wdiff draft-ietf-ldapbis-protocol-17.txt draft-ietf-ldapbis-protocol-18.txt

Internet-Draft Editor: J. Sermersheim
Intended Category: Standard Track Novell, Inc
Document: draft-ietf-ldapbis-protocol-17.txt Sep draft-ietf-ldapbis-protocol-18.txt Oct 2003
Obsoletes: RFC 2251

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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editorial comments directly to the editor <jimse@novell.com>.

Abstract

This document describes the protocol elements, along with their
semantics and encodings, for 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
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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4.1.4. Attribute Descriptions......................................7
4.1.5. Attribute Value.............................................7
4.1.6. Attribute Value Assertion...................................7
4.1.7. Attribute...................................................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
4.5. Search Operation.............................................16
4.6. Modify Operation.............................................24
4.7. Add Operation................................................25 Operation................................................26
4.8. Delete Operation.............................................26
4.9. Modify DN Operation..........................................27
4.10. Compare Operation...........................................28
4.11. Abandon Operation...........................................29
4.12. Extended Operation..........................................30 Operation..........................................29
4.13. Start TLS Operation.........................................31
5. Protocol Element Encodings and Transfer........................33
5.1. Protocol Encoding............................................33
5.2. Transfer Protocols...........................................33
6. Implementation Guidelines......................................33
6.1. Server Implementations.......................................34 Implementations.......................................33
6.2. Client Implementations.......................................34
7. Security Considerations........................................34
8. Acknowledgements...............................................35
9. Normative References...........................................35
10. Informative References........................................37
11. IANA Considerations...........................................37
12. Editor's Address..............................................37
Appendix A - LDAP Result Codes....................................38
A.1 Non-Error Result Codes........................................38
A.2 Result Codes..................................................38
Appendix C - Change History.......................................49 History.......................................47
C.1 Changes made to RFC 2251:.....................................49 2251:.....................................47
C.2 Changes made to draft-ietf-ldapbis-protocol-00.txt:...........49 draft-ietf-ldapbis-protocol-00.txt:...........47
C.3 Changes made to draft-ietf-ldapbis-protocol-01.txt:...........50 draft-ietf-ldapbis-protocol-01.txt:...........48
C.4 Changes made to draft-ietf-ldapbis-protocol-02.txt:...........50 draft-ietf-ldapbis-protocol-02.txt:...........48
C.5 Changes made to draft-ietf-ldapbis-protocol-03.txt:...........52 draft-ietf-ldapbis-protocol-03.txt:...........50
C.6 Changes made to draft-ietf-ldapbis-protocol-04.txt:...........54 draft-ietf-ldapbis-protocol-04.txt:...........52
C.7 Changes made to draft-ietf-ldapbis-protocol-05.txt:...........54 draft-ietf-ldapbis-protocol-05.txt:...........52
C.8 Changes made to draft-ietf-ldapbis-protocol-06.txt:...........55 draft-ietf-ldapbis-protocol-06.txt:...........53
C.9 Changes made to draft-ietf-ldapbis-protocol-07.txt:...........58 draft-ietf-ldapbis-protocol-07.txt:...........56
C.10 Changes made to draft-ietf-ldapbis-protocol-08.txt:..........58 draft-ietf-ldapbis-protocol-08.txt:..........56
C.11 Changes made to draft-ietf-ldapbis-protocol-09.txt:..........58 draft-ietf-ldapbis-protocol-09.txt:..........56
C.12 Changes made to draft-ietf-ldapbis-protocol-10.txt:..........58 draft-ietf-ldapbis-protocol-10.txt:..........56
C.13 Changes made to draft-ietf-ldapbis-protocol-11.txt:..........59 draft-ietf-ldapbis-protocol-11.txt:..........57
C.14 Changes made to draft-ietf-ldapbis-protocol-12.txt:..........59 draft-ietf-ldapbis-protocol-12.txt:..........57
C.15 Changes made to draft-ietf-ldapbis-protocol-13.txt...........59 draft-ietf-ldapbis-protocol-13.txt...........57
C.16 Changes made to draft-ietf-ldapbis-protocol-14.txt...........60 draft-ietf-ldapbis-protocol-14.txt...........58
C.17 Changes made to draft-ietf-ldapbis-protocol-15.txt...........62 draft-ietf-ldapbis-protocol-15.txt...........60
C.18 Changes made to draft-ietf-ldapbis-protocol-16.txt...........62 draft-ietf-ldapbis-protocol-16.txt...........60

