Network Working Group W. Yeong

Network Working Group W. Yeong
Request for Comments: 1777 Performance Systems International
Obsoletes: 1487 T. Howes
Category: Standards Track University of Michigan
S. Kille
ISODE Consortium
March 1995

Lightweight Directory Access Protocol

Status of this Memo

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

Abstract

The protocol described in this document is designed to provide access
to the X.500 Directory while not incurring the resource requirements
of the Directory Access Protocol (DAP). This protocol is specifically
targeted at simple management applications and browser applications
that provide simple read/write interactive access to the X.500
Directory, and is intended to be a complement to the DAP itself.

Key aspects of LDAP are:

- Protocol elements are carried directly over TCP or other transport,
bypassing much of the session/presentation overhead.

- Many protocol data elements are encoding as ordinary strings (e.g.,
Distinguished Names).

- A lightweight BER encoding is used to encode all protocol elements.

1. History

The tremendous interest in X.500 [1,2] technology in the Internet has
lead to efforts to reduce the high "cost of entry" associated with
use of the technology, such as the Directory Assistance Service [3]
and DIXIE [4]. While efforts such as these have met with success,
they have been solutions based on particular implementations and as
such have limited applicability. This document continues the efforts
to define Directory protocol alternatives but departs from previous
efforts in that it consciously avoids dependence on particular

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implementations.

2. Protocol Model

The general model adopted by this protocol is one of clients
performing protocol operations against servers. In this model, this
is accomplished by a client transmitting a protocol request
describing the operation to be performed to a server, which is then
responsible for performing the necessary operations on the Directory.
Upon completion of the necessary operations, the server returns a
response containing any results or errors to the requesting client.
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 utilizing the Directory.

Note that, 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 client or server
implementations: requests and responses for multiple operations may
be exchanged by client and servers in any order, as long as clients
eventually receive a response for every request that requires one.

Consistent with the model of servers performing protocol operations
on behalf of clients, it is also to be noted that protocol servers
are expected to handle referrals without resorting to the return of
such referrals to the client. This protocol makes no provisions for
the return of referrals to clients, as the model is one of servers
ensuring the performance of all necessary operations in the
Directory, with only final results or errors being returned by
servers to clients.

Note that this protocol can be mapped to a strict subset of the
directory abstract service, so it can be cleanly provided by the DAP.

3. Mapping Onto Transport Services

This protocol is designed to run over connection-oriented, reliable
transports, with all 8 bits in an octet being significant in the data
stream. Specifications for two underlying services are defined here,
though others are also possible.

3.1. Transmission Control Protocol (TCP)

The LDAPMessage PDUs are mapped directly onto the TCP bytestream.
Server implementations running over the TCP should provide a protocol
listener on port 389.

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3.2. Connection Oriented Transport Service (COTS)

The connection is established. No special use of T-Connect is made.
Each LDAPMessage PDU is mapped directly onto T-Data.

4. Elements of Protocol

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,
bindResponse BindResponse,
unbindRequest UnbindRequest,
searchRequest SearchRequest,
searchResponse SearchResponse,
modifyRequest ModifyRequest,
modifyResponse ModifyResponse,
addRequest AddRequest,
addResponse AddResponse,
delRequest DelRequest,
delResponse DelResponse,
modifyRDNRequest ModifyRDNRequest,
modifyRDNResponse ModifyRDNResponse,
compareDNRequest CompareRequest,
compareDNResponse CompareResponse,
abandonRequest AbandonRequest
}
}

MessageID ::= INTEGER (0 .. maxInt)

The function of the LDAPMessage is to provide an envelope containing
common fields required in all protocol exchanges. At this time the
only common field is a message ID, which is required to have a value
different from the values of any other requests outstanding in the
LDAP session of which this message is a part.

The message ID value must be echoed in all LDAPMessage envelopes
encapsulting responses corresponding to the request contained in the
LDAPMessage in which the message ID value was originally used.

In addition to the LDAPMessage defined above, the following
definitions are also used in defining protocol operations:

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LDAPString ::= OCTET STRING

The LDAPString is a notational convenience to indicate that, although
strings of LDAPString type encode as OCTET STRING types, the legal
character set in such strings is limited to the IA5 character set.

