported SASL mechanisms

An LDAP client and server.

For example, may determine the userid could identify a user of SASL mechanisms a specific
directory service, or be server supports
by performing a login name or search request on the local-part of an RFC
822 email address. In general, a uAuthzId MUST NOT be assumed to be
globally unique.

Additional authorization identity schemes MAY be defined in future
versions root DSE, requesting the
supportedSASLMechanisms attribute. The values of this document.

3.5. SASL Service Name attribute, if
any, list the mechanisms the server supports.

3.3.5. Rules for LDAP

For use with using SASL [RFC2222], a protocol must specify security layers

If a service name
to be used with various SASL mechanisms, such as GSSAPI. For LDAP,
the service name security layer is "ldap", which has been registered with negotiated, the IANA
as a GSSAPI service name.

3.6. SASL Integrity and Privacy Protections

Any negotiated SASL integrity and privacy protections SHALL start on client MUST discard all
information about the first octet of server fetched prior to the first LDAP PDU following successful
completion initiation of the
SASL bind operation. negotiation. If lower level the client is configured to support multiple
SASL mechanisms, it SHOULD fetch the supportedSASLmechanisms list
both before and after the SASL security layer is negotiated, such as TLS, any negotiated. This
allows the client to detect active attacks that remove supported
SASL security services SHALL be
layered on top of such security layers regardless of mechanisms from the order of
their negotiation.

4. Start TLS Operation

The Start Transport Layer Security (StartTLS) operation defined in
section 4.13 of [PROTOCOL] provides supportedSASLMechanisms list and allows the ability
client to establish
Transport Layer Security [RFC2246] on an LDAP association.

4.1. Sequencing of the Start TLS Operation

This section describes ensure that it is using the overall procedures clients best mechanism supported by
both client and servers
must follow server. (This requirement is a SHOULD to allow for TLS establishment. These procedures take into
consideration various aspects of the overall security of the LDAP
association including discovery of resultant security level and
assertion of the client's authorization identity.

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Note that

environments where the precise effects, on supportedSASLMechanisms list is provided to
the client through a client's authorization identity, different trusted source, e.g. as part of establishing TLS on an LDAP association are described in detail
in section 4.5.

4.1.1. Requesting to Start TLS a
digitally signed object.)

If a lower level security layer (such as TLS) is negotiated, any
SASL security services SHALL be layered on an LDAP Association

The top of such security
layers regardless of the order of their negotiation.

3.3.6. Use of EXTERNAL SASL Mechanism

A client MAY send can use the Start TLS extended "EXTERNAL" SASL mechanism to request at any time after
establishing an LDAP association, except that in the following cases the client MUST NOT send LDAP
server to make use of security credentials exchanged by a lower
layer. If a Start TLS extended request:

- if TLS is currently session has not been established on between the client
and server prior to making the connection, or
- during a multi-stage SASL negotiation, or
- if there are any LDAP operations outstanding on the
connection.

The result of violating any of these requirements is a resultCode of
operationsError, as described above in [PROTOCOL] section 14.3.2.2.

In particular, EXTERNAL Bind request and there
is no requirement that the client have or have
not already performed a Bind operation before sending a Start TLS
operation request. The client may have already performed a Bind
operation when it sends a Start TLS request, other external source of authentication credentials (e.g. IP-
level security [RFC2401]), or if during the client might
have not yet bound.

If process of establishing
the client did not establish a TLS connection before sending any
other requests, and session, the server requires did not request the client to establish a
TLS connection before performing a particular request, client's
authentication credentials, the server SASL EXTERNAL bind MUST reject that request by sending fail with a
resultCode of
confidentialityRequired or strongAuthRequired. In response, the inappropriateAuthentication. Any client MAY send a Start TLS extended request, or it MAY choose to
close authentication
and authorization state of the connection.

4.1.2. Starting TLS

The server will return an extended response with LDAP association is lost, so the resultCode of
success if it LDAP
association is willing and able to negotiate TLS. It will return
other resultCodes (documented in [PROTOCOL] an anonymous state after the failure (see
[Protocol] section 4.13.2.2) if it 4.2.1).

3.4. SASL Authorization Identity

The authorization identity is unable to do so.

In the successful case, carried as part of the client (which has ceased to transfer
LDAP requests on SaslCredentials
credentials field in the connection) MUST either begin a TLS negotiation
or close Bind request and response.

When the connection. The client will send PDUs in the TLS Record
Protocol directly over "EXTERNAL" SASL mechanism is being negotiated, if the underlying transport connection to
credentials field is present, it contains an authorization identity
of the
server to initiate TLS negotiation [RFC2246].

4.1.3. TLS Version Negotiation

Negotiating authzId form described below.

Other mechanisms define the version location of TLS or SSL to be used the authorization identity
in the credentials field.

3.4.1. Authorization Identity Syntax

The authorization identity is a part of the
TLS Handshake Protocol, as documented string in [RFC2246]. Please refer the UTF-8 character set,
corresponding to
that document for details.

4.1.4. Discovery of Resultant Security Level the following ABNF grammar [RFC2234]:

; Specific predefined authorization (authz) id schemes are
; defined below -- new schemes may be defined in the future.

authzId = dnAuthzId / uAuthzId

DNCOLON = %x64 %x6e %x3a ; "dn:"
UCOLON = %x75 %x3a ; "u:"

; distinguished-name-based authz id.
dnAuthzId = DNCOLON dn
dn = utf8string ; with syntax defined in [LDAPDN] section 3.

; unspecified authorization id, UTF-8 encoded.

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After

uAuthzId = UCOLON userid
userid = utf8string ; syntax unspecified

The dnAuthzId choice allows client applications to assert
authorization identities in the form of a TLS connection is established on an LDAP association, both
parties MUST individually decide whether distinguished name. The
decision to allow or not disallow an authentication identity to have
access to continue based on
the privacy level achieved. Ascertaining the TLS connection's
privacy level requested authorization identity is implementation dependent, and accomplished by
communicating with one's respective a matter of local TLS implementation.

If the client or server decides
policy ([SASL] section 4.2). For this reason there is no requirement
that the level asserted dn be that of authentication or
privacy is not high enough an entry in directory.

The uAuthzId choice allows for it to continue, it SHOULD gracefully
close the TLS connection immediately after the TLS negotiation has
completed (see [PROTOCOL] section 4.13.3.1 and section 4.2.3 below).
If the compatibility with client decides to continue, it MAY attempt
applications that wish to Start TLS
again, it MAY send assert an unbind request, or it MAY send any other LDAP
request.

4.1.5. Assertion of Client's Authorization Identity authorization identity to a
local directory but do not have that identity in distinguished name
form. The client MAY, upon receipt format of utf8string is defined as only a Start TLS response indicating
success, assert that sequence of UTF-
8 encoded ISO 10646 characters, and further interpretation is
subject to prior agreement between the client and server.

For example, the userid could identify a user of a specific
directory service, or be a login name or the local-part of an RFC
822 email address. In general, a uAuthzId MUST NOT be assumed to be
globally unique.

Additional authorization identity schemes MAY be utilized defined in determining the client's authorization status. The client
accomplishes future
versions of this via an LDAP Bind request specifying a document.

3.5. SASL
mechanism of "EXTERNAL" [RFC2222] (see section 4.5.1.2 below).

4.1.6. Server Identity Check

The client MUST check its understanding Integrity and Privacy Protections

Any negotiated SASL integrity and privacy protections SHALL start on
the first octet of the server's hostname
against first LDAP PDU following successful
completion of the server's identity SASL bind operation. If lower level security layer
is negotiated, such as presented in TLS, any SASL security services SHALL be
layered on top of such security layers regardless of the server's
Certificate message in order to prevent man-in-the-middle attacks.

Matching is performed according to these rules:

- of
their negotiation.

4. Start TLS Operation

The client MUST use Start Transport Layer Security (StartTLS) operation defined in
section 4.13 of [Protocol] provides the server hostname it used ability to open the establish
Transport Layer Security [RFC2246] on an LDAP
connection as association.

4.1. Sequencing of the value to compare against Start TLS Operation

This section describes the server name as
expressed in overall procedures clients and servers
must follow for TLS establishment. These procedures take into
consideration various aspects of the server's certificate. The client MUST NOT use
any other derived form overall security of name (including the LDAP
association including discovery of resultant security level and
assertion of the client's authorization identity.

Note that derived by DNS
canonicalization).

- If the precise effects, on a subjectAltName extension client's authorization identity,
of type dNSName is present establishing TLS on an LDAP association are described in detail
in section 4.2.

4.1.1. Requesting to Start TLS on an LDAP Association

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The client MAY send the
certificate, it SHOULD be used as Start TLS extended request at any time after
establishing an LDAP association, except that in the source of following cases
the server's
identity. client MUST NOT send a Start TLS extended request:

- Matching if TLS is case-insensitive. currently established on the connection, or
- The "*" wildcard character is allowed. If present, it applies
only to the left-most name component.

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 than one identity of a given type is present in the
certificate (e.g. more than one dNSName name), during a match in multi-stage SASL negotiation, or
- if there are any
one of the set is considered acceptable.

If the hostname does not match the dNSName-based identity in the
certificate per the above check, user-oriented clients SHOULD either
notify the user (clients MAY give the user the opportunity to

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continue with operations outstanding on the connection in
connection.

The result of violating any case) or terminate the
connection and indicate that the server's identity is suspect.
Automated clients SHOULD close the connection, returning and/or
logging an error indicating that the server's identity of these requirements is suspect.

Beyond the server identity checks a resultCode of
operationsError, as described in this section, clients
SHOULD be prepared to do further checking to ensure [Protocol] section 4.13.2.2. Client
implementers should note that the server
is authorized to provide the service it is observed to provide. The
client MAY need possible to make use of local policy information.

4.1.7. Refresh get back a
resultCode of Server Capabilities Information

Upon success in the case where LDAP operations are
outstanding on the connection at the time a Start TLS session establishment, operation
request is sent by the client MUST discard all
information about but they are processed by the server fetched
prior to its receiving the initiation of the Start TLS negotiation and MUST refresh any cached server capabilities
information (e.g. request from the server's root DSE; see section 3.4 of
[PROTOCOL]). This is necessary to protect against active-
intermediary attacks client.
Implementors should ensure that may have altered any server capabilities
information retrieved prior to TLS establishment.

The server MAY advertise different capabilities after TLS
establishment. they do not inadvertently depend
upon this race condition for proper functioning of their
applications.

In particular, there is no requirement that the value of supportedSASLMechanisms
MAY be different after TLS has been negotiated (specifically, the
EXTERNAL mechanism client have or the proposed PLAIN mechanism are likely to
only be listed after have
not already performed a Bind operation before sending a Start TLS negotiation has been performed).

4.2. Effects of TLS on
operation request. The client may have already performed a Client's Authorization Identity

This section describes the effects on Bind
operation when it sends a client's authorization
identity brought about by establishing Start TLS on an LDAP association.
The default effects are described first, and next request, or the facilities for client assertion of authorization identity are discussed including
error conditions. Finally, the effects of closing might
have not yet bound.

If the client did not establish a TLS connection
are described.

Authorization identities and related concepts are described in
Appendix B.

4.2.1. Default Effects

Upon establishment of the TLS session onto the LDAP association, before sending any
previously established authentication
other requests, and authorization identities
MUST remain in force, including anonymous state. This holds even in
the case where the server requests client authentication via TLS --
e.g. requests requires the client to supply its certificate during establish a
TLS
negotiation (see [RFC2246]).

4.2.2. Client Assertion of Authorization Identity

A client MAY either implicitly request connection before performing a particular request, the server
MUST reject that its LDAP authorization
identity be derived from its authenticated request by sending a resultCode of
confidentialityRequired or strongAuthRequired. In response, the
client MAY send a Start TLS credentials extended request, or it MAY
explicitly provide choose to
close the connection.

4.1.2. Starting TLS

The server will return an authorization identity extended response with the resultCode of
success if it is willing and assert that able to negotiate TLS. It will return
other resultCodes (documented in [Protocol] section 4.13.2.2) if it
is unable to do so.

In the successful case, the client (which has ceased to transfer
LDAP requests on the connection) MUST either begin a TLS negotiation
or close the connection. The client will send PDUs in the TLS Record
Protocol directly over the underlying transport connection to the
server to initiate TLS negotiation [RFC2246].

4.1.3. TLS Version Negotiation

Negotiating the version of TLS or SSL to be used in combination with its authenticated is a part of the
TLS credentials. The Handshake Protocol, as documented in [RFC2246]. Please refer to
that document for details.

4.1.4. Discovery of Resultant Security Level

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former

After a TLS connection is known as established on an implicit assertion, and LDAP association, both
parties MUST individually decide whether or not to continue based on
the latter as an
explicit assertion.

4.2.2.1. Implicit Assertion

An implicit authorization identity assertion privacy level achieved. Ascertaining the TLS connection's
privacy level is implementation dependent, and accomplished after
TLS establishment by invoking a Bind request of
communicating with one's respective local TLS implementation.

If the SASL form using
the "EXTERNAL" mechanism name [RFC2222] [PROTOCOL] client or server decides that SHALL NOT
include the optional credentials octet string (found within the
SaslCredentials sequence in level of authentication or
privacy is not high enough for it to continue, it SHOULD gracefully
close the Bind Request). The server will
derive TLS connection immediately after the client's authorization identity from TLS negotiation has
completed (see [Protocol] section 4.13.3.1 and section 4.2.3 below).
If the authentication
identity supplied in client decides to continue, it MAY gracefully close the client's TLS credentials (typically a
public key certificate) according
connection and attempt to local policy. Start TLS again, it MAY send an unbind
request, or it MAY send any other LDAP request.

4.1.5. Assertion of Client's Authorization Identity

The underlying
mechanics client MAY, upon receipt of how this is accomplished are implementation specific.

