wdiff draft-ietf-ldapbis-protocol-18.txt draft-ietf-ldapbis-protocol-19.txt

Internet-Draft Editor: J. Sermersheim
Intended Category: Standard Track Novell, Inc
Document: draft-ietf-ldapbis-protocol-18.txt Oct draft-ietf-ldapbis-protocol-19.txt Dec 2003
Obsoletes: RFC 2251 2251, 2830

LDAP: The Protocol

Status of this Memo

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

Internet-Drafts are working documents of the Internet Engineering
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Distribution of this memo is unlimited. Technical discussion of this
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Abstract

This document describes the protocol elements, along with their
semantics and encodings, of the Lightweight Directory Access Protocol
(LDAP). LDAP provides access to distributed directory services that
act in accordance with X.500 data and service models. These protocol
elements are based on those described in the X.500 Directory Access
Protocol (DAP).

Table of Contents

1. Introduction....................................................3 Introduction....................................................2
1.1. Relationship to Obsolete Specifications.......................3
2. Conventions.....................................................3
3. Protocol Model..................................................3
4. Elements of Protocol............................................4
4.1. Common Elements...............................................4
4.1.1. Message Envelope............................................4
4.1.2. String Types................................................6
4.1.3. Distinguished Name and Relative Distinguished Name..........6

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4.1.3. Distinguished Name and Relative Distinguished Name..........6
4.1.4. Attribute Descriptions......................................7
4.1.5. Attribute Value.............................................7
4.1.6. Attribute Value Assertion...................................7
4.1.7. Attribute...................................................8 Attribute and PartialAttribute..............................8
4.1.8. Matching Rule Identifier....................................8
4.1.9. Result Message..............................................8
4.1.10. Referral..................................................10
4.1.11. Controls..................................................11
4.2. Bind Operation...............................................12
4.3. Unbind Operation.............................................15
4.4. Unsolicited Notification.....................................15 Notification.....................................16
4.5. Search Operation.............................................16 Operation.............................................17
4.6. Modify Operation.............................................24 Operation.............................................25
4.7. Add Operation................................................26
4.8. Delete Operation.............................................26 Operation.............................................27
4.9. Modify DN Operation..........................................27 Operation..........................................28
4.10. Compare Operation...........................................28 Operation...........................................29
4.11. Abandon Operation...........................................29 Operation...........................................30
4.12. Extended Operation..........................................29 Operation..........................................30
4.13. Start TLS Operation.........................................31 StartTLS Operation..........................................31
5. Protocol Element Encodings and Transfer........................33
5.1. Protocol Encoding............................................33 Encoding............................................34
5.2. Transfer Protocols...........................................33 Protocols...........................................34
6. Implementation Guidelines......................................33
6.1. Server Implementations.......................................33
6.2. Client Implementations.......................................34
7. Security Considerations........................................34
7. Acknowledgements...............................................36
8. Acknowledgements...............................................35
9. Normative References...........................................35
10. References...........................................36
9. Informative References........................................37
11. References.........................................37
10. IANA Considerations...........................................37
12.
11. Editor's Address..............................................37 Address..............................................38
Appendix A - LDAP Result Codes....................................38 Codes....................................39
A.1 Non-Error Result Codes........................................38 Codes........................................39
A.2 Result Codes..................................................38 Codes..................................................39
Appendix B - Complete ASN.1 Definition............................43
Appendix C - Change History.......................................47 Changes..............................................48
C.1 Changes made to RFC 2251:.....................................47
C.2 Changes made to draft-ietf-ldapbis-protocol-00.txt:...........47
C.3 Changes made to draft-ietf-ldapbis-protocol-01.txt:...........48
C.4 Changes made to draft-ietf-ldapbis-protocol-02.txt:...........48
C.5 Changes made to draft-ietf-ldapbis-protocol-03.txt:...........50
C.6 Changes made to draft-ietf-ldapbis-protocol-04.txt:...........52
C.7 Changes made to draft-ietf-ldapbis-protocol-05.txt:...........52
C.8 Changes made to draft-ietf-ldapbis-protocol-06.txt:...........53
C.9 Changes made to draft-ietf-ldapbis-protocol-07.txt:...........56
C.10 Changes made to draft-ietf-ldapbis-protocol-08.txt:..........56
C.11 Changes made to draft-ietf-ldapbis-protocol-09.txt:..........56
C.12 Changes made to draft-ietf-ldapbis-protocol-10.txt:..........56
C.13 Changes made to draft-ietf-ldapbis-protocol-11.txt:..........57
C.14 Changes made to draft-ietf-ldapbis-protocol-12.txt:..........57
C.15 Changes made to draft-ietf-ldapbis-protocol-13.txt...........57
C.16 Changes made to draft-ietf-ldapbis-protocol-14.txt...........58
C.17 Changes made to draft-ietf-ldapbis-protocol-15.txt...........60
C.18 RFC 2251:.............................48
C.2 Changes made to draft-ietf-ldapbis-protocol-16.txt...........60

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C.19 Changes made to draft-ietf-ldapbis-protocol-17.txt...........61 RFC 2830:.............................53

1. Introduction

The Directory is "a collection of open systems cooperating to provide
directory services" [X.500]. A directory user, which may be a human
or other entity, accesses the Directory through a client (or
Directory User Agent (DUA)). The client, on behalf of the directory
user, interacts with one or more servers (or Directory System Agents
(DSA)). Clients interact with servers using a directory access
protocol.

This document details the protocol elements of the Lightweight
Directory Access Protocol (LDAP), along with their semantics.
Following the description of protocol elements, it describes the way
in which the protocol elements are encoded and transferred.

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1.1. Relationship to Obsolete Specifications

This document is an integral part of the LDAP Technical Specification
[Roadmap].
[Roadmap] which obsoletes the previously defined LDAP technical
specification, RFC 3377, in its entirety.

This document replaces obsoletes all of RFC 2251. 2251 except the following:
Sections 3.2, 3.4, 4.1.3 (last paragraph), 4.1.4, 4.1.5, 4.1.5.1,
4.1.9 (last paragraph), 5.1, 6.1, and 6.2 (last paragraph) are
obsoleted by [Models].
Section 3.3 is obsoleted by [Roadmap].
Sections 4.2.1 (portions), and 4.2.2 are obsoleted by [AuthMeth].

Appendix C holds a detailed log of C.1 summarizes substantive changes to the remaining
sections.

This document also obsoletes RFC 2251. After Working Group Last Call, this appendix
will be distilled to a summary 2830, Sections 2 and 4 in entirety.
The remainder of RFC 2830 is obsoleted by [AuthMeth]. Appendix C.2
summarizes substantive changes to RFC 2251. the remaining sections.

2. Conventions

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

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

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

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

3. Protocol Model

The general model adopted by this protocol is one of clients
performing protocol operations against servers. In this model, a
client transmits a protocol request describing the operation to be
performed to a server. The server is then responsible for performing
the necessary operation(s) in the Directory. Upon completion of the
operation(s), the server returns a response containing an appropriate
result code to the requesting client.

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Although servers are required to return responses whenever such
responses are defined in the protocol, there is no requirement for
synchronous behavior on the part of either clients or servers.
Requests and responses for multiple operations may be exchanged
between a client and server in any order, provided the client
eventually receives a response for every request that requires one.

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The core protocol operations defined in this document can be mapped
to a subset of the X.500 (1993) Directory Abstract Service. However
there is not a one-to-one mapping between LDAP protocol operations
and X.500 Directory Access Protocol (DAP) operations. Server
implementations acting as a gateway to X.500 directories may need to
make multiple DAP requests to service a single LDAP request.

4. Elements of Protocol

The LDAP protocol is described using Abstract Syntax Notation One
[ASN.1],
([ASN.1]), and is transferred using a subset of ASN.1 Basic Encoding
Rules [BER]. ([BER]). Section 5.1 specifies how the protocol elements are
encoded and transferred.

In order to support future Standards Track extensions to this
protocol, extensibility is implied where it is allowed (per ASN.1).
In addition, ellipses (...) have been supplied in ASN.1 types that
are explicitly extensible as discussed in [LDAPIANA]. Because of the
implied extensibility, clients and servers MUST (unless otherwise
specified) ignore trailing SEQUENCE components whose tags they do not
recognize.

Changes to the LDAP protocol other than through the extension
mechanisms described here require a different version number. A
client indicates the version it is using as part of the bind request,
described in section Section 4.2. If a client has not sent a bind, the server
MUST assume the client is using version 3 or later.

Clients may determine the protocol versions a server supports by
reading the supportedLDAPVersion attribute from the root DSE (DSA-
Specific Entry) [Models]. Servers which implement version 3 or later
MUST provide this attribute.

4.1. Common Elements

This section describes the LDAPMessage envelope PDU (Protocol Protocol Data
Unit) Unit
(PDU) format, as well as data type definitions, which are used in the
protocol operations.

4.1.1. Message Envelope

For the purposes of protocol exchanges, all protocol operations are
encapsulated in a common envelope, the LDAPMessage, which is defined
as follows:

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searchRequest SearchRequest,
searchResEntry SearchResultEntry,
searchResDone SearchResultDone,
searchResRef SearchResultReference,
modifyRequest ModifyRequest,
modifyResponse ModifyResponse,
addRequest AddRequest,
addResponse AddResponse,
delRequest DelRequest,
delResponse DelResponse,
modDNRequest ModifyDNRequest,
modDNResponse ModifyDNResponse,
compareRequest CompareRequest,
compareResponse CompareResponse,
abandonRequest AbandonRequest,
extendedReq ExtendedRequest,
extendedResp ExtendedResponse,
... },
controls [0] Controls OPTIONAL }

MessageID ::= INTEGER (0 .. maxInt)

maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) --

The function of the LDAPMessage is to provide an envelope containing
common fields required in all protocol exchanges. At this time the
only common fields are the message ID and the controls.

If the server receives a PDU from the client in which the LDAPMessage
SEQUENCE tag cannot be recognized, the messageID cannot be parsed,
the tag of the protocolOp is not recognized as a request, or the
encoding structures or lengths of data fields are found to be
incorrect, then the server SHOULD return the Notice of Disconnection
described in section Section 4.4.1, with the resultCode set to protocolError,
and MUST immediately close the connection.

In other cases where the client or server cannot parse a PDU, it
SHOULD abruptly close the connection where further communication
(including providing notice) would be pernicious. Otherwise, server
implementations MUST return an appropriate response to the request,
with the resultCode set to protocolError.

The ASN.1 type Controls is defined in section Section 4.1.11.

4.1.1.1. Message ID

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All LDAPMessage envelopes encapsulating responses contain the
messageID value of the corresponding request LDAPMessage.

The message ID of a request MUST have a non-zero value different from
the values of any other requests outstanding in the LDAP association
of which this message is a part. The zero value is reserved for the
unsolicited notification message.

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Typical clients increment a counter for each request.

A client MUST NOT send a request with the same message ID as an
earlier request on the same LDAP association unless it can be
determined that the server is no longer servicing the earlier
request. Otherwise the behavior is undefined. For operations that do
not return responses (unbind, abandon, and abandoned operations), the
client SHOULD assume the operation is in progress until a subsequent
bind request completes.

4.1.2. String Types

The LDAPString is a notational convenience to indicate that, although
strings of LDAPString type encode as ASN.1 OCTET STRING types, the
[ISO10646] character set (a superset of [Unicode]) is used, encoded
following the [UTF-8] algorithm. Note that Unicode characters U+0000
through U+007F are the same as ASCII 0 through 127, respectively, and
have the same single octet UTF-8 encoding. Other Unicode characters
have a multiple octet UTF-8 encoding.

LDAPString ::= OCTET STRING -- UTF-8 encoded,
-- [ISO10646] characters

The LDAPOID is a notational convenience to indicate that the
permitted value of this string is a (UTF-8 encoded) dotted-decimal
representation of an OBJECT IDENTIFIER. Although an LDAPOID is
encoded as an OCTET STRING, values are limited to the definition of
<numericoid> given in Section 1.3 of [Models].

LDAPOID ::= OCTET STRING -- Constrained to <numericoid> [Models]

For example,

1.3.6.1.4.1.1466.1.2.3

4.1.3. Distinguished Name and Relative Distinguished Name

An LDAPDN is defined to be the representation of a distinguished name Distinguished Name
(DN) after encoding according to the specification in [LDAPDN].

LDAPDN ::= LDAPString
-- Constrained to <distinguishedName> [LDAPDN]

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A RelativeLDAPDN is defined to be the representation of a relative
distinguished name Relative
Distinguished Name (RDN) after encoding according to the
specification in [LDAPDN].

RelativeLDAPDN ::= LDAPString
-- Constrained to <name-component> [LDAPDN]

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4.1.4. Attribute Descriptions

The definition and encoding rules for attribute descriptions are
defined in Section 2.5 of [Models]. Briefly, an attribute description
is an attribute type and zero or more options.

AttributeDescription ::= LDAPString
-- Constrained to <attributedescription>
-- [Models]

4.1.5. Attribute Value

A field of type AttributeValue is an OCTET STRING containing an
encoded attribute value. The attribute value is encoded according to
the LDAP-specific encoding definition of its corresponding syntax.
The LDAP-specific encoding definitions for different syntaxes and
attribute types may be found in other documents and in particular
[Syntaxes].

AttributeValue ::= OCTET STRING

Note that there is no defined limit on the size of this encoding;
thus protocol values may include multi-megabyte attributes (e.g.
photographs).

Attributes may be defined which have arbitrary and non-printable
syntax. Implementations MUST NOT display nor attempt to decode a
value if its syntax is not known. The implementation may attempt to
discover the subschema of the source entry, and retrieve the
descriptions of attributeTypes from it [Models].

Clients MUST NOT send attribute values in a request that are not
valid according to the syntax defined for the attributes.

4.1.6. Attribute Value Assertion

The AttributeValueAssertion type definition is similar to the one in
the X.500 Directory standards. It contains an attribute description
and a matching rule assertion value suitable for that type.

AttributeValueAssertion ::= SEQUENCE {
attributeDesc AttributeDescription,
assertionValue AssertionValue }

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AssertionValue ::= OCTET STRING

The syntax of the AssertionValue depends on the context of the LDAP
operation being performed. For example, the syntax of the EQUALITY
matching rule for an attribute is used when performing a Compare
operation. Often this is the same syntax used for values of the
attribute type, but in some cases the assertion syntax differs from

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the value syntax. See objectIdentiferFirstComponentMatch in
[Syntaxes] for an example.

4.1.7. Attribute

An attribute consists and PartialAttribute

Attributes and partial attributes consist of an attribute description
and one or more values of that attribute description. A PartialAttribute allows
zero values, while Attribute requires at least one value.

PartialAttribute ::= SEQUENCE {
type AttributeDescription,
vals SET SIZE (1..MAX) OF value AttributeValue }

Attribute ::= PartialAttribute(WITH COMPONENTS {
...,
vals (SIZE(1..MAX))})

Each attribute value is distinct in the set (no duplicates). The set
of attribute values is unordered. Implementations MUST NOT rely upon
the ordering being repeatable.