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Appendix D - Outstanding Work Items...............................63

C.19 Changes made to draft-ietf-ldapbis-protocol-17.txt...........61

1. Introduction

The Directory is "a collection of open systems cooperating to provide
directory services" [X.500]. A Directory 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, Protocol (LDAP), along with their semantics.
Following the description of protocol elements, it describes the way
in which the protocol is elements are encoded and transferred.

This document is an integral part of the LDAP Technical Specification
[Roadmap].

This document replaces RFC 2251. Appendix C holds a detailed log of
changes to RFC 2251. Prior to After Working Group Last Call, this appendix
will be distilled to a summary of changes to RFC 2251.

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 [RFC2119]. [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. 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

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between a client and server in any order, provided the client
eventually receives a response for every request that requires one.

The core protocol operations defined in this document can be mapped
to a subset of the X.500 (1997) directory abstract service. (1993) Directory Abstract Service. However
there is not a one-to-one mapping between LDAP protocol operations
and DAP X.500 Directory Access Protocol (DAP) operations. Server
implementations acting as a gateway to X.500 directories may need to
make multiple DAP requests. requests to service a single LDAP request.

4. Elements of Protocol

The LDAP protocol is described using Abstract Syntax Notation 1
(ASN.1) [X.680], One
[ASN.1], and is transferred using a subset of ASN.1 Basic Encoding
Rules [X.690]. [BER]. Section 5.1 specifies how the protocol is 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 elements 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 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 Data
Unit) 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:

LDAPMessage ::= SEQUENCE {
messageID MessageID,
protocolOp CHOICE {
bindRequest BindRequest,

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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) --

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 MAY SHOULD return the Notice of Disconnection
described in 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 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

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of which this message is a part. The zero value is reserved for the
unsolicited notification message.

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 OCTET STRING types, the
[ISO10646] character set (a superset of [Unicode]) is used, encoded
following the UTF-8 algorithm [RFC2279]. [UTF-8] algorithm. Note that in the UTF-8
algorithm Unicode characters which U+0000
through U+007F are the same as ASCII (0x0000 0 through
0x007F) are represented as that 127, respectively, and
have the same ASCII character in a single
byte. The other byte values are used to form octet UTF-8 encoding. Other Unicode characters
have a variable-length
encoding of an arbitrary character. multiple octet UTF-8 encoding.

LDAPString ::= OCTET STRING -- UTF-8 encoded,
-- ISO 10646 [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
<numericoid> given in Section 1.3 of [Models].

LDAPOID ::= OCTET STRING -- Constrained to numericoid <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 and a RelativeLDAPDN are respectively is defined to be the representation of a distinguished-name and a relative-distinguished- distinguished name
(DN) after encoding according to the specification in [LDAPDN].

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

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

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

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

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 <attributedescription>
-- [Models]

4.1.5. Attribute Value

A field of type AttributeValue is an OCTET STRING containing an
encoded attribute value data type. value. The attribute value is encoded according to
its
the LDAP-specific encoding definition. 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 as
ASN.1, a
value if its syntax is not known. The implementation may attempt to
discover the subschema of the source entry, and retrieve the values
descriptions of attributeTypes from it. 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 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
the value syntax. See objectIdentiferFirstComponentMatch in
[Syntaxes] for an example.

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4.1.7. Attribute

An attribute consists of an attribute description and one or more
values of that attribute description. (Though attributes MUST have at
least one value when stored, due to access control restrictions the
set may be empty when transferred from the server to the client. This
is described in section 4.5.2, concerning the PartialAttributeList
type.)

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

Each attribute value is distinct in the set (no duplicates). The set
of attribute values is unordered. Implementations MUST NOT reply rely upon
any apparent
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, <numericoid>, or one of its short name descriptors, 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 of the LDAPResult type MUST contain a zero
length string.