4.2.2.2. Explicit Assertion

An explicit authorization identity assertion is accomplished after a Start TLS establishment by invoking response indicating
success, assert that a specific authorization identity be utilized
in determining the client's authorization status. The client
accomplishes this via an LDAP Bind request of the specifying a SASL form using
the "EXTERNAL"
mechanism name [RFC2222] [PROTOCOL] that SHALL
include the credentials octet string. This string MUST be
constructed as documented in of "EXTERNAL" [SASL] (see section 3.4.1.

4.2.2.3. Error Conditions

For either form 4.2.2 below).

4.1.6. Server Identity Check

The client MUST check its understanding of assertion, the server MUST verify that server's hostname
against the
client's authentication server's identity as supplied presented in its TLS credentials
is permitted the server's
Certificate message in order to be mapped prevent man-in-the-middle attacks.

Matching is performed according to the asserted authorization identity. these rules:

- The server client MUST reject use the Bind operation with an invalidCredentials
resultCode in server hostname it used to open the Bind response if LDAP
connection as the value to compare against the server name as
expressed in the server's certificate. The client is not so authorized.

Additionally, with either MUST NOT use
any other derived form of assertion, if name (including that derived by DNS
canonicalization).

- If a TLS session has
not been established between subjectAltName extension of type dNSName is present in the client and server prior
certificate, it SHOULD be used as the source of the server's
identity.

- Matching is case-insensitive.

- The "*" wildcard character is allowed. If present, it applies
only to making the SASL EXTERNAL Bind request left-most name component.

For example, *.bar.com would match a.bar.com and there is no other external source b.bar.com, but
it would not match a.x.bar.com nor would it match bar.com. If
more than one identity of authentication credentials (e.g. IP-level security [RFC2401]), or
if during a given type is present in the process
certificate (e.g. more than one dNSName name), a match in any
one of establishing the TLS session, set is considered acceptable.

If the server
did hostname does not request match the client's authentication credentials, dNSName-based identity in the SASL
EXTERNAL bind MUST fail with a result code of
inappropriateAuthentication.

After
certificate per the above Bind operation failures, check, user-oriented clients SHOULD either

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notify the user (clients MAY give the user the opportunity to
continue with the connection in any client authentication case) or terminate the
connection and authorization state of indicate that the LDAP association server's identity is lost (see
[PROTOCOL] section 4.2.1), so suspect.
Automated clients SHOULD close the LDAP association is in connection, returning and/or
logging an
anonymous state after error indicating that the failure. The TLS session state server's identity is
unaffected, though a suspect.

Beyond the server MAY end identity checks described in this section, clients
SHOULD be prepared to do further checking to ensure that the TLS session, via a TLS
close_notify message, based on server
is authorized to provide the Bind failure (as service it is observed to provide. The
client MAY at any
time).

4.2.3. TLS Connection Closure Effects

Closure need to make use of the local policy information.

4.1.7. Refresh of Server Capabilities Information

Upon TLS session establishment, the client MUST cause discard all
information about the LDAP association to move server fetched prior to an anonymous authentication and authorization state regardless the initiation of the state established over
TLS negotiation and regardless of MUST refresh any cached server capabilities
information (e.g. from the authentication
and authorization state server's root DSE; see [Model] section
5.1). This is necessary to protect against active-intermediary
attacks that may have altered any server capabilities information
retrieved prior to TLS session establishment.

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5. LDAP Association State Transition Tables

To comprehensively diagram

The server MAY advertise different capabilities after TLS
establishment. In particular, the various authentication value of supportedSASLMechanisms
MAY be different after TLS has been negotiated (specifically, the
EXTERNAL and PLAIN [PLAIN] mechanisms are likely to be listed only
after a TLS states
through which an LDAP association may pass, this negotiation has been performed).

4.2. Effects of TLS on a Client's Authorization Identity

This section provides describes the effects on a
state transition table to represent a state diagram for the various
states through which client's authorization
identity brought about by establishing TLS on an LDAP association may pass during association.
The default effects are described first, and next the course facilities for
client assertion of its existence and authorization identity are discussed including
error conditions. Finally, the actions that cause these changes effects of closing the TLS connection
are described.

Authorization identities and related concepts are described in state.

5.1. LDAP Association States

The following table lists
Appendix B.

4.2.1. Default Effects

Upon establishment of the TLS session onto the valid LDAP association states association, any
previously established authentication and
provides a description of each authorization identities
MUST remain in force, including anonymous state. The ID for each state is used This holds even in
the state transition table in section 5.4.

ID State Description case where the server requests client authentication via TLS -- --------------------------------------------------------------
S1 Anonymous
no Authentication ID is associated with
e.g. requests the LDAP connection
no client to supply its certificate during TLS
negotiation (see [RFC2246]).

4.2.2. Client Assertion of Authorization ID is Identity

A client MAY either implicitly request that its LDAP authorization
identity be derived from its authenticated TLS credentials or it MAY
explicitly provide an authorization identity and assert that it be
used in force
No security layer combination with its authenticated TLS credentials. The

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former is in effect.
No known as an implicit assertion, and the latter as an
explicit assertion.

4.2.2.1. Implicit Assertion

An implicit authorization identity assertion is accomplished after
TLS credentials have been provided
TLS: no Creds, OFF] establishment by invoking a Bind request of the SASL form using
the "EXTERNAL" mechanism name [SASL] [Protocol] that SHALL NOT
include the optional credentials octet string (found within the
SaslCredentials sequence in the Bind Request). The server will
derive the client's authorization identity from the authentication
identity supplied in the client's TLS credentials (typically a
public key certificate) according to local policy. The underlying
mechanics of how this is accomplished are implementation specific.

4.2.2.2. Explicit Assertion

An explicit authorization identity assertion is accomplished after
TLS establishment by invoking a Bind request of the SASL form using
the "EXTERNAL" mechanism name [SASL] [Protocol] that SHALL include
the credentials octet string. This string MUST be constructed as
documented in section 3.4.1.

The server MUST verify that the client's authentication identity as
supplied in its TLS credentials is permitted to be mapped to the
asserted authorization identity. The server MUST reject the Bind
operation with an invalidCredentials resultCode in the Bind response
if the client is not so authorized.

4.2.2.3. Error Conditions

Additionally, with either form of assertion, if a TLS session has
not been established between the client and server prior to making
the SASL EXTERNAL Bind request and there is no other external source
of authentication credentials (e.g. IP-level security [RFC2401]), or
if during the process of establishing the TLS session, the server
did not request the client's authentication credentials, the SASL
EXTERNAL bind MUST fail with a result code of
inappropriateAuthentication.

After the above Bind operation failures, any client authentication
and authorization state of the LDAP association is lost (see
[Protocol] section 4.2.1), so the LDAP association is in an
anonymous state after the failure. The TLS session state is
unaffected, though a server MAY end the TLS session, via a TLS
close_notify message, based on the Bind failure (as it MAY at any
time).

4.2.3. TLS Connection Closure Effects

Closure of the TLS session MUST cause the LDAP association to move
to an anonymous authentication and authorization state regardless of
the state established over TLS and regardless of the authentication
and authorization state prior to TLS session establishment.

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5. LDAP Association State Transition Tables

To comprehensively diagram the various authentication and TLS states
through which an LDAP association may pass, this section provides a
state transition table to represent a state diagram for the various
states through which an LDAP association may pass during the course
of its existence and the actions that cause these changes in state.

5.1. LDAP Association States

The following table lists the valid LDAP association states and
provides a description of each state. The ID for each state is used
in the state transition table in section 5.4.

ID State Description
-- --------------------------------------------------------------
S1 Anonymous
no Authentication ID is associated with the LDAP connection
no Authorization ID is in force
No security layer is in effect.
No TLS credentials have been provided
TLS: no Creds, OFF]
S2 no Auth ID
no AuthZ ID
[TLS: no Creds, ON]
S3 no Auth ID
no AuthZ ID
[TLS: Creds Auth ID "I", ON]
S4 Auth ID = Xn
AuthZ ID= Y
[TLS: no Creds, OFF]
S5 Auth ID = Xn
AuthZ ID= Yn
[TLS: no Creds, ON]
S6 Auth ID = Xn
AuthZ ID= Yn
[TLS: Creds Auth ID "I", ON]
S7 Auth ID = I
AuthZ ID= J
[TLS: Creds Auth ID "I", ON]
S8 Auth ID = I
AuthZ ID= K
[TLS: Creds Auth ID "I", ON]

5.2. Actions that Affect LDAP Association State

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
transition table in section 5.4.

ID Action

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-- ------------------------------------------------
A1 Client binds anonymously
A2 Inappropriate authentication: client attempts an anonymous
bind or a bind without supplying credentials to a server that
requires the client to provide some form of credentials.
A3 Client Start TLS request
Server: client auth NOT required
A4 Client: Start TLS request
Server: client creds requested
Client: [TLS creds: Auth ID "I"]
A5 Client or Server: send TLS closure alert ([PROTOCOL] ([Protocol] section
X)
A6 Client: Bind w/simple password or SASL mechanism (e.g. DIGEST-
MD5 password, Kerberos, etc. -- etc., except EXTERNAL [Auth ID "X"
maps to AuthZ ID "Y"]
A7 Client Binds SASL EXTERNAL with credentials: AuthZ ID "J"
[Explicit Assertion (section 4.2.1.2.2)]
A8 Client Bind SASL EXTERNAL without credentials [Implicit
Assertion (section 4.2.1.2.1)]
A9 Client abandons a bind operation or bind operation fails

5.3. Decisions Used in Making LDAP Association State Changes

Certain changes in the state of an LDAP association are only allowed
if the server can affirmatively answer a question. These questions
are applied as part of the criteria for allowing or disallowing a
state change in the state transition table in section 5.4.

ID Decision Question
-- --------------------------------------------------------------
D1 Can TLS Credentials Auth ID "I" be mapped to AuthZ ID "J"?
D2 Can a valid AuthZ ID "K" be derived from TLS Credentials Auth
ID "I"?

5.4. LDAP Association State Transition Table

The LDAP Association table below lists the valid states for an LDAP
association and the actions that could affect them. For any given
row in the table, the Current State column gives the state of an
LDAP association, the Action column gives an action that could
affect the state of an LDAP assocation, and the Next State column
gives the resulting state of an LDAP association after the action
occurs.

The initial state for the state machine described in this table is
S1.

Current Next
State Action State Comment
------- ------------- ----- -----------------------------------
S1 A1 S1
S1 A2 S1 Error: Inappropriate authentication
S1 A3 S2

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S1 A4 S3
S1 A6 S4
S1 A7 ? identity could be provided by
another underlying mechanism such
as IPSec.
S1 A8 ? identity could be provided by
another underlying mechanism such
as IPSec.
S2 A1 S2
S2 A2 S2 Error: Inappropriate authentication
S2 A5 S1
S2 A6 S5
S2 A7 ? identity could be provided by
another underlying mechanism such
as IPSec.
S2 A8 ? identity could be provided by
another underlying mechanism such
as IPSec.
S3 A1 S3
S3 A2 S3 Error: Inappropriate authentication
S3 A5 S1
S3 A6 S6
S3 A7 and D1=NO S3 Error: InvalidCredentials
S3 A7 and D1=YES S7
S3 A8 and D2=NO S3 Error: InvalidCredentials
S3 A8 and D2=YES S8
S4 A1 S1
S4 A2 S4 S1 Error: Inappropriate Authentication
S4 A3 S5
S4 A4 S6
S4 A5 S1
S4 A6 S4
S4 A7 ? identity could be provided by
another underlying mechanism such
as IPSec.
S4 A8 ? identity could be provided by
another underlying mechanism such
as IPSec.
S5 A1 S2
S5 A2 S5 S2 Error: Inappropriate Authentication
S5 A5 S1
S5 A6 S5
S5 A7 ? identity could be provided by
another underlying mechanism such
as IPSec.
S5 A8 ? identity could be provided by
another underlying mechanism such
as IPSec.
S6 A1 S3
S6 A2 S6 S2 Error: Inappropriate Authentication
S6 A5 S1
S6 A6 S6

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S6 A7 and D1=NO S6 Error: InvalidCredentials
S6 A7 and D1=YES S7
S6 A8 and D2=NO S6 S3 Error: InvalidCredentials
S6 A8 and D2=YES S8
S7 A1 S3
S7 A2 S7 S2 Error: Inappropriate Authentication
S7 A5 S1
S7 A6 S6
S7 A7 S7
S7 A8 and D2=NO S3 Error: InvalidCredentials
S7 A8 and D2=YES S8
S8 A1 S3
S8 A2 S8 S2 Error: Inappropriate Authentication
S8 A5 S1
S8 A6 S6
S8 A7 and D1=NO S6 Error: InvalidCredentials
S8 A7 and D1=YES S7
S8 A8 S8
Any A9 S1 See [Protocol] section 4.2.1.

6. Anonymous Authentication

Directory operations that modify entries or access protected
attributes or entries generally require client authentication.
Clients that do not intend to perform any of these operations
typically use anonymous authentication. Servers SHOULD NOT allow
clients with anonymous authentication to modify directory entries or
access sensitive information in directory entries.

LDAP implementations MUST support anonymous authentication, as
defined in section 6.1.

LDAP implementations MAY support anonymous authentication with TLS,
as defined in section 6.2.

While there MAY be access control restrictions to prevent access to
directory entries, an LDAP server SHOULD allow an anonymously-bound
client to retrieve the supportedSASLMechanisms attribute of the root
DSE.

An LDAP server MAY use other information about the client provided
by the lower layers or external means to grant or deny access even
to anonymously authenticated clients.

6.1. Anonymous Authentication Procedure

An LDAPv3 client that has not successfully completed a bind
operation on a connection is anonymously authenticated. See section
3.3.3.
3.1.