LDAPDN ::= LDAPString

RelativeLDAPDN ::= LDAPString

An LDAPDN and a RelativeLDAPDN are respectively defined to be the
representation of a Distinguished Name and a Relative Distinguished
Name after encoding according to the specification in [5], such that

<distinguished-name> ::= <name>

<relative-distinguished-name> ::= <name-component>

where <name> and <name-component> are as defined in [5].

AttributeValueAssertion ::=
SEQUENCE {
attributeType AttributeType,
attributeValue AttributeValue
}

The AttributeValueAssertion type definition is similar to the one in
the X.500 Directory standards.

AttributeType ::= LDAPString

AttributeValue ::= OCTET STRING

An AttributeType value takes on as its value the textual string
associated with that AttributeType in the X.500 Directory standards.
For example, the AttributeType 'organizationName' with object
identifier 2.5.4.10 is represented as an AttributeType in this
protocol by the string "organizationName". In the event that a
protocol implementation encounters an Attribute Type with which it
cannot associate a textual string, an ASCII string encoding of the
object identifier associated with the Attribute Type may be
subsitituted. For example, the organizationName AttributeType may be
represented by the ASCII string "2.5.4.10" if a protocol
implementation is unable to associate the string "organizationName"
with it.

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A field of type AttributeValue takes on as its value an octet string
encoding of a Directory AttributeValue type. The definition of these
string encodings for different Directory AttributeValue types may be
found in companions to this document that define the encodings of
various attribute syntaxes such as [6].

LDAPResult ::=
SEQUENCE {
resultCode ENUMERATED {
success (0),
operationsError (1),
protocolError (2),
timeLimitExceeded (3),
sizeLimitExceeded (4),
compareFalse (5),
compareTrue (6),
authMethodNotSupported (7),
strongAuthRequired (8),
noSuchAttribute (16),
undefinedAttributeType (17),
inappropriateMatching (18),
constraintViolation (19),
attributeOrValueExists (20),
invalidAttributeSyntax (21),
noSuchObject (32),
aliasProblem (33),
invalidDNSyntax (34),
isLeaf (35),
aliasDereferencingProblem (36),
inappropriateAuthentication (48),
invalidCredentials (49),
insufficientAccessRights (50),
busy (51),
unavailable (52),
unwillingToPerform (53),
loopDetect (54),
namingViolation (64),
objectClassViolation (65),
notAllowedOnNonLeaf (66),
notAllowedOnRDN (67),
entryAlreadyExists (68),
objectClassModsProhibited (69),
other (80)
},
matchedDN LDAPDN,
errorMessage LDAPString
}

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The LDAPResult is the construct used in this protocol to return
success or failure indications from servers to clients. In response
to various requests, servers will return responses containing fields
of type LDAPResult to indicate the final status of a protocol
operation request. The errorMessage field of this construct may, at
the servers option, be used to return an ASCII string containing a
textual, human-readable error diagnostic. As this error diagnostic is
not standardized, implementations should not rely on the values
returned. If the server chooses not to return a textual diagnostic,
the errorMessage field of the LDAPResult type should contain a zero
length string.

For resultCodes of noSuchObject, aliasProblem, invalidDNSyntax,
isLeaf, and aliasDereferencingProblem, the matchedDN field is set to
the name of the lowest entry (object or alias) in the DIT that was
matched and is a truncated form of the name provided or, if an alias
has been dereferenced, of the resulting name. The matchedDN field
should be set to NULL DN (a zero length string) in all other cases.

4.1. Bind Operation

The function of the Bind Operation is to initiate a protocol session
between a client and a server, and to allow the authentication of the
client to the server. The Bind Operation must be the first operation
request received by a server from a client in a protocol session.
The Bind Request is defined as follows:

BindRequest ::=
[APPLICATION 0] SEQUENCE {
version INTEGER (1 .. 127),
name LDAPDN,
authentication CHOICE {
simple [0] OCTET STRING,
krbv42LDAP [1] OCTET STRING,
krbv42DSA [2] OCTET STRING
}
}

Parameters of the Bind Request are:

- version: A version number indicating the version of the protocol to
be used in this protocol session. This document describes version
2 of the LDAP protocol. Note that there is no version negotiation,
and the client should just set this parameter to the version it
desires.

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- name: The name of the Directory object that the client wishes to
bind as. This field may take on a null value (a zero length
string) for the purposes of anonymous binds.