4.1.8. Matching Rule Identifier

Matching rules are defined in 4.1.3 of [Models]. A matching rule is
identified in the LDAP protocol by the printable representation of
either its <numericoid>, or one of its short name descriptors
[Models], e.g. "caseIgnoreIA5Match" or "1.3.6.1.4.1.453.33.33".

MatchingRuleId ::= LDAPString

4.1.9. Result Message

The LDAPResult is the construct used in this protocol to return
success or failure indications from servers to clients. To various
requests, servers will return responses of LDAPResult or responses
containing the components of LDAPResult to indicate the final status
of a protocol operation request.

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referral (10),
adminLimitExceeded (11),

unavailableCriticalExtension (12),
confidentialityRequired (13),
saslBindInProgress (14),
noSuchAttribute (16),
undefinedAttributeType (17),
inappropriateMatching (18),
constraintViolation (19),
attributeOrValueExists (20),
invalidAttributeSyntax (21),
-- 22-31 unused --
noSuchObject (32),
aliasProblem (33),
invalidDNSyntax (34),
-- 35 reserved for undefined isLeaf --
aliasDereferencingProblem (36),
-- 37-47 unused --
inappropriateAuthentication (48),
invalidCredentials (49),
insufficientAccessRights (50),
busy (51),
unavailable (52),
unwillingToPerform (53),
loopDetect (54),
-- 55-63 unused --
namingViolation (64),
objectClassViolation (65),
notAllowedOnNonLeaf (66),
notAllowedOnRDN (67),
entryAlreadyExists (68),
objectClassModsProhibited (69),
-- 70 reserved for CLDAP --
affectsMultipleDSAs (71),
-- 72-79 unused --
other (80),
... },
-- 81-90 reserved for APIs --
matchedDN LDAPDN,
diagnosticMessage LDAPString,
referral [3] Referral OPTIONAL }

The resultCode enumeration is extensible as defined in Section 3.5 of
[LDAPIANA]. The meanings of the result codes are given in Appendix A.
If a server detects multiple errors for an operation, only one result
code is returned. The server should return the result code that best
indicates the nature of the error encountered.

The diagnosticMessage field of this construct may, at the server's
option, be used to return a string containing a textual, human-
readable (terminal control and page formatting characters should be
avoided) diagnostic message. As this diagnostic message is not
standardized, implementations MUST NOT rely on the values returned.

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If the server chooses not to return a textual diagnostic, the
diagnosticMessage field MUST be empty.

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For certain result codes (typically, but not restricted to
noSuchObject, aliasProblem, invalidDNSyntax and
aliasDereferencingProblem), the matchedDN field is set to the name of
the lowest entry (object or alias) in the Directory that was matched.
If no aliases were dereferenced while attempting to locate the entry,
this will be a truncated form of the name provided, or if aliases
were dereferenced, of the resulting name, as defined in section Section 12.5
of [X.511]. Otherwise the matchedDN field is empty.

4.1.10. Referral

The referral result code indicates that the contacted server does not
hold the target entry of the request. The referral field is present
in an LDAPResult if the resultCode field value is referral, and
absent with all other result codes. It contains one or more
references to one or more servers or services that may be accessed
via LDAP or other protocols. Referrals can be returned in response to
any operation request (except unbind and abandon which do not have
responses). At least one URI MUST be present in the Referral.

During a search operation, after the baseObject is located, and
entries are being evaluated, the referral is not returned. Instead,
continuation references, described in section Section 4.5.3, are returned
when the search scope spans multiple naming contexts, and several
different servers would need to be contacted to complete the
operation.

Referral ::= SEQUENCE SIZE (1..MAX) OF uri URI

URI ::= LDAPString -- limited to characters permitted in
-- URIs

If the client wishes to progress the operation, it MUST follow the
referral by contacting one of the services. If multiple URIs are
present, the client assumes that any URI may be used to progress the
operation.

Clients that follow referrals MUST ensure that they do not loop
between servers. They MUST NOT repeatedly contact the same server for
the same request with the same target entry name, scope and filter.
Some clients use a counter that is incremented each time referral
handling occurs for an operation, and these kinds of clients MUST be
able to handle at least ten nested referrals between the root and a
leaf entry.

A URI for a server implementing LDAP and accessible via [TCP]/[IP]
(v4 or v6) is written as an LDAP URL according to [LDAPURL].

When an LDAP URL is used, the following instructions are followed:
- If an alias was dereferenced, the <dn> part of the URL MUST be
present, with the new target object name. Note that UTF-8
characters appearing in a DN or search filter may not be legal
for URLs (e.g. spaces) and

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for URLs (e.g. spaces) and MUST be escaped using the % method in
[URI].
- It is RECOMMENDED that the <dn> part be present to avoid
ambiguity.
- If the <dn> part is present, the client MUST use this name in
its next request to progress the operation, and if it is not
present the client will use the same name as in the original
request.

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- Some servers (e.g. participating in distributed indexing) may
provide a different filter in a URL of a referral for a search
operation.
- If the <filter> part of the LDAP URL is present, the client MUST
use this filter in its next request to progress this search, and
if it is not present the client MUST use the same filter as it
used for that search.
- For search, it is RECOMMENDED that the <scope> part be present
to avoid ambiguity.
- If the <scope> part is missing, the scope of the original search
is used by the client to progress the operation.
- Other aspects of the new request may be the same as or different
from the request which generated the referral.

Other kinds of URIs may be returned, so long as the operation could
be performed using that protocol. returned. The definition syntax and semantics of such
URIs and
instructions on their use is left to future specifications. Clients ignore URIs that they
do not support.

4.1.11. Controls

A control is a way to specify extension information for an LDAP
message. A control only alters the semantics of the message it is
attached to.

Controls ::= SEQUENCE OF control Control

Control ::= SEQUENCE {
controlType LDAPOID,
criticality BOOLEAN DEFAULT FALSE,
controlValue OCTET STRING OPTIONAL }

The controlType field is the UTF-8 encoded dotted-decimal
representation of an OBJECT IDENTIFIER which uniquely identifies the
control, or the request control and its paired response control. This
prevents conflicts between control names.

The criticality field is either TRUE or FALSE and only applies to
request messages that have a corresponding response message. For all
other messages (such as abandonRequest, unbindRequest and all
response messages), the criticality field SHOULD be FALSE.

If the server recognizes the control type and it is appropriate for
the operation, the server will make use of the control when
performing the operation.

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If the server does not recognize the control type or it is not
appropriate for the operation, and the criticality field is TRUE, the
server MUST NOT perform the operation, and for operations that have a
response, MUST set the resultCode to unavailableCriticalExtension.

If the control is unrecognized or inappropriate but the criticality
field is FALSE, the server MUST ignore the control.

The controlValue contains any information associated with the
control. Its format is defined by the specification of the control.
Implementations MUST be prepared to handle arbitrary contents of the
controlValue octet string, including zero bytes. It is absent only if

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there is no value information which is associated with a control of
its type. controlValues that are defined in terms of ASN.1 and BER
encoded according to Section 5.1, also follow the extensibility rules
in Section 4.

Servers list the controlType of all request controls they recognize
in the supportedControl attribute [Models] in the root DSE.

Controls SHOULD NOT be combined unless the semantics of the
combination has been specified. The semantics of control
combinations, if specified, are generally found in the control
specification most recently published. In the absence of combination
semantics, the behavior of the operation is undefined.
Additionally, unless order-dependent semantics are given in a
specification, the order of a combination of controls in the SEQUENCE
is ignored.

This document does not specify any controls. Controls may be
specified in other documents. The specification of a control consists
of:

- the OBJECT IDENTIFIER assigned to the control,

- whether the control is always non critical, always critical, or
optionally critical,

- whether there is information associated with the control, and if
so, the format of the controlValue contents,

- the semantics of the control, and

- optionally, semantics regarding the combination of the control
with other controls.

4.2. Bind Operation

The function of the Bind Operation is to allow authentication
information to be exchanged between the client and server. The Bind
operation should be thought of as the "authenticate" operation.
Authentication and security-related semantics of this operation are
given in [AuthMeth].

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The Bind Request is defined as follows:

BindRequest ::= [APPLICATION 0] SEQUENCE {
version INTEGER (1 .. 127),
name LDAPDN,
authentication AuthenticationChoice }

AuthenticationChoice ::= CHOICE {
simple [0] OCTET STRING,
-- 1 and 2 reserved
sasl [3] SaslCredentials,
... }

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SaslCredentials ::= SEQUENCE {
mechanism LDAPString,
credentials OCTET STRING OPTIONAL }

Parameters of the Bind Request are:

- version: A version number indicating the version of the protocol
to be used in this protocol association. This document describes
version 3 of the LDAP protocol. Note that there is no version
negotiation. The client sets this parameter to the version it
desires. If the server does not support the specified version, it
MUST respond with protocolError in the resultCode field of the
BindResponse.

- name: The name of the Directory object that the client wishes to
bind as. This field may take on a null value (a zero length
string) for the purposes of anonymous binds ([AuthMeth] section Section 7)
or when using Simple Authentication and Security Layer [SASL]
authentication ([AuthMeth] section Section 4.3). Server behavior is
undefined when the name is a null value, simple authentication is
used, and a password is specified. The server SHALL NOT perform
alias dereferencing in determining the object to bind as.

- authentication: information used to authenticate the name, if any,
provided in the Bind Request. This type is extensible as defined
in Section 3.6 of [LDAPIANA]. Servers that do not support a choice
supplied by a client will return authMethodNotSupported in the
resultCode field of the BindResponse.
The simple form of an AuthenticationChoice specifies a simple
password to be used for authentication. Passwords consisting
Textual passwords (consisting of a character data (text passwords) sequence with a known
character set and encoding) SHALL be transferred as [UTF-8]
encoded [Unicode]. The determination of whether a password is
textual is a local client matter.
Prior to transfer, clients SHOULD prepare text passwords by
applying the [SASLprep] profile of the [Stringprep] algorithm.
Passwords consisting of other data (such as random octets) MUST
NOT be altered.

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Authorization is the use of this authentication information when
performing operations. Authorization MAY be affected by factors
outside of the LDAP Bind Request, such as those provided by lower
layer security services.

4.2.1. Processing of the Bind Request

Before processing a BindResponse, all outstanding operations MUST
either complete or be abandoned. The server may either wait for the
outstanding operations to complete, or abandon them. The server then
proceeds to authenticate the client in either a single-step, or
multi-step bind process. Each step requires the server to return a
BindResponse to indicate the status of authentication.

If the client did not bind before sending a request and receives an
operationsError to that request, it may then send a Bind Request. If

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this also fails or the client chooses not to bind on the existing
connection, it may close the connection, reopen it and begin again by
first sending a PDU with a Bind Request. This will aid in
interoperating with servers implementing other versions of LDAP.

Clients may send multiple Bind Requests on a connection to change the
authentication and/or security associations or to complete a multi-
stage bind process. Authentication from earlier binds is subsequently
ignored.

For some SASL authentication mechanisms, it may be necessary for the
client to invoke the BindRequest multiple times. This is indicated by
the server sending a BindResponse with the resultCode set to
saslBindInProgress. This indicates that the server requires the
client to send a new bind request, with the same sasl mechanism, to
continue the authentication process. If at any stage the client
wishes to abort the bind process it MAY unbind and then drop the
underlying connection. Clients MUST NOT invoke operations between two
Bind Requests made as part of a multi-stage bind.

A client may abort a SASL bind negotiation by sending a BindRequest
with a different value in the mechanism field of SaslCredentials, or
an AuthenticationChoice other than sasl.

If the client sends a BindRequest with the sasl mechanism field as an
empty string, the server MUST return a BindResponse with
authMethodNotSupported as the resultCode. This will allow clients to
abort a negotiation if it wishes to try again with the same SASL
mechanism.

A failed Bind Operation has the effect of leaving the connection in
an anonymous state. An abandoned Bind operation also has the effect
of leaving the connection in an anonymous state when (and if) the
server processes the abandonment of the bind. Client implementers
should note that the client has no way of being sure when (or if) an
abandon request succeeds, therefore, to arrive at a known
authentication state after abandoning a bind operation, clients may

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either unbind (which results in the underlying connection being
closed) or by issuing a bind request and then examining the
BindResponse returned by the server.

4.2.2. Bind Response

The Bind Response is defined as follows.

BindResponse ::= [APPLICATION 1] SEQUENCE {
COMPONENTS OF LDAPResult,
serverSaslCreds [7] OCTET STRING OPTIONAL }

BindResponse consists simply of an indication from the server of the
status of the client's request for authentication.

A successful bind operation is indicated by a BindResponse with a
resultCode set to success. Otherwise, an appropriate result code is

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set in the BindResponse. For bind, the protocolError result code may
be used to indicate that the version number supplied by the client is
unsupported.

If the client receives a BindResponse response where the resultCode
field is protocolError, it MUST close the connection as the server
will be unwilling to accept further operations. (This is for
compatibility with earlier versions of LDAP, in which the bind was
always the first operation, and there was no negotiation.)

The serverSaslCreds are used as part of a SASL-defined bind mechanism
to allow the client to authenticate the server to which it is
communicating, or to perform "challenge-response" authentication. If
the client bound with the simple choice, or the SASL mechanism does
not require the server to return information to the client, then this
field SHALL NOT be included in the BindResponse.

4.3. Unbind Operation

The function of the Unbind Operation is to terminate an LDAP
association and connection. The Unbind Operation operation is defined not the
antithesis of the Bind operation as
follows:

UnbindRequest the name implies. The naming of
these operations is historical. The Unbind operation should be
thought of as the "quit" operation.

The Unbind Operation is defined as follows:

UnbindRequest ::= [APPLICATION 2] NULL

The Unbind Operation has no response defined. Upon transmission of
the UnbindRequest, each protocol peer is to consider the LDAP
association terminated, MUST cease transmission of messages to the
other peer, and MUST close the connection. Any outstanding operations
on the server are, when possible, abandoned, and when not possible,
completed without transmission of the response.

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4.4. Unsolicited Notification

An unsolicited notification is an LDAPMessage sent from the server to
the client which is not in response to any LDAPMessage received by
the server. It is used to signal an extraordinary condition in the
server or in the connection between the client and the server. The
notification is of an advisory nature, and the server will not expect
any response to be returned from the client.

The unsolicited notification is structured as an LDAPMessage in which
the messageID is zero and protocolOp is of the extendedResp form. The
responseName field of the ExtendedResponse always contains an LDAPOID
which is unique for this notification.

One unsolicited notification (Notice of Disconnection) is defined in
this document. The specification of an unsolicited notification
consists of:

- the OBJECT IDENTIFIER assigned to the notification (to be
specified in the responseName,

- the format of the contents (if any) of the responseValue,

- the circumstances which will cause the notification to be
returned, and

- the semantics of the operation.