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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 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 12.5
of [X.511]. Unless otherwise defined, Otherwise the matchedDN field contains a
zero length string with all other result codes. 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 URL 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 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 URL -- one or more

URL uri URI

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

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

A URL 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 MUST be escaped using the % method in
[RFC2396].
[URI].
- 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 <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.
- Other aspects of the new request may be the same as or different as
from the request which generated the referral.

Other kinds of URLs URIs may be returned, so long as the operation could
be performed using that protocol. The definition of such URLs URIs and
instructions on their use is left to future specifications.

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 MUST be a 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 is treated as 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.

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 instead 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.

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
critical at the client's option,

- the format of the controlValue contents of the control,

- the semantics of the control,

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

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

Controls should not 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 unless the control specification(s) describe(s)
combination semantics.

4.2. Bind Operation

The function of the Bind Operation is to allow 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. Prior to
the first BindRequest, the implied identity is anonymous. Refer to
[AuthMeth] for the authentication-related
Authentication and security-related semantics of this
operation. operation are
given in [AuthMeth].

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, and the
negotiation. The client just 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 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 7)
or when using SASL Simple Authentication and Security Layer [SASL]
authentication ([AuthMeth] 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
SHOULD SHALL NOT perform any
alias dereferencing in determining the object to bind as.

- authentication: information used to authenticate the name, if any,
provided in the Bind Request. 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. To improve matching, applications SHOULD prepare
textual strings used as passwords. Applications which prepare
textural strings used Passwords consisting of
character data (text passwords) SHALL be transferred as password are REQUIRED [UTF-8]
encoded [Unicode]. Prior to transfer, clients SHOULD prepare them text
passwords by
transcoding applying the string to [Unicode], apply [SASLprep], and encode [SASLprep] profile of the [Stringprep]
algorithm. Passwords consisting of other data (such as UTF-8. random
octets) MUST NOT be altered.

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

Upon receipt of

Before processing a BindRequest, the server MUST ensure there are no BindResponse, all outstanding operations in progress on the connection (this simplifies
server implementation). To do this, the MUST
either complete or be abandoned. The server may cause them either wait for the
outstanding operations to be
abandoned complete, or allow them to finish. 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,
operationsError to that request, it may then send a Bind Request. If this also fails

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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 may send multiple Bind Requests on a connection to change
their credentials. 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
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
set in the BindResponse. For bind, the protocolError result code may

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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 is not to 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 is defined as
follows:

UnbindRequest ::= [APPLICATION 2] NULL

The Unbind Operation has no response defined. Upon transmission of an
the UnbindRequest, a each protocol client MUST assume that peer is to consider the LDAP
association is terminated. Upon receipt of an UnbindRequest, a
protocol server terminated, MUST assume that the requesting client has terminated cease transmission of messages to the association and that all outstanding requests may be discarded,
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.

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 0 zero and protocolOp is of the extendedResp form. The
responseName field of the ExtendedResponse is present. The always contains an LDAPOID
value MUST be
which is unique for this notification, and not be used in any
other situation. notification.

One unsolicited notification (Notice of Disconnection) is defined in
this document.

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 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 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
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.

After sending this notice, the server MUST close

Upon transmission of the connection.
After receiving this notice, UnbindRequest, each protocol peer is to
consider the client LDAP association terminated, MUST NOT transmit any further
on cease transmission of
messages to the connection, other peer, and may abruptly MUST close the connection.

4.5. Search Operation

The Search Operation allows a client is used to request that a search be
performed on its behalf by server to return, subject
to access controls and other restrictions, a server. set of entries matching
a complex search criterion. This can be used to read attributes from
a single entry, from entries immediately below 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) },
derefAliases ENUMERATED {

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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 <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,
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: An LDAPDN that is The name of the base object entry relative to which
the search is to be performed.

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

baseObject: The scope is constrained to the semantics 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 field in is constrained to the X.511 Search Operation. 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:

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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.

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 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 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 will 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 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

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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
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 matching semantics for approxMatch filter items evaluates to TRUE when there is
implementation-defined. 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
by the server, the
supported, this filter item should be treated as an equalityMatch.