- authentication: information used to authenticate the name, if any,
provided in the Bind Request. The "simple" authentication option
provides minimal authentication facilities, with the contents of
the authentication field consisting only of a cleartext password.
This option should also be used when unauthenticated or anonymous
binds are to be performed, with the field containing a zero length
string in such cases. Kerberos version 4 [7] authentication to the
LDAP server and the DSA is accomplished by using the "krbv42LDAP"
and "krbv42DSA" authentication options, respectively. Note that
though they are referred to as separate entities here, there is no
requirement these two entities be distinct (i.e., a DSA could speak
LDAP directly). Two separate authentication options are provided
to support all implementations. Each octet string should contain
the kerberos ticket (e.g., as returned by krb_mk_req()) for the
appropriate service. The suggested service name for authentication
to the LDAP server is "ldapserver". The suggested service name for
authentication to the DSA is "x500dsa". In both cases, the
suggested instance name for the service is the name of the host on
which the service is running. Of course, the actual service names
and instances will depend on what is entered in the local kerberos
principle database.

The Bind Operation requires a response, the Bind Response, which is
defined as:

BindResponse ::= [APPLICATION 1] LDAPResult

A Bind Response consists simply of an indication from the server of
the status of the client's request for the initiation of a protocol
session.

Upon receipt of a Bind Request, a protocol server will authenticate
the requesting client if necessary, and attempt to set up a protocol
session with that client. The server will then return a Bind Response
to the client indicating the status of the session setup request.

4.2. Unbind Operation

The function of the Unbind Operation is to terminate a protocol
session. The Unbind Operation is defined as follows:

UnbindRequest ::= [APPLICATION 2] NULL

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The Unbind Operation has no response defined. Upon transmission of an
UnbindRequest, a protocol client may assume that the protocol session
is terminated. Upon receipt of an UnbindRequest, a protocol server
may assume that the requesting client has terminated the session and
that all outstanding requests may be discarded.

4.3. Search Operation

The Search Operation allows a client to request that a search be
performed on its behalf by a server. The Search Request is defined as
follows:

SearchRequest ::=
[APPLICATION 3] SEQUENCE {
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),
attrsOnly BOOLEAN,
filter Filter,
attributes SEQUENCE OF AttributeType
}

Filter ::=
CHOICE {
and [0] SET OF Filter,
or [1] SET OF Filter,
not [2] Filter,
equalityMatch [3] AttributeValueAssertion,
substrings [4] SubstringFilter,
greaterOrEqual [5] AttributeValueAssertion,
lessOrEqual [6] AttributeValueAssertion,
present [7] AttributeType,
approxMatch [8] AttributeValueAssertion
}

SubstringFilter
SEQUENCE {

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type AttributeType,
SEQUENCE OF CHOICE {
initial [0] LDAPString,
any [1] LDAPString,
final [2] LDAPString
}
}

Parameters of the Search Request are:

- baseObject: An LDAPDN that is the base object entry relative to
which the search is to be performed.

- scope: An indicator of the scope of the search to be performed. The
semantics of the possible values of this field are identical to the
semantics of the scope field in the Directory Search Operation.

- derefAliases: An indicator as to how alias objects should be
handled in searching. The semantics of the possible values of
this field are, in order of increasing value:

neverDerefAliases: do not dereference aliases in searching
or in locating the base object of the search;

derefInSearching: dereference aliases in subordinates of
the base object in searching, but not in locating the
base object of the search;

derefFindingBaseObject: 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 sizelimit 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 sizelimit restrictions are in effect for
the search.

- timelimit: A timelimit that restricts the maximum time (in seconds)
allowed for a search. A value of 0 in this field indicates that no
timelimit restrictions are in effect for the search.

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

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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.

- attributes: A list of the attributes from each entry found as a
result of the search to be returned. An empty list signifies that
all attributes from each entry found in the search are to be
returned.

The results of the search attempted by the server upon receipt of a
Search Request are returned in Search Responses, defined as follows:

Search Response ::=
CHOICE {
entry [APPLICATION 4] SEQUENCE {
objectName LDAPDN,
attributes SEQUENCE OF SEQUENCE {
AttributeType,
SET OF AttributeValue
}
},
resultCode [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
comprised of:

- Zero or more Search Responses each consisting of an entry found
during the search; with the response sequence terminated by

- A single Search Response containing an indication of success, or
detailing any errors that have occurred.

