Network Working Group A. Newton
Request for Comments: 3663 VeriSign, Inc.
Category: Experimental December 2003
Domain Administrative Data
in Lightweight Directory Access Protocol (LDAP)
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
Domain registration data has typically been exposed to the general
public via Nicname/Whois for administrative purposes. This document
describes the Referral Lightweight Directory Access Protocol (LDAP)
Service, an experimental service using LDAP and well-known LDAP types
to make domain administrative data available.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Historical Directory Services for Domain Registration
Data . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Motivations. . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Abbreviations Used . . . . . . . . . . . . . . . . . . . 4
2. Service Description. . . . . . . . . . . . . . . . . . . . . . 4
3. Registry LDAP Service. . . . . . . . . . . . . . . . . . . . . 6
3.1. TLD DIT. . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1.1. DIT Structure. . . . . . . . . . . . . . . . . . 6
3.1.2. Allowed Searches . . . . . . . . . . . . . . . . 7
3.1.3. Access Control . . . . . . . . . . . . . . . . . 7
3.2. Name Server DIT. . . . . . . . . . . . . . . . . . . . . 8
3.2.1. DIT Structure. . . . . . . . . . . . . . . . . . 8
3.2.2. Allowed Searches . . . . . . . . . . . . . . . . 8
3.3. Registrar Referral DIT . . . . . . . . . . . . . . . . . 9
3.3.1. DIT Structure. . . . . . . . . . . . . . . . . . 9
4. Registrar LDAP Service . . . . . . . . . . . . . . . . . . . . 10
4.1. TLD DIT. . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1.1. DIT Structure. . . . . . . . . . . . . . . . . . 10
4.1.2. Allowed Searches . . . . . . . . . . . . . . . . 11
4.1.3. Access Control . . . . . . . . . . . . . . . . . 11
4.2. Name Server and Contact DIT. . . . . . . . . . . . . . . 12
4.2.1. DIT Structure. . . . . . . . . . . . . . . . . . 12
4.2.2. Allowed Searches . . . . . . . . . . . . . . . . 13
5. Clients. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6. Lessons Learned. . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Intra-Server Referrals . . . . . . . . . . . . . . . . . 14
6.2. Inter-Server Referrals . . . . . . . . . . . . . . . . . 15
6.3. Common DIT . . . . . . . . . . . . . . . . . . . . . . . 15
6.4. Universal Client . . . . . . . . . . . . . . . . . . . . 16
6.5. Targeting Searches by Tier . . . . . . . . . . . . . . . 16
6.6. Data Mining. . . . . . . . . . . . . . . . . . . . . . . 16
7. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 16
8. Internationalization Considerations. . . . . . . . . . . . . . 16
9. Security Considerations. . . . . . . . . . . . . . . . . . . . 17
10. Intellectual Property Statement. . . . . . . . . . . . . . . . 17
11. Normative References . . . . . . . . . . . . . . . . . . . . . 18
Appendix A. Other Work. . . . . . . . . . . . . . . . . . . . . . 19
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 20
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
This document describes the Referral Lightweight Directory Access
Protocol (LDAP) Service, an experimental project launched by
VeriSign, Inc., to explore the use of LDAP and LDAP-related
technologies for use as a directory service of administrative domain
registration information.
1.1. Historical Directory Services for Domain Registration Data
The original National Science Foundation contract for the InterNIC
called for the creation of an X.500 directory service for the
administrative needs of the domain registration data and information.
Due to problems with implementations of X.500 server software, a
server based on the Nicname/Whois [1] protocol was temporarily
erected.
In 1994, the Rwhois [3] protocol was introduced to enhance the
Nicname/Whois protocol. This directory service never gained wide
acceptance for use with domain data.
Presently, ICANN requires the operation of Nicname/Whois servers by
registries and registrars of generic Top-Level Domains (TLD's).
1.2. Motivations
With the recent split in functional responsibilities between
registries and registrars, the constant misuse and data-mining of
domain registration data, and the difficulties with machine-
readability of Nicname/Whois output, the creation of the Referral
LDAP Service had the following motivations:
o Use a mechanism native to the directory protocol to refer clients
from inquiries about specific domains made at a registry to the
appropriate domain within the appropriate directory service at a
registrar.
o Limit access to domain data based on authentication of the client.
o Provide structured queries and well-known and structured results.
o Use a directory service technology already in general use.
Given these general criteria, LDAP [5] was selected as the protocol
for this directory service. The decision was also made to restrict
the use of LDAP to features most readily available in common
implementations. Therefore, a goal was set to not define any new
object classes, syntaxes, or matching rules.