The

An extensibleMatch is new in this version of LDAP. evaluated as follows:

If the matchingRule field is absent, the type field MUST be
present, and
the 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, and the matchingRule. The matchingRule determines the
syntax for the assertion value (the 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 cannot be
parsed.) 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 permitted
suitable for use with that type, 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 as well, name, and also evaluates to TRUE if there is
at least one attribute in the distinguished name for which the
filter item evaluates to TRUE. (Editors note: The dnAttributes field is present so that
there does not need
to be alleviate the need for multiple versions of generic matching

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rules such (such as for word matching, matching), where one to apply applies to entries and
another to apply applies to entries and dn attributes as well). 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 cannot be parsed, 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, or assertion values cannot
be parsed. are
invalid, or the assertion syntax is not supported. More details of
filter processing are given in 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:

attributeSelection = noattrs /
*( attributedescription / specialattr )

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

attributedescription = ; attributedescription from 2.5 of [Models]

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).

Attributes MUST Client implementors
should note that even if all user attributes are requested, some
attributes and or attribute values of the entry may not be named at most once
included in the list, 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.

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 arbitrarily and because it does not (and can not) correspond to any
attribute in use.

Client implementors should note that even if all user attributes
are requested, some attributes of the entry may not be included in

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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, since there may be extremely large number of values for
certain operational attributes. (A list of operational attributes
for use in LDAP is given in [Syntaxes].)

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 attempted by the server upon receipt of a
Search Request operation are returned in Search Responses, which are LDAP
messages containing SearchResultEntry, SearchResultReference, as zero or
SearchResultDone data types. 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 SEQUENCE {
type AttributeDescription,
vals SET OF AttributeValue }
attribute PartialAttribute
-- implementors should note Note that the PartialAttributeList may
-- have hold zero elements (if elements.
-- This may happen when none of the attributes of that an entry
-- were requested, or could be returned), and returned.

PartialAttribute ::= SEQUENCE {
type AttributeDescription,

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vals SET OF value AttributeValue }
-- Note that the vals set
-- may also have hold zero elements (if types only was elements.
-- This may happen when typesOnly is requested, or access controls
-- all values were excluded from prevent the result.) return of values, or other reasons.

SearchResultReference ::= [APPLICATION 19] SEQUENCE
SIZE (1..MAX) OF URL
-- at least one URL element must be present uri URI

SearchResultDone ::= [APPLICATION 5] LDAPResult

Upon receipt of a Search Request, a server will perform the necessary
search of the DIT.

The server will return to the client a sequence of responses in
separate LDAP messages. There may be zero or more responses
containing SearchResultEntry, one for each

Each SearchResultEntry represents an entry found during the search. There may also be zero or more responses containing
SearchResultReference, one for each
Each SearchResultReference represents an area not yet explored by this server during
the search. The SearchResultEntry and SearchResultReference PDUs may
come in any order. Following all the SearchResultReference
responses and all
SearchResultEntry responses to be returned by the
server, responses, the server will return returns a response containing the

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SearchResultDone, 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
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 a textual name short names [Models] for an attribute type,
it
type then the server SHOULD use a textual name for attributes of that attribute type by
specifying one of the textual those names as the value of the in attribute
type. Otherwise, the server uses the object identifier
descriptions for the that attribute type by specifying the object identifier, in ldapOID form,
as (in preference to using the value
<numericoid> [Models] format of attribute type. If the attribute type's object
identifier). The server determines SHOULD NOT use the short name if that
returning a textual name will is
known by the server to be ambiguous, or otherwise likely to cause
interoperability problems, it
SHOULD return the ldapOID form of the attribute type. 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 under 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 URL 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:
- 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 [RFC2396]. [URI].
- Some servers (e.g. participating in distributed indexing) may
provide a different filter in a URL of a SearchResultReference.
- If the filter <filter> part of the URL is present, the client MUST use
this filter in its next request to progress this search, and if

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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 <scope>
part of the URL will be baseObject. "base".
- Other aspects of the new search request may be the same as or
different as 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 MUST issue 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, and if the
server. The client has multiple outstanding must abandon subsequent search operations, operations it MUST abandon each operation
wishes to individually.