Each entry returned will contain all attributes, complete with
associated values if necessary, as specified in the 'attributes'
field of the Search Request.

Note that an X.500 "list" operation can be emulated by a one-level
LDAP search operation with a filter checking for the existence of the
objectClass attribute, and that an X.500 "read" operation can be
emulated by a base object LDAP search operation with the same filter.

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4.4. Modify Operation

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

ModifyRequest ::=
[APPLICATION 6] SEQUENCE {
object LDAPDN,
modification SEQUENCE OF SEQUENCE {
operation ENUMERATED {
add (0),
delete (1),
replace (2)
},
modification SEQUENCE {
type AttributeType,
values SET OF
AttributeValue
}
}
}

Parameters of the Modify Request are:

- object: The object to be modified. The value of this field should
name the object to be modified after all aliases have been
dereferenced. The server will not perform any alias dereferencing
in determining the object to be modified.

- A list of modifications to be performed on the entry to be modified.
The entire list of entry modifications should be performed
in the order they are listed, as a single atomic operation. While
individual modifications may violate the Directory schema, the
resulting entry after the entire list of modifications is performed
must conform to the requirements of the Directory schema. The
values that may be taken on by the 'operation' field in each
modification construct have the following semantics respectively:

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

delete: delete values listed from the given 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 existing values of the given attribute
with the new values listed, creating the attribute if
necessary.

The result of the modify attempted by the server upon receipt of a
Modify Request is returned 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 DIB.

The server will return to the client a single Modify Response
indicating either the successful completion of the DIB 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 DIB 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.

4.5. Add Operation

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

AddRequest ::=
[APPLICATION 8] SEQUENCE {
entry LDAPDN,
attrs SEQUENCE OF SEQUENCE {
type AttributeType,
values SET OF AttributeValue
}
}

Parameters of the Add Request are:

- entry: the Distinguished Name of the entry to be added. Note that
all components of the name except for the last RDN component must
exist for the add to succeed.

- attrs: the list of attributes that make up the content of the entry
being added.

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

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AddResponse ::= [APPLICATION 9] LDAPResult

Upon receipt of an Add Request, a server will attempt to perform the
add requested. The result of the add attempt will be returned to the
client in the Add Response.

4.6. Delete Operation

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

DelRequest ::= [APPLICATION 10] LDAPDN

The Delete Request consists only of the Distinguished Name of the
entry to be deleted. 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 the client in the Delete Response. Note that only leaf
objects may be deleted with this operation.

4.7. Modify RDN Operation

The Modify RDN Operation allows a client to change the last component
of the name of an entry in the Directory. The Modify RDN Request is
defined as follows:

ModifyRDNRequest ::=
[APPLICATION 12] SEQUENCE {
entry LDAPDN,
newrdn RelativeLDAPDN,
deleteoldrdn BOOLEAN
}

Parameters of the Modify RDN Request are:

- entry: the name of the entry to be changed.

- newrdn: the RDN that will form the last component of the new name.

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

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

ModifyRDNResponse ::= [APPLICATION 13] LDAPResult

Upon receipt of a Modify RDN Request, a server will attempt to
perform the name change. The result of the name change attempt will
be returned to the client in the Modify RDN Response. The attributes
that make up the old RDN are deleted from the entry, or kept,
depending on the setting of the deleteoldrdn parameter.

4.8. Compare Operation

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

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

Parameters of the Compare Request are:

- entry: the name of the entry to be compared with.

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

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

CompareResponse ::= [APPLICATION 15] LDAPResult

Upon receipt of a Compare Request, a server will attempt to perform
the requested comparison. The result of the comparison will be
returned to the client in the Compare Response. Note that errors and
the result of comparison are all returned in the same construct.

6.9. 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

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There is no response defined in the Abandon Operation. Upon
transmission of an Abandon Operation, a client may expect that the
operation identityfied by the Message ID in the Abandon Request has
been abandoned. In the event that a server receives an Abandon
Request on a Search Operation in the midst of transmitting responses
to that search, that server should cease transmitting responses to
the abandoned search immediately.

5. Protocol Element Encodings

The protocol elements of LDAP are encoded for exchange using the
Basic Encoding Rules (BER) [12] of ASN.1 [11]. 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) Bitstrings and octet strings and all character string types
will be encoded in the primitive form only.

