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INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standard Track OpenLDAP Foundation
Expires in six months 26 May 2003
Feature Discovery in LDAP
<draft-zeilenga-ldap-features-05.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor as an Standard Track document.
Distribution of this memo is unlimited. Technical discussion of this
document will take place on the IETF LDAP Extension Working Group
mailing list <ldapext@ietf.org>. Please send editorial comments
directly to the author <Kurt@OpenLDAP.org>.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as ``work in progress.''
The list of current Internet-Drafts can be accessed at
<http://www.ietf.org/ietf/1id-abstracts.txt>. The list of
Internet-Draft Shadow Directories can be accessed at
<http://www.ietf.org/shadow.html>.
Copyright (C) The Internet Society (2003). All Rights Reserved.
Please see the Full Copyright section near the end of this document
for more information.
Abstract
The Lightweight Directory Access Protocol (LDAP) is an extensible
protocol with numerous elective features. This document introduces a
general mechanism for discovery of elective features and extensions
which cannot be discovered using existing mechanisms.
Zeilenga draft-zeilenga-ldap-features-05 [Page 1]
INTERNET-DRAFT LDAP supportedFeatures 26 May 2003
1. Background and Intended Use
The Lightweight Directory Access Protocol (LDAP) [RFC3377] is an
extensible protocol with numerous elective features. LDAP provides
mechanisms for a client to discover supported protocol versions,
controls, extended operations, Simple Authentication and Security
Layer (SASL) mechanisms, and subschema information. However, these
mechanisms are not designed to support general feature discovery.
This document describes a simple, general-purpose mechanism which
clients may use to discover the set of elective features supported by
a server. For example, this mechanism could be used by a client to
discover whether or not the server supports requests for all
operational attributes, e.g. "+" [OPATTRS]. As another example, this
mechanism could be used to discover absolute true, e.g. "(&)" and
false, e.g. "(|)", search filters [T-F] support.
This document extends the LDAP Protocol Mechanism registry [RFC3383]
to support registration of values of the supportedFeatures attribute.
This registry is managed by the Internet Assigned Numbers Authority
(IANA).
Schema definitions are provided using LDAP description formats
[RFC2252]. Definitions provided here are formatted (line wrapped) for
readability.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [RFC2119].
2. Discovery of supported features
Each elective feature whose support may be discovered SHALL be
identified by an Object Identifier (OID). A server advertises its
support for a given feature by providing the OID associated with the
feature as a value of the 'supportedFeatures' attribute held in the
root DSE. A client may examine the values of this attribute to
determine if a particular feature is supported by the server. A
client MUST ignore values it doesn't recognize as they refer to
elective features it doesn't implement.
Features associated with Standard Track protocol mechanisms MUST be
registered. Features associated with other protocol mechanisms SHOULD
be registered. Procedures for registering protocol mechanisms are are
described in [RFC3383]. "Feature" should be placed in the usage field
of the submitted LDAP Protocol Mechanism template.
Zeilenga draft-zeilenga-ldap-features-05 [Page 2]
INTERNET-DRAFT LDAP supportedFeatures 26 May 2003
The 'supportedFeatures' attribute type is described as follows:
( 1.3.6.1.4.1.4203.1.3.5
NAME 'supportedFeatures'
DESC 'features supported by the server'
EQUALITY objectIdentifierMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.38
USAGE dSAOperation )
Servers MUST be capable of recognizing this attribute type by the name
'supportedFeatures'. Servers MAY recognize the attribute type by
other names.
4. Security Considerations
As rogue clients can discover features of a server by other means
(such as by trial and error), this feature discovery mechanism is not
believed to introduce any new security risk to LDAP.
5. IANA Considerations
5.1. Registration of Features as Protocol Mechanisms
Future specifications detailing LDAP features are to register each
feature as a LDAP Protocol Mechanism per guidance given in BCP 64
[RFC3383]. A usage of "Feature" in a Protocol Mechanism registration
template indicates that the value to be registered is associated with
an LDAP feature.
5.2. Registration of the supportedFeatures descriptor
It is requested that IANA register upon Standards Action the LDAP
'supportedFeatures' descriptor. The following registration template
is suggested:
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): supportedFeatures
Object Identifier: 1.3.6.1.4.1.4203.1.3.5
Person & email address to contact for further information:
Kurt Zeilenga <kurt@OpenLDAP.org>
Usage: Attribute Type
Specification: RFC XXXX
Author/Change Controller: IESG
This OID was assigned [ASSIGN] by OpenLDAP Foundation under its IANA
Zeilenga draft-zeilenga-ldap-features-05 [Page 3]
INTERNET-DRAFT LDAP supportedFeatures 26 May 2003
assigned private enterprise allocation [PRIVATE] for use in this
specification.