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The experiment was successful in exploring how LDAP might be used in
this context and demonstrating the level of customization required
for an operational service. Conclusions and observations about this
experiment are outlined in Section 6.
1.3. Abbreviations Used
The following abbreviations are used to describe the nature of this
experiment:
TLD: Top-Level Domain. Refers to the domain names just beneath
the root in the Domain Name System. This experiment used the
TLD's .com, .net, .org, and .edu.
SLD: Second-Level Domain. Refers to the domain names just beneath
a TLD in the Domain Name System. An example of such a domain name
would be "example.com".
DIT: Directory Information Tree. One of many hierarchies of data
entries in an LDAP server.
DN: Distinguished Name. The unique name of an entry in a DIT.
cn: common name. See RFC 2256 [7].
dc: domain component. See RFC 2247 [4].
uid: user id. See RFC 2798 [9].
2. Service Description
The service is composed of three distinct server types: a registry
LDAP server, registrar LDAP servers, and registrant LDAP servers.
The registry LDAP server contains three Directory Information Trees
(DIT's).
o The Top-Level Domain DIT's follow the DNS hierarchy for domains
(e.g., dc=foo,dc=com).
o The name server DIT allows a view of the name servers, many of
which serve multiple domains.
o The registrar-referral DIT provides referrals from the registry
into the respective TLD DIT of the registrars (on a TLD basis).
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The registrar LDAP server contains two types of DIT's.
o The TLD DIT follows the DNS hierarchy for domains (e.g.,
dc=foo,dc=com) and parallels the TLD DIT of the registry.
o The name server and contact DIT allow a view of the name servers
and contacts, many of which are associated and serve multiple
domains.
There is no specification on the DIT or schema for the registrant
LDAP server. Referrals from the registrar server to the registrant
server are provided solely for the purpose of allowing the registrant
direct control over extra administrative information as it relates to
a particular domain.
Access control for this service is merely a demonstration of using a
Distinguished Name (DN) and password. Should registries and
registrars uniformly adopt LDAP as a means to disseminate domain
registration data, standardization of these DN's would need to be
undertaken based on each type of user base.
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3. Registry LDAP Service
3.1. TLD DIT
3.1.1. DIT Structure
The registry TLD DIT has the following structural hierarchy:
TLD (e.g., dc=net)
|
|
-------------------------------------
| |
SLD (e.g., dc=foo,dc=net) SLD (e.g., dc=bar,dc=net)
| |
--------------------- ---------------------
| | | | | |
name server | | name server | |
(e.g., | | (e.g., | |
cn=nameserver1, | | cn=nameserver1, | |
dc=foo,dc=net ) | | dc=bar,dc=net ) | |
| | | |
name server | name server |
(e.g., | (e.g., |
cn=nameserver2, | cn=nameserver2, |
dc=foo,dc=net ) | dc=bar,dc=net ) |
| |
registrar referral registrar referral
(e.g., (e.g.,
cn=registrar, cn=registrar,
dc=foo,dc=net ) dc=bar,dc=net )
Figure 1: Registry DIT Overview
The root of a TLD DIT is an entry of objectclass domain as specified
by RFC 2247 [4] and represents a top-level domain.
The second tier of the DIT represents second-level domains. Each of
these entries is of objectclass domain as specified by RFC 2247 [4].
The description attribute on these entries often contains descriptive
text giving the name of the registrar through which these domains
have been registered.
The third tier contains entries specific to each second-level domain.
Name server entries are of objectclass ipHost as specified by RFC
2307 [8]. The distinguished names of these name server entries are
algorithmically calculated, where the first component is the word
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"nameserver" concatenated with an index number of the name server
entry and the remaining components are the appropriate domain names.
There is no specification relating the value of the name server entry
to the index it may be assigned other than it is unique and
consistent with respect to the client session. This tier also
contains the referral from the registry to the registrar. This
referral is a direct referral to the entry in the appropriate
registrar LDAP server corresponding to the domain name that the
referral falls beneath in this DIT.
3.1.2. Allowed Searches
Because of the vast number of entries contained within this DIT, only
certain types of searches are allowed. Allowing any search
expressible via LDAP would lead to expensive searches that would be
far too costly for a publicly available service. The searches
allowed are as follows:
o One-level scoped searches based at the root of the DIT. Substring
matching is allowed on dc attributes, but the substring must be at
least be 3 characters in length.
o Base search based at the root of the DIT.
o Base, one-level, and sub-tree searches based at any second level
domain name (the second tier) and below.