6. Security Considerations

This version of the protocol provides facilities only for simple
authentication using a cleartext password, and for kerberos version 4
authentication. Future versions of LDAP will likely include support
for other authentication methods.

7. Bibliography

[1] The Directory: Overview of Concepts, Models and Service. CCITT
Recommendation X.500, 1988.

[2] Information Processing Systems -- Open Systems Interconnection --
The Directory: Overview of Concepts, Models and Service. ISO/IEC
JTC 1/SC21; International Standard 9594-1, 1988

[3] Rose, M., "Directory Assistance Service", RFC 1202, Performance
Systems International, Inc., February 1991.

[4] Howes, T., Smith, M., and B. Beecher, "DIXIE Protocol
Specification, RFC 1249, University of Michigan, August 1991.

[5] Kille, S., "A String Representation of Distinguished Names", RFC
1779, ISODE Consortium, March 1995.

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[6] Howes, T., Kille, S., Yeong, W., and C. Robbins, "Lightweight
Directory Access Protocol", RFC 1488, University of Michigan,
ISODE Consortium, Performance Systems International, NeXor Ltd.,
July 1993.

[7] Kerberos Authentication and Authorization System. S.P. Miller,
B.C. Neuman, J.I. Schiller, J.H. Saltzer; MIT Project Athena
Documentation Section E.2.1, December 1987.

[8] The Directory: Models. CCITT Recommendation X.501 ISO/IEC JTC
1/SC21; International Standard 9594-2, 1988.

[10] The Directory: Abstract Service Definition. CCITT Recommendation
X.511, ISO/IEC JTC 1/SC21; International Standard 9594-3, 1988.

[11] Specification of Abstract Syntax Notation One (ASN.1). CCITT
Recommendation X.208, 1988.

[12] Specification of Basic Encoding Rules for Abstract Syntax
Notation One (ASN.1). CCITT Recommendation X.209, 1988.

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10. Authors' Addresses

Wengyik Yeong
PSI Inc.
510 Huntmar Park Drive
Herndon, VA 22070
USA

Phone: +1 703-450-8001
EMail: [email protected]

Tim Howes
University of Michigan
ITD Research Systems
535 W William St.
Ann Arbor, MI 48103-4943
USA

Phone: +1 313 747-4454
EMail: [email protected]

Steve Kille
ISODE Consortium
PO Box 505
London
SW11 1DX
UK

Phone: +44-71-223-4062
EMail: [email protected]

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Appendix A - Complete ASN.1 Definition

Lightweight-Directory-Access-Protocol DEFINITIONS IMPLICIT TAGS ::=

BEGIN

LDAPMessage ::=
SEQUENCE {
messageID MessageID,
-- unique id in request,
-- to be echoed in response(s)
protocolOp CHOICE {
searchRequest SearchRequest,
searchResponse SearchResponse,
modifyRequest ModifyRequest,
modifyResponse ModifyResponse,
addRequest AddRequest,
addResponse AddResponse,
delRequest DelRequest,
delResponse DelResponse,
modifyDNRequest ModifyDNRequest,
modifyDNResponse ModifyDNResponse,
compareDNRequest CompareRequest,
compareDNResponse CompareResponse,
bindRequest BindRequest,
bindResponse BindResponse,
abandonRequest AbandonRequest,
unbindRequest UnbindRequest
}
}

BindRequest ::=
[APPLICATION 0] SEQUENCE {
version INTEGER (1 .. 127),
-- current version is 2
name LDAPDN,
-- null name implies an anonymous bind
authentication CHOICE {
simple [0] OCTET STRING,
-- a zero length octet string
-- implies an unauthenticated
-- bind.
krbv42LDAP [1] OCTET STRING,
krbv42DSA [2] OCTET STRING
-- values as returned by
-- krb_mk_req()
-- Other values in later versions
-- of this protocol.