An LDAP client MAY also choose to explicitly bind anonymously. A
client that wishes to do so MUST choose the simple authentication

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option in the Bind Request (see section 3.1) and set the password to be of zero
length. (This is often done by LDAPv2 clients.) Typically the name
is also of zero length.

6.2. Anonymous Authentication and TLS

An LDAP client MAY use the Start TLS operation (section 5) to
negotiate the use of TLS security [RFC2246]. If the client has not
bound beforehand, then until the client uses the EXTERNAL SASL
mechanism to negotiate the recognition of the client's certificate,
the client is anonymously authenticated.

Recommendations on TLS ciphersuites are given in section 9.

An LDAP server which requests that clients provide their certificate
during TLS negotiation MAY use a local security policy to determine
whether to successfully complete TLS negotiation if the client did
not present a certificate which could be validated.

7. Password-based Authentication

This section discusses various options for performing password-based
authentication to LDAPv3 compliant servers and the environments
suitable for their use.

7.1. Simple Authentication

The LDAP "simple" authentication choice is not suitable for
authentication in environments where there is no network or
transport layer confidentiality. LDAP implementations SHOULD support
authentication with the "simple" authentication choice when the
connection is protected against eavesdropping using TLS, as defined
in section 4. LDAP implementations SHOULD NOT support authentication
with the "simple" authentication choice unless the data on the
connection is protected using TLS or other data confidentiality and
data integrity protection.

7.2. Digest Authentication

LDAP servers that implement any authentication method or mechanism
(other than simple anonymous bind) MUST implement the SASL
DIGEST-MD5 mechanism.

An LDAP client MAY determine whether the server supports this
mechanism by performing a search request on the root DSE, requesting
the supportedSASLMechanisms attribute, and checking whether the
string "DIGEST-MD5" is present as a value of this attribute.

In the first stage of authentication, when the client is performing
an "initial authentication" as defined in section 2.1 of [RFC2831],
the client sends a bind request in which the version number is 3,
the authentication choice is sasl, the sasl mechanism name is
"DIGEST-MD5", and the credentials are absent. The client then waits
for a response from the server to this request.

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The server will respond with a bind response in which the resultCode
is saslBindInProgress, and the serverSaslCreds field is present. The
contents of this field is a string defined by "digest-challenge" in
section 2.1.1 of [RFC2831]. The server SHOULD include a realm
indication password-based
authentication to LDAPv3 compliant servers and MUST indicate support the environments
suitable for UTF-8. their use.

7.1. Simple Authentication

The client will send a bind request with a distinct message id, LDAP "simple" authentication choice is not suitable for
authentication in
which the version number environments where there is 3, no network or
transport layer confidentiality. LDAP implementations SHOULD support
authentication with the "simple" authentication choice is sasl, when the sasl mechanism name
connection is "DIGEST-MD5", and the credentials contain
the string protected against eavesdropping using TLS, as defined by "digest-response"
in section 2.1.2 of
[RFC2831]. The serv-type is "ldap".

The server will respond 4. LDAP implementations SHOULD NOT support authentication
with a bind response in which the resultCode
is either success, or an error indication. If the "simple" authentication is
successful and the server does not support subsequent
authentication, then choice unless the credentials field is absent. If data on the
authentication
connection is successful protected using TLS or other data confidentiality and
data integrity protection.

7.2. Digest Authentication

LDAP servers that implement any authentication method or mechanism
(other than simple anonymous bind) MUST implement the server supports subsequent
authentication, then the credentials field contains the string
defined by "response-auth" in section 2.1.3 of [RFC2831]. SASL
DIGEST-MD5 mechanism [DigestAuth].

Support for subsequent authentication is OPTIONAL in clients and servers.
servers.

Implementors must take care to ensure that they maintain the
semantics of the DIGEST-MD5 specification even when handling data
that has different semantics in the LDAP protocol.
For example, the SASL DIGEST-MD5 authentication mechanism utilizes
realm and username values ([DigestAuth section 2.1) which are
syntactically simple strings and semsantically simple realm and
username values. These values are not LDAP DNs, and there is no
requirement that they be represented or treated as such. Username

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and realm values that look like LDAP DNs in form, e.g. "cn=bob,
o=Ace Industry ", are syntactically allowed, however DIGEST-MD5
treats them as simple strings for comparison purposes. To illustrate
further, the two DNs "cn=bob, o=Ace Industry" (space between RDNs)
and "cn=bob,o=Ace Industry" (no space between RDNs) would be
equivalent when being compared semantically as LDAP DNs, however
they are not equivalent if they were used to represent username
values in DIGEST-MD5 because simple octet-wise comparision semantics
are used by DIGEST-MD5.

7.3. "simple" authentication choice under TLS encryption

Following the negotiation of an appropriate TLS ciphersuite
providing connection confidentiality [RFC2246], a client MAY
authenticate to a directory that supports the simple authentication
choice by performing a simple bind operation. operation

Simple authentication with TLS encryption protection is performed as
follows:

1. The client will use the Start TLS operation [PROTOCOL] [Protocol] to
negotiate the use of TLS security [RFC2246] on the connection
to the LDAP server. The client need not have bound to the
directory beforehand.

For this the subsequent authentication procedure to be successful, performed
securely, the client and server MUST negotiate a ciphersuite
which contains a bulk encryption algorithm of appropriate
strength. Recommendations on cipher suites are given in
section 9.

2. Following the successful completion of TLS negotiation, the
client MUST send an LDAP bind request with the version number
of 3, the name field containing a DN, and the "simple"
authentication choice, containing a password.

7.3.1. "simple" Authentication Choice

DSAs that map the DN sent in the bind request to a directory entry
with an associated set of one or more passwords will compare the
presented password to the set of passwords associated with that
entry. If there is a match, the presented password matches any member of that set,
then the server will respond with resultCode success, otherwise the
server will respond with resultCode invalidCredentials.

7.4. Other authentication choices with TLS

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

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8. Certificate-based authentication

LDAP server implementations SHOULD support authentication via a
client certificate in TLS, as defined in section 4.2.2. 8.1.

8.1. Certificate-based authentication with TLS

A user who has a public/private key pair in which the public key has
been signed by a Certification Authority may use this key pair to
authenticate to the directory server if the user's certificate is
requested by the server. The user's certificate subject field SHOULD
be the name of the user's directory entry, and the Certification
Authority that issued the user's certificate must be sufficiently
trusted by the directory server in order for the server to process
the certificate. The means by which servers validate certificate
paths is outside the scope of this document.

A server MAY support mappings for certificates in which the subject
field name is different from the name of the user's directory entry.
A server which supports mappings of names MUST be capable of being
configured to support certificates for which no mapping is required.

The client will use the Start TLS operation [PROTOCOL] [Protocol] to negotiate
the use of TLS security [RFC2246] on the connection to the LDAP
server. The client need not have bound to the directory beforehand.

In the TLS negotiation, the server MUST request a certificate. The
client will provide its certificate to the server, and the server
MUST perform a private key-based encryption, proving it has the
private key associated with the certificate.

In deployments that require protection of sensitive data in transit,
the client and server MUST negotiate a ciphersuite that contains a
bulk encryption algorithm of appropriate strength. Recommendations
of cipher suites are given in section 9.

The server MUST verify that the client's certificate is valid. The
server will normally check that the certificate is issued by a known
certification authority (CA), and that none of the certificates on
the client's certificate chain are invalid or revoked. There are
several procedures by which the server can perform these checks.

Following the successful completion of TLS negotiation, the client
will send an LDAP bind request with the SASL "EXTERNAL" mechanism.

9. TLS Ciphersuites

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A client or server that supports TLS MUST support
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA and MAY support other ciphersuites
offering equivalent or better protection.

Several issues should be considered when selecting TLS ciphersuites
that are appropriate for use in a given circumstance. These issues
include the following:

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- The ciphersuite's ability to provide adequate confidentiality
protection for passwords and other data sent over the LDAP
connection. Client and server implementers should recognize that
some TLS ciphersuites provide no confidentiality protection
while other ciphersuites that do provide confidentiality
protection may be vulnerable to being cracked using brute force
methods, especially in light of ever-increasing CPU speeds that
reduce the time needed to successfully mount such attacks.

Client and server implementers SHOULD carefully consider the
value of the password or data being protected versus the level
of confidentially protection provided by the ciphersuite to
ensure that the level of protection afforded by the ciphersuite
is appropriate.

- The ciphersuite's vulnerability (or lack thereof) to man-in-the-
middle attacks. Ciphersuites vulnerable to man-in-the-middle
attacks SHOULD NOT be used to protect passwords or sensitive
data, unless the network configuration is such that the danger
of a man-in-the-middle attack is tolerable.

9.1. TLS Ciphersuites Recommendations

As of the writing of this document, the following recommendations
regarding TLS ciphersuites are applicable. Because circumstances are
constantly changing, this list must not be considered exhaustive,
but is hoped that it will serve as a useful starting point for
implementers.

The following ciphersuites defined in [RFC2246] MUST NOT be used for
confidentiality protection of passwords or data:

TLS_NULL_WITH_NULL_NULL
TLS_RSA_WITH_NULL_MD5
TLS_RSA_WITH_NULL_SHA

The following ciphersuites defined in [RFC2246] can be cracked
easily (less than a day of CPU time on a standard CPU in 2000) and
are NOT RECOMMENDED for use in confidentiality protection of
passwords or data.

TLS_RSA_EXPORT_WITH_RC4_40_MD5
TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5
TLS_RSA_EXPORT_WITH_DES40_CBC_SHA
TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA
TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA

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TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA
TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA

The following ciphersuites are vulnerable to man-in-the-middle
attacks:

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TLS_DH_anon_EXPORT_WITH_RC4_40_MD5
TLS_DH_anon_WITH_RC4_128_MD5
TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA
TLS_DH_anon_WITH_DES_CBC_SHA
TLS_DH_anon_WITH_3DES_EDE_CBC_SHA

10. Security Considerations

Security issues are discussed throughout this memo; the
(unsurprising) conclusion is that mandatory security is important
and that session confidentiality protection is required when
snooping is a problem.

Servers are encouraged to prevent modifications by anonymous users.
Servers may also wish to minimize denial of service attacks by
timing out idle connections, and returning the unwillingToPerform
result code rather than performing computationally expensive
operations requested by unauthorized clients.

Operational experience shows that clients can misuse unauthenticated
access (simple bind with name but no password). For example, a
client program might authenticate a user via LDAP and then grant
access to information not stored in the directory on the basis of
completing a successful bind. Some implementations will return a
success response to a simple bind that consists of a user name and
an empty password thus leaving the impression that the client has
successfully authenticated the identity represented by the user
name, when in reality, the directory server has simply performed an
anonymous bind. For this reason, servers SHOULD by default reject
authentication requests that have a DN with an empty password with
an error of invalidCredentials.

Access control SHOULD always be applied when reading sensitive
information or updating directory information.

A connection on which the client has not performed the Start TLS
operation or negotiated a suitable SASL mechanism for connection
integrity and encryption services is subject to man-in-the-middle
attacks to view and modify information in transit.

10.1. Start TLS Security Considerations

The goals of using the TLS protocol with LDAP are to ensure
connection confidentiality and integrity, and to optionally provide

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for authentication. TLS expressly provides these capabilities, as
described in [RFC2246].

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
provide any additional security.

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Once established, TLS only provides for and ensures confidentiality
and integrity of the operations and data in transit over the LDAP
association--and only if the implementations on the client and
server support and negotiate it. The use of TLS does not provide or
ensure for confidentiality and/or non-repudiation of the data housed
by an LDAP-based directory server. Nor does it secure the data from
inspection by the server administrators.

The level of security provided though the use of TLS depends
directly on both the quality of the TLS implementation used and the
style of usage of that implementation. Additionally, an active-
intermediary attacker can remove the Start TLS extended operation
from the supportedExtension attribute of the root DSE. Therefore,
both parties SHOULD independently ascertain and consent to the
security level achieved once TLS is established and before beginning
use of the TLS connection. For example, the security level of the
TLS connection might have been negotiated down to plaintext.

Clients SHOULD either warn the user when the security level achieved
does not provide confidentiality and/or integrity protection, or be
configurable to refuse to proceed without an acceptable level of
security.

Client and server implementors SHOULD take measures to ensure proper
protection of credentials and other confidential data where such
measures are not otherwise provided by the TLS implementation.

Server implementors SHOULD allow for server administrators to elect
whether and when connection confidentiality and/or integrity is
required, as well as elect whether and when client authentication
via TLS is required.

Additional security considerations relating to the EXTERNAL
mechanism to negotiate TLS can be found in [RFC2222] [SASL] and [RFC2246].

11. IANA Considerations

The following IANA considerations apply to this document:

[To be completed]

Contributors

This document combines information originally contained in RFC 2829
and RFC 2830. The editor acknowledges the work of Harald Tveit
Alvestrand, Jeff Hodges, Tim Howes, Steve Kille, RL "Bob" Morgan ,
and Mark Wahl, each of whom authored one or more of these documents.

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Acknowledgements

This document is based upon input of the IETF LDAP Revision working
group. The contributions and suggestions made by its members in
shaping the contents and technical accuracy of this document is
greatly appreciated.

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Normative References

[RFC2119] Bradner, S., "Key Words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC2222] Myers, J., "Simple Authentication and Security Layer
(SASL)", draft-myers-saslrev-xx.txt, a work in progress.

[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.

[RFC2246] Dierks, T. and C. Allen. "The TLS Protocol Version 1.0",
RFC 2246, January 1999.

[RFC2831]

[DigestAuth] Leach, P. and C. Newman, and A. Melnikov, "Using Digest
Authentication as a SASL Mechanism", RFC 2831, May 2000. draft-ietf-sasl-rfc2831bis-
xx.txt, a work in progress.