3.1.3. Access Control
The registry TLD DIT only has one access control type. When a client
binds with a DN of "cn=trademark" and password of "attorney", the
second-level domain entries also take on an objectclass of
extensibleObject with the added attributes of "createddate" and
"registrationexpirationdate", which are of type Generalized Time, as
specified by RFC 2252 [6].
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3.2. Name Server DIT
3.2.1. DIT Structure
The registry name server DIT has the following structural hierarchy:
(o=nsiregistry.com)
|
|
-------------------------------------
| | |
name server name server name server
(cn=ns1.foo.net) (cn=ns.bar.com) (cn=named.acme.org)
Figure 2: Registry DIT Overview
The root of a name server DIT is an entry of objectclass organization
as specified by RFC 1617 [2]. It has no significance other than to
serve as the root of the DIT.
The second tier of this DIT represents name servers. Each of these
entries is of objectclass ipHost, as specified by RFC 2307 [8].
3.2.2. Allowed Searches
Because of the vast number of entries contained within this DIT, only
certain types of searches are allowed. Allowing any search
expressible via LDAP would lead to searches far too costly for a
publicly available service. The searches allowed are as follows:
o One-level and sub-tree scoped searches based at the root of the
DIT if a filter on the cn attribute is provided.
o Base search based at the root of the DIT.
o Base, one-level, and sub-tree searches based at any name server
entry.
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3.3. Registrar Referral DIT
3.3.1. DIT Structure
The registry registrar-referral DIT has the following structural
hierarchy:
(o=tlds)
|
|
-------------------------------
| | | |
tld tld tld tld
(dc=net) (dc=com) (dc=org) (dc=edu)
| | | |
: : | :
: : | :
|
---------------------------
| | |
referral to referral to referral to
registrar 1 registrar 2 registrar n
dc=org DIT dc=org DIT dc=org DIT
Figure 3: Registry Referral DIT Overview
The root of the registrar referral DIT is an entry of objectclass
organization, as specified by RFC 1617 [2]. It has no significance
other than to serve as the root of this DIT.
The second tier of this DIT represents top-level domains. Each of
these entries is of objectclass domain, as specified by RFC 2247 [4].
Underneath each TLD entry, the third tier contains referrals to the
appropriate TLD DIT of each registrar.
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4. Registrar LDAP Service
4.1. TLD DIT
4.1.1. DIT Structure
The registrar TLD DIT, which is similar to the registry TLD DIT, has
the following structural hierarchy:
TLD (e.g., dc=net)
|
|
------------------------------------------------
| | |
SLD (e.g., dc=foo,dc=net) : :
| : :
---------------------------------------------
| | |
| | |
name server contact referral to
(e.g., cn=nameserver1, (e.g., cn=contact1, registrant
dc=foo,dc=net ) dc=foo,dc=net )
|
|
name server contact
(e.g., cn=contact,
cn=nameserver1,
dc=foo,dc=net )
Figure 4: Registrar DIT Overview
The root of a TLD DIT is an entry of objectclass domain, as specified
by RFC 2247 [4] and represents a top-level domain.
The second tier of the DIT represents second-level domains. Each of
these entries is of objectclass domain, as specified by RFC 2247 [4].
The third tier contains entries specific to each second-level domain.
The entries at this level are as follows:
o Name server entries are of objectclass ipHost, as specified by RFC
2307 [8]. The distinguished names of these name server entries
are algorithmically calculated where the first component is the
word "nameserver" concatenated with an index number of the name
server entry and the remaining components are the appropriate
domain names. There is no specification relating the value of the
name server entry to the index it may be assigned other than it is
unique and consistent with respect to the client session.
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o Contact entries are of objectclass inetOrgPerson, as specified by
RFC 2798 [9]. The distinguished names of these contact entries
are algorithmically calculated, where the first component is the
word "contact" concatenated with an index number of the contact
and the remaining components are the appropriate domain names.
There is no specification relating the value of the contact entry
to the index it may be assigned other than it is unique and
consistent with respect to the client session. The description
attribute of the entry contains the role for which a contact is
related to a domain. These roles are identified as "Admin
Contact", "Technical Contact", and "Billing Contact", and may
appear in any order.
o Finally, this third tier contains the referral from the registrar
to the registrant.
The fourth tier only contains name server contact entries. These
entries are of objectclass inetOrgPerson, as specified by RFC 2798
[9].