4.4.1. Notice of Disconnection

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This notification may be used by the server to advise the client that
the server is about to close the connection due to an error
condition. Note that this notification is NOT a response to an unbind
requested by the client: the server MUST follow the procedures of
section
Section 4.3. This notification is intended to assist clients in
distinguishing between an error condition and a transient network
failure. As with a connection close due to network failure, the
client MUST NOT assume that any outstanding requests which modified
the Directory have succeeded or failed.

The responseName is 1.3.6.1.4.1.1466.20036, the response field is
absent, and the resultCode is used to indicate the reason for the
disconnection.

The following result codes have these meanings when used in this
notification:

- protocolError: The server has received data from the client in
which the LDAPMessage structure could not be parsed.

- strongAuthRequired: The server has detected that an established
security association between the client and server has

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unexpectedly failed or been compromised, or that the server now
requires the client to authenticate using a strong(er) mechanism.

- unavailable: This server will stop accepting new connections and
operations on all existing connections, and be unavailable for an
extended period of time. The client may make use of an alternative
server.

Upon transmission of the UnbindRequest, each protocol peer is to
consider the LDAP association terminated, MUST cease transmission of
messages to the other peer, and MUST close the connection.

4.5. Search Operation

The Search Operation is used to request a server to return, subject
to access controls and other restrictions, a set of entries matching
a complex search criterion. This can be used to read attributes from
a single entry, from entries immediately subordinate to a particular
entry, or a whole subtree of entries.

4.5.1. Search Request

The Search Request is defined as follows:

SearchRequest ::= [APPLICATION 3] SEQUENCE {
baseObject LDAPDN,
scope ENUMERATED {
baseObject (0),
singleLevel (1),
wholeSubtree (2) },

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derefAliases ENUMERATED {
neverDerefAliases (0),
derefInSearching (1),
derefFindingBaseObj (2),
derefAlways (3) },
sizeLimit INTEGER (0 .. maxInt),
timeLimit INTEGER (0 .. maxInt),
typesOnly BOOLEAN,
filter Filter,
attributes AttributeSelection }

AttributeSelection ::= SEQUENCE OF selection LDAPString
-- constrained to the <attributeSelection> ABNF below

Filter ::= CHOICE {
and [0] SET SIZE (1..MAX) OF filter Filter,
or [1] SET SIZE (1..MAX) OF filter Filter,
not [2] Filter,
equalityMatch [3] AttributeValueAssertion,
substrings [4] SubstringFilter,
greaterOrEqual [5] AttributeValueAssertion,
lessOrEqual [6] AttributeValueAssertion,

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present [7] AttributeDescription,
approxMatch [8] AttributeValueAssertion,
extensibleMatch [9] MatchingRuleAssertion }

SubstringFilter ::= SEQUENCE {
type AttributeDescription,
-- at least one must be present,
-- initial and final can occur at most once
substrings SEQUENCE SIZE (1..MAX) OF substring CHOICE {
initial [0] AssertionValue,
any [1] AssertionValue,
final [2] AssertionValue } }

MatchingRuleAssertion ::= SEQUENCE {
matchingRule [1] MatchingRuleId OPTIONAL,
type [2] AttributeDescription OPTIONAL,
matchValue [3] AssertionValue,
dnAttributes [4] BOOLEAN DEFAULT FALSE }

Parameters of the Search Request are:

- baseObject: The name of the base object entry relative to which
the search is to be performed.

- scope: Specifies the scope of the search to be performed. The
semantics (as described in [X.511]) of the possible values of this
field are:

baseObject: The scope is constrained to the entry named by
baseObject.

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oneLevel: The scope is constrained to the immediate
subordinates of the entry named by baseObject.

wholeSubtree: the scope is constrained to the entry named
by the baseObject, and all its subordinates.

- derefAliases: An indicator as to how alias objects (as defined in
[X.501]) are to be handled in searching. The semantics of the
possible values of this field are:

neverDerefAliases: Do not dereference aliases in searching
or in locating the base object of the search.

derefInSearching: While searching, dereference any alias
object subordinate to the base object which is also in the
search scope. The filter is applied to the dereferenced
object(s). If the search scope is wholeSubtree, the search
continues in the subtree of any dereferenced object.
Aliases in that subtree are also dereferenced. Servers
SHOULD detect looping in this process to prevent denial of
service attacks and duplicate entries.

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derefFindingBaseObj: Dereference aliases in locating the
base object of the search, but not when searching
subordinates of the base object.

derefAlways: Dereference aliases both in searching and in
locating the base object of the search.

- sizeLimit: A size limit that restricts the maximum number of
entries to be returned as a result of the search. A value of 0 zero
in this field indicates that no client-requested size limit
restrictions are in effect for the search. Servers may enforce a
maximum number of entries to return.

- timeLimit: A time limit that restricts the maximum time (in
seconds) allowed for a search. A value of 0 zero in this field
indicates that no client-requested time limit restrictions are in
effect for the search. Servers may enforce a maximum time limit
for the search.

- typesOnly: An indicator as to whether search results are to
contain both attribute descriptions and values, or just attribute
descriptions. Setting this field to TRUE causes only attribute
descriptions (no values) to be returned. Setting this field to
FALSE causes both attribute descriptions and values to be
returned.

- filter: A filter that defines the conditions that must be
fulfilled in order for the search to match a given entry.

The 'and', 'or' and 'not' choices can be used to form combinations
of filters. At least one filter element MUST be present in an

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'and' or 'or' choice. The others match against individual
attribute values of entries in the scope of the search.
(Implementor's note: the 'not' filter is an example of a tagged
choice in an implicitly-tagged module. In BER this is treated as
if the tag was explicit.)

A server MUST evaluate filters according to the three-valued logic
of X.511 (1993) section Section 7.8.1. In summary, a filter is evaluated
to either "TRUE", "FALSE" or "Undefined". If the filter evaluates
to TRUE for a particular entry, then the attributes of that entry
are returned as part of the search result (subject to any
applicable access control restrictions). If the filter evaluates
to FALSE or Undefined, then the entry is ignored for the search.

A filter of the "and" choice is TRUE if all the filters in the SET
OF evaluate to TRUE, FALSE if at least one filter is FALSE, and
otherwise Undefined. A filter of the "or" choice is FALSE if all
of the filters in the SET OF evaluate to FALSE, TRUE if at least
one filter is TRUE, and Undefined otherwise. A filter of the "not"
choice is TRUE if the filter being negated is FALSE, FALSE if it
is TRUE, and Undefined if it is Undefined.

The present match evaluates to TRUE where there is an attribute or

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subtype of the specified attribute description present in an
entry, and FALSE otherwise (including a presence test with an
unrecognized attribute description.)

The matching rule for equalityMatch filter items is defined by the
EQUALITY matching rule for the attribute type.

The matching rule for AssertionValues in a substrings filter item
is defined by the SUBSTR matching rule for the attribute type.
Note that the AssertionValue in a substrings filter item MUST
conform to the assertion syntax of the EQUALITY matching rule for
the attribute type rather than the assertion syntax of the SUBSTR
matching rule for the attribute type. The entire SubstringFilter
is converted into an assertion value of the substrings matching
rule prior to applying the rule.

The matching rule for greaterOrEqual and lessOrEqual filter items
is defined by the ORDERING matching rule for the attribute type.

The approxMatch evaluates to TRUE when there is a value of the
attribute or subtype for which some locally-defined approximate
matching algorithm (e.g. spelling variations, phonetic match,
etc.) returns TRUE. If an item matches for equality, it also
satisfies an approximate match. If approximate matching is not
supported, this filter item should be treated as an equalityMatch.

An extensibleMatch is evaluated as follows:

If the matchingRule field is absent, the type field MUST be
present, and an equality match is performed for that type.

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If the type field is absent and the matchingRule is present, the
matchValue is compared against all attributes in an entry which
support that matchingRule. The matchingRule determines the
syntax for the assertion value. The filter item evaluates to
TRUE if it matches with at least one attribute in the entry,
FALSE if it does not match any attribute in the entry, and
Undefined if the matchingRule is not recognized or the
assertionValue is invalid.

If the type field is present and the matchingRule is present,
the matchValue is compared against entry attributes of the
specified type. In this case, the matchingRule MUST be one
suitable for use with the specified type (see [Syntaxes]),
otherwise the filter item is undefined.

If the dnAttributes field is set to TRUE, the match is
additionally applied against all the AttributeValueAssertions in
an entry's distinguished name, and evaluates to TRUE if there is
at least one attribute in the distinguished name for which the
filter item evaluates to TRUE. The dnAttributes field is present
to alleviate the need for multiple versions of generic matching
rules (such as word matching), where one applies to entries and

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another applies to entries and dn attributes as well.

A filter item evaluates to Undefined when the server would not be
able to determine whether the assertion value matches an entry. If
an attribute description in an equalityMatch, substrings,
greaterOrEqual, lessOrEqual, approxMatch or extensibleMatch filter
is not recognized by the server, a matching rule id in the
extensibleMatch is not recognized by the server, the assertion
value is invalid, or the type of filtering requested is not
implemented, then the filter is Undefined. Thus for example if a
server did not recognize the attribute type shoeSize, a filter of
(shoeSize=*) would evaluate to FALSE, and the filters
(shoeSize=12), (shoeSize>=12) and (shoeSize<=12) would evaluate to
Undefined.

Servers MUST NOT return errors if attribute descriptions or
matching rule ids are not recognized, assertion values are
invalid, or the assertion syntax is not supported. More details of
filter processing are given in section Section 7.8 of [X.511].

- attributes: A list of the attributes to be returned from each
entry which matches the search filter. LDAPString values of this
field are constrained to the following ABNF: Augmented Backus-Naur Form
[(ABNF)]:

attributeSelection = noattrs /
*( attributedescription / specialattr )

noattrs = %x31 %x2E %x31 ; "1.1"

specialattr = ASTERISK

ASTERISK = %x2A ; asterisk ("*")

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<attributedescription> is defined in Section 2.5 of [Models].

There are two special values which may be used: an empty list with
no attributes, and the attribute description string "*". Both of
these signify that all user attributes are to be returned. (The
"*" allows the client to request all user attributes in addition
to any specified operational attributes). Client implementors
should note that even if all user attributes are requested, some
attributes and or attribute values of the entry may not be
included in search results due to access controls or other
restrictions. Furthermore, servers will not return operational
attributes, such as objectClasses or attributeTypes, unless they
are listed by name. Operational attributes are described in
[Models].

Attributes MUST NOT be named more than once in the list, and are
returned at most once in an entry. If there are attribute
descriptions in the list which are not recognized, they are
ignored by the server.

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If the client does not want any attributes returned, it can
specify a list containing only the attribute with OID "1.1". This
OID was chosen because it does not (and can not) correspond to any
attribute in use.

Note that an X.500 "list"-like operation can be emulated by the
client requesting a one-level LDAP search operation with a filter
checking for the presence of the objectClass attribute, and that an
X.500 "read"-like operation can be emulated by a base object LDAP
search operation with the same filter. A server which provides a
gateway to X.500 is not required to use the Read or List operations,
although it may choose to do so, and if it does, it must provide the
same semantics as the X.500 search operation.

4.5.2. Search Result

The results of the search operation are returned as zero or more
searchResultEntry messages, zero or more SearchResultReference
messages, followed by a single searchResultDone message.

SearchResultEntry ::= [APPLICATION 4] SEQUENCE {
objectName LDAPDN,
attributes PartialAttributeList }

PartialAttributeList ::= SEQUENCE OF
attribute
partialAttribute PartialAttribute
-- Note that the PartialAttributeList may hold zero elements.
-- This may happen when none of the attributes of an entry
-- were requested, or could be returned.

PartialAttribute ::= SEQUENCE {
type AttributeDescription,

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vals SET OF value AttributeValue }
-- Note also that the partialAttribute vals set may hold zero elements.
-- elements. This may happen when typesOnly is requested, access controls
-- controls prevent the return of values, or other reasons.

SearchResultReference ::= [APPLICATION 19] SEQUENCE
SIZE (1..MAX) OF uri URI

SearchResultDone ::= [APPLICATION 5] LDAPResult

Each SearchResultEntry represents an entry found during the search.
Each SearchResultReference represents an area not yet explored during
the search. The SearchResultEntry and SearchResultReference PDUs may
come in any order. Following all the SearchResultReference and
SearchResultEntry responses, the server returns a SearchResultDone
response, which contains an indication of success, or detailing any
errors that have occurred.

Each entry returned in a SearchResultEntry will contain all
appropriate attributes as specified in the attributes field of the
Search Request. Return of attributes is subject to access control and
other administrative policy.

Some attributes may be constructed by the server and appear in a
SearchResultEntry attribute list, although they are not stored

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attributes of an entry. Clients SHOULD NOT assume that all attributes
can be modified, even if permitted by access control.

If the server's schema defines short names [Models] for an attribute
type then the server SHOULD use one of those names in attribute
descriptions for that attribute type (in preference to using the
<numericoid> [Models] format of the attribute type's object
identifier). The server SHOULD NOT use the short name if that name is
known by the server to be ambiguous, or otherwise likely to cause
interoperability problems.

4.5.3. Continuation References in the Search Result

If the server was able to locate the entry referred to by the
baseObject but was unable to search all the entries in the scope at
and subordinate to the baseObject, the server may return one or more
SearchResultReference entries, each containing a reference to another
set of servers for continuing the operation. A server MUST NOT return
any SearchResultReference if it has not located the baseObject and
thus has not searched any entries; in this case it would return a
SearchResultDone containing a referral result code.

If a server holds a copy or partial copy of the subordinate naming
context, it may use the search filter to determine whether or not to
return a SearchResultReference response. Otherwise
SearchResultReference responses are always returned when in scope.

The SearchResultReference is of the same data type as the Referral.

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A URI for a server implementing LDAP and accessible via [TCP]/[IP]
(v4 or v6) is written as an LDAP URL according to [LDAPURL].

In order to complete the search, the client issues a new search
operation for each SearchResultReference that is returned. Note that
the abandon operation described in Section 4.11 applies only to a
particular operation sent on an association between a client and
server. The client must abandon subsequent search operations it
wishes to individually.

Clients that follow search continuation references MUST ensure that
they do not loop between servers. They MUST NOT repeatedly contact
the same server for the same request with the same target entry name,
scope and filter. Some clients use a counter that is incremented each
time search result reference handling occurs for an operation, and
these kinds of clients MUST be able to handle at least ten nested
search result references between the root and a leaf entry.

When an LDAP URL is used, the following instructions are followed:
- The <dn> part of the URL MUST be present, with the new target
object name. The client MUST use this name when following the
referral. Note that UTF-8 characters appearing in a DN or search
filter may not be legal for URLs (e.g. spaces) and MUST be
escaped using the % method in [URI].