[LDAPDN] Zeilenga, Kurt D. (editor), "LDAP: String Representation of
Distinguished Names", draft-ietf-ldapbis-dn-xx.txt, a work in
progress.

[PROTOCOL]

[Model] Zeilenga, Kurt D. (editor), "LDAP: Directory Information
Models", draft-ietf-ldapbis-models-xx.txt, a work in progress.

[Protocol] Sermersheim, J., "LDAP: The Protocol", draft-ietf-
ldapbis-protocol-xx.txt, a work in progress.

[ROADMAP] K. Zeilenga, "LDAP: Technical Specification Road Map",
draft-ietf-ldapbis-roadmap-xx.txt, a work in progress.
[SASL] Melnikov, A. (editor), "Simple Authentication and Security
Layer (SASL)", draft-ietf-sasl-rfc2222bis-xx.txt, a work in
progress.

Informative References

[ANONYMOUS] Zeilenga, K.,"Anonymous SASL Mechanism", draft-zeilenga-
sasl-anon-xx.txt, a work in progress.

[PLAIN] Zeilenga, K.,"Plain SASL Mechanism", draft-zeilenga-sasl-
plain-xx.txt, a work in progress.

[RFC2828] Shirey, R., "Internet Security Glossary", RFC 2828, May
2000.

[RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.

Author's Address

Roger Harrison
Novell, Inc.
1800 S. Novell Place

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Provo, UT 84606
+1 801 861 2642
roger_harrison@novell.com

Full Copyright Statement

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This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Appendix A. Example Deployment Scenarios

The following scenarios are typical for LDAP directories on the
Internet, and have different security requirements. (In the
following discussion, "sensitive data" refers to information whose
disclosure, alteration, destruction, or loss would adversely affect
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
intended to be a comprehensive list; other scenarios are possible,
especially on physically protected networks.

(1) A read-only directory, containing no sensitive data, accessible
to "anyone", and TCP connection hijacking or IP spoofing is not
a problem. Anonymous authentication, described in section 7, is
suitable for this type of deployment, and requires no additional
security functions except administrative service limits.

(2) A read-only directory containing no sensitive data; read access
is granted based on identity. TCP connection hijacking is not
currently a problem. This scenario requires data confidentiality
for sensitive authentication information AND data integrity for
all authentication information.

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(3) A read-only directory containing no sensitive data; and the
client needs to ensure the identity of the directory server and
that the directory data is not modified while being returned

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from the server. A data origin authentication service AND data
integrity service are required.

(4) A read-write directory, containing no sensitive data; read
access is available to "anyone", update access to properly
authorized persons. TCP connection hijacking is not currently a
problem. This scenario requires data confidentiality for
sensitive authentication information AND data integrity for all
authentication information.

(5) A directory containing sensitive data. This scenario requires
data confidentiality protection AND secure authentication.

Appendix B. Authentication and Authorization: Definitions and Concepts

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

B.1. Access Control Policy

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

B.2. Access Control Factors

A request, when it is being processed by a server, may be associated
with a wide variety of security-related factors (section 4.2 of
[PROTOCOL]).
[Protocol]). The server uses these factors to determine whether and
how to process the request. These are called access control factors
(ACFs). They might include source IP address, encryption strength,
the type of operation being requested, time of day, etc. Some
factors may be specific to the request itself, others may be
associated with the connection via which the request is transmitted,
others (e.g. time of day) may be "environmental".

Access control policies are expressed in terms of access control
factors. E.g., a request having ACFs i,j,k can perform operation Y
on resource Z. The set of ACFs that a server makes available for
such expressions is implementation-specific.

B.3. Authentication, Credentials, Identity

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Authentication credentials are the evidence supplied by one party to
another, asserting the identity of the supplying party (e.g. a user)
who is attempting to establish an association with the other party
(typically a server). Authentication is the process of generating,

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transmitting, and verifying these credentials and thus the identity
they assert. An authentication identity is the name presented in a
credential.

There are many forms of authentication credentials -- the form used
depends upon the particular authentication mechanism negotiated by
the parties. For example: X.509 certificates, Kerberos tickets,
simple identity and password pairs. Note that an authentication
mechanism may constrain the form of authentication identities used
with it.

B.4. Authorization Identity

An authorization identity is one kind of access control factor. It
is the name of the user or other entity that requests that
operations be performed. Access control policies are often expressed
in terms of authorization identities; e.g., entity X can perform
operation Y on resource Z.

The authorization identity bound to an association is often exactly
the same as the authentication identity presented by the client, but
it may be different. SASL allows clients to specify an authorization
identity distinct from the authentication identity asserted by the
client's credentials. This permits agents such as proxy servers to
authenticate using their own credentials, yet request the access
privileges of the identity for which they are proxying [RFC2222]. [SASL]. Also,
the form of authentication identity supplied by a service like TLS
may not correspond to the authorization identities used to express a
server's access control policy, requiring a server-
specific server-specific mapping
to be done. The method by which a server composes and validates an
authorization identity from the authentication credentials supplied
by a client is implementation-specific.

Appendix C. RFC 2829 Change History

This appendix lists the changes made to the text of RFC 2829 in
preparing this document.

C.0. General Editorial Changes
Version -00

- Changed other instances of the term LDAP to LDAPv3 where v3 of
the protocol is implied. Also made all references to LDAPv3 use
the same wording.

- Miscellaneous grammatical changes to improve readability.

- Made capitalization in section headings consistent.

Version -01

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- Changed title to reflect inclusion of material from RFC 2830 and
2251.

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C.1. Changes to Section 1

Version -01

- Moved conventions used in document to a separate section.

C.2. Changes to Section 2

Version -01

- Moved section to an appendix.

C.3. Changes to Section 3

Version -01

- Moved section to an appendix.

C.4 Changes to Section 4

Version -00

- Changed "Distinguished Name" to "LDAP distinguished name".

C.5. Changes to Section 5

Version -00

- Added the following sentence: "Servers SHOULD NOT allow clients
with anonymous authentication to modify directory entries or
access sensitive information in directory entries."

C.5.1. Changes to Section 5.1

Version -00

- Replaced the text describing the procedure for performing an
anonymous bind (protocol) with a reference to section 4.2 of RFC
2251 (the protocol spec).

Version -01

- Brought text describing procedure for performing an anonymous
bind from section 4.2 of RFC 2251 bis. This text will be
removed from the draft standard version of that document.

C.6. Changes to Section 6.

Version -00

Reorganized text in section 6.1 as follows:

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Reorganized text in section 6.1 as follows:

1. Added a new section (6.1) titled "Simple Authentication" and
moved one of two introductory paragraphs for section 6 into
section 6.1. Added sentences to the paragraph indicating:

a. simple authentication is not suitable for environments where
confidentiality is not available.

b. LDAP implementations SHOULD NOT support simple
authentication unless confidentiality and data integrity
mechanisms are in force.

2. Moved first paragraph of section 6 (beginning with "LDAP
implementations MUST support authentication with a password...")
to section on Digest Authentication (Now section 6.2).

C.6.1. Changes to Section 6.1.

Version -00 Renamed section to 6.2

- Added sentence from original section 6 indicating that the
DIGEST-MD5 SASL mechanism is required for all conforming LDAPv3
implementations

C.6.2. Changes to Section 6.2

Version -00

- Renamed section to 6.3

- Reworded first paragraph to remove reference to user and the
userPassword password attribute Made the first paragraph more
general by simply saying that if a directory supports simple
authentication that the simple bind operation MAY performed
following negotiation of a TLS ciphersuite that supports
confidentiality.

- Replaced "the name of the user's entry" with "a DN" since not
all bind operations are performed on behalf of a "user."

- Added Section 6.3.1 heading just prior to paragraph 5.

- Paragraph 5: replaced "The server" with "DSAs that map the DN
sent in the bind request to a directory entry with a
userPassword attribute."

C.6.3. Changes to section 6.3. 6.3.

Version -00

- Renamed to section 6.4.

C.7. Changes to section 7.

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none

C.7.1. Changes to section 7.1.

Version -00

- Clarified the entity issuing a certificate by moving the phrase
"to have issued the certificate" immediately after
"Certification Authority."

C.8. Changes to section 8.

Version -00

- Removed the first paragraph because simple authentication is
covered explicitly in section 6.

- Added section 8.1. heading just prior to second paragraph.

- Added section 8.2. heading just prior to third paragraph.

- Added section 8.3. heading just prior to fourth paragraph.

Version -01

- Moved entire section 8 of RFC 2829 into section 3.4 (Using SASL
for Other Security Services) to bring material on SASL
mechanisms together into one location.

C.9. Changes to section 9.

Version -00

- Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL
mechanism."

- Added section 9.1. heading.

- Modified a comment in the ABNF from "unspecified userid" to
"unspecified authz id".

- Deleted sentence, "A utf8string is defined to be the UTF-8
encoding of one or more ISO 10646 characters," because it is
redundant.

- Added section 9.1.1. heading.

- Added section 9.1.2. heading.

Version -00 -01

- Renamed to Moved entire section 6.4.

C.7. Changes 9 to become section 7.

none 3.5 so that it would be
with other SASL material.

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C.7.1.

C.10. Changes to section 7.1. Section 10.

Version -00

- Clarified the entity issuing Updated reference to cracking from a certificate by moving week of CPU time in 1997 to
be a day of CPU time in 2000.

- Added text: "These ciphersuites are NOT RECOMMENDED for use...
and server implementers SHOULD" to sentence just prior the phrase
"to have issued
second list of ciphersuites.

- Added text: "and MAY support other ciphersuites offering
equivalent or better protection," to the certificate" immediately after
"Certification Authority."

C.8. last paragraph of the
section.

C.11. Changes to Section 11.

Version -01

- Moved to section 8. 3.6 to be with other SASL material.

C.12. Changes to Section 12.

Version -00

- Removed the first paragraph because simple authentication Inserted new section 12 that specifies when SASL protections
begin following SASL negotiation, etc. The original section 12
is
covered explicitly in renumbered to become section 6. 13.

Version -01

- Added Moved to section 8.1. heading just prior 3.7 to be with other SASL material.

C.13. Changes to Section 13 (original section 12).

None

Appendix D. RFC 2830 Change History

This appendix lists the changes made to the text of RFC 2830 in
preparing this document.

D.0. General Editorial Changes

- Material showing the PDUs for the Start TLS response was broken
out into a new section.

- The wording of the definition of the Start TLS request and Start
TLS response was changed to second paragraph.

- Added section 8.2. heading just prior make them parallel. NO changes were
made to third paragraph. the ASN.1 definition or the associated values of the
parameters.

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- Added A separate section 8.3. heading just prior for graceful TLS closure was added
for parallelism with section on abrupt TLS closure.

Appendix E. RFC 2251 Change History

This appendix lists the changes made to fourth paragraph.

Version -01 the text of RFC 2251 in
preparing this document.

E.0. General Editorial Changes

- Moved entire All material from section 8 4.2 of RFC 2829 2251 was moved into this
document.

- A new section 3.4 (Using SASL was created for Other Security Services) to bring material on SASL
mechanisms together into one location.

C.9. Changes to section 9.

Version -00

- Paragraph 2: changed "EXTERNAL mechanism" to "EXTERNAL SASL
mechanism." the Bind Request

- Added Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved
after the section 9.1. heading.

- Modified a comment in on the ABNF from "unspecified userid" Bind Response for parallelism with the
presentation of the Start TLS operations. The section was also
subdivided to
"unspecified authz id". explicitly call out the various effects being
described within it.

- Deleted sentence, "A utf8string is defined to be All SASL profile information from RFC 2829 was brought within
the UTF-8
encoding discussion of one or more ISO 10646 characters," because it is
redundant. the Bind operation (primarily sections 4.4 -
4.7).

Appendix F. Change History to Combined Document

F.1. Changes for draft-ldap-bis-authmeth-02

General

- Added section 9.1.1. heading. references to other LDAP standard documents, to sections
within the document, and fixed broken references.

- General editorial changes--
-
-
punctuation, spelling, formatting,
etc.

Section 1.

- Added section 9.1.2. heading.

Version -01 glossary of terms and added sub-section headings

Section 2.

- Moved entire section 9 to become section 3.5 so that it would be Clarified security mechanisms 3, 4, & 5 and brought language in
line with other SASL material.

C.10. Changes to IETF security glossary.

Section 10. 3.

- Brought language in requirement (3) in line with security
glossary.

- Clarified that information fetched prior to initiation of TLS
negotiation must be discarded

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Version -00

- Updated reference

-Clarified that information fetched prior to cracking from a week initiation of CPU time in 1997 to SASL
negotiation must be a day of CPU time in 2000.

- Added text: "These ciphersuites are NOT RECOMMENDED for use...
and server implementers SHOULD" to sentence just prior the
second list of ciphersuites. discarded

- Added text: "and MAY support other ciphersuites offering
equivalent or better protection," to the last Rewrote paragraph of the
section.

C.11. Changes to Section 11.

Version -01

- Moved to section 3.6 to be with other on SASL material.

C.12. Changes negotiation requirements to clarify
intent

Section 12.

Version -00 4.4.

- Inserted new section 12 Added stipulation that specifies when SASL protections
begin following sasl choice allows for any SASL negotiation, etc. The original section 12
is renumbered to become section 13.

Version -01 mechanism
not prohibited by this document. (Resolved conflict between this
statement and one that prohibited use of ANONYMOUS and PLAIN
SASL mechanisms.)

Section 5.3.6

- Moved Added a.x.bar.com to section 3.7 wildcard matching example on hostname
check.

Section 6

- Added LDAP Association State Transition Tables to be show the
various states through which an LDAP association may pass along
with other SASL material.

C.13. Changes to Section 13 (original section 12).

None

Appendix D. RFC 2830 Change History

This appendix lists the changes made actions and decisions required to the text of RFC 2830 in
preparing this document.