6. Acknowledgment
This document is based upon input from the IETF LDAPEXT working group.
7. Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
<Kurt@OpenLDAP.org>
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14 (also RFC 2119), March 1997.
[RFC2252] Wahl, M., A. Coulbeck, T. Howes, and S. Kille,
"Lightweight Directory Access Protocol (v3): Attribute
Syntax Definitions", RFC 2252, December 1997.
[RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377,
September 2002.
[RFC3383] Zeilenga, K., "IANA Considerations for LDAP", BCP 64
(also RFC 3383), September 2002.
9. Informative References
[OPATTRS] Zeilenga, K., "LDAPv3: All Operational Attributes",
draft-zeilenga-ldap-opattrs-xx.txt, a work in progress.
[T-F] Zeilenga, K., "LDAP True/False Filters",
draft-zeilenga-ldap-t-f-xx.txt, a work in progress.
[ASSIGN] OpenLDAP Foundation, "OpenLDAP OID Delegations",
http://www.openldap.org/foundation/oid-delegate.txt.
[PRIVATE] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers.
Zeilenga draft-zeilenga-ldap-features-05 [Page 4]
INTERNET-DRAFT LDAP supportedFeatures 26 May 2003
Intellectual Property Rights
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to pertain
to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; neither does it represent that it has made any
effort to identify any such rights. Information on the IETF's
procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such proprietary
rights by implementors or users of this specification can be obtained
from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be followed,
or as required to translate it into languages other than English.
Zeilenga draft-zeilenga-ldap-features-05 [Page 5]

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@ -1,283 +0,0 @@
INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standard Track OpenLDAP Foundation
Expires in six months 1 November 2002
LDAPv3: All Operational Attributes
<draft-zeilenga-ldap-opattrs-05.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
This document is intended to be, after appropriate review and
revision, submitted to the RFC Editor as a Standard Track document.
Distribution of this memo is unlimited. Technical discussion of this
document will take place on the IETF LDAP Extensions Working Group
mailing list <ldapext@ietf.org>. Please send editorial comments
directly to the author <Kurt@OpenLDAP.org>.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as ``work in progress.''
The list of current Internet-Drafts can be accessed at
<http://www.ietf.org/ietf/1id-abstracts.txt>. The list of
Internet-Draft Shadow Directories can be accessed at
<http://www.ietf.org/shadow.html>.
Copyright 2002, The Internet Society. All Rights Reserved.
Please see the Copyright section near the end of this document for
more information.
Abstract
The Lightweight Directory Access Protocol (LDAP) supports a mechanism
for requesting the return of all user attributes but not all
operational attributes. This document describes an LDAP extension
which clients may use to request the return of all operational
attributes.
Zeilenga LDAP All Op Attrs [Page 1]
INTERNET-DRAFT draft-zeilenga-ldap-opattrs-05 1 November 2002
1. Overview
X.500 [X.500] provides a mechanism for clients to request all
operational attributes be returned with entries provided in response
to a search operation. This mechanism is often used by clients to
discover which operational attributes are present in an entry.
This documents extends the Lightweight Directory Access Protocol
(LDAP) [RFC3377] to provide a simple mechanism which clients may use
to request the return of all operational attributes. The mechanism is
designed for use with existing general purpose LDAP clients (including
web browsers which support LDAP URLs) and existing LDAP APIs.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [RFC2119].
2. All Operational Attributes
The presence of the attribute description "+" (ASCII 43) in the list
of attributes in a Search Request [RFC2251] SHALL signify a request
for the return of all operational attributes.
As with all search requests, client implementors should note that
results may not include all requested attributes due to access
controls or other restrictions. Client implementors should also note
that certain operational attributes may be returned only if requested
by name even when "+" is present. This is because some operational
attributes are very expensive to return.
Servers supporting this feature SHOULD publish the Object Identifier
1.3.6.1.4.1.4203.1.5.1 as a value of the 'supportedFeatures'
[FEATURES] attribute in the root DSE.
3. Interoperability Considerations
This mechanism is specifically designed to allow users to request all
operational attributes using existing LDAP clients. In particular,
the mechanism is designed to be compatible with existing general
purpose LDAP clients including those supporting LDAP URLs [RFC2255].