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}
}

BindResponse ::= [APPLICATION 1] LDAPResult

UnbindRequest ::= [APPLICATION 2] NULL

SearchRequest ::=
[APPLICATION 3] SEQUENCE {
baseObject LDAPDN,
scope ENUMERATED {
baseObject (0),
singleLevel (1),
wholeSubtree (2)
},
derefAliases ENUMERATED {
neverDerefAliases (0),
derefInSearching (1),
derefFindingBaseObj (2),
alwaysDerefAliases (3)
},
sizeLimit INTEGER (0 .. maxInt),
-- value of 0 implies no sizelimit
timeLimit INTEGER (0 .. maxInt),
-- value of 0 implies no timelimit
attrsOnly BOOLEAN,
-- TRUE, if only attributes (without values)
-- to be returned.
filter Filter,
attributes SEQUENCE OF AttributeType
}

SearchResponse ::=
CHOICE {
entry [APPLICATION 4] SEQUENCE {
objectName LDAPDN,
attributes SEQUENCE OF SEQUENCE {
AttributeType,
SET OF
AttributeValue
}
},
resultCode [APPLICATION 5] LDAPResult
}

ModifyRequest ::=
[APPLICATION 6] SEQUENCE {
object LDAPDN,

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RFC 1777 LDAP March 1995

modifications SEQUENCE OF SEQUENCE {
operation ENUMERATED {
add (0),
delete (1),
replace (2)
},
modification SEQUENCE {
type AttributeType,
values SET OF
AttributeValue
}
}
}

ModifyResponse ::= [APPLICATION 7] LDAPResult

AddRequest ::=
[APPLICATION 8] SEQUENCE {
entry LDAPDN,
attrs SEQUENCE OF SEQUENCE {
type AttributeType,
values SET OF AttributeValue
}
}

AddResponse ::= [APPLICATION 9] LDAPResult

DelRequest ::= [APPLICATION 10] LDAPDN

DelResponse ::= [APPLICATION 11] LDAPResult

ModifyRDNRequest ::=
[APPLICATION 12] SEQUENCE {
entry LDAPDN,
newrdn RelativeLDAPDN -- old RDN always deleted
}

ModifyRDNResponse ::= [APPLICATION 13] LDAPResult

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

CompareResponse ::= [APPLICATION 15] LDAPResult

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RFC 1777 LDAP March 1995

AbandonRequest ::= [APPLICATION 16] MessageID

MessageID ::= INTEGER (0 .. maxInt)

LDAPDN ::= LDAPString

RelativeLDAPDN ::= LDAPString

Filter ::=
CHOICE {
and [0] SET OF Filter,
or [1] SET OF Filter,
not [2] Filter,
equalityMatch [3] AttributeValueAssertion,
substrings [4] SubstringFilter,
greaterOrEqual [5] AttributeValueAssertion,
lessOrEqual [6] AttributeValueAssertion,
present [7] AttributeType,
approxMatch [8] AttributeValueAssertion
}

LDAPResult ::=
SEQUENCE {
resultCode ENUMERATED {
success (0),
operationsError (1),
protocolError (2),
timeLimitExceeded (3),
sizeLimitExceeded (4),
compareFalse (5),
compareTrue (6),
authMethodNotSupported (7),
strongAuthRequired (8),
noSuchAttribute (16),
undefinedAttributeType (17),
inappropriateMatching (18),
constraintViolation (19),
attributeOrValueExists (20),
invalidAttributeSyntax (21),
noSuchObject (32),
aliasProblem (33),
invalidDNSyntax (34),
isLeaf (35),
aliasDereferencingProblem (36),
inappropriateAuthentication (48),
invalidCredentials (49),
insufficientAccessRights (50),
busy (51),

Yeong, Howes & Kille [Page 21]

RFC 1777 LDAP March 1995

unavailable (52),
unwillingToPerform (53),
loopDetect (54),
namingViolation (64),
objectClassViolation (65),
notAllowedOnNonLeaf (66),
notAllowedOnRDN (67),
entryAlreadyExists (68),
objectClassModsProhibited (69),
other (80)
},
matchedDN LDAPDN,
errorMessage LDAPString
}

AttributeType ::= LDAPString
-- text name of the attribute, or dotted
-- OID representation

AttributeValue ::= OCTET STRING

AttributeValueAssertion ::=
SEQUENCE {
attributeType AttributeType,
attributeValue AttributeValue
}

SubstringFilter ::=
SEQUENCE {
type AttributeType,
SEQUENCE OF CHOICE {
initial [0] LDAPString,
any [1] LDAPString,
final [2] LDAPString
}
}

LDAPString ::= OCTET STRING

maxInt INTEGER ::= 65535
END

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