D.0. General Editorial Changes traverse from state
to state.

Appendix A

- Material showing Brought security terminology in line with IETF security glossary
throughout the PDUs appendix.

F.2. Changes for the Start TLS response was broken
out into a new section. draft-ldap-bis-authmeth-03

General

- The wording of the definition of the Start TLS request Added introductory notes and Start
TLS response was changed title of document and
references to make them parallel. NO changes were
made conform to the ASN.1 definition or the associated values of the
parameters.

- A separate section heading for graceful TLS closure was added WG chair suggestions for parallelism with section on abrupt TLS closure.

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Appendix E. RFC 2251 Change History

This appendix lists the overall
technical specification.

- Several issues--G.13, G.14, G.16, G.17--were resolved without
requiring changes made to the text of RFC 2251 in
preparing this document.

E.0. General Editorial Changes

Section 3

- All material from section 4.2 of RFC 2251 was moved into this
document. Removed reference to /etc/passwd file and associated text.

Section 4

- A new Removed sections 4.1, 4.2 and parts of section 4.3. This
information was created for being duplicated in the Bind Request protocol specification
and will now reside there permanently.
Section 4.2

- changed words, "not recommended" to "strongly discouraged"

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Section 4.2.1 of RFC 2251 (Sequencing Bind Request) was moved
after the section 4.3

- Based on the Bind Response for parallelism ldapbis WG discussion at IETF52 two sentences were
added indicating that clients SHOULD NOT send a DN value when
binding with the
presentation of sasl choice and servers SHALL ignore any value
received in this circumstance.
-

Section 8.3.1

- Generalized the Start TLS operations. The language of this section was also
subdivided to explicitly call out not refer to any
specific password attribute or to refer to the various effects being
described within it. directory entry
as a "user" entry.

Section 11

- All SASL profile information from RFC 2829 was brought within
the discussion Added security consideration regarding misuse of the Bind operation (primarily sections 4.4 unauthenticated
access.

-
4.7).

Appendix F. Change History Added security consideration requiring access control to Combined Document

F.1. be
applied only to authenticated users and recommending it be
applied when reading sensitive information or updating directory
information.

F.3. Changes for draft-ldap-bis-authmeth-02 draft-ldap-bis-authmeth-04

General

- Added Changed references to other LDAP standard documents, use [RFCnnnn] format wherever possible.
(References to sections
within the document, and fixed broken references.

- General editorial changes
--
-
-
punctuation, spelling, formatting,
etc.

Section 1.

- Added glossary of terms and added sub-section headings

Section 2. works in progress still use [name] format.)
- Clarified security mechanisms 3, 4, & 5 Various edits to correct typos and brought language bring field names, etc. in
line with IETF security glossary. specification in [Protocol] draft.

- Several issues--G.13, G.14, G.16, G.17--were resolved without
requiring changes to the document.

Section 3. 4.4.1.

- Brought language in requirement (3) Changed ABNF grammar to use productions that are like those in line with security
glossary.
the model draft.

Section 5

- Clarified Removed sections 5.1, 5.2, and 5.4 that information fetched prior to initiation of TLS
negotiation must will be discarded

-Clarified that information fetched prior added to
[Protocol]. Renumbered sections to accommodate this change.
-

Section 6

- Reviewed LDAP Association State table for completeness and
accuracy. Renumbered actions A3, A4, and A5 to initiation of SASL
negotiation must be discarded A5, A3, and A4
respectively. Re-ordered several lines in the table to ensure
that actions are in ascending order (makes analyzing the table

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- Rewrote paragraph on SASL negotiation requirements to clarify
intent

Section 4.4.

- Added stipulation that sasl choice allows for any SASL mechanism
not prohibited by this document. (Resolved conflict between this
statement and one that prohibited use of ANONYMOUS and PLAIN
SASL mechanisms.)

Section 5.3.6

much more logical). Added a.x.bar.com action A2 to wildcard matching example on hostname
check.

Section 6

- several states where it
was missing and valid. Added LDAP Association State Transition Tables actions A7 and A8 placeholders to show the
various
states through which an LDAP association may pass along
with the actions S1, S2, S4 and decisions required S5 pending resolution of issue G.28.

Section 11

- Modified security consideration (originally added in -03)
requiring access control to traverse from state be applied only to state.

Appendix A authenticated
users. This seems nonsensical because anonymous users may have
access control applied to limit permissible actions.
- Brought security terminology in line with IETF security glossary
throughout the appendix.

F.2.
Section 13

- Verified all normative references and moved informative
references to a new section 14.

F.4. Changes for draft-ldap-bis-authmeth-03 draft-ldap-bis-authmeth-05

General

- Added introductory notes General editory changes to fix punctuation, spelling, line
length issues, etc.
- Verified and changed title of document updated intra- and inter-document references to conform to WG chair suggestions for the overall
technical specification.
throughout.
- Several issues--G.13, G.14, G.16, G.17--were resolved without
requiring Document-wide review for proper usage of RFC 2119 keywords with
several changes to the document.

Section 3 correct improper usage.

Abstract
- Removed reference Updated to /etc/passwd file match current contents of documents. This was needed
due to movement of material on Bind and associated text. Start TLS operations to
[Protocol] in this revision.

Section 4 3.

- Removed sections 4.1, 4.2 Renamed section to "Rationale for LDAPv3 Security Mechanisms"
and parts removed text that did not support this theme. Part of section 4.3. This
information the
motivation for this change was being duplicated in to remove the protocol specification implication of the
previous section title, "Required Security Mechanisms", and
other text found in the section that everything in the section
was a requirement

- Information from several removed paragraphs that describe
deployment scenarios will now reside there permanently.
Section 4.2 be added Appendix A in the next
revision of the draft.

- Paragraph beginning, " If TLS is negotiated, the client MUST
discard all information..." was moved to section 5.1.7 and
integrated with related material there.

- changed words, "not recommended" Paragraph beginning, "If a SASL security layer is negotiated..."
was moved to "strongly discouraged" section 4.2

Section 4.3 4.l.

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- 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. Changed wording of first paragraph to clarify meaning.

Section 4.2.
- Added paragraph from section 3 of -04 beginning, "If a SASL
security layer is negotiated..."

Section 8.3.1 4.3.3.
- Generalized Renamed to "Other SASL Mechanisms" and completely rewrote the language of this
section (one sentence) to not refer to any
specific password attribute or to refer to generalize the directory entry
as a "user" entry.

Section 11

- Added security consideration regarding misuse treatment of unauthenticated
access. SASL
mechanisms not explicitly mentioned in this document.

Section 4.4.1.

- Added security consideration requiring access control paragraph beginning, "The dnAuthzID choice allows client
applications..." to be
applied only clarify whether DN form authorization
identities have to authenticated users and recommending it be
applied when reading sensitive information or updating also have a corresponding directory
information.

F.3. Changes for draft-ldap-bis-authmeth-04

General

- Changed references to use [RFCnnnn] format wherever possible.
(References to works in progress still use [name] format.) entry.
This change was based on editor's perception of WG consensus.

- Various Made minor clarifying edits to correct typos and bring field names, etc. in
line with specification the paragraph beginning, "The
uAuthzID choice allows for compatibility..."

Section 5.1.1.

- Made minor clarifying edits in [PROTOCOL] draft. the last paragraph of the
section.

Section 5.1.7.

- Several issues--G.13, G.14, G.16, G.17--were resolved without
requiring changes to Wording from section 3 paragraph beginning " If TLS is
negotiated, the document. client MUST discard all information..." was
moved to this section and integrated with existing text.

Section 4.4.1. 5.2.

- Changed ABNF grammar usage of "TLS connection" to use productions that are like those in
the model draft.

Section 5 "TLS session" throughout.

- Removed sections 5.1, 5.2, empty section 5.2.1 and 5.4 that will be added to
[PROTOCOL]. Renumbered renumbered sections to accommodate this change. it had
previously contained.

Section 8.

- Added introductory paragraph at beginning of section.

Section 6 8.1.

- Reviewed LDAP Association State table for completeness and
accuracy. Renumbered actions A3, A4, and A5 Changed term "data privacy" to "data confidentiality" to be A5, A3, and A4
respectively. Re-ordered several lines
consistent with usage in the table rest of document.

Section 8.2.

- Changed first paragraph to ensure require implementations that actions are in ascending order (makes analyzing the table
much more logical). Added action A2
implement *password-based* authentication to several states where it implement and
support DIGEST-MD5 SASL authentication.

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was missing and valid. Added actions A7 and A8 placeholders to
states S1, S2, S4 and S5 pending resolution of issue G.28.

Section 11 11.

- Modified security consideration (originally added in -03)
requiring access control to be applied only First paragraph: changed "session encryption" to authenticated
users. This seems nonsensical because anonymous users may have
access control applied "session
confidentiality protection" to limit permissible actions.
-
Section 13 be consistent with usage in rest
of document.

Appendix A.

- Verified all normative references and moved informative
references Began changes to a new incorporate information on deployment scenarios
removed from section 14.

F.4. 3.

F.5. Changes for draft-ldap-bis-authmeth-05

General

- draft-ldap-bis-authmeth-06

General editory changes to fix punctuation, spelling, line
length issues, etc.

- Verified Combined Section 2 (Introduction) and updated intra- Section 3 (Motivation) and inter-document references
throughout.
- Document-wide review for proper usage of RFC 2119 keywords with
several changes
moved Introduction to correct improper usage.

Abstract section 1. All following sections numbers
were decremented by one as result.

- Updated to match current contents of documents. This was needed
due to movement of material on Bind and Start TLS operations Edits to
[PROTOCOL] fix typos, I-D nits, etc.

- Opened several new issues in this revision. Appendix G based on feedback from
WG. Some of these have been resolved. Others require further
discussion.

Section 3. 1

- Renamed section to "Rationale for LDAPv3 Security Mechanisms"
and removed text that did not support this theme. Part Added additional example of the
motivation for this change was to remove the implication spoofing under threat (7).

Section 2.1

- Changed definition of the
previous section title, "Required Security Mechanisms", "LDAP association" and
other text found in the section that everything in the section
was a requirement

- Information from several removed paragraphs that describe
deployment scenarios will be added Appendix A terms,
"connection" and "TLS connection" to bring usage in the next
revision of the draft. line with
[Protocol].

Section 4.1.6

- Paragraph beginning, " If TLS is negotiated, Clarified sentence stating that the client MUST
discard all information..." was moved NOT use derived
forms of DNS names.

Section 5.1

- Began edits to section 5.1.7 LDAP Association state table to clarify meaning
of various states and
integrated with related material there. actions.

- Paragraph beginning, "If a SASL security layer is negotiated..."
was moved Added action A9 to section 4.2 cover abandoned bind operation and added
appropriate transitions to the state transition table to
accommodate it.

Section 4.l. 7.2

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- Changed wording of Replaced first paragraph to clarify meaning.

Section 4.2.
- Added paragraph from section 3 of -04 beginning, "If a that the "DIGEST-MD5" SASL
security layer
mechanism is negotiated..." required to implement.

Section 4.3.3. 9

- Renamed to "Other SASL Mechanisms" and completely rewrote Rewrote the section (one sentence) to generalize make the treatment advice more applicable over the
long term, i.e. more "timeless." The intent of SASL
mechanisms not explicitly mentioned content in this document. the
original section was preserved.

Section 4.4.1. 10

- Added paragraph beginning, "The dnAuthzID choice allows client
applications..." to clarify whether DN form authorization
identities have to also have a corresponding directory entry.
This change was based on editor's perception of WG consensus.

- Made minor clarifying edits in example to the paragraph beginning, "The
uAuthzID choice allows consideration regarding misuse
of unauthenticated access.

F.6. Changes for compatibility..."

Section 5.1.1. draft-ldap-bis-authmeth-07

General

- Made minor clarifying edits Updated external and internal references to accommodate changes
in the last paragraph recent drafts.

- Opened several new issues in Appendix G based on feedback from
WG. Some of the
section. these have been resolved. Others require further
discussion.

Section 5.1.7. 3

- Wording from Rewrote much of section 3 paragraph beginning " If TLS is
negotiated, the client MUST discard all information..." was
moved 3.3 to this mee the SASL profile requirements
of draft-ietf-sasl-rfc2222bis-xx.txt section 5.

- Changed treatement of SASL ANONYMOUS and integrated PLAIN mechanisms to
bring in line with existing text. WG consensus.

Section 5.2. 4

- Changed usage of "TLS connection" Note to "TLS session" throughout. implementers in section 4.1.1 based on operational
experience.

- Removed empty Clarification on client continuing by performing a Start TLS
with TLS already established in section 5.2.1 and renumbered sections it had
previously contained.

Section 8. 4.1.4.

- Added introductory paragraph at beginning Moved verification of section.

Section 8.1.

- Changed term "data privacy" mapping of client's authentication ID to "data confidentiality"
asserted authorization ID to be
consistent with usage apply only to explicit assertion.
The local policy in rest of document. place for implicit assertion is adequate.

Section 8.2. 7

- Changed first paragraph to require implementations that
implement *password-based* authentication Removed most of section 7.2 as the information is now covered
adequately via the new SASL profile in section 3.3. Added note
to implement implementors regarding the treatment of username and
support DIGEST-MD5 SASL authentication. realm
values in DIGEST-MD5.

- Section 7.3. Minor clarifications in wording.

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Section 11.

- First paragraph: changed "session encryption" to "session
confidentiality protection" Section 7.3.1. Clarification that a match of the presented value
to be consistent with usage in rest any member of document. the set of stored passwords constitutes a
successful authentication.

Appendix A.

- Began changes to incorporate information on deployment scenarios
removed from section 3.

F.5. Changes for draft-ldap-bis-authmeth-06

General

- Combined Section 2 (Introduction) and Section 3 (Motivation) and
moved Introduction to section 1. All following sections numbers
were decremented by one as result.