The addition of this mechanism to LDAP is not believed to cause any
significant interoperability issues (this has been confirmed through
testing). Servers which have yet to implement this specification
should ignore the "+" as an unrecognized attribute description per
[RFC2251, Section 4.5.1]. From the client's perspective, a server
Zeilenga LDAP All Op Attrs [Page 2]
INTERNET-DRAFT draft-zeilenga-ldap-opattrs-05 1 November 2002
which does not return all operational attributes when "+" is requested
should be viewed as having other restrictions.
It is also noted that this mechanism is believed to require no
modification of existing LDAP APIs.
4. Security Considerations
This document provides a general mechanism which clients may use to
discover operational attributes. Prior to the introduction of this
mechanism, operational attributes where only returned when requested
by name. Some might have viewed this as obscurity" feature. However,
this sense of security as the attributes were still transferable.
Implementations SHOULD implement appropriate access controls
mechanisms to restricts access to operational attributes.
5. IANA Considerations
This document uses the OID 1.3.6.1.4.1.4203.1.5.1 to identify the
feature described above. This OID was assigned [ASSIGN] by OpenLDAP
Foundation, under its IANA-assigned private enterprise allocation
[PRIVATE], for use in this specification.
Registration of this feature is requested [FEATURES][RFC3383].
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: 1.3.6.1.4.1.4203.1.5.1
Description: All Op Attrs
Person & email address to contact for further information:
Kurt Zeilenga <kurt@openldap.org>
Usage: Feature
Specification: RFCxxxx
Author/Change Controller: IESG
Comments: none
6. Acknowledgment
Zeilenga LDAP All Op Attrs [Page 3]
INTERNET-DRAFT draft-zeilenga-ldap-opattrs-05 1 November 2002
The "+" mechanism is believed to have been first suggested by Bruce
Greenblatt in a November 1998 post to the IETF LDAPext Working Group
mailing list.
7. Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
<Kurt@OpenLDAP.org>
8. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14 (also RFC 2119), March 1997.
[RFC2251] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
Protocol (v3)", RFC 2251, December 1997.
[RFC3377] J. Hodges, R. Morgan, "Lightweight Directory Access Protocol
(v3): Technical Specification", RFC 3377, September 2002.
[FEATURES] K. Zeilenga, "Feature Discovery in LDAP", draft-zeilenga-
ldap-features-xx.txt (a work in progress).
9. Informative References
[RFC2255] T. Howes and M. Smith, "The LDAP URL Format", RFC 2255,
December 1997.
[RFC3383] K. Zeilenga, "IANA Considerations for LDAP", BCP 64 (also
RFC 3383), September 2002.
[X.500] ITU-T Rec. X.500, "The Directory: Overview of Concepts,
Models and Service", 1993.
[ASSIGN] OpenLDAP Foundation, "OpenLDAP OID Delegations",
http://www.openldap.org/foundation/oid-delegate.txt.
[PRIVATE] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers.
Copyright 2002, The Internet Society. All Rights Reserved.
This document and translations of it may be copied and furnished to
Zeilenga LDAP All Op Attrs [Page 4]
INTERNET-DRAFT draft-zeilenga-ldap-opattrs-05 1 November 2002
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be followed,
or as required to translate it into languages other than English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE AUTHORS, THE INTERNET SOCIETY, AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Zeilenga LDAP All Op Attrs [Page 5]

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@ -32,7 +32,8 @@ rfc3112.txt LDAP Authentication Password Schema (I)
rfc3296.txt Named Subordinate References in LDAP (PS)
rfc3377.txt LDAP(v3): Technical Specification (PS)
rfc3383.txt IANA Considerations for LDAP (BCP)
rfc3673.txt LDAPv3: All Operational Attributes (PS)
rfc3674.txt Feature Discovery in LDAP (PS)
Legend:
STD Standard
@ -43,4 +44,6 @@ E Experimental
FYI For Your Information
BCP Best Common Practice
Please see http://www.rfc-editor.org/ for up-to-date status information.
$OpenLDAP$

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@ -0,0 +1,283 @@
Network Working Group K. Zeilenga
Request for Comments: 3673 OpenLDAP Foundation
Category: Standards Track December 2003
Lightweight Directory Access Protocol version 3 (LDAPv3):
All Operational Attributes
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.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
The Lightweight Directory Access Protocol (LDAP) supports a mechanism
for requesting the return of all user attributes but not all
operational attributes. This document describes an LDAP extension
which clients may use to request the return of all operational
attributes.
1. Overview
X.500 [X.500] provides a mechanism for clients to request all
operational attributes be returned with entries provided in response
to a search operation. This mechanism is often used by clients to
discover which operational attributes are present in an entry.