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 }
SearchResultReference {
ldap://hostd/OU=Roles,DC=Example,DC=NET }

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

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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 Attribute 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 will not
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
listed, or if all current values of the attribute are
listed for deletion;

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

The result of the modification attempted by the server upon

Upon receipt of a Modify Request is returned 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

Upon receipt of a Modify Request, a server will perform the necessary
modifications to the DIT.

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 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. Directory. The Add Request is defined as follows:

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

AttributeList ::= SEQUENCE OF SEQUENCE {

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type AttributeDescription,
vals SET OF AttributeValue } attribute Attribute

Parameters of the Add Request are:

- entry: the Distinguished Name name of the entry to be added. Note that the server will not
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 the an
object and or alias entries 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 Directory unless DIT structure rules are in place.
Some servers MAY allow the administrator to restrict the classes of
entries which can be added to the directory. 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.
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. Directory. The Delete Request is defined as follows:

DelRequest ::= [APPLICATION 10] LDAPDN

The Delete Request consists of the Distinguished Name name of the entry to be deleted. Note that the
The server will not SHALL NOT dereference aliases while resolving the name of
the target entry to be removed, and that only removed.

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

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The result of the delete attempted by the server upon receipt of a
Delete Request is returned in the Delete Response, defined as
follows:

DelResponse ::= [APPLICATION 11] LDAPResult

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

DelResponse ::= [APPLICATION 11] LDAPResult

4.9. Modify DN Operation

The Modify DN Operation allows a client to change the leftmost (least
significant) component of the name Relative
Distinguished Name (RDN) of an entry in the directory, Directory, and/or to move
a subtree of entries to a new location in the
directory. 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 Distinguished Name name of the entry to be changed. This entry may or may
not have subordinate entries. Note that the server will not SHALL NOT
dereference any aliases in locating the entry to be changed.

- newrdn: the RDN that will form the leftmost component of the new
name 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 Distinguished Name name of an existing object
entry which becomes the immediate superior
(parent)of (parent) of the
existing entry.

The result of the name change attempted by the server upon receipt of
a Modify DN Request is returned in the Modify DN Response, defined as
follows:

ModifyDNResponse ::= [APPLICATION 13] LDAPResult

Upon receipt of a ModifyDNRequest, a server will attempt to perform
the name change. The result of the name change attempt will be
returned to and return the client result in the Modify DN Response. 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".

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 may not perform 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 general, clients MUST NOT expect to be able to perform
arbitrary movements of entries and subtrees between servers. 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. 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 with. compared. Note that the server SHOULD
SHALL NOT dereference any aliases in locating the entry to be compared with.
compared.

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

The result of the compare attempted by the server upon

Upon receipt of a Compare Request is returned 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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Upon receipt of a Compare Request, a server will attempt to perform
the requested comparison using the EQUALITY matching rule for the
attribute type. The result of the comparison will be returned to the
client in the Compare Response.

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.

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 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 no response defined in the
directory has changed due to Abandon operation. Upon receipt
of an AbandonRequest, the operation, it should server MAY abandon the operation identified
by the MessageID. Operation responses are not use sent for successfully
abandoned operations, thus the application of the Abandon operation
is limited to cancel uses where the update operation. 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).

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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 be defined for services not
available elsewhere in this protocol, for instance digitally signed
operations and results.

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
request MUST have a unique OBJECT IDENTIFIER assigned to it.

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

The requestName is a dotted-decimal representation of the 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 }

If the server does not recognize the request name, it MUST return
only the response fields from LDAPResult, containing the
protocolError result code.

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.

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

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

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

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- the semantics of the operation,

Servers

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

requestValues and responseValues that are defined in terms of ASN.1
and BER encoded according to Section 5.1, also follow the
extensibility rules in Section 4.

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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] on an LDAP
connection.

4.13.1. Start TLS Request

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

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

4.13.2. Start TLS Response

When a Start TLS request is made, servers supporting the operation
MUST return a Start TLS response PDU to the requestor. The Start TLS
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 4.13.2.2.