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- It is RECOMMENDED that the <dn> part be present to avoid
ambiguity.
- Some servers (e.g. participating in distributed indexing) may
provide a different filter in a URL of a SearchResultReference.
- If the <filter> part of the URL is present, the client MUST use
this filter in its next request to progress this search, and if
it is not present the client MUST use the same filter as it used
for that search.
- If the originating search scope was singleLevel, the <scope>
part of the URL will be "base".
- it is RECOMMENDED that the <scope> part be present to avoid
ambiguity.
- If the <scope> part is missing, the scope of the original search
is used by the client to progress the operation.
- Other aspects of the new search request may be the same as or
different from the search request which generated the
SearchResultReference.
- The name of an unexplored subtree in a SearchResultReference
need not be subordinate to the base object.

In order to complete the search, the client issues a new search
operation for each SearchResultReference that is returned. Note Clients ignore URIs that
the abandon operation described in section 4.11 applies only to a
particular operation sent on an association between a client and
server. The client must abandon subsequent search operations it
wishes to individually. they
do not support.

4.5.3.1. Example

For example, suppose the contacted server (hosta) holds the entry
"DC=Example,DC=NET" and the entry "CN=Manager,DC=Example,DC=NET". It
knows that either LDAP-capable servers (hostb) or (hostc) hold
"OU=People,DC=Example,DC=NET" (one is the master and the other server
a shadow), and that LDAP-capable server (hostd) holds the subtree
"OU=Roles,DC=Example,DC=NET". If a subtree search of
"DC=Example,DC=NET" is requested to the contacted server, it may
return the following:

SearchResultEntry for DC=Example,DC=NET
SearchResultEntry for CN=Manager,DC=Example,DC=NET
SearchResultReference {
ldap://hostb/OU=People,DC=Example,DC=NET
ldap://hostc/OU=People,DC=Example,DC=NET
ldap://hostb/OU=People,DC=Example,DC=NET??sub
ldap://hostc/OU=People,DC=Example,DC=NET??sub }
SearchResultReference {
ldap://hostd/OU=Roles,DC=Example,DC=NET
ldap://hostd/OU=Roles,DC=Example,DC=NET??sub }

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SearchResultDone (success)

Client implementors should note that when following a
SearchResultReference, additional SearchResultReference may be
generated. Continuing the example, if the client contacted the server
(hostb) and issued the search for the subtree
"OU=People,DC=Example,DC=NET", the server might respond as follows:

SearchResultEntry for OU=People,DC=Example,DC=NET
SearchResultReference {
ldap://hoste/OU=Managers,OU=People,DC=Example,DC=NET
ldap://hoste/OU=Managers,OU=People,DC=Example,DC=NET??sub }

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SearchResultReference {
ldap://hostf/OU=Consultants,OU=People,DC=Example,DC=NET
ldap://hostf/OU=Consultants,OU=People,DC=Example,DC=NET??sub }
SearchResultDone (success)

If the contacted server does not hold the base object for the search,
then it will return a referral to the client. For example, if the
client requests a subtree search of "DC=Example,DC=ORG" to hosta, the
server may return only a SearchResultDone containing a referral.

SearchResultDone (referral) {
ldap://hostg/DC=Example,DC=ORG??sub }

4.6. Modify Operation

The Modify Operation allows a client to request that a modification
of an entry be performed on its behalf by a server. The Modify
Request is defined as follows:

ModifyRequest ::= [APPLICATION 6] SEQUENCE {
object LDAPDN,
changes SEQUENCE OF change SEQUENCE {
operation ENUMERATED {
add (0),
delete (1),
replace (2) },
modification PartialAttribute } }

Parameters of the Modify Request are:

- object: The name of the object to be modified. The value of this
field contains the DN of the entry to be modified. The server
SHALL NOT perform any alias dereferencing in determining the
object to be modified.

- changes: A list of modifications to be performed on the entry. The
entire list of modifications MUST be performed in the order they
are listed, as a single atomic operation. While individual
modifications may violate certain aspects of the directory schema
(such as the object class definition and DIT content rule), the
resulting entry after the entire list of modifications is
performed MUST conform to the requirements of the directory
schema.

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- operation: Used to specify the type of modification being
performed. Each operation type acts on the following
modification. The values of this field have the following
semantics respectively:

add: add values listed to the modification attribute,
creating the attribute if necessary;

delete: delete values listed from the modification
attribute, removing the entire attribute if no values are

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listed, or if all current values of the attribute are
listed for deletion;

replace: replace all existing values of the modification
attribute with the new values listed, creating the
attribute if it did not already exist. A replace with no
value will delete the entire attribute if it exists, and is
ignored if the attribute does not exist.

- modification: A PartialAttribute (which may have an empty SET of
vals) used to hold the attribute type or attribute type and
values being modified.

Upon receipt of a Modify Request, the server attempts to perform the
necessary modifications to the DIT and returns the result in a Modify
Response, defined as follows:

ModifyResponse ::= [APPLICATION 7] LDAPResult

The server will return to the client a single Modify Response
indicating either the successful completion of the DIT modification,
or the reason that the modification failed. Note that due to the
requirement for atomicity in applying the list of modifications in
the Modify Request, the client may expect that no modifications of
the DIT have been performed if the Modify Response received indicates
any sort of error, and that all requested modifications have been
performed if the Modify Response indicates successful completion of
the Modify Operation. If the association changes or the connection
fails, whether the modification occurred or not is indeterminate.

The Modify Operation cannot be used to remove from an entry any of
its distinguished values, i.e. those values which form the entry's
relative distinguished name. An attempt to do so will result in the
server returning the notAllowedOnRDN result code. The Modify DN
Operation described in section Section 4.9 is used to rename an entry.

Note that due to the simplifications made in LDAP, there is not a
direct mapping of the changes in an LDAP ModifyRequest onto the
changes of a DAP ModifyEntry operation, and different implementations
of LDAP-DAP gateways may use different means of representing the
change. If successful, the final effect of the operations on the
entry MUST be identical.

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4.7. Add Operation

The Add Operation allows a client to request the addition of an entry
into the Directory. The Add Request is defined as follows:

AddRequest ::= [APPLICATION 8] SEQUENCE {
entry LDAPDN,
attributes AttributeList }

AttributeList ::= SEQUENCE OF attribute Attribute

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Parameters of the Add Request are:

- entry: the name of the entry to be added. Note that the server
SHALL NOT dereference any aliases in locating the entry to be
added.

- attributes: the list of attributes that make up the content of the
entry being added. Clients MUST include distinguished values
(those forming the entry's own RDN) in this list, the objectClass
attribute, and values of any mandatory attributes of the listed
object classes. Clients MUST NOT supply NO-USER-MODIFICATION
attributes such as the createTimestamp or creatorsName attributes,
since the server maintains these automatically.

The entry named in the entry field of the AddRequest MUST NOT exist
for the AddRequest to succeed. The immediate superior (parent) of an
object or alias entry to be added MUST exist. For example, if the
client attempted to add "CN=JS,DC=Example,DC=NET", the
"DC=Example,DC=NET" entry did not exist, and the "DC=NET" entry did
exist, then the server would return the noSuchObject result code with
the matchedDN field containing "DC=NET". If the parent entry exists
but is not in a naming context held by the server, the server SHOULD
return a referral to the server holding the parent entry.

Server implementations SHOULD NOT restrict where entries can be
located in the Directory unless DIT structure rules are in place.
Some servers allow the administrator to restrict the classes of
entries which can be added to the Directory.

Upon receipt of an Add Request, a server will attempt to add the
requested entry. The result of the add attempt will be returned to
the client in the Add Response, defined as follows:

AddResponse ::= [APPLICATION 9] LDAPResult

A response of success indicates that the new entry is present in the
Directory.

4.8. Delete Operation

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The Delete Operation allows a client to request the removal of an
entry from the Directory. The Delete Request is defined as follows:

DelRequest ::= [APPLICATION 10] LDAPDN

The Delete Request consists of the name of the entry to be deleted.
The server SHALL NOT dereference aliases while resolving the name of
the target entry to be removed.

Only leaf entries (those with no subordinate entries) can be deleted
with this operation.

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Upon receipt of a Delete Request, a server will attempt to perform
the entry removal requested and return the result in the Delete
Response defined as follows:

DelResponse ::= [APPLICATION 11] LDAPResult

4.9. Modify DN Operation

The Modify DN Operation allows a client to change the Relative
Distinguished Name (RDN) of an entry in the Directory, and/or to move
a subtree of entries to a new location in the Directory. The Modify
DN Request is defined as follows:

ModifyDNRequest ::= [APPLICATION 12] SEQUENCE {
entry LDAPDN,
newrdn RelativeLDAPDN,
deleteoldrdn BOOLEAN,
newSuperior [0] LDAPDN OPTIONAL }

Parameters of the Modify DN Request are:

- entry: the name of the entry to be changed. This entry may or may
not have subordinate entries. Note that the server SHALL NOT
dereference any aliases in locating the entry to be changed.

- newrdn: the new RDN of the entry.

- deleteoldrdn: a boolean parameter that controls whether the old
RDN attribute values are to be retained as attributes of the
entry, or deleted from the entry.

- newSuperior: if present, this is the name of an existing object
entry which becomes the immediate superior (parent) of the
existing entry.

Upon receipt of a ModifyDNRequest, a server will attempt to perform
the name change and return the result in the Modify DN Response,
defined as follows:

ModifyDNResponse ::= [APPLICATION 13] LDAPResult

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For example, if the entry named in the "entry" parameter was "cn=John
Smith,c=US", the newrdn parameter was "cn=John Cougar Smith", and the
newSuperior parameter was absent, then this operation would attempt
to rename the entry to be "cn=John Cougar Smith,c=US". If there was
already an entry with that name, the operation would fail with the
entryAlreadyExists result code.

The object named in newSuperior MUST exist. For example, if the
client attempted to add "CN=JS,DC=Example,DC=NET", the
"DC=Example,DC=NET" entry did not exist, and the "DC=NET" entry did
exist, then the server would return the noSuchObject result code with
the matchedDN field containing "DC=NET".

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If the deleteoldrdn parameter is TRUE, the values forming the old RDN
are deleted from the entry. If the deleteoldrdn parameter is FALSE,
the values forming the old RDN will be retained as non-distinguished
attribute values of the entry. The server MUST fail the operation and
return an error in the result code if the setting of the deleteoldrdn
parameter would cause a schema inconsistency in the entry.

Note that X.500 restricts the ModifyDN operation to only affect
entries that are contained within a single server. If the LDAP server
is mapped onto DAP, then this restriction will apply, and the
affectsMultipleDSAs result code will be returned if this error
occurred. In general, clients MUST NOT expect to be able to perform
arbitrary movements of entries and subtrees between servers or
between naming contexts.

4.10. Compare Operation

The Compare Operation allows a client to compare an assertion
provided with an entry in the Directory. The Compare Request is
defined as follows:

CompareRequest ::= [APPLICATION 14] SEQUENCE {
entry LDAPDN,
ava AttributeValueAssertion }

Parameters of the Compare Request are:

- entry: the name of the entry to be compared. Note that the server
SHALL NOT dereference any aliases in locating the entry to be
compared.

- ava: the assertion with which an attribute in the entry is to be
compared.

Upon receipt of a Compare Request, a server will attempt to perform
the requested comparison using the EQUALITY matching rule for the
attribute type and return the result in the Compare Response, defined
as follows:

CompareResponse ::= [APPLICATION 15] LDAPResult

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In the event that the attribute or subtype is not present in the
entry, the resultCode field is set to noSuchAttribute. If the
attribute is unknown, the resultCode is set to
undefinedAttributeType. Note that errors and the result of comparison
are all returned in the same construct.

Note that some directory systems may establish access controls which
permit the values of certain attributes (such as userPassword) to be
compared but not interrogated by other means.

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4.11. Abandon Operation

The function of the Abandon Operation is to allow a client to request
that the server abandon an outstanding operation. The Abandon Request
is defined as follows:

AbandonRequest ::= [APPLICATION 16] MessageID

The MessageID MUST be that of an operation which was requested
earlier in this LDAP association. The abandon request itself has its
own message id. This is distinct from the id of the earlier operation
being abandoned.

There is no response defined in the Abandon operation. Upon receipt
of an AbandonRequest, the server MAY abandon the operation identified
by the MessageID. Operation responses are not sent for successfully
abandoned operations, thus the application of the Abandon operation
is limited to uses where the client does not require an indication of
its outcome.

Abandon and Unbind operations cannot be abandoned. The ability to
abandon other (particularly update) operations is at the discretion
of the server.

In the event that a server receives an Abandon Request on a Search
Operation in the midst of transmitting responses to the search, that
server MUST cease transmitting entry responses to the abandoned
request immediately, and MUST NOT send the SearchResponseDone. Of
course, the server MUST ensure that only properly encoded LDAPMessage
PDUs are transmitted.

Clients MUST NOT send abandon requests for the same operation
multiple times, and MUST also be prepared to receive results from
operations it has abandoned (since these may have been in transit
when the abandon was requested, or are not able to be abandoned).

Servers MUST discard abandon requests for message IDs they do not
recognize, for operations which cannot be abandoned, and for
operations which have already been abandoned.

4.12. Extended Operation

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An extension mechanism has been added in this version of LDAP, in
order to allow additional operations to

The extended operation allows additional operations to be defined for
services not already available elsewhere in this protocol, for instance digitally signed the protocol. For example, to add
operations and results. to install transport layer security (see Section 4.13).

The extended operation allows clients to make requests and receive
responses with predefined syntaxes and semantics. These may be
defined in RFCs or be private to particular implementations.

Each extended operation consists of an extended request MUST have a unique OBJECT IDENTIFIER assigned to it. and an
extended response.

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ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID,
requestValue [1] OCTET STRING OPTIONAL }

The requestName is a dotted-decimal representation of the unique
OBJECT IDENTIFIER corresponding to the request. The requestValue is
information in a form defined by that request, encapsulated inside an
OCTET STRING.

The server will respond to this with an LDAPMessage containing the
ExtendedResponse.

ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
COMPONENTS OF LDAPResult,
responseName [10] LDAPOID OPTIONAL,
responseValue [11] OCTET STRING OPTIONAL }

The responseName is typically not required to be present as the
syntax and semantics of the response (including the format of the
responseValue) is implicitly known and associated with the request by
the messageID.

If the server does requestName is not recognize recognized by the request name, it server, the server MUST
NOT provide a responseName nor a responseValue and MUST return
only the response fields from LDAPResult, containing the
protocolError result code. a
resultCode of protocolError.

The requestValue and responseValue fields contain any information
associated with the operation. The format of these fields is defined
by the specification of the extended operation. Implementations MUST
be prepared to handle arbitrary contents of these fields, including
zero bytes. Values that are defined in terms of ASN.1 and BER encoded
according to Section 5.1, also follow the extensibility rules in
Section 4.

It is RECOMMENDED that servers list the requestName of extended
operations they support in the supportedExtension attribute [Models]
of the root DSE.

Extended operations may be specified in other documents. The
specification of an extended operation consists of:

- the OBJECT IDENTIFIER assigned to the ExtendedRequest.requestName requestName (and possibly ExtendedResponse.responseName),
responseName),

- the format of the contents of the requestValue and responseValue
(if any),

- the semantics of the operation,

It is RECOMMENDED that servers list the requestName of
ExtendedRequests they support in the supportedExtension attribute
[Models] in the root DSE.