4.1.2. Allowed Searches
Because of the vast number of entries contained within this DIT, only
certain types of searches are allowed. Allowing any search
expressible via LDAP would lead to searches far too costly for a
publicly available service. The searches allowed are as follows:
o One-level scoped searches based at the root of the DIT. Substring
matching is allowed on dc and o attributes, but the substring must
be at least 3 characters in length.
o Base search based at the root of the DIT.
o Base, one-level, and sub-tree searches based at any second level
domain name (the second tier) and below.
4.1.3. Access Control
The registrar TLD DIT has two access control types. When binding
anonymously, a client only sees dc, o, and c attributes of the
second-level domain entries. When a client binds with a DN of
"cn=trademark" and password of "attorney", all of the other
attributes normally available on entries of objectclass domain are
visible if they have values. In addition, if a client binds with the
DN of a contact and password of "password", all attributes for
second-level domain entries for which the bind DN has a relation are
visible.
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4.2. Name Server and Contact DIT
4.2.1. DIT Structure
The registrar name server and contact DIT has the following
structural hierarchy:
(o=nsi.com)
|
|
--------------------------------------
| |
Contacts Name Servers
(ou=contacts) (ou=name servers)
| |
----------------- ------------------------
| | | | | |
Contact : : Name Server : :
(uid=handle) : : (cn=handle) : :
|
Name Server
Contact
(cn=contact1)
Figure 5: Registrar DIT Overview
The first tier of the name server and contact DIT is an entry of
objectclass organization, as specified by RFC 1617 [2].
The second tier of the DIT contains two entries, each of which is of
objectclass organizationalUnit, as specified by RFC 2256 [7]. One
entry represents the part of the DIT containing contacts and the
other entry represents the part of the DIT containing name servers.
Entries underneath the contacts organizationalUnit entry are of
objectclass inetOrgPerson and represent contacts registered with the
registrar. Their RDN is composed of the uid attribute. The uid
attribute's value is a unique identifier or handle that is registrar
assigned.
Entries underneath the name server organizationalUnit entry are of
objectclass ipHost and represent name servers registered with the
registrar. Their RDN is composed of the cn attribute. The cn
attribute's value is a unique identifier or handle that is registrar
assigned. Each name server entry may optionally have children
entries of objectclass inetOrgPerson. These entries represent the
contacts of the name server they fall beneath.
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4.2.2. Allowed Searches
Because of the vast number of entries contained within this DIT, only
certain types of searches are allowed. Allowing any search
expressible via LDAP would lead to searches far too costly for a
publicly available service. The searches allowed are as follows:
o One-level and base searches at the root of the DIT.
o Sub-tree searches at the root of the DIT using cn and uid
attributes as a filter.
o Base searches at either entry of the second tier.
o One-level and sub-tree searches at either entry of the second
tier, using cn or uid attributes as a filter.
o Base, one-level, and sub-tree searches based at any contact or
name server entry and below.
5. Clients
Early scoping and analysis of this project were based on the use of
output from command line clients, specifically the "ldapsearch"
command present with many implementations of LDAP servers. Our
survey of this tool, available from many vendors, showed that
referral chasing was difficult to control or predict, and the
behavior between these implementations with respect to referral
chasing was inconsistent.
Based on the limited nature of the expressive capabilities present
with just command line tools, searches involving nested queries or
advanced referral chasing were deemed the domain of clients making
direct use of LDAP client libraries. Three of these types of clients
were produced: a web-based client, a cross-platform C-based client,
and a Java client. No significant deficiencies or problems were
found with the LDAP client libraries in the construction of these
clients, and the level of control provided by their programming
interfaces was adequate to create the necessary searches. Instead,
most of the problems encountered with these clients were based on
usability concerns.
It was found that the web-based client caused a great amount of
confusion for users not familiar with LDAP or Nicname/Whois with
respect to the underlying technology and the network model. Thus,
many users believed the web-based client to be the only interface to
the data and were unaware or confused by the intermediate LDAP
protocol. In addition, it was difficult to express to users the
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registry-registrar-registrant service model in adequate terms from
search results where the results could be rendered properly among the
various common web browsers.