- Edits G. Issues to fix typos, I-D nits, etc.

- Opened several new be Resolved

This appendix lists open questions and issues in Appendix G based that need to be
resolved before work on feedback from
WG. Some of these have been resolved. Others require further
discussion. this document is deemed complete.

G.1.

Section 1

- Added additional example lists 6 security mechanisms that can be used by LDAP
servers. I'm not sure what mechanism 5, "Resource limitation by
means of spoofing under threat (7).

Section 2.1

- administrative limits on service controls" means.

Status: resolved. Changed definition of "LDAP association" and added terms,
"connection" and "TLS connection" wording to "administrative service limits"
to clarify meaning.

G.2.

Section 2 paragraph 1 defines the term, "sensitive." Do we want to
bring usage this term and other security-related terms in line alignment with
[Protocol].

Section 4.1.6

- Clarified sentence stating
usage with the IETF security glossary (RFC 2828)?

Status: resolved. WG input at IETF 51 was that we should do this, so
the client MUST NOT use derived
forms of DNS names. appropriate changes have been made.

G.3.

Section 5.1

- Began edits to LDAP Association state table to clarify meaning
of various states and actions.

- Added action A9 2, deployment scenario 2: What is meant by the term "secure
authentication function?"

Status: resolved. Based on the idea that a "secure authentication
function" could be provided by TLS, I changed the wording to cover abandoned bind operation require
data confidentiality for sensitive authentication information and added
appropriate transitions
data integrity for all authentication information.

G.4.

Section 3, deployment scenario 3: What is meant by the phrase,
"directory data is authenticated by the server?"

Status: resolved. I interpreted this to mean the state transition table ability to
accommodate it. ensure
the identity of the directory server and the integrity of the data
sent from that server to the client, and explictly stated such.

G.5.

Section 7.2

- Replaced first 4 paragraph to clarify that 3: What is meant by the "DIGEST-MD5" SASL
mechanism phrase, "this means that
either this data is required useless for faking authentication (like the Unix
"/etc/passwd" file format used to implement. be)?"

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Section 9

- Rewrote the section to make the advice more applicable over

Status: resolved. Discussion at IETF 52 along with discussions with
the
long term, i.e. more "timeless." The intent original authors of content this material have convinced us that this
reference is simply too arcane to be left in place. In -03 the
original section was preserved.

Section 10

- Added a clarifying example text
has been modified to focus on the consideration regarding misuse need to either update password
information in a protected fashion outside of unauthenticated access.

Appendix G. Issues the protocol or to be Resolved

This appendix lists open questions
update it in session well protected against snooping, and issues that need the
reference to be
resolved before work on this document is deemed complete.

G.1. /etc/passwd has been removed.

G.6.

Section 1 lists 6 security mechanisms that can be used by LDAP
servers. I'm not sure what mechanism 5, "Resource limitation by
means of administrative limits on service controls" means. 4 paragraph 7 begins: "For a directory needing session
protection..." Is this referring to data confidentiality or data
integrity or both?

Status: resolved. Changed wording to "administrative service limits"
to clarify meaning.

G.2. say, "For a directory needing
data security (both data integrity and data confidentiality)..."

G.7.

Section 2 4 paragraph 1 defines 8 indicates that "information about the term, "sensitive." server
fetched fetched prior to the TLS negotiation" must be discarded. Do
we want to
bring explicitly state that this term and other security-related terms in alignment with
usage with applies to information fetched
prior to the IETF security glossary (RFC 2828)?

Status: resolved. WG input at IETF 51 was that we should do this, so *completion* of the appropriate changes have been made.

G.3.

Section 2, deployment scenario 2: What TLS negotiation or is meant by the term "secure
authentication function?" this going
too far?

Status: resolved. Based on comments in the idea that a "secure authentication
function" could be provided by TLS, I IETF 51 LDAPBIS WG
meeting, this has been changed the wording to require
data confidentiality for sensitive authentication information and
data integrity for all authentication information.

G.4. explicitly state, "fetched prior
to the initiation of the TLS negotiation..."

G.8.

Section 3, deployment scenario 3: What is meant by 4 paragraph 9 indicates that clients SHOULD check the phrase,
"directory data
supportedSASLMechanisms list both before and after a SASL security
layer is authenticated negotiated to ensure that they are using the best available
security mechanism supported mutually by the server?"

Status: resolved. I interpreted client and server. A
note at the end of the paragraph indicates that this to mean is a SHOULD
since there are environments where the ability to ensure client might get a list of
supported SASL mechanisms from a different trusted source.

I wonder if the identity intent of this could be restated more plainly using
one of these two approaches (I've paraphrased for the directory server and the integrity sake of
brevity):

Approach 1: Clients SHOULD check the data
sent from that server supportedSASLMechanisms
list both before and after SASL negotiation or clients SHOULD
use a different trusted source to determine available supported
SASL mechanisms.

Approach 2: Clients MUST check the client, supportedSASLMechanisms list
both before and explictly stated such. after SASL negotiation UNLESS they use a
different trusted source to determine available supported SASL
mechanisms.

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G.5.

Section 4 paragraph 3: What is meant by the phrase, "this means that
either this data is useless for faking authentication (like the Unix
"/etc/passwd" file format used to be)?"

Status: resolved. Discussion WG input at IETF 52 along with discussions with
the original authors of this material have convinced us 51 was that this
reference is simply too arcane to be left in place. In -03 Approach 1 was
probably best. I ended up keeping the text
has been modified basic structure similar to focus on the need
original to either update password
information in a protected fashion outside of meet this intent.

G.9.

Section 6.3.1 states: "DSAs that map the protocol or to
update it DN sent in session well protected against snooping, and the
reference bind request
to /etc/passwd has been removed.

G.6.

Section 4 paragraph 7 begins: "For a directory needing session
protection..." Is this referring to data confidentiality or data
integrity or both?

Status: resolved. Changed wording to say, "For entry with a directory needing
data security (both data integrity and data confidentiality)..."

G.7.

Section 4 paragraph 8 indicates that "information about userPassword attribute will... compare
[each value in the server
fetched fetched prior named user's entry]... with the presented
password." This implies that this applies only to user entries with
userPassword attributes. What about other types of entries that
might allow passwords and might store in the TLS negotiation" must be discarded. password information in
other attributes? Do we want to explicitly state that make this applies text more general?

Status: resolved in -03 draft by generalizing section 8.3.1 to information fetched
prior not
refer to any specific password attribute and by removing the *completion* of term
"user" in referring to the TLS negotiation or is this going
too far?

Status: resolved. Based on comments directory entry specified by the DN in
the IETF 51 LDAPBIS WG
meeting, this has been changed bind request.

G.10 userPassword and simple bind

We need to explicitly state, "fetched prior be sure that we don't require userPassword to be the initiation of only
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.
On publication state something like: "This is the TLS negotiation..."

G.8.

Section 4 paragraph 9 indicates that clients SHOULD check specific
implementation of what we discussed in our general reorg
conversation on the
supportedSASLMechanisms list both before list." (Source: Kurt Zeilenga)

Status: resolved in -03 draft by generalizing section 8.3.1 to not
refer to any specific password attribute and after a SASL security
layer is negotiated by removing the term
"user" in referring to ensure that they are using the best available
security mechanism supported mutually directory entry specified by the DN in
the bind request.

G.11. Meaning of LDAP Association

The original RFC 2830 uses the term "LDAP association" in describing
a connection between an LDAP client and server. A
note at the end server regardless of the paragraph indicates
state of TLS on that connection. This term needs to be defined or
possibly changed.

Status: resolved. at IETF 51 Bob Morgan indicated that this is a SHOULD
since there are environments where the client might get a list of
supported SASL mechanisms term
"LDAP association" was intended to distinguish the LDAP-level
connection from a different trusted source.

I wonder if the intent of this could TLS-level connection. This still needs to be restated more plainly using
one of these two approaches (I've paraphrased for the sake of
brevity):

Approach 1: Clients SHOULD check
clarified somewhere in the supportedSASLMechanisms
list both before and after SASL negotiation or clients SHOULD
use draft. Added "LDAP association" to a different trusted source
glossary in section 1.

G.12. Is DIGEST-MD5 mandatory for all implementations?

Reading 2829bis I think DIGEST-MD5 is mandatory ONLY IF your server
supports password based authentication...but the following makes it
sound mandatory to determine available supported
SASL mechanisms. provide BOTH password authentication AND DIGEST-
MD5:

"6.2. Digest authentication

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Approach 2: Clients

LDAP implementations MUST check support authentication with a password
using the supportedSASLMechanisms list
both before and after DIGEST-MD5 SASL negotiation UNLESS they use mechanism for password protection, as
defined in section 6.1."

The thing is for acl it would be nice (though not critical) to be
able to default the required authentication level for a
different trusted source subject to determine available supported SASL
mechanisms. a
single "fairly secure" mechanism--if there is no such mandatory
authentication scheme then you cannot do that. (Source: Rob Byrne)

Status: resolved. WG input -00 version of the draft added a sentence at IETF 51 was the
beginning of section 8.2 stating that Approach 1 was
probably best. I ended up keeping LDAP server implementations
must support this method.

G.13. Ordering of authentication levels requested

Again on the basic structure similar subject of authentication level, is it possible to the
original
define an ordering on authentication levels which defines their
relative "strengths" ? This would be useful in acl as you could say
things like"a given aci grants access to meet a given subject at this intent.

G.9.

Section 6.3.1 states: "DSAs that map the DN sent
authentication level AND ABOVE". David Chadwick raised this before
in the bind request context of denying access to a directory entry with subject at a userPassword attribute will... compare
[each value given
authentication level, in the named user's entry]... with the presented
password." This implies that this applies only which case he wanted to user entries with
userPassword attributes. What about other types of entries that
might allow passwords and might store in the password information in
other attributes? Do we want express "deny
access to make this text more general? subject at this authentication level AND TO ALL
IDENTITIES AUTHENTICATED BELOW THAT LEVEL". (Source: Rob Byrne)

Status: resolved in -03 draft by generalizing section 8.3.1 to out of scope. This is outside the scope of this document and
will not
refer be addressed.

G.14. Document vulnerabilities of various mechanisms

While I'm here...in 2829, I think it would be good to have some
comments or explicit reference to any specific password attribute and by removing a place where the term
"user" in referring to security
properties of the directory entry specified by particular mandatory authentication schemes are
outlined. When I say "security properties" I mean stuff like "This
scheme is vulnerable to such and such attacks, is only safe if the DN in
key size is > 50, this hash is widely considered the bind request.

G.10 userPassword and simple bind

We need best, etc...".
I think an LDAP implementor is likely to be sure interested in that we don't require userPassword
information, without having to be wade through the only
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.
On publication state something like: "This security RFCs.
(Source: Rob Byrne)

Status: out of scope. This is outside the specific
implementation scope of what we discussed in our general reorg
conversation this document and
will not be addressed.

G.15. Include a StartTLS state transition table

The pictoral representation it is nominally based on the list." is here (URL
possibly folded):

http://www.stanford.edu/~hodges/doc/LDAPAssociationStateDiagram-
1999-12-14.html

(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 Jeff Hodges)

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The original RFC 2830 uses the term "LDAP association" Authentication Methods 7 October 2003

Status: In Process. Table provided in describing
a connection between an LDAP client and server regardless of the
state -03. Review of TLS on content for
accuracy in -04. Additional review is needed, plus comments from WG
members indicate that connection. This term needs to additional description of each state's meaning
would be defined or
possibly changed.

Status: resolved. helpful.

G.16. Empty sasl credentials question

I spent some more time looking microscopically at IETF 51 Bob Morgan indicated ldap-auth-methods
and ldap-ext-tls drafts. The drafts say that the term
"LDAP association" was intended to distinguish the LDAP-level
connection from credential must
have the TLS-level connection. This still needs to form dn:xxx or u:xxx or be
clarified somewhere in the draft. Added "LDAP association" absent, and although they don't
say what to a
glossary do in section 1.

G.12. Is DIGEST-MD5 mandatory for all implementations?

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Reading 2829bis the case of an empty octet string I think DIGEST-MD5 would say that
we could send protocolError (claim it is mandatory ONLY IF your server
supports password based authentication...but a bad PDU).

There is still the following makes it
sound mandatory question of what to provide BOTH password authentication AND DIGEST-
MD5:

"6.2. Digest authentication

LDAP implementations MUST support authentication with a password
using do if the DIGEST-MD5 credential is 'dn:'
(or 'u:') followed by the empty string. (Source: ariel@columbia.edu
via Jeff Hodges)

Status: resolved. Kurt Zeilenga indicated during ldapbis WG
discussion at IETF 52 that SASL mechanism for password protection, as
defined AuthzID credentials empty and absent
are equivalent in section 6.1."

The thing is for acl it would be nice (though not critical) to be
able the latest SASL ID. This resolves the issue.

G.17. Hostname check from MUST to default SHOULD?

I am uneasy about the required authentication level for hostname check. My experience from PKI with
HTTP probably is a subject contributing factor; we have people using the
short hostname to get to a
single "fairly secure" mechanism--if there is no such mandatory
authentication scheme then you cannot do that. (Source: Rob Byrne)

Status: resolved. -00 version of server which naturally has the draft added a sentence at FQDN in
the
beginning of section 8.2 stating that LDAP server implementations
must support this method.