4.13. StartTLS Operation

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4.13. Start TLS Operation

The Start Transport Layer Security (StartTLS) operation provides the
ability to establish Transport Layer Security [RFC2246] ([TLS]) on an LDAP
connection. The StartTLS operation is defined using the extended
operation mechanism described in Section 4.12.

4.13.1. Start TLS StartTLS Request

A client requests TLS establishment by transmitting a Start TLS StartTLS
request PDU to the server. The Start TLS StartTLS request is defined in terms
of an ExtendedRequest. The requestName is "1.3.6.1.4.1.1466.20037",
and the requestValue field is always absent.

The client MUST NOT send any PDUs on this connection following this
request until it receives a Start TLS StartTLS extended response.

4.13.2. Start TLS StartTLS Response

When a Start TLS StartTLS request is made, servers supporting the operation
MUST return a Start TLS StartTLS response PDU to the requestor. The Start TLS StartTLS
response responseName is also "1.3.6.1.4.1.1466.20037", and the
response field is absent.

The server MUST set the resultCode field to either success or one of
the other values outlined in section Section 4.13.2.2.

4.13.2.1. "Success" Response

If the Start TLS StartTLS Response contains a result code of success, this
indicates that the server is willing and able to negotiate TLS. Refer
to section Section 5.3 of [AuthMeth] for details.

4.13.2.2. Response other than "success"

If the ExtendedResponse contains a result code other than success,
this indicates that the server is unwilling or unable to negotiate
TLS. The following result codes have these meanings for this
operation:

- operationsError: operations sequencing incorrect; e.g. TLS is
already
established) established.

- protocolError: (TLS TLS is not supported or incorrect PDU structure) structure.

- unavailable: (e.g. some Some major problem with TLS, or the server is
shutting down) down.

The server MUST return operationsError if the client violates any of
the Start TLS StartTLS extended operation sequencing requirements described in
section
Section 5.3 of [AuthMeth].

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If the server does not support TLS (whether by design or by current
configuration), it MUST set the resultCode field to protocolError.
The client's current association is unaffected if the server does not
support TLS. The client

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support TLS. The client may proceed with any LDAP operation, or it
may close the connection.

The server MUST return unavailable if it supports TLS but cannot
establish a TLS connection for some reason, e.g. the certificate
server not responding, it cannot contact its TLS implementation, or
if the server is in process of shutting down. The client may retry
the StartTLS operation, or it may proceed with any other LDAP
operation, or it may close the LDAP connection.

4.13.3. Closing a TLS Connection

Two forms of TLS connection closure -- graceful and abrupt -- are
supported.

4.13.3.1. Graceful Closure

Either the client or server MAY terminate the TLS connection and
leave the LDAP connection intact by sending and receiving a TLS
closure alert.

The initiating protocol peer sends the TLS closure alert. If it
wishes to leave the LDAP connection intact, it then MUST cease to
send further PDUs and MUST ignore any received PDUs until it receives
a TLS closure alert from the other peer.

Once the initiating protocol peer receives a TLS closure alert from
the other peer it MAY send and receive LDAP PDUs.

When a protocol peer receives the initial TLS closure alert, it may
choose to allow the underlying LDAP connection intact. In this case,
it MUST immediately transmit a TLS closure alert. Following this, it
MAY send and receive LDAP PDUs.

Protocol peers MAY drop the underlying LDAP connection after sending
or receiving a TLS closure alert.

After the TLS connection has been closed, the server MUST NOT send
responses to any request message received before the TLS closure.
Thus, clients wishing to receive responses to messages sent while the
TLS connection is intact MUST wait for those message responses before
sending the TLS closure alert.

4.13.3.2. Abrupt Closure

Either the client or server MAY abruptly close the TLS connection by
dropping the underlying transfer protocol connection. In this
circumstance, a server MAY send the client a Notice of Disconnection
before dropping the underlying LDAP connection.

5. Protocol Element Encodings and Transfer

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5. Protocol Element Encodings and Transfer

One underlying service service, LDAP over TCP, is defined here. Clients and servers SHOULD
implement This service
is generally applicable to applications providing or consuming X.500-
based directory services on the mapping Internet.

Implementations of LDAP over [TCP] TCP MUST implement the mapping as
described in 5.2.1. Section 5.2.1

5.1. Protocol Encoding

The protocol elements of LDAP are SHALL be encoded for exchange using the
Basic Encoding Rules [BER] of [ASN.1]. However, due to the high
overhead involved in using certain elements of the BER, [ASN.1] with the following
additional restrictions are placed on BER-encodings of LDAP protocol
elements:
restrictions:

(1) Only the definite form of length encoding will be is used.

(2) OCTET STRING values will be are encoded in the primitive form only.

(3) If the value of a BOOLEAN type is true, the encoding MUST have
its contents octets of the
value octet is set to hex "FF".

(4) If a value of a type is its default value, it MUST be is absent. Only
some BOOLEAN and INTEGER types have default values in this
protocol definition.

These restrictions are meant to ease the overhead of encoding and
decoding certain elements in BER.

These restrictions do not apply to ASN.1 types encapsulated inside of
OCTET STRING values, such as attribute values, unless otherwise
noted.
stated.

5.2. Transfer Protocols

This protocol is designed to run over connection-oriented, reliable
transports, with all 8 bits in an octet being significant in the data
stream.

5.2.1. Transmission Control Protocol (TCP)

The encoded LDAPMessage PDUs are mapped directly onto the [TCP]
bytestream using the BER-based encoding described in section Section 5.1. It
is recommended that server implementations running over the TCP
provide a protocol listener on the assigned port, 389. Servers may
instead provide a listener on a different port number. Clients MUST
support contacting servers on any valid TCP port.

6. Implementation Guidelines

6.1. Server Implementations Security Considerations

This version of the protocol provides facilities for simple
authentication using a cleartext password, as well as any [SASL]

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The server MUST be capable of recognizing all the mandatory attribute
types specified in [Models],

mechanism. SASL allows for integrity and implement the syntaxes used by those
attributes specified in [Syntaxes]. Servers MAY privacy services to be
negotiated.

It is also recognize
additional attribute type names.

6.2. Client Implementations

Clients that follow referrals or search continuation references MUST
ensure permitted that they do not loop between servers. They MUST NOT
repeatedly contact the same server for can return its credentials to
the same request with client, if it chooses to do so.

Use of cleartext password is strongly discouraged where the same
target entry name, scope and filter. Some clients use a counter that
is incremented each time referral handling occurs for an operation,
and these kinds of clients MUST be able to handle at least ten nested
referrals between the root and a leaf entry.

In the absence of prior agreements with servers, clients SHOULD NOT
assume that servers support any particular schemas beyond those
referenced in section 6.1. Different schemas can have different
attribute types with the same names. The client can retrieve the
subschema entries referenced by the subschemaSubentry attribute in
the entries held by the server.

7. Security Considerations

This version of the protocol provides facilities for simple
authentication using a cleartext password, as well as any [SASL]
mechanism. SASL allows for integrity and privacy services to be
negotiated.

It is also permitted that the server can return its credentials to
the client, if it chooses to do so.

Use of cleartext password is strongly discouraged where the
underlying transport service cannot guarantee confidentiality
underlying transport service cannot guarantee confidentiality and may
result in disclosure of the password to unauthorized parties.

Servers are encouraged to prevent directory modifications by clients
that have authenticated anonymously [AuthMeth].

Requirements of authentication methods, SASL mechanisms, and TLS are
described in [AUTHMETH].

When used with SASL, it [AuthMeth].

It should be noted that the name field of the
BindRequest is SASL authentication exchanges do not protected against modification. Thus if provide
data confidentiality nor integrity protection for the
distinguished version or name
fields of the client (an LDAPDN) is agreed through bind request nor the
negotiation resultCode, diagnosticMessage, or
referral fields of the credentials, it takes precedence over bind response nor of any value information contained
in controls attached to bind request or responses. Thus information
contained in these fields SHOULD NOT be relied on unless otherwise
protected (such as by establishing protections at the unprotected name field. transport
layer).

Server implementors should plan for the possibility of an identity
associated with an LDAP connection being deleted, renamed, or
modified, and take appropriate actions to prevent insecure side
effects. The way in which this is dealt with is implementation
specific. Likewise, server implementors should plan for the
possibility of an associated identity's credentials becoming invalid.

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or an identities privileges being changed. The way in which these
issues are addressed are application
and/or implementation specific.

Implementations which cache attributes and entries obtained via LDAP
MUST ensure that access controls are maintained if that information
is to be provided to multiple clients, since servers may have access
control policies which prevent the return of entries or attributes in
search results except to particular authenticated clients. For
example, caches could serve result information only to the client
whose request caused it to be in the cache.

Protocol servers may return referrals which redirect protocol clients
to peer servers. It is possible for a rogue application to inject
such referrals into the data stream in an attempt to redirect a
client to a rogue server. Protocol clients are advised to be aware of
this, and possibly reject referrals when confidentiality measures are
not in place. Protocol clients are advised to ignore reject referrals from
the Start TLS StartTLS operation.

Protocol peers MUST be prepared to handle invalid and arbitrary
length protocol encodings. A number of LDAP security advisories are
available through [CERT].

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7. Acknowledgements

This document is an update to updates RFC 2251, 2251 by Mark Wahl, Tim Howes, and Steve
Kille. It also updates RFC 2830 by Jeff Hodges, RL "Bob" Morgan, and
Mark Wahl. Their work along with the input of individuals of the IETF
ASID, LDAPEXT, LDUP, LDAPBIS, and other Working Groups is gratefully
acknowledged.

8. Normative References

[X.500] ITU-T Rec. X.500, "The Directory: Overview of Concepts,
Models and Service", 1993.

[Roadmap] Zeilenga, K., "LDAP: Technical Specification Road Map",
draft-ietf-ldapbis-roadmap-xx.txt (a work in progress).

[Keyword] Bradner, S., "Key words

[ABNF] Crocker, D. and P. Overell, "Augmented BNF for use in RFCs to Indicate
Requirement Levels", Syntax
Specifications: ABNF", RFC 2119, March 2234, November 1997.

[ASN.1] ITU-T Recommendation X.680 (07/2002) | ISO/IEC 8824-1:2002
"Information Technology - Abstract Syntax Notation One
(ASN.1): Specification of basic notation"

[AuthMeth] Harrison, R., "LDAP: Authentication Methods and Connection
Level Security Mechanisms ", draft-ietf-ldapbis-authmeth-
xx.txt, (a work in progress).

[BER] ITU-T Rec. X.690 (07/2002) | ISO/IEC 8825-1:2002,
"Information technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", 2002.

[LDAPIANA] Zeilenga, K., "IANA Considerations for LDAP", draft-ietf-
ldapbis-bcp64-00.txt, (a work in progress).

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[IP] Postel, J., "Internet Protocol", STD5 and RFC 791,
September 1981

[ISO10646] Universal Multiple-Octet Coded Character Set (UCS) -
Architecture and Basic Multilingual Plane, ISO/IEC 10646-1
: 1993.

[UTF-8] Yergeau, F., "UTF-8, a transformation format

[Keyword] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.

[LDAPDN] Zeilenga, K., "LDAP: String Representation of Unicode
and ISO 10646", draft-yergeau-rfc2279bis-xx.txt,
Distinguished Names", draft-ietf-ldapbis-dn-xx.txt, (a
work in progress).

[LDAPIANA] Zeilenga, K., "IANA Considerations for LDAP", draft-ietf-
ldapbis-bcp64-xx.txt, (a work in progress).

[LDAPURL] Smith, M., "LDAP: Uniform Resource Locator", draft-ietf-
ldapbis-url-xx.txt, (a work in progress).

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

[LDAPDN]

[Roadmap] Zeilenga, K., "LDAP: String Representation of
Distinguished Names", draft-ietf-ldapbis-dn-xx.txt, Technical Specification Road Map",
draft-ietf-ldapbis-roadmap-xx.txt (a work in progress).

[Syntaxes] Legg, S., and K. Dally, "LDAP: Syntaxes

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[SASL] Melnikov, A., "Simple Authentication and Matching
Rules", draft-ietf-ldapbis-syntaxes-xx.txt, Security Layer",
draft-ietf-sasl-rfc2222bis-xx.txt (a work in progress).

[X.501] ITU-T Rec. X.501, "The Directory: Models", 1993.

[X.511] ITU-T Rec. X.511, "The Directory: Abstract Service
Definition", 1993.

[URI] Berners-Lee, T., Fielding, R., and L. Masinter Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.

[AuthMeth] Harrison, R., "LDAP: Authentication Methods and Connection
Level Security Mechanisms ", draft-ietf-ldapbis-authmeth-
xx.txt, (a work in progress).

[SASL] Meyers, J., "Simple Authentication and Security Layer",
RFC 2222, October 1997.

[SASLPrep] Zeilenga, K., "Stringprep profile for user names and
passwords", draft-ietf-sasl-saslprep-xx.txt, (a work in
progress).

[StringPrep] Hoffman P. and M. Blanchet, "Preparation of
Internationalized Strings ('stringprep')", draft-hoffman-
rfc3454bis-xx.txt, a work in progress.

[Syntaxes] Legg, S., and K. Dally, "LDAP: Syntaxes and Matching
Rules", draft-ietf-ldapbis-syntaxes-xx.txt, (a work in
progress).

[TCP] Postel, J., "Transmission Control Protocol", STD7 and RFC
793, September 1981

[TLS] Dierks, T. and C. Allen. "The TLS Protocol Version 1.1",
draft-ietf-tls-rfc2246-bis-xx.txt, a work in progress.

[Unicode] The Unicode Consortium, "The Unicode Standard, Version
3.2.0" is defined by "The Unicode Standard, Version 3.0"
(Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5),
as amended by the "Unicode Standard Annex #27: Unicode
3.1" (http://www.unicode.org/reports/tr27/) and by the
"Unicode Standard Annex #28: Unicode 3.2"
(http://www.unicode.org/reports/tr28/).

[TCP] Postel, J., "Transmission Control Protocol", STD7

[URI] Berners-Lee, T., Fielding, R., and L. Masinter Uniform
Resource Identifiers (URI): Generic Syntax", RFC
793, September 1981

[IP] Postel, J., "Internet Protocol", STD5 2396,
August 1998.

[UTF-8] Yergeau, F., "UTF-8, a transformation format of Unicode
and RFC 791,
September 1981 ISO 10646", STD63 and RFC3629.

[X.500] ITU-T Rec. X.500, "The Directory: Overview of Concepts,
Models and Service", 1993.

[X.501] ITU-T Rec. X.501, "The Directory: Models", 1993.

[X.511] ITU-T Rec. X.511, "The Directory: Abstract Service
Definition", 1993.

9. Informative References

[CERT] the CERT(R) Center, (http://www.cert.org)

10. IANA Considerations

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10. Informative References

[CERT] the CERT(R) Center, (http://www.cert.org)

11. IANA Considerations

It is requested that the Internet Assigned Numbers Authority (IANA)
update the occurrence of "RFC XXXX" in Appendix B with this RFC
number at publication.