Both the C and Java based clients were built to be both graphical and
cross-platform (in the case of the C-based client, the Linux and
Windows platforms were chosen as targets). The LDAP client libraries
chosen for both clients proved to be quite capable and offered the
necessary levels of control for conducting nested queries and
advanced referral chasing. Expectations at the outset for
construction of both clients, based on past experience, were that the
C-based client would not only perform better than the Java client but
also have a better appearance. In reality, these assumptions were
incorrect as there was no perceivable difference in performance and
the look of the Java client was often considered to be far superior
to its counter-part. In addition, the Java client required much less
time to create. Both clients are available under the terms of an
open source license. Though it is impossible to have accurate
measurements of their popularity, through monitoring and feedback it
was perceived that the web-based client had far greater use.
6. Lessons Learned
Based on the experience of piloting this experimental service,
feedback from users of the service, and general comments and
observations of current and common opinions, the following items have
been noted.
6.1. Intra-Server Referrals
Original analysis of the data set to be used revealed a high degree
of relationships between name servers, contacts, and domains.
Storing the data in non-normalized form according to the DIT outlined
in this document would make an original relational dataset of roughly
20 million objects explode to over 115 million objects.
To combat this problem, the first pass at defining the DIT's made
heavy use of referrals between the TLD DIT's and the name server and
contact DIT's. The use of the 'alias' objectclass was considered but
ruled out in hopes of using referrals for load balancing across
servers (i.e., placing each TLD DIT on a separate server, and
separate servers for the name server and contact DIT's). However,
initial testing with the 'ldapsearch' command found inconsistencies
with the interpretation of the referrals and how they were managed.
Not only were the results inconsistent between implementations, but
many of these clients would easily get caught in referral loops.
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The final solution to the problem was to create a customized back-end
data store containing the data in a normalized form. This gave the
client the appearance of having a non-normalized data set which
required no intra-server referrals. Aliases may have been a better
solution, however our interpretation of their output with
implementations of the 'ldapsearch' tool was not satisfactory. It
was also later learned that some LDAP server implementations place
certain restrictions on aliases that would have conflicted with our
overall DIT structure. In the end, it was felt that a customized
back-end would be required by any server with a large data-set, but
smaller data-sets for less populated domains could easily use off-
the-shelf implementations.
6.2. Inter-Server Referrals
The modeling of the overall service to provide the split in
operational responsibility between registry and registrar required
the use of referrals (i.e., the two servers would not be operated by
the same organization, therefore would most likely not co-exist on
the same physical machine or network). The chief problem with LDAP
referrals returned for this purpose grew out of the need to limit
data returned to the client and the priority given to referrals. It
was quite easy to cause a sub-tree query at certain levels, for
instance a TLD level, to return nothing but referrals. This was true
because referrals would be returned out of the scope of the supplied
search filter and therefore would fill the result set to its limit,
normally set to 50 entries.
In certain use cases, a result set with nothing but referrals was
desired (e.g., o=tlds). However, even in these cases it was possible
for some referrals to not be returned due to the size limit. In this
case, it was felt that a result set of 50 referrals, the default for
the size limit in most cases, was too large for any practical use by
a client and was a failing of query distribution in general rather
than a limitation of LDAP.
6.3. Common DIT
Because of the nature of software development, the graphical and web
clients were developed after the development of the server software.
The 'ldapsearch' client was used for testing and development during
server software creation. It was not until the creation of more
advanced clients that it was discovered that the design decision of
uniform DIT naming should have been made. Technically, this would
have allowed for slightly better software modularization and re-use.
In addition, the use of a company name in the DIT structure did not
allow the easy integration of another domain registry, as in the
registry-registrar model. Not only would clients have to be
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reconfigured for each new registry operator, but this would most
likely have social implications as well.
6.4. Universal Client
The construction of the clients revealed yet another misconception.
Though this project used a generic directory service technology, the
clients required a high-degree of algorithmic knowledge about the DIT
structure and schemas being used. The graphical clients could not be
used against an LDAP service with another DIT or schema. Therefore,
a generic or universal client, one that could be used for all LDAP
applications, would either not be able to make full use of the data
provided by the service or would be far too complex for operation by
the average user.
6.5. Targeting Searches by Tier
The network model for this service was divided into three tiers:
registry, registrar, and registrant. Despite this, all searches
needed to start at the registry level causing overhead for searches
that could be targeted at a select tier. This service did not
implement a solution to this problem, such as using SRV and/or NAPTR
records in DNS to allow a client to find a responsible LDAP server.
6.6. Data Mining
Section 3.1.2 and Section 4.1.2 describe the searches allowed by this
service. However, the most common question asked by users of the
service revolved around getting around these restrictions. Because
browsing at the TLD level was not permitted, many users asked about
the feasibility of using recursive dictionary queries to circumvent
the search restrictions.