G.13. Ordering certificate, no end of authentication levels requested

Again problems. I have a certificate on my
laptop which has the subject of authentication level, FQDN for the casse when the system is it possible to
define an ordering on authentication levels which defines their
relative "strengths" ? This would be useful in acl as you could say
things like"a given aci grants access to our
Columbia network with a given subject at this
authentication level AND ABOVE". David Chadwick raised this before fixed IP; when I dial in however, I have
some horrible dialup name, and using the context of denying access to a subject at local https server becomes
annoying. Issuing a given
authentication level, certificate in which case he wanted to express "deny
access to this subject at the name 'localhost' is not a
solution! Wildcard match does not solve this authentication level AND TO ALL
IDENTITIES AUTHENTICATED BELOW THAT LEVEL". (Source: Rob Byrne)

Status: out problem. For these
reasons I am inclined to argue for 'SHOULD' instead of scope. This is outside
'MUST' in paragraph...

Also, The hostname check against the name in the scope certificate is a
very weak means of this document and
will preventing man-in-the-middle attacks; the proper
solution is not be addressed.

G.14. Document vulnerabilities of various mechanisms

While I'm here...in 2829, I think it would be good to have some
comments here yet (SecureDNS or explicit reference to some equivalent). Faking out
DNS is not so hard, and we see this sort of thing in the press on a place
pretty regular basis, where site A hijacks the security
properties of the particular mandatory authentication schemes are
outlined. When I say "security properties" I mean stuff like "This
scheme is vulnerable to such DNS server for site B
and such attacks, is only safe if gets all their requests. Some mention of this should be made in
the
key size is > 50, draft. (Source: ariel@columbia.edu via Jeff Hodges)

Status: resolved. Based on discussion at IETF 52 ldapbis WG meeting,
this hash text will stand as it is. The check is widely considered a MUST, but the best, etc...".
I think an LDAP implementor behavior
afterward is likely a SHOULD. This gives server implementations the room to be interested
maneuver as needed.

G.18. Must SASL DN exist in that
information, without having to wade through the security RFCs.
(Source: Rob Byrne)

Status: out directory?

If the 'dn:' form of scope. This sasl creds is outside used, is it the scope intention of the
draft(ers) that this document DN must exist in the directory and the client
will not be addressed.

G.15. Include a StartTLS state transition table

The pictoral representation it is nominally based on is here (URL
possibly folded): have the privileges associated with that entry, or can the
server map the sasl DN to perhaps some other DN in the directory,

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http://www.stanford.edu/~hodges/doc/LDAPAssociationStateDiagram-
1999-12-14.html

(Source: Jeff Hodges)

Status: In Process. Table provided

in -03. Review of content for
accuracy in -04. Additional review is needed, plus comments from WG
members indicate an implementation-dependent fashion?

We already know that additional description of each state's meaning
would be helpful.

G.16. Empty if *no* sasl credentials question

I spent some more time looking microscopically at ldap-auth-methods
and ldap-ext-tls drafts. The drafts say that the credential must
have are presented, the form dn:xxx or u:xxx DN
or altname in the client certificate may be absent, and although they don't
say what mapped to do a DN in the case of an empty octet string
implementation-dependent fashion, or indeed to something not in the
directory at all. (Right?) (Source: ariel@columbia.edu via Jeff
Hodges)

Status: resolved. (11/12/02)Based on my research I would say propose that
we could send protocolError (claim it is a bad PDU).

There the
DN MUST exist in the directory when the DN form of sasl creds is still
used. I have made this proposal to the question ldapbis mailing list.

(11/21/02) Feedback from mailing list has proposed removing this
paragraph entirely because (1) explicit assertion of what authorization
identity should only be done when proxying (2) mapping of the
asserted authorization identity is implementation specific and
policy driven [SASL] section 4.2, and (3) keeping this paragraph is
not required for interoperability.

G.19. DN used in conjunction with SASL mechanism

We need to do if specify whether the credential DN field in Bind operation can/cannot
be used when SASL mechanism is 'dn:'
(or 'u:') followed by the empty string. (Source: ariel@columbia.edu
via Jeff Hodges) specified. (source: RL Bob)

Status: resolved. Kurt Zeilenga indicated during (-03) Based on 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?

I am uneasy about the hostname check. My experience from PKI with
HTTP probably is a contributing factor; we have people using the
short hostname to get IETF52 two
sentences were added to section 4.3 indicating that clients SHOULD
NOT send a server which naturally has DN value when binding with the FQDN sasl choice and servers
SHALL ignore any value received in
the certificate, no end this circumstance. During edits
for -04 version of problems. I have a certificate on my
laptop which draft it was noted that [Protocol] section 4.2
conflicts with this draft. The editor of [Protocol] has been
notified of the FQDN for the casse when the system discrepancy, and they have been handled.

G.20. Bind states

Differences between unauthenticated and anonymous. There are four
states you can get into. One is on our
Columbia network with a fixed IP; when I dial completely undefined (this is now
explicitly called out in however, I have
some horrible dialup [Protocol]). This text needs to be moved
from [Protocol] to this draft. (source: Jim Sermersheim)

Status: Resolved. There are four states: (1) no name, and using the local https server becomes
annoying. Issuing a certificate no password
(anon); (2) name, no password (anon); (3) no name, password
(invalid); (4) name, password (simple bind). States 1, 2, and 4 are
called out in the name 'localhost' [AuthMeth]. State 3 is not a
solution! Wildcard match does not solve called out in [Protocol]; this problem. For these
reasons I am inclined to argue for 'SHOULD' instead
seems appropriate based on review of
'MUST' in paragraph...

Also, The hostname check against the alternatives.

G.21. Misuse of unauthenticated access

Add a security consideration that operational experience shows that
clients can misuse unauthenticated access (simple bind with name in the certificate is but
no password). Servers SHOULD by default reject authentication
requests that have a
very weak means DN with an empty password with an error of preventing man-in-the-middle attacks; the proper
solution is not here yet (SecureDNS or some equivalent). Faking out
DNS is not so hard,
invalidCredentials. (Source: Kurt Zeilenga and we see this sort of thing Chris Newman (Sun))

Status: Resolved. Added to security considerations in the press on a
pretty regular basis, where site A hijacks the DNS server -
-03.

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G.22. Need to move StartTLS protocol information to [Protocol]

Status: Resolved. Removed Sections 5.1, 5.2, and 5.4 for site B -04 and gets all their requests. Some mention of this should be
they are [Protocol] -11.

G.23. Split Normative and Non-normative references into separate
sections.

Status: Resolved. Changes made in
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 -04

G.24. What is a MUST, but the behavior
afterward authentication state if a Bind operation is a SHOULD.
abandoned?

Status: Resolved.

(3/24/03) This gives server implementations the room to
maneuver as needed.

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G.18. Must SASL DN exist following text appears in the directory?

If the 'dn:' form section 4.2.1 of sasl creds is used, [Protocol]
revision -13 to cover what happens if a bind operation is it abandoned:

A failed or abandoned Bind Operation has the intention effect of leaving the
draft(ers) that this DN must exist
connection in the directory and the client
will have the privileges associated with that entry, an anonymous state. To arrive at a known
authentication state after abandoning a bind operation, clients may
unbind, rebind, or can the
server map make use of the sasl DN BindResponse.

(6/28/03): The state table in section 6 of [AuthMeth] has been
updated to perhaps some other DN reflect this wording.

G.25. Difference between checking server hostname and server's
canonical DNS name in Server Identity Check?

Section 4.1.6: I now understand the directory,
in an implementation-dependent fashion?

We already know that if *no* sasl credentials are presented, intent of the DN
or altname in check (prevent
man-in-the-middle attacks). But what is the client certificate may be mapped to a DN in an
implementation-dependent fashion, or indeed to something not in subtle difference
between the
directory at all. (Right?) "server hostname" and the "server's canonical DNS name"?
(Source: ariel@columbia.edu via Jeff
Hodges) Tim Hahn)

Status: resolved. (11/12/02)Based on my research I propose that In Process.

(11/12/02) Sent suggested wording change to this paragraph to the
ldapbis mail list and also asked for opinion as to whether we should
discuss the
DN MUST exist distinction between server DNS hostname and server
canonical DNS hostname in [AuthMeth].

(11/21/02): RL Bob Morgan will provide wording that allows
derivations of the directory when name that are provided securely.

(6/28/03): posted to the DN form of sasl creds WG list asking Bob or any other WG member
who is
used. knowledgeable about the issues involved to help me with
wording or other information I have made this proposal can use to the ldapbis mailing list.

(11/21/02) Feedback' from mailing list has proposed removing make this
paragraph entirely because (1) explicit assertion of authorization
identity change and close
the work item.

G.26. Server Identity Check using servers located via SRV records

Section 4.1.6: What should only be done when proxying (2) mapping if the server was found using SRV
records based on the "locate" draft/RFC? (Source: Tim Hahn).

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Status: Resolved. Section 5 of draft-ietf-ldapext-locate-08
specifically calls out how the
asserted authorization server identity should be performed
if the server is implementation specific and
policy driven [SASL] section 4.2, and (3) keeping this paragraph is
not required for interoperability.

G.19. DN used in conjunction with SASL mechanism

We need to specify whether located using the DN field method defined in Bind operation can/cannot
be used when SASL mechanism is specified. (source: RL Bob)

Status: resolved. (-03) Based on ldapbis WG discussion at IETF52 two
sentences were added to section 4.3 indicating that clients SHOULD
NOT send a DN value when binding with draft.
This is the sasl choice right location for this information, and servers
SHALL ignore any value received the coverage
appears to be adequate.

G.27 Inconsistency in this circumstance. During edits
for -04 version effect of draft it was noted TLS closure on LDAP association.

Section 4.4.1 of authmeth -03 (section 4.1 of RFC2830) states that [PROTOCOL] section 4.2
conflicts with
TLS closure alert will leave the LDAP association intact. Contrast
this draft. The editor with Section 4.5.2 (section 5.2 of [PROTOCOL] has been
notified RFC2830) that says that the
closure of the discrepancy, and they have been handled.

G.20. Bind states

Differences between unauthenticated and anonymous. There are four
states you can get into. One is completely undefined (this TLS connection MUST cause the LDAP association to
move to an anonymous authentication.

Status: Resolved. (11/12/02) This is actually a [Protocol] issue
because these sections have now
explicitly called out in [PROTOCOL]). This been moved to [Protocol] -11. I have
proposed the following text needs for Section 4.4.1 of [AuthMeth] -03
(section 4.13.3.1 of [Protocol]) to be moved
from [PROTOCOL] resolve this apparent
discrepancy:

"Either the client or server MAY terminate the TLS connection on an
LDAP association by sending a TLS closure alert. The LDAP
connection remains open for further communication after TLS closure
occurs although the authentication state of the LDAP connection is
affected (see [AuthMeth] section 4.2.2).

(11/21/02): resolution to this draft. (source: Jim Sermersheim)

Status: Resolved. There are four states: (1) no name, no password
(anon); (2) name, no password (anon); (3) no name, password
(invalid); (4) name, password (simple bind). States 1, 2, and 4 are
called out in [AuthMeth]. State 3 is called out expected in [Protocol] -12

(06/28/03): [Protocol]-15 clarifies that a TLS closure alert
terminates the TLS connection while leaving the LDAP connection
intact. The authentication state table in [PROTOCOL]; this
seems appropriate based [AuthMeth] specifies the
effect on review the LDAP association.

G.28 Ordering of alternatives.

G.21. Misuse external sources of unauthenticated access

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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 authorization identities

Section 4.3.2 implies that have a DN with an empty password with an error external sources of
invalidCredentials. (Source: Kurt Zeilenga and Chris Newman (Sun))

Status: Resolved. Added to security considerations in -
-03.

G.22. Need to move StartTLS protocol information to [PROTOCOL]

Status: Resolved. Removed Sections 5.1, 5.2, and 5.4 for -04 and
they authorization
identities other than TLS are [PROTOCOL] -11.

G.23. Split Normative and Non-normative references into separate
sections.

Status: Resolved. Changes made in -04

G.24. permitted. What is the behavior when
two external sources of authentication state if credentials are available
(e.g. TLS and IPsec are both present (is this possible?)) and a SASL
EXTERNAL Bind operation is
abandoned? performed?

Status: Resolved.

(3/24/03) This following text appears in section 4.2.1 resolved. 11/20/02: Resolved by Section 4.2 of [PROTOCOL]
revision -13 [SASL] which
states that the decision to cover what happens if a bind operation is abandoned:

A failed allow or abandoned Bind Operation has disallow the effect asserted identity
is based on an implementation defined policy.

G.29 Rewrite of leaving the
connection Section 9, TLS Ciphersuites

This section contains anachronistic references and needs to be
updated/rewritten in an anonymous state. To arrive at a known
authentication state after abandoning way that provides useful guidance for future
readers in a bind operation, clients may
unbind, rebind, or make use of way that will transcend the BindResponse. passage of time.

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Status: Resolved. (6/28/03): The state table Rewrote the section to cover the
general issues and considerations involved in selecting TLS
ciphersuites.

G.30 Update to Appendix A, Example Deployment Scenarios

This section 6 of [AuthMeth] has been needs to be updated to reflect indicate which security
mechanisms and/or combinations of security mechanisms described
elsewhere in the document can provide the types of protections
suggested in this wording.

G.25. Difference between checking appendix.

G.31 Use of PLAIN SASL Mechanism

At least one LDAP server hostname and server's
canonical DNS name implementer has found the SASL "PLAIN"
mechanism useful in Server Identity Check? authenticating to legacy systems that do not
represent authentication identities as DNs. Section 4.1.6: I now understand 3.3.1 appears to
implicitly disallow the intent use of the check (prevent
man-in-the-middle attacks). But what SASL "PLAIN" mechanism with LDAP.
Should we allow the use of this mechanism? I.e. is this "SASL"
"PLAIN" MUST NOT be used with LDAP, or is it simply that LDAP
doesn't define bindings for these mechanism. If SASL "PLAIN" is
allowed, the subtle difference
between following adjustments will be needed to section 3.3.1:
(a) change section heading, (b) remove reference to "PLAIN" in the "server hostname" and
section, (c) ensure wording of last sentence regarding non-DN
AuthZIDs is consistent with rest of the "server's canonical DNS name"?
(Source: Tim Hahn) section.