12.

11. Editor's Address

Jim Sermersheim
Novell, Inc.
1800 South Novell Place
Provo, Utah 84606, USA
jimse@novell.com
+1 801 861-3088

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Appendix A - LDAP Result Codes

This normative appendix details additional considerations regarding
LDAP result codes and provides a brief, general description of each
LDAP result code enumerated in Section 4.1.10.

Additional result codes MAY be defined for use with extensions
[LDAPIANA]. Client implementations SHALL treat any result code which
they do not recognize as an unknown error condition.

A.1 Non-Error Result Codes

These result codes (called "non-error" result codes) do not indicate
an error condition:
success (0),
compareTrue (6),
compareFalse (7),
referral (10), and
saslBindInProgress (14).

The success, compareTrue, and compare result codes indicate
successful completion (and, hence, are referred to as "successful"
result codes).

The referral and saslBindInProgress result codes indicate the client
is required to take additional action to complete the operation

A.2 Result Codes

Existing LDAP result codes are described as follows:

success (0)
Indicates the successful completion of an operation. Note:
this code is not used with the compare operation. See
compareTrue (5) and compareFalse (6).

operationsError (1)
Indicates that the operation is not properly sequenced with
relation to other operations (of same or different type).

For example, this code is returned if the client attempts to
Start TLS
StartTLS [RFC2246] while there are other operations
outstanding or if TLS was already established.

protocolError (2)
Indicates the server received data which has incorrect
structure.

For bind operation only, the this code may be returned is also used to indicate
that the server does not support the requested protocol
version.

timeLimitExceeded (3)

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Indicates that the time limit specified by the client was
exceeded before the operation could be completed.

sizeLimitExceeded (4)

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Indicates that the size limit specified by the client was
exceeded before the operation could be completed.

compareFalse (5)
Indicates that the compare operation has successfully
completed and the assertion has evaluated to FALSE.

compareTrue (6)
Indicates that the compare operation has successfully
completed and the assertion has evaluated to TRUE.

authMethodNotSupported (7)
Indicates that the authentication method or mechanism is not
supported.

strongAuthRequired (8)
Indicates that the server has detected that an established
security association between the client and server has
unexpectedly failed or been compromised, or that the server
now requires the client to authenticate using a strong(er)
mechanism.

referral (10)
Indicates that a referral needs to be chased to complete the
operation (see section Section 4.1.11).

adminLimitExceeded (11)
Indicates that an administrative limit has been exceeded.

unavailableCriticalExtension (12)
Indicates that the server cannot is unable or unwilling to perform a
critical extension (see section Section 4.1.12).

confidentialityRequired (13)
Indicates that data confidentiality protections are required.

saslBindInProgress (14)
Indicates the server requires the client to send a new bind
request, with the same SASL mechanism, to continue the
authentication process (see section Section 4.2).

noSuchAttribute (16)
Indicates that the named entry does not contain the specified
attribute or attribute value.

undefinedAttributeType (17)
Indicates that a request field contains an undefined unrecognized
attribute type. description.

inappropriateMatching (18)

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Indicates that an attempt was made, e.g. in a filter, to use
a matching rule not defined for the attribute type concerned.

constraintViolation (19)

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Indicates that the client supplied an attribute value which
does not conform to the constraints placed upon it by the
data model.

For example, this code is returned when multiple values are
supplied to an attribute which has a SINGLE-VALUE constraint.

attributeOrValueExists (20)
Indicates that the client supplied an attribute or value to
be added to an entry, but the attribute or value already
exists.

invalidAttributeSyntax (21)
Indicates that a purported attribute value does not conform
to the syntax of the attribute.

noSuchObject (32)
Indicates that the object does not exist in the DIT.

aliasProblem (33)
Indicates that an alias problem has occurred. Typically For example,
the code may used to indicate an alias has been dereferenced
which names no object.

invalidDNSyntax (34)
Indicates that an LDAPDN or RelativeLDAPDN field (e.g. search
base, target entry, ModifyDN newrdn, etc.) of a request does
not conform to the required syntax or contains attribute
values which do not conform to the syntax of the attribute's
type.

aliasDereferencingProblem (36)
Indicates that a problem occurred while dereferencing an
alias. Typically an alias was encountered in a situation
where it was not allowed or where access was denied.

inappropriateAuthentication (48)
Indicates the server requires the client which had attempted
to bind anonymously or without supplying credentials to
provide some form of credentials.

invalidCredentials (49)
Indicates that the supplied password or SASL provided credentials (e.g. the user's name
and password) are invalid.

insufficientAccessRights (50)
Indicates that the client does not have sufficient access
rights to perform the operation.

busy (51)

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Indicates that the server is busy. too busy to service the
operation.

unavailable (52)
Indicates that the server is shutting down or a subsystem
necessary to complete the operation is offline.

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unwillingToPerform (53)
Indicates that the server is unwilling to perform the
operation.

loopDetect (54)
Indicates that the server has detected an internal loop.

namingViolation (64)
Indicates that the entry entry's name violates naming restrictions.

objectClassViolation (65)
Indicates that the entry violates object class restrictions.

notAllowedOnNonLeaf (66)
Indicates that the operation is inappropriately acting upon a
non-leaf entry.

notAllowedOnRDN (67)
Indicates that the operation is inappropriately attempting to
remove a value which forms the entry's relative distinguished
name.

entryAlreadyExists (68)
Indicates that the request cannot be fulfilled (added, moved,
or renamed) as the target entry already exists.

objectClassModsProhibited (69)
Indicates that the an attempt to modify the object class(es) of
an entry's objectClass attribute is prohibited.

For example, this code is returned when a client attempts to
modify the structural object class of an entry.

affectsMultipleDSAs (71)
Indicates that the operation cannot be completed as it
affects multiple servers (DSAs).

other (80)
Indicates the server has encountered an internal error.

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Appendix B - Complete ASN.1 Definition

This appendix is normative.

Lightweight-Directory-Access-Protocol-V3
-- Copyright (C) The Internet Society (2003). This version of
-- this ASN.1 module is part of RFC XXXX; see the RFC itself
-- for full legal notices.
DEFINITIONS
IMPLICIT TAGS
EXTENSIBILITY IMPLIED ::=

BEGIN

LDAPMessage ::= SEQUENCE {
messageID MessageID,
protocolOp CHOICE {
bindRequest BindRequest,
bindResponse BindResponse,
unbindRequest UnbindRequest,
searchRequest SearchRequest,
searchResEntry SearchResultEntry,
searchResDone SearchResultDone,
searchResRef SearchResultReference,
modifyRequest ModifyRequest,
modifyResponse ModifyResponse,
addRequest AddRequest,
addResponse AddResponse,
delRequest DelRequest,
delResponse DelResponse,
modDNRequest ModifyDNRequest,
modDNResponse ModifyDNResponse,
compareRequest CompareRequest,
compareResponse CompareResponse,
abandonRequest AbandonRequest,
extendedReq ExtendedRequest,
extendedResp ExtendedResponse,
... },
controls [0] Controls OPTIONAL }

MessageID ::= INTEGER (0 .. maxInt)

maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) --

LDAPString ::= OCTET STRING -- UTF-8 encoded,
-- [ISO10646] characters

LDAPOID ::= OCTET STRING -- Constrained to <numericoid> [Models]

LDAPDN ::= LDAPString

RelativeLDAPDN ::= LDAPString

AttributeDescription ::= LDAPString

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-- Constrained to <attributedescription>
-- [Models]

AttributeValue ::= OCTET STRING

AttributeValueAssertion ::= SEQUENCE {
attributeDesc AttributeDescription,
assertionValue AssertionValue }

AssertionValue ::= OCTET STRING

Attribute

PartialAttribute ::= SEQUENCE {
type AttributeDescription,
vals SET SIZE (1..MAX) OF value AttributeValue }

Attribute ::= PartialAttribute(WITH COMPONENTS {
...,
vals (SIZE(1..MAX))})

MatchingRuleId ::= LDAPString

LDAPResult ::= SEQUENCE {
resultCode ENUMERATED {
success (0),
operationsError (1),
protocolError (2),
timeLimitExceeded (3),
sizeLimitExceeded (4),
compareFalse (5),
compareTrue (6),
authMethodNotSupported (7),
strongAuthRequired (8),
-- 9 reserved --
referral (10),
adminLimitExceeded (11),
unavailableCriticalExtension (12),
confidentialityRequired (13),
saslBindInProgress (14),
noSuchAttribute (16),
undefinedAttributeType (17),
inappropriateMatching (18),
constraintViolation (19),
attributeOrValueExists (20),
invalidAttributeSyntax (21),
-- 22-31 unused --
noSuchObject (32),
aliasProblem (33),
invalidDNSyntax (34),
-- 35 reserved for undefined isLeaf --
aliasDereferencingProblem (36),
-- 37-47 unused --
inappropriateAuthentication (48),
invalidCredentials (49),
insufficientAccessRights (50),
busy (51),
unavailable (52),
unwillingToPerform (53),
loopDetect (54),

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busy (51),
unavailable (52),
unwillingToPerform (53),
loopDetect (54),
-- 55-63 unused --
namingViolation (64),
objectClassViolation (65),
notAllowedOnNonLeaf (66),
notAllowedOnRDN (67),
entryAlreadyExists (68),
objectClassModsProhibited (69),
-- 70 reserved for CLDAP --
affectsMultipleDSAs (71),
-- 72-79 unused --
other (80),
... },
-- 81-90 reserved for APIs --
matchedDN LDAPDN,
diagnosticMessage LDAPString,
referral [3] Referral OPTIONAL }

Referral ::= SEQUENCE SIZE (1..MAX) OF uri URI

URI ::= LDAPString -- limited to characters permitted in
-- URIs

Controls ::= SEQUENCE OF control Control

Control ::= SEQUENCE {
controlType LDAPOID,
criticality BOOLEAN DEFAULT FALSE,
controlValue OCTET STRING OPTIONAL }

BindRequest ::= [APPLICATION 0] SEQUENCE {
version INTEGER (1 .. 127),
name LDAPDN,
authentication AuthenticationChoice }

AuthenticationChoice ::= CHOICE {
simple [0] OCTET STRING,
-- 1 and 2 reserved
sasl [3] SaslCredentials,
... }

SaslCredentials ::= SEQUENCE {
mechanism LDAPString,
credentials OCTET STRING OPTIONAL }

BindResponse ::= [APPLICATION 1] SEQUENCE {
COMPONENTS OF LDAPResult,
serverSaslCreds [7] OCTET STRING OPTIONAL }

UnbindRequest ::= [APPLICATION 2] NULL

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SearchRequest ::= [APPLICATION 3] SEQUENCE {
baseObject LDAPDN,
scope ENUMERATED {
baseObject (0),

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singleLevel (1),
wholeSubtree (2) },
derefAliases ENUMERATED {
neverDerefAliases (0),
derefInSearching (1),
derefFindingBaseObj (2),
derefAlways (3) },
sizeLimit INTEGER (0 .. maxInt),
timeLimit INTEGER (0 .. maxInt),
typesOnly BOOLEAN,
filter Filter,
attributes AttributeSelection }

AttributeSelection ::= SEQUENCE OF selection LDAPString

MatchingRuleAssertion ::= SEQUENCE {
matchingRule [1] MatchingRuleId OPTIONAL,
type [2] AttributeDescription OPTIONAL,
matchValue [3] AssertionValue,
dnAttributes [4] BOOLEAN DEFAULT FALSE }

SearchResultEntry ::= [APPLICATION 4] SEQUENCE {
objectName LDAPDN,
attributes PartialAttributeList }

PartialAttributeList ::= SEQUENCE OF
attribute PartialAttribute
partialAttribute PartialAttribute ::= SEQUENCE {
type AttributeDescription,
vals SET OF value AttributeValue }

SearchResultReference ::= [APPLICATION 19] SEQUENCE

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SIZE (1..MAX) OF uri URI

SearchResultDone ::= [APPLICATION 5] LDAPResult

ModifyRequest ::= [APPLICATION 6] SEQUENCE {
object LDAPDN,
changes SEQUENCE OF change SEQUENCE {
operation ENUMERATED {
add (0),
delete (1),
replace (2) },
modification PartialAttribute } }

ModifyResponse ::= [APPLICATION 7] LDAPResult

AddRequest ::= [APPLICATION 8] SEQUENCE {
entry LDAPDN,
attributes AttributeList }

AttributeList ::= SEQUENCE OF attribute Attribute

AddResponse ::= [APPLICATION 9] LDAPResult

DelRequest ::= [APPLICATION 10] LDAPDN

DelResponse ::= [APPLICATION 11] LDAPResult

ModifyDNRequest ::= [APPLICATION 12] SEQUENCE {
entry LDAPDN,
newrdn RelativeLDAPDN,
deleteoldrdn BOOLEAN,
newSuperior [0] LDAPDN OPTIONAL }

ModifyDNResponse ::= [APPLICATION 13] LDAPResult

CompareRequest ::= [APPLICATION 14] SEQUENCE {
entry LDAPDN,
ava AttributeValueAssertion }

CompareResponse ::= [APPLICATION 15] LDAPResult

AbandonRequest ::= [APPLICATION 16] MessageID

ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID,
requestValue [1] OCTET STRING OPTIONAL }

ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
COMPONENTS OF LDAPResult,
responseName [10] LDAPOID OPTIONAL,
responseValue [11] OCTET STRING OPTIONAL }

END

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Appendix C - Change History
<Note to RFC editor: Changes

This section appendix is to be removed prior non-normative.

This appendix summarizes substantive changes made to RFC
publication> 2251 and RFC
2830.

C.1 Changes made to made to RFC 2251:

C.1.1 Editorial

- Bibliography References: Changed all bibliography references

This section summarizes the substantive changes made to
use a long name form for readability.
- Changed occurrences Sections 1,
2, 3.1, and 4 through the remainder of "unsupportedCriticalExtension"
"unavailableCriticalExtension"
- Fixed a small number RFC 2251. Readers should
consult [Models] and [AuthMeth] for summaries of misspellings (mostly dropped letters).

C.1.2 changes to other
sections.

C.1.1 Section 1

- Removed IESG note.

C.1.3 Post publication of RFC 2251, mandatory LDAP
authentication mechanisms have been standardized which are
sufficient to remove this note. See [AuthMeth] for authentication
mechanisms.

C.1.2 Section 9 3.1 and others

- Added references to RFCs 1823, 2234, 2829 Removed notes giving history between LDAP v1, v2 and 2830.

C.2 Changes made to draft-ietf-ldapbis-protocol-00.txt:

C.2.1 v3. Instead,
added sufficient language so that this document can stand on its
own.