4.13.2.1. "Success" Response

If the Start TLS Response contains a result code of success, this
indicates that the server is willing and able to negotiate TLS. Refer
to 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 already
established)

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

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

The server MUST return operationsError if the client violates any of
the Start TLS extended operation sequencing requirements described in
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 MAY may proceed with any LDAP operation, or it
MAY
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 may retry
the StartTLS operation, or it MAY may proceed with any other LDAP
operation, or it MAY may close the LDAP connection.

4.13.3. Closing a TLS Connection

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

Before sending a

The initiating protocol peer sends the TLS closure alert, the client MUST either wait for
any outstanding LDAP operations alert. If it
wishes to complete, or explicitly abandon
them.

After leave the initiator of a close has sent a TLS closure alert, LDAP connection intact, it then MUST
discard cease to
send further PDUs and MUST ignore any TLS messages received PDUs until it has received receives
a TLS closure alert from the other party. It will cease to send TLS Record Protocol
PDUs, and following peer.

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

The other party, if it receives

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. It will subsequently cease to send TLS
Record Protocol PDUs, and 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

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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.

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5. Protocol Element Encodings and Transfer

One underlying service is defined here. Clients and servers SHOULD
implement the mapping of LDAP over [TCP] described in 5.2.1.

5.1. Protocol Encoding

The protocol elements of LDAP are encoded for exchange using the
Basic Encoding Rules (BER) [X.690] [BER] of ASN.1 [X.680]. [ASN.1]. However, due to the high
overhead involved in using certain elements of the BER, the following
additional restrictions are placed on BER-encodings of LDAP protocol
elements:

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

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

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

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

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

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 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

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6.1. Server Implementations

The server MUST be capable of recognizing all the mandatory attribute
types specified in [Models], and implement the syntaxes used by those
attributes specified in [Syntaxes]. Servers MAY also recognize
additional attribute type names.

6.2. Client Implementations

Clients that follow referrals or 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 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 [RFC2222]. [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 and may
result in disclosure of the password to unauthorized parties.

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

When used with SASL, it should be noted that the name field of the
BindRequest is not protected against modification. Thus if the
distinguished name of the client (an LDAPDN) is agreed through the
negotiation of the credentials, it takes precedence over any value in
the unprotected name field.

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

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effects. The way in which this is dealt with is implementation
specific. Likewise, server implementors should plan for the
possibility of an associated identities identity's credentials becoming invalid.

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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 referrals from
the Start TLS operation.

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

8. Acknowledgements

This document is an update to RFC 2251, by Mark Wahl, Tim Howes, and
Steve Kille. Their work along with the input of individuals of the
IETF LDAPEXT, LDUP, LDAPBIS, and other Working Groups is gratefully
acknowledged.

9. Normative References

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

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

[RFC2119]

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

[X.680]

[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"

[X.690]

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

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

[RFC2279]

[UTF-8] Yergeau, F., "UTF-8, a transformation format of Unicode
and ISO 10646", RFC 2279, January 1998. draft-yergeau-rfc2279bis-xx.txt, (a work
in progress).

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

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

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

[RFC2396]

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

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

[RFC2222]

[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).

[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, STD7 and RFC
793, September 1981

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

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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. 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. 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 called 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 successful completion of an operation.

This result code is normally not returned by the compare
operation, see compareFalse and compareTrue. It is possible
that a future extension mechanism would allow this to be
returned by a compare operation

A.2 Result Codes
Existing LDAP result codes are described as follows:

success (0)
Indicates the successful completion of an operation.

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 [RFC2246] while there are other operations
outstanding or if TLS was already established.

protocolError (2)

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Indicates the server received data which has incorrect
structure.

For bind operation only, the code may be resulted returned to indicate
the server does not support the requested protocol version.

timeLimitExceeded (3)
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 completes
completed and the assertion has evaluated to FALSE.

This result code is normally only returned by the compare
operation.

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

This result code is normally only returned by the compare
operation.

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)

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

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

unavailableCriticalExtension (12)
Indicates that server cannot perform a critical extension
(see 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 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
attribute type.

inappropriateMatching (18)
Indicates that an attempt was made, e.g. in a request cannot be completed due filter, to an
inappropriate matching. 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 the multiple values are
supplied to an attribute which has a SINGLE-VALUE constraint.