Status: In Process.

(11/12/02) Sent suggested wording change to this paragraph Resolved.

(6/28/03): email to the
ldapbis mail WG list stating issue and also asked for opinion as to whether asking if we should
discuss
remove the distinction between server DNS hostname and server
canonical DNS hostname reference to SASL "PLAIN".

For -07 draft I've generalized the SASL profile in [AuthMeth].

(11/21/02): RL Bob Morgan will provide wording that allows
derivations section 3.3 to
allow any SASL mechanism.

G.32 Clarification on use of SASL mechanisms

Section 3.3.1: BTW, what _are_ the name that "ANONYMOUS" and "PLAIN" SASL
mechanisms? They are provided securely.

(6/28/03): posted not defined in RFC2222. If you refer to the WG other
SASL mechanisms than those in rfc2222, Maybe you should only list asking Bob or any
which mechanisms _are_used, instead of which ones are _not. (Source:
Hallvard Furuseth)

I (Kurt Zeilenga) note[s] as well that the ANONYMOUS/PLAIN section
(4.2) should
be deleted. ANONYMOUS and PLAIN, like in other WG member
who mechanism,
can be used in LDAP if a) supported and b) enabled. I note
that they each offer capabilities not found in their simple
bind equivalents (and hence are used in some deployments).
For example, PLAIN (over TLS) is knowledgeable about the issues involved to help me quite useful when interacting
with legacy authentication subsystems. (Source: Kurt Zeilenga)

Status: Resolved.

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wording or other information I can use to make this change and close

For -07 draft I've generalized the work item.

G.26. Server Identity Check using servers located via SRV records SASL profile in section 3.3 to
allow any SASL mechanism.

G.33 Clarification on use of password protection based on AuthZID form

Section 4.1.6: 3.3.1: "If an authorization identity of a form different
from a DN is requested by the client, a mechanism that protects the
password in transit SHOULD be used." What has that to do with DNs?
A mechanism that protects the password in transit should be done if the server was found using SRV
records based used in
any case, shouldn't it?

G.34 Clarification on the "locate" draft/RFC? (Source: Tim Hahn).

Status: Resolved. Section 5 use of draft-ietf-ldapext-locate-08
specifically calls out how the server identity matching rules in Server Identity Check

The text in section 4.1.6 isn't explicit on whether all rules apply
to both CN and dNSName values. The text should be performed
if clear as to which
rules apply to which values.... in particular, the server is located using wildcard
rules. (Source: Kurt Zeilenga)

G.35 Requested Additions to Security Considerations

Requested to mention hostile servers which the method defined in user might have been
fooled to into contacting. Which mechanisms that draft.
This is are standardized by
the right location for this information, and LDAP standard do/do not disclose the coverage
appears user's password to be adequate.

G.27 Inconsistency in effect of TLS closure on LDAP association.

Section 4.4.1 the
server? (Or to servers doing man-in-the-middle attack? Or is that a
stupid question?)

Requested to mention denial of authmeth -03 (section 4.1 service attacks.

Requested list of RFC2830) states methods that
TLS closure alert will leave need/don't need the LDAP association intact. Contrast
this with Section 4.5.2 (section 5.2 of RFC2830) that says that server to know
the
closure user's plaintext password. (I say 'know' instead of 'store'
because it could still store the TLS connection MUST cause the LDAP association password encrypted, but in a way
which it knows how to
move decrypt.)

(Source: Hallvard Furuseth)

G.36 Add reference to an anonymous authentication. definition of DIGEST-MD5

Need a reference to the definition of DIGEST-MD5 SASL mechanism in
section 7.2 (Source: Hallvard Furuseth)

Status: Resolved. (11/12/02) This is actually a [PROTOCOL] issue
because these sections have now been moved A reference to to [PROTOCOL] -11. I have
proposed the following text DIGEST-MD5 SASL mechanism,
[DigestAuth], is included in the -07 revision.

G.37 Clarification on procedure for Section 4.4.1 of [AuthMeth] -03
(section 4.13.3.1 certificate-based authentication

8.1. Certificate-based authentication with TLS states: "Following
the successful completion of [PROTOCOL]) to resolve this apparent
discrepancy:

"Either TLS negotiation, the client or server MAY terminate the TLS connection on will send
an LDAP association by sending a TLS closure alert. The bind request with the SASL "EXTERNAL" mechanism." Is this

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connection remains open for further communication after TLS closure
occurs although Authentication Methods 7 October 2003

immediately following, or just some time later? Should the wording,
"the client will send..." actually read, "the client MUST send..."?

G.38 Effect of StartTLS on authentication state of

Should the LDAP connection is
affected (see [AuthMeth] section 4.2.2).

(11/21/02): resolution server drop all knowledge of connection, i.e. return to this
anonymous state, if it gets a StartTLS request on a connection that
has successfully bound using the simple method?

G.39 Be sure that there is expected a consideration in [PROTOCOL] -12

(06/28/03): [PROTOCOL]-15 clarifies [SCHEMA] that discusses
multiple password values in userPassword

Allowing multiple values obviously does raise a TLS closure alert
terminates number of security
considerations and these need to be discussed in the TLS connection while leaving document.

Certainly applications which intend to replace the LDAP connection
intact. The userPassword with
new value(s) should use modify/replaceValues (or
modify/deleteAttribute+addAttribute). Additionally, server
implementations should be encouraged to provide administrative
controls which, if enabled, restrict userPassword to one value.

G.40. Clarify need to verify mapping between authentication state table in [AuthMeth] specifies the
effect identity
and resulting authorization identity on the LDAP association.

G.28 Ordering implicit assertion of external sources AuthZID.

4.2.2.3. Error Conditions

"For either form of authorization identities

Section 4.3.2 implies assertion, the server MUST verify that external sources of authorization
identities other than the
client's authentication identity as supplied in its TLS are permitted. What credentials
is permitted to be mapped to the behavior when asserted authorization identity."

This makes sense for the explicit assertion case, but seems to be
ambiguous for the implicit case.
IMHO, the mapping can be done as two external sources of steps:
a). deriving LDAP authentication credentials are available
(e.g. identity from TLS and IPsec are both present (is credentials; If t
this possible?)) and a SASL steps fails, EXTERNAL Bind operation mechanism returns failure.
b). verify that the authorization identity is performed? allowed for the
derived authentication identity. This is always "noop" for the
implicit case.
I am not sure that the text is saying this.
(Source: Alexey Melnikov email 8/1/2003 5:30:43 PM)

Status: resolved. 11/20/02: Resolved by Section 4.2 in -07. After reading the comments and the text of [SASL] which
states
the draft, I believe that this should be clarified. The local policy
used to map the decision AuthNID to allow or disallow the asserted identity AuthZID in the implicit case is based on an implementation defined policy.

G.29 Rewrite of Section 9, TLS Ciphersuites

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sufficient and that no additional verification is useful or needed.
This section text has been moved to apply only to the explicit assertion
case.

G.41. Section 7.2 contains anachronistic references unnecessary and needs to be
updated/rewritten misleading detail.

" I am not sure why this section is required in a way that provides useful guidance for future
readers the document.
DIGEST-MD5 is defined in a way that will transcend the passage of time.

Status: Resolved. (6/28/03): Rewrote separate document and there should be
nothing magical about its usage in LDAP. If DIGEST-MD5 description
creates confusion for LDAP implementors, let's fix the DIGEST-MD5

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document! Also, this section tries to cover redefine DIGEST-MD5 behavior,
which is explicitly prohibited by the
general issues SASL specification."
(Source: Alexey Melnikov: email 8/1/2003 5:30:43 PM)

Status: Resolved.

After reading the comments and considerations involved the text of the draft plus the
related text in selecting TLS
ciphersuites.

G.30 Update draft-ietf-sasl-rfc2831bis-02.txt plus
http://www.ietf.org/internet-drafts/draft-ietf-sasl-rfc2222bis-
02.txt, I am inclined to Appendix A, Example Deployment Scenarios

This agree with Alexey. In -07 I rewrote section needs to be updated
3.3 (SASL mechanisms) to indicate which security
mechanisms and/or combinations of security mechanisms described
elsewhere in the document can provide match the types of protections
suggested in this appendix.

G.31 Use of PLAIN SASL Mechanism

At least one LDAP server implementer has found profiling requirements
rfc2831bis. I then dramatically reduced the SASL "PLAIN"
mechanism useful material in authenticating to legacy systems that do not
represent authentication identities as DNs. Section 3.3.1 appears section 7.2
to
implicitly disallow the use of a bare minimum and let the SASL "PLAIN" mechanism with LDAP.
Should we allow the use of this mechanism? I.e. profile stand on its own.

G.42. Does change for G.41 cause interoperability issue?

There is this "SASL"
"PLAIN" MUST NOT be used one issue with LDAP, or the way the authmeth draft is it simply currently
written that LDAP
doesn't define bindings for these mechanism. If changes the SASL "PLAIN" is
allowed, DIGEST-MD5 behavior on the following adjustments will be needed to section 3.3.1:
(a) change section heading, (b) remove reference to "PLAIN" in way the
section, (c) ensure wording of last sentence regarding non-DN
AuthZIDs is consistent
server responds with rest of the section.

Status: In process.

(6/28/03): email to WG list stating subsequent authentication information .
This has been documented in this fashion since RFC 2829 (section
6.1) was originally published and may cause an interoperability
issue and asking at this point if we should
remove the reference it changed to SASL "PLAIN".

G.32 Clarification on use follow the DIGEST-MD5 spec (as
it was in -07 of SASL mechanisms

Section 3.3.1: BTW, what _are_ AuthMeth). Take this issue to the "ANONYMOUS" and "PLAIN" SASL
mechanisms? They list.

G.43. DIGEST-MD5 Realms recommendations for LDAP

From http://www.ietf.org/internet-drafts/draft-ietf-sasl-rfc2222bis-
02.txt: A protocol profile SHOULD provide a guidance how realms are not defined in RFC2222. If you refer
to other
SASL mechanisms than those be constructed and used in rfc2222, Maybe you should only list
which mechanisms _are_used, instead of which ones are _not. (Source:
Hallvard Furuseth)

G.33 Clarification on use of password protection based on AuthZID form

Section 3.3.1: "If an authorization identity of a form different
from a DN is requested by the client, a mechanism protocol and MAY further restrict
its syntax and protocol-specific semantics."

I don't believe that protects any such guidance exists within the
password in transit SHOULD be used." What has that LDAP TS.
The most likely place for this to do reside is in the authmeth draft.

Related email from Alexey Melnikov (8/4/2003 1:08:40 PM):

"The problem I have with DNs?
A mechanism that protects the password in transit document is that it references realm
without explaining what it is (or at least some examples of valid
values). For LDAP, some recommendations should be used given. For
example:
1). Use a hardcoded string as the realm (one of the implementations
I worked on was doing that)
2). Use hostname (realm==host) or domain/cluster name (realm
includes multiple hosts).
3). Use a node in
any case, shouldn't it? DIT above user entry, for example for "cn=Barbara
Jensen, ou=Accounting, o=Ace Industry, c=US"
and "cn=John Doe, ou=Accounting, o=Ace Industry, c=US" realm can be
"ou=Accounting, o=Ace Industry, c=US"
(or "o=Ace Industry, c=US"); for "cn=Gern Jensen, ou=Product
Testing,o=Ace Industry, c=US" realm can be "ou=Product Testing,
o=Ace Industry, c=US".

Of course other choices are possible.

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G.34 Clarification on

Alexey

To summarize: I'd like authmeth to define a realm name for use with
Digest-MD5 that corresponds to LDAP DNs known to this server.
Authzid is okay, but perhaps could be better put into context.

John McMeeking (5/12/2003)

G.44. Use of matching rules DNs in Server Identity Check

The text usernames and realms in section 4.1.6 isn't explicit DIGEST-MD5

In reading the discussion on whether all rules apply
to both CN the mailing list, I reach the following
conclusions:

DIGEST-MD5 username and dNSName values. realm are simple strings. The text should be clear syntax of
these strings allows strings that look like DNs in form, however,
DIGEST-MD5 treats them a simple strings for comparision purposes.
For example, the DNs cn=roger, o=US and cn=roger,o=us are equivalent
when being compared semantically as DNs, however, these would be
considered two different username values in DIGEST-MD5 because
simple octet-wise semantics (rather than DN semantics) are used to which
rules apply to which values....
compare username values in particular, the wildcard
rules. (Source: Kurt Zeilenga)

G.35 Requested Additions DIGEST-MD5. Ditto for realm values.

Status: Resolved.

In -07 revision I added notes to Security Considerations

Requested implementors expressing this issue
in section 7.2.

G.45: Open Issue: Is Simple+TLS mandatory to mention hostile servers which the user might have been
fooled implement?

Going forward, it would be much better to into contacting. Which mechanisms clarify that are standardized by simple
+TLS is to be used for DN/password credentials and DIGEST-MD5
(or PLAIN+TLS) be used for username/password credentials. (Kurt
Zeilenga, 5/12/2003)

I don't believe you can mandate simple/TLS! At the LDAP standard do/do time RFC 2829 was
debated, a large number on the WG wanted this. They did not disclose get
their way because of the user's password to complexity of the
server? (Or to servers doing man-in-the-middle attack? Or is solution. It was argued
that a
stupid question?)

Requested to mention denial password-based method would be better. I think they believed
it would still be DN/password, though. (Ron Ramsay, 5/12/2003)

This was officially opened as an issue by WG co-chair Kurt Zeilenga
on 5/12/03. Little direct discussion has occurred since, however
there has been significant discussion on the use of service attacks. (Source: Hallvard
Furuseth) DN values as the
username for DIGEST-MD5.

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