C.1.3 Section 4.1.6 4

- In the first paragraph, clarified what Clarified where the contents extensibility features of an
AttributeValue are. There was confusion regarding whether or not
an AttributeValue that is BER encoded (due ASN.1 apply to the "binary" option)
is to be wrapped in an extra OCTET STRING.
protocol. This change also affected various ASN.1 types.
- To Removed the first paragraph, added wording requirement that doesn't restrict other
transfer encoding specifiers from being used. The previous wording
only allowed for the string encoding and the ;binary encoding.
- To servers which implement version 3 or
later MUST provide the first paragraph, added a statement restricting multiple
options that specify transfer encoding from being present. supportedLDAPVersion attribute. This
was never specified in the previous version and was seen as a
potential
statement provided no interoperability problem. advantages.

C.1.4 Section 4.1.1

- Added There was a third paragraph stating that the ;binary option is
currently the only option defined that specifies the transfer
encoding. This is mandatory requirement for completeness.

C.2.2 Section 4.1.7

- Generalized the second paragraph server to read "If an option specifying return a
Notice of Disconnection and drop the transfer encoding connection when a PDU is present
malformed in attributeDesc, a certain way. This has been clarified such that the
AssertionValue is encoded as specified by
server SHOULD return the option...".
Previously, only Notice of Disconnection, and MUST drop
the ;binary option was mentioned.

C.2.3 Sections 4.2, 4.9, 4.10 connection.

C.1.5 Section 4.1.1.1

- Added alias dereferencing specifications. In the case of modDN,
followed precedent set on other update operations (... alias is
not dereferenced...) In Clarified that the case messageID of bind and compare stated that requests MUST be non-zero.

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servers SHOULD NOT dereference aliases. Specifications were added
because they were missing from the previous version and caused
interoperability problems. Concessions were made for bind and
compare (neither should have ever allowed alias dereferencing) by
using SHOULD NOT language, due to the behavior of some existing
implementations.

C.2.4 Sections 4.5 and Appendix A

- Changed SubstringFilter.substrings.initial, any, and all from
LDAPString to AssertionValue. This was causing an incompatibility
with X.500 and confusion among other TS RFCs.

C.3 Changes made to draft-ietf-ldapbis-protocol-01.txt:

C.3.1 Section 3.4

- Reworded text surrounding subschemaSubentry to reflect that it is
a single-valued attribute that holds the schema for the root DSE.
Also noted that if the server masters entries that use differing
schema, each entry's subschemaSubentry attribute must be
interrogated. This may change as further fine-tuning is done to
the data model.

C.3.2 Section 4.1.12

- Specified that the criticality field is only used for requests and
not for unbind or abandon. Noted that it is ignored for all other
operations.

C.3.3 Section 4.2

- Noted that Server behavior is undefined when the name is a null
value, simple authentication is used, and a password is specified.

C.3.4 Section 4.2.(various)

- Changed "unauthenticated" to "anonymous" and "DN" and "LDAPDN" to
"name"

C.3.5 Section 4.2.2

- Changed "there is no authentication or encryption being performed
by a lower layer" to "the underlying transport service cannot
guarantee confidentiality"

C.3.6 Section 4.5.2

- Removed all mention of ExtendedResponse due to lack of
implementation.

C.4 Changes made to draft-ietf-ldapbis-protocol-02.txt:

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C.4.1 Section 4

- Removed "typically" from "and is typically transferred" in the
first paragraph. We know of no (and can conceive of no) case where
this isn't true.
- Added "Section 5.1 specifies how the LDAP protocol is encoded." To
the first paragraph. Added this cross reference for readability.
- Changed "version 3 " to "version 3 or later" in the second
paragraph. This was added to clarify the original intent.
- Changed "protocol version" to "protocol versions" in the third
paragraph. This attribute is multi-valued with the intent of
holding all supported versions, not just one.

C.4.2 Section 4.1.8

- Changed "when transferred in protocol" to "when transferred from
the server to the client" in the first paragraph. This is to
clarify that this behavior only happens when attributes are being
sent from the server.

C.4.3 Section 4.1.10

- Changed "servers will return responses containing fields of type
LDAPResult" to "servers will return responses of LDAPResult or
responses containing the components of LDAPResponse". This
statement was incorrect and at odds with the ASN.1. The fix here
reflects the original intent.
- Dropped '--new' from result codes ASN.1. This simplification in
comments just reduces unneeded verbiage.

C.4.4 Section 4.1.11

- Changed "It contains a reference to another server (or set of
servers)" to "It contains one or more references to one or more
servers or services" in the first paragraph. This reflects the
original intent and clarifies that the URL may point to non-LDAP
services.

C.4.5 Section 4.1.12

- Changed "The server MUST be prepared" to "Implementations MUST be
prepared" in the eighth paragraph to reflect that both client and
server implementations must be able to handle this (as both parse
controls).

C.4.6 Section 4.4

- Changed "One unsolicited notification is defined" to "One
unsolicited notification (Notice of Disconnection) is defined" in
the third paragraph. For clarity and readability.

C.4.7 Section 4.5.1

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- Changed "checking for the existence of the objectClass attribute"
to "checking for the presence of the objectClass attribute" in the
last paragraph. This was done as a measure of consistency (we use
the terms present and presence rather than exists and existence in
search filters).

C.4.8 Section 4.5.3

- Changed "outstanding search operations to different servers," to
"outstanding search operations" in the fifth paragraph as they may
be to the same server. This is a point of clarification.

C.4.9 Section 4.6

- Changed "clients MUST NOT attempt to delete" to "clients MUST NOT
attempt to add or delete" in the second to last paragraph.
- Change "using the "delete" form" to "using the "add" or "delete"
form" in the second to last paragraph.

C.4.10 Section 4.7

- Changed "Clients MUST NOT supply the createTimestamp or
creatorsName attributes, since these will be generated
automatically by the server." to "Clients MUST NOT supply NO-USER-
MODIFICATION attributes such as createTimestamp or creatorsName
attributes, since these are provided by the server." in the
definition of the attributes field. This tightens the language to
reflect the original intent and to not leave a hole in which one
could interpret the two attributes mentioned as the only non-
writable attributes.

C.4.11 Section 4.11

- Changed "has been" to "will be" in the fourth paragraph. This
clarifies that the server will (not has) abandon the operation.

C.5 Changes made to draft-ietf-ldapbis-protocol-03.txt:

C.5.1 Section 3.2.1

- Changed "An attribute is a type with one or more associated
values. The attribute type is identified by a short descriptive
name and an OID (object identifier). The attribute type governs
whether there can be more than one value of an attribute of that
type in an entry, the syntax to which the values must conform, the
kinds of matching which can be performed on values of that
attribute, and other functions." to " An attribute is a
description (a type and zero or more options) with one or more
associated values. The attribute type governs whether the
attribute can have multiple values, the syntax and matching rules
used to construct and compare values of that attribute, and other
functions. Options indicate modes of transfer and other

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functions.". This points out that an attribute consists of both
the type and options.

C.5.2 Section 4

- Changed "Section 5.1 specifies the encoding rules for the LDAP
protocol" to "Section 5.1 specifies how the protocol is encoded
and transferred."

C.5.3 Section 4.1.2

- Added ABNF for the textual representation of LDAPOID. Previously,
there was no formal BNF for this construct.

C.5.4 Section 4.1.4

- Changed "This identifier may be written as decimal digits with
components separated by periods, e.g. "2.5.4.10"" to "may be
written as defined by ldapOID in section 4.1.2" in the second
paragraph. This was done because we now have a formal BNF
definition of an oid.

C.5.5 Section 4.1.5

- Changed the BNF for AttributeDescription to ABNF. This was done
for readability and consistency (no functional changes involved).
- Changed "Options present in an AttributeDescription are never
mutually exclusive." to "Options MAY be mutually exclusive. An
AttributeDescription with mutually exclusive options is treated as
an undefined attribute type." for clarity. It is generally
understood that this is the original intent, but the wording could
be easily misinterpreted.
- Changed "Any option could be associated with any AttributeType,
although not all combinations may be supported by a server." to
"Though any option or set of options could be associated with any
AttributeType, the server support for certain combinations may be
restricted by attribute type, syntaxes, or other factors.". This
is to clarify the meaning of 'combination' (it applies both to
combination of attribute type and options, and combination of
options). It also gives examples of *why* they might be
unsupported.

C.5.6 Section 4.1.11

- Changed the wording regarding 'equally capable' referrals to "If
multiple URLs are present, the client assumes that any URL may be
used to progress the operation.". The previous language implied
that the server MUST enforce rules that it was practically
incapable of. The new language highlights the original intent--
that is, that any of the referrals may be used to progress the
operation, there is no inherent 'weighting' mechanism.

C.5.7 Section 4.5.1 and Appendix A

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- Added the comment "-- initial and final can occur at most once",
to clarify this restriction.

C.5.8 Section 5.1

- Changed heading from "Mapping Onto BER-based Transport Services"
to "Protocol Encoding".

C.5.9 Section 5.2.1

- Changed "The LDAPMessage PDUs" to "The encoded LDAPMessage PDUs"
to point out that the PDUs are encoded before being streamed to
TCP.

C.6 Changes made to draft-ietf-ldapbis-protocol-04.txt:

C.6.1 Section 4.5.1 and Appendix A

- Changed the ASN.1 for the and and or choices of Filter to have a
lower range of 1. This was an omission in the original ASN.1

C.6.2 Various

- Fixed various typo's

C.7 Changes made to draft-ietf-ldapbis-protocol-05.txt:

C.7.1 Section 3.2.1

- Added "(as defined in Section 12.4.1 of [X.501])" to the fifth
paragraph when talking about "operational attributes". This is
because the term "operational attributes" is never defined.
Alternately, we could drag a definition into the spec, for now,
I'm just pointing to the reference in X.501.

C.7.2 Section 4.1.5

- Changed "And is also case insensitive" to "The entire
AttributeDescription is case insensitive". This is to clarify
whether we're talking about the entire attribute description, or
just the options.

- Expounded on the definition of attribute description options. This
doc now specifies a difference between transfer and tagging
options and describes the semantics of each, and how and when
subtyping rules apply. Now allow options to be transmitted in any
order but disallow any ordering semantics to be implied. These
changes are the result of ongoing input from an engineering team
designed to deal with ambiguity issues surrounding attribute
options.

C.7.3 Sections 4.1.5.1 and 4.1.6

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- Refer to non "binary" transfer encodings as "native encoding"
rather than "string" encoding to clarify and avoid confusion.

C.8 Changes made to draft-ietf-ldapbis-protocol-06.txt:

C.8.1 Title

- Changed to "LDAP: The Protocol" to be consisted with other working
group documents

C.8.2 Abstract

- Moved above TOC to conform to new guidelines

- Reworded to make consistent with other WG documents.

- Moved 2119 conventions to "Conventions" section

C.8.3 Introduction

- Created to conform to new guidelines

C.8.4 Models

- Removed section. There is only one model in this document
(Protocol Model)

C.8.5 Protocol Model

- Removed antiquated paragraph: "In keeping with the goal of easing
the costs associated with use of the directory, it is an objective
of this protocol to minimize the complexity of clients so as to
facilitate widespread deployment of applications capable of using
the directory."

- Removed antiquated paragraph concerning LDAP v1 and v2 and
referrals.

C.8.6 Data Model

- Removed Section 3.2 and subsections. These have been moved to
[Models]

C.8.7 Relationship to X.500

- Removed section. It has been moved to [Roadmap]

C.8.8 Server Specific Data Requirements

- Removed section. It has been moved to [Models]

C.8.9 Elements of Protocol

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- Added "Section 5.1 specifies how the protocol is encoded and
transferred." to the end of the first paragraph for reference.

- Reworded notes about extensibility, and now talk about implied
extensibility and the use of ellipses in the ASN.1

- Removed references to LDAPv2 in third and fourth paragraphs.

C.8.10 Message ID

- Reworded second paragraph to "The message ID of a request MUST
have a non-zero value different from the values of any other
requests outstanding in the LDAP session of which this message is
a part. The zero value is reserved for the unsolicited
notification message." (Added notes about non-zero and the zero
value).

C.8.11 String Types

- Removed ABNF for LDAPOID and added "Although an LDAPOID is encoded
as an OCTET STRING, values are limited to the definition of
numericoid given in Section 1.3 of [Models]."

C.8.12 Distinguished Name and Relative Distinguished Name

- Removed ABNF and referred to [Models] and [LDAPDN] where this is
defined.

C.8.13 Attribute Type

- Removed sections. It's now in the [Models] doc.

C.8.14 Attribute Description

- Removed ABNF and aligned section with [Models]

- Moved AttributeDescriptionList here.

C.8.15 Transfer Options

- Added section and consumed much of old options language (while
aligning with [Models]

C.8.16 Binary Transfer Option

- Clarified intent regarding exactly what is to be BER encoded.

- Clarified that clients must not expect ;binary when not asking for
it (;binary, as opposed to ber encoded data).

C.8.17 Attribute

- Use the term "attribute description" in lieu of "type"

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- Clarified the fact that clients cannot rely on any apparent
ordering of attribute values.

C.8.18 LDAPResult

- To resultCode, added ellipses "..." to the enumeration to indicate
extensibility. and added a note, pointing to [LDAPIANA]

- Removed error groupings ad refer to Appendix A.

C.8.19 Bind Operation

- Added "Prior to the BindRequest, the implied identity is
anonymous. Refer to [AuthMeth] for the authentication-related
semantics of this operation." to the first paragraph.

- Added ellipses "..." to AuthenticationChoice and added a note
"This type is extensible as defined in Section 3.6 of [LDAPIANA].
Servers that do not support a choice supplied by a client will
return authMethodNotSupported in the result code of the
BindResponse."

- Simplified text regarding how the server handles unknown versions.
Removed references to LDAPv2

C.8.20 Sequencing of the Bind Request

- Aligned with [AuthMeth] In particular, paragraphs 4 and 6 were
removed, while a portion of 4 was retained (see C.8.9)

C.8.21 Authentication and other Security Service

- Section was removed. Now in [AuthMeth]

C.8.22 Continuation References in the Search Result

- Added "If the originating search scope was singleLevel, the scope
part of the URL will be baseObject."

C.8.23 Security Considerations

- Removed reference to LDAPv2

C.8.24 Result Codes

- Added as normative appendix A

C.8.25 ASN.1

- Added EXTENSIBILITY IMPLIED

- Added a number of comments holding referenced to [Models] and
[ISO10646].

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- Removed AttributeType. It is not used.

C.9 Changes made to draft-ietf-ldapbis-protocol-07.txt:

- Removed all mention of transfer encodings and the binary attribute
option. Please refer to draft-legg-ldap-binary-00.txt and draft-
legg-ldap-transfer-00.txt

- Further alignment with [Models].

- Added extensibility ellipsis to protocol op choice

- In 4.1.1, clarified when connections may be dropped due to
malformed PDUs

- Specified which matching rules and syntaxes are used for various
filter items

C.10 Changes made to draft-ietf-ldapbis-protocol-08.txt:

C.10.1 Section 4.1.1.1:

- Clarified when it is and isn't appropriate to return an already
used message id.

C.10.2 Section 4.1.11:

- Clarified that a control only applies to the message it's attached
to.