It should be noted that many operators of Nicname/Whois server
consider this practice to be data mining and often refer to it
specifically as a dictionary attack.
7. IANA Considerations
There are no applicable IANA considerations presented in this
document.
8. Internationalization Considerations
The domain administrative data in this service did not cover
Internationalized Domain Names (IDN's).
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9. Security Considerations
This experiment did not endeavor to use security mechanisms beyond
those readily available in LDAP [5]. Section 3.1.3 and Section 4.1.3
describe the various access controls used within the scope of the
defined security mechanisms. While these mechanisms were adequate
for this experimental deployment, they would not be adequate for a
production environment, and they should not be taken as a model for
those contemplating deployment on the Internet.
10. 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
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proprietary rights by implementors or users of this specification can
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The IETF invites any interested party to bring to its attention any
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11. Normative References
[1] Harrenstien, K., Stahl, M. and E. Feinler, "NICNAME/WHOIS", RFC
954, October 1985.
[2] Barker, P., Kille, S. and T. Lenggenhager, "Naming and
Structuring Guidelines for X.500 Directory Pilots", RFC 1617,
May 1994.
[3] Williamson, S., Kosters, M., Blacka, D., Singh, J. and K.
Zeilstra, "Referral Whois (RWhois) Protocol V1.5", RFC 2167,
June 1997.
[4] Kille, S., Wahl, M., Grimstad, A., Huber, R. and S. Sataluri,
"Using Domains in LDAP/X.500 Distinguished Names", RFC 2247,
January 1998.
[5] Wahl, M., Howes, T. and S. Kille, "Lightweight Directory Access
Protocol (v3)", RFC 2251, December 1997.
[6] Wahl, M., Coulbeck, A., Howes, T. and S. Kille, "Lightweight
Directory Access Protocol (v3): Attribute Syntax Definitions",
RFC 2252, December 1997.
[7] Wahl, M., "A Summary of the X.500(96) User Schema for use with
LDAPv3", RFC 2256, December 1997.
[8] Howard, L., "An Approach for Using LDAP as a Network Information
Service", RFC 2307, March 1998.
[9] Smith, M., "Definition of the inetOrgPerson LDAP Object Class",
RFC 2798, April 2000.
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Appendix A. Other Work
In addition to the deployment of servers and development of clients,
VeriSign conducted two sub-projects related to this experiment.
The first project was a Nicname/Whois-to-LDAP gateway. The goal of
the project was to create an LDAP server for use by registrars to
deploy in front of their Nicname/Whois servers. This gateway would
take LDAP requests, translate them to Nicname/Whois requests, issue
the request to a specific Nicname/Whois server deployed on port 43,
interpret the response, and return LDAP result sets. Because of the
unspecified nature of Nicname/Whois result sets, the gateway was
programmed to specifically recognize only the output of three
distinct registrars. While this gateway proved valuable enough to
allow domain lookups and limited searches, it was unable to provide
consistent contact lookups, nameserver lookups, or registrant
referrals. This software was also made publicly available under the
terms of an open source license.
The second project was an informal survey of registrants with
deployed LDAP servers. This was conducted by using the com, net,
org, and edu zone files and testing for the existence of an LDAP
server on port 389 using the name of the domain, a host named "ldap"
in the domain, and a host named "dir" in the domain (e.g., "foo.com",
"ldap.foo.com", and "dir.foo.com"). This survey did not attempt to
resolve LDAP services using SRV records in DNS.
The result of this survey found that roughly 0.5% of active domains
had an LDAP server. By profiling a server's root DSA-specific Entry
(DSE), the survey found that about 90% of the servers were
implementations provided by vendor A, 9% of the servers were
implementations provided by vendor B, and 1% of the servers were
implementations provided by other vendors. Of the servers queried
that were determined to be implementations provided by vendor A, it
appeared that about only 10% contained public data (this also led to
the assumption that the other 90% were not intended to be publicly
queried). Of the servers queried that were determined to be
implementations provided by vendor B, it appears that nearly all
contained public data.
Appendix B. Acknowledgments
Significant analysis, design, and implementation for this project
were conducted by Brad McMillen, David Blacka, Anna Zhang, and
Michael Schiraldi. Mark Kosters and Leslie Daigle provided guidance
by reviewing this project, the project's goals, and this document.
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Author's Address
Andrew Newton
VeriSign, Inc.
21345 Ridgetop Circle
Sterling, VA 20166
USA
Phone: +1 703 948 3382
EMail:
[email protected];
[email protected]
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Full Copyright Statement
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