This documents extends the Lightweight Directory Access Protocol
(LDAP) [RFC3377] to provide a simple mechanism which clients may use
to request the return of all operational attributes. The mechanism
is designed for use with existing general purpose LDAP clients
(including web browsers which support LDAP URLs) and existing LDAP
APIs.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [RFC2119].
Zeilenga Standards Track [Page 1]
RFC 3673 LDAPv3: All Operational Attributes December 2003
2. All Operational Attributes
The presence of the attribute description "+" (ASCII 43) in the list
of attributes in a Search Request [RFC2251] SHALL signify a request
for the return of all operational attributes.
As with all search requests, client implementors should note that
results may not include all requested attributes due to access
controls or other restrictions. Client implementors should also note
that certain operational attributes may be returned only if requested
by name even when "+" is present. This is because some operational
attributes are very expensive to return.
Servers supporting this feature SHOULD publish the Object Identifier
1.3.6.1.4.1.4203.1.5.1 as a value of the 'supportedFeatures'
[RFC3674] attribute in the root DSE.
3. Interoperability Considerations
This mechanism is specifically designed to allow users to request all
operational attributes using existing LDAP clients. In particular,
the mechanism is designed to be compatible with existing general
purpose LDAP clients including those supporting LDAP URLs [RFC2255].
The addition of this mechanism to LDAP is not believed to cause any
significant interoperability issues (this has been confirmed through
testing). Servers which have yet to implement this specification
should ignore the "+" as an unrecognized attribute description per
[RFC2251, Section 4.5.1]. From the client's perspective, a server
which does not return all operational attributes when "+" is
requested should be viewed as having other restrictions.
It is also noted that this mechanism is believed to require no
modification of existing LDAP APIs.
4. Security Considerations
This document provides a general mechanism which clients may use to
discover operational attributes. Prior to the introduction of this
mechanism, operational attributes were only returned when requested
by name. Some might have viewed this as obscurity feature. However,
this feature offers a false sense of security as the attributes were
still transferable.
Implementations SHOULD implement appropriate access controls
mechanisms to restricts access to operational attributes.
Zeilenga Standards Track [Page 2]
RFC 3673 LDAPv3: All Operational Attributes December 2003
5. IANA Considerations
This document uses the OID 1.3.6.1.4.1.4203.1.5.1 to identify the
feature described above. This OID was assigned [ASSIGN] by OpenLDAP
Foundation, under its IANA-assigned private enterprise allocation
[PRIVATE], for use in this specification.
Registration of this feature has been completed by IANA [RFC3674],
[RFC3383].
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: 1.3.6.1.4.1.4203.1.5.1
Description: All Op Attrs
Person & email address to contact for further information:
Kurt Zeilenga <kurt@openldap.org>
Usage: Feature
Specification: RFC3673
Author/Change Controller: IESG
Comments: none
6. Acknowledgment
The "+" mechanism is believed to have been first suggested by Bruce
Greenblatt in a November 1998 post to the IETF LDAPext Working Group
mailing list.
7. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
Zeilenga Standards Track [Page 3]
RFC 3673 LDAPv3: All Operational Attributes December 2003
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2251] Wahl, M., Howes, T. and S. Kille, "Lightweight Directory
Access Protocol (v3)", RFC 2251, December 1997.
[RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377,
September 2002.
[RFC3674] Zeilenga, K., "Feature Discovery in Lightweight Directory
Access Protocol (LDAP)", RFC 3674, December 2003.
8.2. Informative References
[RFC2255] Howes, T. and M. Smith, "The LDAP URL Format", RFC 2255,
December 1997.
[RFC3383] Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
Considerations for the Lightweight Directory Access
Protocol (LDAP)", BCP 64, RFC 3383, September 2002.
[X.500] ITU-T Rec. X.500, "The Directory: Overview of Concepts,
Models and Service", 1993.
[ASSIGN] OpenLDAP Foundation, "OpenLDAP OID Delegations",
http://www.openldap.org/foundation/oid-delegate.txt.
[PRIVATE] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers.
9. Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
EMail: Kurt@OpenLDAP.org
Zeilenga Standards Track [Page 4]
RFC 3673 LDAPv3: All Operational Attributes December 2003
10. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Zeilenga Standards Track [Page 5]

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@ -0,0 +1,283 @@
Network Working Group K. Zeilenga
Request for Comments: 3674 OpenLDAP Foundation
Category: Standards Track December 2003
Feature Discovery in Lightweight Directory Access Protocol (LDAP)
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.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
The Lightweight Directory Access Protocol (LDAP) is an extensible
protocol with numerous elective features. This document introduces a
general mechanism for discovery of elective features and extensions
which cannot be discovered using existing mechanisms.