- Explained that the criticality field is only applicable to certain
request messages.

- Added language regarding the combination of controls.

C.10.3 Section 4.11:

- Explained that Abandon and Unbind cannot be abandoned, and
illustrated how to determine whether an operation has been
abandoned.

C.11 Changes made to draft-ietf-ldapbis-protocol-09.txt:

- Fixed formatting

C.12 Changes made to draft-ietf-ldapbis-protocol-10.txt:

C.12.1 Section 4.1.4:

- Removed second paragraph as this language exists in MODELS

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C.12.2 Section 4.2.1:

- Replaced fourth paragraph. It was RFC 2251 accidentally removed imposed synchronous server
behavior in an
earlier edit.

C.12.2 its wording of this.

C.1.6 Section 4.13: 4.1.2

- Added section describing the StartTLS operation (moved from
authmeth)

C.13 Changes made Stated that LDAPOID is constrained to draft-ietf-ldapbis-protocol-11.txt:

C.13.1 <numericoid> from [Models].

C.1.7 Section 4.1.9 4.1.5.1

- Changed "errorMessage" to "diagnosticMessage". Simply to indicate
that Removed the field may be non-empty even if Binary Option from the specification. There are
numerous interoperability problems associated with this method of
alternate attribute type encoding. Work to specify a non-error resultCode suitable
replacement is
present.

C.13.2 Section 4.2:

- Reconciled language in "name" definition with [AuthMeth]

C.13.3 ongoing.

C.1.8 Section 4.2.1 4.1.6

- Renamed Removed references to "Processing of the Bind Request", and moved some text "binary" encoding as it has been removed
from 4.2 into this section. the specification.

C.1.9 Section 4.1.7

- Rearranged paragraphs Removed references to flow better.

- Specified that (as well the "binary" encoding as failed) an abandoned bind operation
will leave it has been removed
from the connection in an anonymous state.

C.13.4 specification.

C.1.10 Section 4.5.3 4.1.8

- Generalized Combined the second paragraph which cited indexing definitions of PartialAttribute and
searchreferralreferences.

C.14 Changes made to draft-ietf-ldapbis-protocol-12.txt: Attribute here,
and defined Attribute in terms of PartialAttribute.

C.1.11 Section 4.1.10

- Reworked bind errors. Renamed "errorMessage" to "diagnosticMessage" as it is allowed to
be sent for non-error results.
- General clarifications Moved some language into Appendix A, and edits

C.15 Changes made refer the reader there.
- Allowed matchedDN to draft-ietf-ldapbis-protocol-13.txt

C.15.1 be present for other result codes than those
listed in RFC 2251.

C.1.12 Section 2 & various 4.1.11

- Added definitions for LDAP connection, TLS connection, and LDAP
association, Defined referrals in terms of URIs rather than URLs.
- Removed the requirement that all referral URIs MUST be equally
capable of progressing the operation. The statement was ambiguous
and updated appropriate fields provided no instructions on how to use proper terms.

C.15.2 Section 4.2 carry it out.
- Added text to authentication, specifying the way requirement that clients MUST NOT loop between servers.
- Clarified the instructions for using LDAPURLs in which textual
strings used as passwords are to referrals, and in
doing so added a recommendation that the scope part be prepared. present.

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C.15.3

C.1.13 Section 4.5.1 4.1.12

- Clarified derefInSearching. Specifically Specified how it works control values defined in terms of
subtree and one level searches

C.15.4 Section 4.5.2 ASN.1 are to be
encoded.
- Added language regarding combinations of controls on a message.
- Changed "The server MUST be prepared" to SHOULD for returning textual attribute name, The "Implementations MUST be
prepared" in the eighth paragraph to reflect that both client and
server implementations must be able to handle this (as both parse
controls).

C.1.14 Section 4.2

- Mandated that servers return protocolError when the version is unreasonable. There are likely cases (such as not
supported.
- Clarified behavior when the
server knows multiple attributes in separate entries of a search
result set share simple authentication is used, the same short name) where returning a numericoid
name is better than returning a short name. That is, empty and the MUST may
actually disallow servers from preventing misinterpretation of
short names. This password is not only an interop issue, but likely a
security consideration.

C.15.4 Section 4.9 non-empty.
- Made modify consistent Required servers to not dereference aliases for bind. This was
added for consistency with add in regards other operations and to the need of parent
entries already existing.

C.15.6 Section 4.13.2.2 help ensure
data consistency
- Removed wording indicating Required that referrals can textual passwords be returned from
StartTLS

C.16 Changes made transferred as UTF-8 encoded
Unicode, and added recommendations on string preparation. This was
to draft-ietf-ldapbis-protocol-14.txt

C.16.1 Section 4.1.9

- Added: If a server detects multiple errors for an operation, only
one resultCode is returned. The server should return the
resultCode that best indicates the nature help ensure interoperability of the error
encountered.

C.16.2 passwords being sent from
different clients.

C.1.15 Section 4.1.11 4.2.1

- Added: controlValues that are defined in terms of ASN.1 This section was largely reorganized for readability and BER
encoded according language
was added to Section 5.1, also follow clarify the extensibility
rules in Section 4. authentication state of failed and
abandoned bind operations.
- Removed: "If a SASL transfer encryption or integrity mechanism has
been negotiated, that mechanism does not support the changing of
credentials from one identity to another, then the client MUST
instead establish a new connection."
Each SASL negotiation is, generally, independent of other SASL
negotiations. If there were dependencies between multiple
negotiations of a particular mechanism, the mechanism technical
specification should detail how applications are to deal with
them. LDAP should not require any special handling. And if an LDAP
client had used such a mechanism, it would have the option of
using another mechanism.

C.16.3
- Dropped MUST imperative in paragraph 3 to align with [Keywords].

C.1.16 Section 4.5.2 4.2.3

- Moved most error-related text to Appendix A, and Section 7 added text
regarding certain errors used in conjunction with the bind
operation.
- Removed: "If Prohibited the LDAP association is operating over a connection-
oriented transport such as TCP" server from specifying serverSaslCreds when not
appropriate.

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This is always true.

C.16.4

C.1.17 Section 4.11 4.3

- Added: thus a client SHOULD NOT use the Abandon operation when it
needs an indication of whether the operation was abandoned. For
example, if a client performs an update operation (Add, Modify, or
ModifyDN), and it needs to know whether the directory has changed
due Required both peers to cease transmission and close the operation, it should not use the Abandon operation to
cancel connection
for the update operation. Clients can determine that an
operation has been abandoned by performing a subsequent bind unbind operation.

C.16.5

C.1.18 Section 4.12 4.4

- Added:
"The requestValue and responseValue fields contain any information
associated with the operation. The format Added instructions for future specifications of these fields Unsolicited
Notifications.

C.1.19 Section 4.5.1

- SearchRequest attributes is now defined by the specification of as an AttributeSelection
type rather than AttributeDescriptionList.
- The Filter choices 'and' and 'or', and the extended operation.
Implementations MUST be prepared to handle arbitrary contents of
these fields, including zero bytes. Values that SubstringFilter
substrings types are now defined in
terms of ASN.1 and BER encoded according to Section 5.1, also
follow the extensibility rules in Section 4.

Extended operations may be specified in other documents. The
specification with a lower bound of an extended operation consists of:

- the OBJECT IDENTIFIER assigned to the
ExtendedRequest.requestName (and possibly
ExtendedResponse.responseName), 1.
- the format of the contents of the requestValue The SubstringFilter substrings 'initial, 'any', and responseValue
(if any), 'final' types
are now AssertionValue rather than LDAPString.
- Clarified the semantics of the operation,

Servers list the requestName of all ExtendedRequests they
recognize in the supportedExtension attribute [Models] in the root
DSE.

requestValues derefAliases choices.
- Added instructions for equalityMatch, substrings, greaterOrEqual,
lessOrEqual, and responseValues approxMatch.

C.1.20 Section 4.5.2

- Recommended that servers not use attribute short names when it
knows they are defined in terms ambiguous or may cause interoperability problems.
- Removed all mention of
ASN.1 and BER encoded according ExtendedResponse due to lack of
implementation.

C.1.21 Section 5.1, also follow the
extensibility rules in Section 4."

This was 4.5.3

- Made changes similar to those made to align with controls and control values.

C.16.6 Section 4.13.3.1 4.1.11.

C.1.22 Section 4.5.3.1

- Added: After the TLS connection has been closed, the server MUST
NOT send responses Fixed examples to adhere to changes made to any request message received before the TLS
closure.

C.16.7 Section A2 4.5.3.

C.1.23 Section 4.6

- Removed precedence rules restriction that required an equality match filter in
order to perform value delete modifications. It is sufficiently
documented that in absence of an equality matching rule, octet
equality is used.
- Replaced AttributeTypeAndValues with Attribute as they are
equivalent.

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C.17 Changes made to draft-ietf-ldapbis-protocol-15.txt

C.17.1

- Clarified what type of modification changes might temporarily
violate schema.

C.1.24 Section 4.1.8 4.9

- Removed: "Servers which support matching rules Required servers to not dereference aliases for use in the
extensibleMatch search filter MUST list the matching rules they
implement in subschema entries, using the matchingRules
attributes. The server SHOULD also list there, using the
matchingRuleUse attribute, the attribute types with which each
matching rule can be used. More information is given in section
4.5 of [Syntaxes]." modify DN. This language is moved
was added for consistency with other operations and to help ensure
data consistency.
- Allow modify DN to [Models]

C.17.2 fail when moving between naming contexts.

C.1.25 Section 4.10

- Added: "In Clarified the event that semantics of Compare when the attribute or subtype is not
present
in the entry, the resultCode field and when it is set unknown.
- Required servers to noSuchAttribute. If
the attribute is unknown, the resultCode is set not dereference aliases for compare. This was
added for consistency with other operations and to
undefinedAttributeType."

C.17.3 help ensure
data consistency.

C.1.26 Section 7
- Added: Requirements of authentication methods, SASL mechanisms,
and TLS are described in [AUTHMETH]. 4.11

- Added: Protocol peers MUST be prepared Explained that since abandon returns no response, clients hould
not use it if they need to handle invalid know the outcome.
- Specified that Abandon and
arbitrary length protocol encodings. A number Unbind cannot be abandoned.

C.1.27 Section 4.12

- Specified how values of LDAP security
advisories extended operations defined in terms of
ASN.1 are available through [CERT].

C.17.4 Section 10 to be encoded.
- Added as Informative References

C.17.5 Various instructions on what extended operation specifications
consist of.
- Clarified Added a recommendation that the [LDAPURL] form or URLs in referrals specifies
LDAP servers implementing TCP/IP.

C.18 Changes made to draft-ietf-ldapbis-protocol-16.txt

C.18.1 advertise supported extended
operations.

C.1.28 Section 4.1.4 and others 5.2

- Renamed AttributeDescriptionList to AttributeSelection and moved
its definition to 4.5.1 (the only place it is referenced).

C.18.2 Sections 4.1.10, 4.5.3
- Made obvious the fact that Moved referral-specific instructions regarding LDAP URLS used
as referrals and search result references only apply to LDAP URLs,
and that other URLs need to define their own instructions.

C.18.3 into referral-related
sections.

C.1.29 Section 4.2.1 7

- Further clarified the authentication state Reworded notes regarding SASL not protecting certain aspects of an abandoned
the LDAP bind

C.18.4 Section 4.5.1 PDU.
- Added: "Note Noted that the AssertionValue in a substrings filter item
MUST conform Servers are encouraged to prevent directory
modifications by clients that have authenticated anonymously
[AuthMeth].
- Added a note regarding the assertion syntax of the EQUALITY matching rule
for the attribute type rather than the assertion syntax of the
SUBSTR matching rule for the attribute type. The entire scenario where an identity is changed
(deleted, privileges or credentials modified, etc.).

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SubstringFilter is converted into an assertion value of the
substrings matching rule prior to applying the rule."

C.18.5 Section 4.6
- Replaced AttributeTypeAndValues with Attribute as they are
equivalent.

- Reformatted documentation of the various fields.

- Clarified what type of modification changes might temporarily
violate schema.

C.18.6 Section 7

- Added: "Server implementors should plan for the possibility of an
identity or associated with an LDAP connection being deleted,
renamed, or modified, and take appropriate actions to prevent
insecure side effects. The way Warned against following referrals that may have been injected in which this is dealt with is
implementation specific. Likewise, server implementors should plan
for
the possibility of an associated identities credentials
becoming invalid."

C.18.7 Section 9
- Updated references to X.680 and X.690

C.18.8 Section 11 data stream.
- Added IANA considerations

C.18.9 Section A.2
- Clarified that strongAuthRequired could be sent any time
(including when credentials have been weakened or compromised.

C.18.10 a note regarding malformed and long encodings.

C.1.30 Appendix B A

- Added copyright "EXTESIBILITY IMPLIED" to ASN.1 definition

C.19 definition.
- Removed AttributeType. It is not used.

C.2 Changes made to draft-ietf-ldapbis-protocol-17.txt

C.19.1 Section 4.1.1
- Changed MAY made to SHOULD when stating when a Notice of Disconnect is RFC 2830:

This section summarizes the substantive changes made to be returned.

C.19.2 Sections 4.1.10 and 4.5.3
- Changed occurrences of URL to URI
RFC 2830. Readers should consult [AuthMeth] for format summaries of referrals.

C.19.3 Section 4.1.11
- Dropped MUST imperative in paragraph 2, and added a SHOULD in
paragraph 3 changes
to align with [Keywords].

C.19.4 other sections.

C.2.1 Section 4.2 2.3

- Reworded section on string prep for simple passwords for clarity.

C.19.5 Removed wording indicating that referrals can be returned from
StartTLS

C.2.1 Section 4.2.1 4.13.3.1

- Dropped Reworded most of this section and added the requirement that after
the TLS connection has been closed, the server MUST imperative in paragraph 3 NOT send
responses to align with [Keywords]. any request message received before the TLS closure.

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C.19.6 Section 4.2.2
- Added SHALL NOT imperative

Intellectual Property Rights

The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to last paragraph
pertain to align the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with
[Keywords].

C.19.7 Section 4.5.1
- Added correct approxMatch semantics.

C.19.8 Various
- Added SHALL NOT imperative respect to rights in standards-track and
standards-related documentation can be found in regards BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to dereferencing aliases be made available, or the result of
base objects.

C.19.9 Section 4.9
- Allow modDN an attempt made to fail when moving between naming contexts.

C.19.10 Section 4.12
- Added RECOMMENDED imperative
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.

The IETF invites any interested party to paragraph that talks about
advertising supported extended operations.

C.19.11 Section 4.1.11
- Dropped all MAY imperative bring to align with [Keywords].

C.19.12 Various
- Made it more obvious its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that Attribute contains at least one value,
while PartialAttribute now allows zero values. Added appropriate
references back may be required to Attribute and PartialAttribute.

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this standard. Please address the information to the IETF Executive
Director.

Full Copyright Statement

This document and translations of it may be copied and furnished to
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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
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