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attributeOrValueExists (20)
Indicates that the client supplied an attribute or value to
be added to an entry 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 an
alias has been dereferenced which names no object.

invalidDNSyntax (34)
Indicates that a 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, credentials.

invalidCredentials (49)
Indicates the supplied password or SASL credentials are
invalid.

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

busy (51)
Indicates that the server is busy.

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 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 added fulfilled (added, moved,
or renamed) as the target entry already exists.

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

For example, this code is returned when a 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

MessageID ::= INTEGER (0 .. maxInt)

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

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

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

LDAPDN ::= LDAPString

RelativeLDAPDN ::= LDAPString

AttributeDescription ::= LDAPString

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

AttributeSelection ::= SEQUENCE OF
LDAPString

AttributeValue ::= OCTET STRING

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

AssertionValue ::= OCTET STRING

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

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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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 URL

URL uri URI

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

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

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baseObject LDAPDN,
scope ENUMERATED {
baseObject (0),

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 ::= SEQUENCE {
type AttributeDescription,
vals SET OF value AttributeValue }

SearchResultReference ::= [APPLICATION 19] SEQUENCE OF URL

SearchResultDone ::= [APPLICATION 5] LDAPResult

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SIZE (1..MAX) OF uri URI

SearchResultDone ::= [APPLICATION 5] LDAPResult

ModifyResponse ::= [APPLICATION 7] LDAPResult

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

AttributeList ::= SEQUENCE OF SEQUENCE {
type AttributeDescription,
vals SET OF AttributeValue } 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: This section is to be removed prior to RFC
publication>

C.1 Changes made to RFC 2251:

C.1.1 Editorial

- Bibliography References: Changed all bibliography references to
use a long name form for readability.
- Changed occurrences of "unsupportedCriticalExtension"
"unavailableCriticalExtension"
- Fixed a small number of misspellings (mostly dropped letters).

C.1.2 Section 1

- Removed IESG note.

C.1.3 Section 9

- Added references to RFCs 1823, 2234, 2829 and 2830.

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

C.2.1 Section 4.1.6

- In the first paragraph, clarified what the contents of an
AttributeValue are. There was confusion regarding whether or not
an AttributeValue that is BER encoded (due to the "binary" option)
is to be wrapped in an extra OCTET STRING.
- To the first paragraph, added wording 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 the first paragraph, added a statement restricting multiple
options that specify transfer encoding from being present. This
was never specified in the previous version and was seen as a
potential interoperability problem.
- Added a third paragraph stating that the ;binary option is
currently the only option defined that specifies the transfer
encoding. This is for completeness.

C.2.2 Section 4.1.7

- Generalized the second paragraph to read "If an option specifying
the transfer encoding is present in attributeDesc, the
AssertionValue is encoded as specified by the option...".
Previously, only the ;binary option was mentioned.

C.2.3 Sections 4.2, 4.9, 4.10

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

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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 accidentally removed in an
earlier edit.

C.12.2 Section 4.13:

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

C.13 Changes made to draft-ietf-ldapbis-protocol-11.txt:

C.13.1 Section 4.1.9

- Changed "errorMessage" to "diagnosticMessage". Simply to indicate
that the field may be non-empty even if a non-error resultCode is
present.

C.13.2 Section 4.2:

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

C.13.3 Section 4.2.1

- Renamed to "Processing of the Bind Request", and moved some text
from 4.2 into this section.

- Rearranged paragraphs to flow better.

- Specified that (as well as failed) an abandoned bind operation
will leave the connection in an anonymous state.

C.13.4 Section 4.5.3

- Generalized the second paragraph which cited indexing and
searchreferralreferences.

C.14 Changes made to draft-ietf-ldapbis-protocol-12.txt:

- Reworked bind errors.
- General clarifications and edits

C.15 Changes made to draft-ietf-ldapbis-protocol-13.txt

C.15.1 Section 2 & various
- Added definitions for LDAP connection, TLS connection, and LDAP
association, and updated appropriate fields to use proper terms.