1. Background and Intended Use
The Lightweight Directory Access Protocol (LDAP) [RFC3377] is an
extensible protocol with numerous elective features. LDAP provides
mechanisms for a client to discover supported protocol versions,
controls, extended operations, Simple Authentication and Security
Layer (SASL) mechanisms, and subschema information. However, these
mechanisms are not designed to support general feature discovery.
This document describes a simple, general-purpose mechanism which
clients may use to discover the set of elective features supported by
a server. For example, this mechanism could be used by a client to
discover whether or not the server supports requests for all
operational attributes, e.g., "+" [RFC3673]. As another example,
this mechanism could be used to discover absolute true, e.g., "(&)"
and false, e.g., "(|)", search filters [T-F] support.
This document extends the LDAP Protocol Mechanism registry [RFC3383]
to support registration of values of the supportedFeatures attribute.
This registry is managed by the Internet Assigned Numbers Authority
(IANA).
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RFC 3674 Feature Discovery in LDAP December 2003
Schema definitions are provided using LDAP description formats
[RFC2252]. Definitions provided here are formatted (line wrapped)
for readability.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [RFC2119].
2. Discovery of supported features
Each elective feature whose support may be discovered SHALL be
identified by an Object Identifier (OID). A server advertises its
support for a given feature by providing the OID associated with the
feature as a value of the 'supportedFeatures' attribute held in the
root DSE. A client may examine the values of this attribute to
determine if a particular feature is supported by the server. A
client MUST ignore values it doesn't recognize as they refer to
elective features it doesn't implement.
Features associated with Standard Track protocol mechanisms MUST be
registered. Features associated with other protocol mechanisms
SHOULD be registered. Procedures for registering protocol mechanisms
are described in BCP 64 [RFC3383]. The word "Feature" should be
placed in the usage field of the submitted LDAP Protocol Mechanism
template.
The 'supportedFeatures' attribute type is described as follows:
( 1.3.6.1.4.1.4203.1.3.5
NAME 'supportedFeatures'
DESC 'features supported by the server'
EQUALITY objectIdentifierMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.38
USAGE dSAOperation )
Servers MUST be capable of recognizing this attribute type by the
name 'supportedFeatures'. Servers MAY recognize the attribute type
by other names.
3. Security Considerations
As rogue clients can discover features of a server by other means
(such as by trial and error), this feature discovery mechanism is not
believed to introduce any new security risk to LDAP.
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RFC 3674 Feature Discovery in LDAP December 2003
4. IANA Considerations
4.1. Registration of Features as Protocol Mechanisms
Future specifications detailing LDAP features are to register each
feature as a LDAP Protocol Mechanism per guidance given in BCP 64
[RFC3383]. A usage of "Feature" in a Protocol Mechanism registration
template indicates that the value to be registered is associated with
an LDAP feature.
4.2. Registration of the supportedFeatures descriptor
The IANA has registered the LDAP 'supportedFeatures' descriptor. The
following registration template is suggested:
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): supportedFeatures
Object Identifier: 1.3.6.1.4.1.4203.1.3.5
Person & email address to contact for further information:
Kurt Zeilenga <kurt@OpenLDAP.org>
Usage: Attribute Type
Specification: RFC 3674
Author/Change Controller: IESG
This OID was assigned [ASSIGN] by OpenLDAP Foundation under its IANA
assigned private enterprise allocation [PRIVATE] for use in this
specification.
5. Acknowledgment
This document is based upon input from the IETF LDAPEXT working
group.
6. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
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RFC 3674 Feature Discovery in LDAP December 2003
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2252] Wahl, M., Coulbeck, A., Howes, T. and S. Kille,
"Lightweight Directory Access Protocol (v3): Attribute
Syntax Definitions", RFC 2252, December 1997.
[RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377,
September 2002.
[RFC3383] Zeilenga, K., "Internet Assigned Numbers Authority
(IANA) Considerations for Lightweight Directory Access
Protocol (LDAP)", BCP 64, RFC 3383, September 2002.
7.2. Informative References
[RFC3673] Zeilenga, K., "Lightweight Directory Access Protocol
version 3 (LDAPv3): All Operational Attributes", RFC
3673, December 2003.
[T-F] Zeilenga, K., "LDAP True/False Filters", Work in
Progress.
[ASSIGN] OpenLDAP Foundation, "OpenLDAP OID Delegations",
http://www.openldap.org/foundation/oid-delegate.txt.
[PRIVATE] IANA, "Private Enterprise Numbers",
http://www.iana.org/assignments/enterprise-numbers.
8. Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
EMail: Kurt@OpenLDAP.org
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9. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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