C.15.2 Section 4.2
- Added text to authentication, specifying the way in which textual
strings used as passwords are to be prepared.

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C.15.3 Section 4.5.1
- Clarified derefInSearching. Specifically how it works in terms of
subtree and one level searches

C.15.4 Section 4.5.2

- Changed MUST to SHOULD for returning textual attribute name, The
MUST is unreasonable. There are likely cases (such as when the
server knows multiple attributes in separate entries of a search
result set share the same short name) where returning a numericoid
is better than returning a short name. That is, the MUST may
actually disallow servers from preventing misinterpretation of
short names. This is not only an interop issue, but likely a
security consideration.

C.15.4 Section 4.9
- Made modify consistent with add in regards to the need of parent
entries already existing.

C.15.6 Section 4.13.2.2
- Removed wording indicating that referrals can be returned from
StartTLS

C.16 Changes made 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 of the error
encountered.

C.16.2 Section 4.1.11
- Added: 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.

- 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 Section 4.5.2 and Section 7
- Removed: "If the LDAP association is operating over a connection-
oriented transport such as TCP"

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This is always true.

C.16.4 Section 4.11
- 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 to the operation, it should not use the Abandon operation to
cancel the update operation. Clients can determine that an
operation has been abandoned by performing a subsequent bind
operation.

C.16.5 Section 4.12

- Added:
"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.

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

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

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

- the semantics of the operation,

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

requestValues and responseValues that are defined in terms of
ASN.1 and BER encoded according to Section 5.1, also follow the
extensibility rules in Section 4."

This was to align with controls and control values.

C.16.6 Section 4.13.3.1

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

C.16.7 Section A2
- Removed precedence rules

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

C.17.1 Section 4.1.8
- Removed: "Servers which support matching rules 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]."

This language is moved to [Models]

C.17.2 Section 4.10
- Added: "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."

C.17.3 Section 7
- Added: Requirements of authentication methods, SASL mechanisms,
and TLS are described in [AUTHMETH].

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

C.17.4 Section 10
- Added as Informative References

C.17.5 Various
- Clarified 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 Section 4.1.4 and others
- 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 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 Section 4.2.1
- Further clarified the authentication state of an abandoned bind

C.18.4 Section 4.5.1
- Added: "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

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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 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
- 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 Appendix B
- Added copyright to ASN.1 definition

Appendix D

C.19 Changes made to draft-ietf-ldapbis-protocol-17.txt

C.19.1 Section 4.1.1
- Outstanding Work Items

D.1 General Changed MAY to SHOULD when stating when a Notice of Disconnect is
to be returned.

C.19.2 Sections 4.1.10 and 4.5.3
- Reconcile problems with [Models]. Changed occurrences of URL to URI for format of referrals.

C.19.3 Section 3.2 was wholly removed.
There were some protocol semantics 4.1.11
- Dropped MUST imperative in that paragraph 2, and added a SHOULD in
paragraph 3 to align with [Keywords].

C.19.4 Section 4.2
- Reworded section that need on string prep for simple passwords for clarity.

C.19.5 Section 4.2.1
- Dropped MUST imperative in paragraph 3 to be
brought back. Specifically, there was the notion align with [Keywords].

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C.19.6 Section 4.2.2
- Added SHALL NOT imperative to last paragraph to align with
[Keywords].

C.19.7 Section 4.5.1
- Added correct approxMatch semantics.

C.19.8 Various
- Added SHALL NOT imperative in regards to dereferencing aliases of the server
implicitly adding objectClass superclasses
base objects.

C.19.9 Section 4.9
- Allow modDN to fail when a value is added.

D.2 Verify references. moving between naming contexts.

C.19.10 Section 4.12
- Many referenced documents have changed. Ensure Added RECOMMENDED imperative to paragraph that talks about
advertising supported extended operations.

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

C.19.12 Various
- Made it more obvious that Attribute contains at least one value,
while PartialAttribute now allows zero values. Added appropriate
references back to Attribute and
section numbers are correct.

D.3 Review 2119 usage

D.4 Reconcile with I-D Nits PartialAttribute.

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