Internet Draft
Best Current Practice for the Internet White Pages Service
Tue Apr 29 23:55:31 MET DST 1997
Harald Tveit Alvestrand
UNINETT
Harald.T.Alvestrand@uninett.no
Peter Jurg
SURFnet
Peter.Jurg@surfnet.nl
Status of this Memo
Please send comments to the IDS working group, ietf-ids@umich.edu
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The file name of this version is draft-ietf-ids-ds-bcp-05.txt
draft BCP for the Internet White Pages Service April 97
1. Summary and recommendations
This document makes the following recommendations for
organizations on the Internet:
(1) An organization SHOULD publish public E-mail addresses and
other public address information about Internet users
within their site.
(2) Most countries have laws concerning publication of
information about persons. Above and beyond these, the
organization SHOULD follow the recommendations of [1].
(3) The currently preferable way for publishing the information
is by using X.500 as its data structure and naming scheme
(defined in [4] and discussed in [3], but some countries
use a refinement nationally, like [15] for the US). The
organization MAY additionally publish it using additional
data structures such as whois++.
(4) The organization SHOULD make the published information
available to LDAP clients, by allowing LDAP servers access
to their data".
(5) The organization SHOULD NOT attempt to charge for simple
access to the data.
In addition, it makes the following recommendations for various
and sundry other parties:
(1) E-mail vendors SHOULD include LDAP lookup functionality
into their products, either as built-in functionality or by
providing translation facilities.
(2) Internet Service providers SHOULD help smaller
organizations follow this recommendation, either by
providing services for hosting their data, by helping them
find other parties to do so, or by helping them bring their
own service on-line.
(3) All interested parties SHOULD make sure there exists a core
X.500 name space in the world, and that all names in this
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name space are resolvable. (National name spaces may
elobarate on the core name space).
The rest of this document is justification and details for this
recommendation.
The words "SHOULD", "MUST" and "MAY", when written in UPPER CASE,
have the meaning defined in RFC 2119 [17]
2. Introduction
The Internet is used for information exchange and communication
between its users. It can only be effective as such if users are
able to find each other's addresses. Therefore the Internet
benefits from an adequate White Pages Service, i.e., a directory
service offering (Internet) address information related to people
and organizations.
This document describes the way in which the Internet White Pages
Service (from now on abbreviated as IWPS) is best exploited using
today's experience, today's protocols, today's products and
today's procedures.
Experience [2] has shown that a White Pages Service based on self-
registration of users or on centralized servers tends to gather
data in a haphazard fashion, and, moreover, collects data that
ages rapidly and is not kept up to date.
The most vital attempts to establish the IWPS are based on models
with distributed (local) databases each holding a manageable part
of the IWPS information. Such a part mostly consists of all
relevant IWPS information from within a particular organization or
from within an Internet service provider and its users. On top of
the databases there is a directory services protocol that connects
them and provides user access. Today X.500 is the most popular
directory services protocol on the Internet, connecting the
address information of about 1,5 million individuals and 3,000
organizations. Whois++ is the second popular protocol. X.500 and
Whois++ may also be used to interconnect other information than
only IWPS information, but here we only discuss the IWPS features.
Note: there are other, not interconnected, address databases on
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the Internet that are also very popular for storing address
information about people. "Ph" is a popular protocol for use with
a stand-alone database. There are over 300 registered Ph
databases on the Internet. Interconnection of databases however,
is highly recommended for an IWPS, since it ensures that data can
be found. Hence Ph as it is now is not considered to be a good
candidate for an IWPS, but future developments may change this
situation (see section 12).
Currently X.500 must be recommended as the directory services
protocol to be used for the IWPS. However, future technology may
make it possible to use other protocols as well or instead.
Since many people think that X.500 on the Internet will be
replaced by other protocols in the near future, it should be
mentioned here that currently LDAP is seen as the surviving
component of today's implementations and the main access protocol
for tomorrow's directory services. As soon as new technology (that
will probably use LDAP) becomes available and experiments show
that they work, this document will be updated.
A summary of X.500 products can be found in [14] (a document that
will be updated regularly).
The sections 3-7 below contain recommendations related to the
publication of information in the IWPS that are independent of a
directory services protocol. The sections 8-11 discuss X.500
specific issues. In section 12 some future developments are
discussed as they can be foreseen at the time of writing this
document.
3. Who should publish IWPS information and how?
IWPS information is public address information regarding
individuals and organizations. The IWPS information concerning an
individual should be published and maintained by an organization
that has a direct, durable link with this individual, like in the
following cases:
- The individual is employed by the maintainer's organization
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- The individual is enrolled in the university/school that
maintains the data
- The individual is a (personal) subscriber of the maintainer's
Internet service
The organization that maintains the data does not have to store
the data in a local database of its own. Though running a local
database in the X.500 or Whois++ service is not a too difficult
job, it is recommended that Internet service providers provide
database facilities for those organizations among its customers
that only maintain a small part of the IWPS information or don't
have enough system management resources. This will encourage such
organizations to join the IWPS. Collection of IWPS information and
keeping it up-to-date should always be in the hands of the
organization the information relates to.
Within the current (national) naming schemes for X.500, entries of
individuals reside under an organization. In the case of Internet
service providers that hold the entries of their subscribers this
would mean that individuals can only be found if one knows the
name of the service provider. The problem of this restriction
could be solved by using a more topographical approach in the
X.500 naming scheme, but will more likely be solved by a future
index service for directory services, which will allow searches
for individuals without organization names (see section 12).
4. What kind of information should be published?
The information to be published about an individual should at
least include:
- The individual's name
- The individual's e-mail address, in RFC-822 format; if not
present, some other contact information is to be included
- Some indication of the individual's relationship with the
maintainer
When X.500 is used as directory services protocol the last
requirement may be fulfilled by using the "organizationalStatus"
attribute (see [3]) or by adding a special organizational unit to
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the local X.500 name space that reflects the relation (like
ou=students or ou=employees).
Additionally some other public address information about
individuals may be included in the IWPS:
- The individual's phone number
- The individual's fax number
- The individual's postal address
- The URL of the individual's home page on the Web
In the near future it will be a good idea to also store public key
information.
More information about a recommended Internet White Pages Schema
is found in The Internet White Pages Schema [16]
Organizations should publish the following information about
themselves in the IWPS:
- The URL of the organizations home page on the Web
- Postal address
- Fax numbers
- Internet domain
- Various names and abbreviations for the organization that
people can be expected to search for, such as the English
name, and often the domain name of an organization.
Organizations may also publish phone numbers and a presentation of
themselves.
5. Data management
Data management, i.e. collecting the IWPS information and keeping
it up-to-date, is a task that must not be underestimated for
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larger organizations. The following recommendations can be made
with respect to these issues:
- An organization should achieve an executive level commitment
to start a local database with IWPS information. This will
make it much easier to get cooperation from people within the
organization that are to be involved in setting up a
Directory Service.
- An organization should decide on the kind of information the
database should contain and how it should be structured. It
should follow the Internet recommendations for structuring
the information. Besides the criteria in the previous
section, [3] and [4] should be followed if X.500 is used as
directory services protocol.
- An organization should define criteria for the quality of the
data in the Directory, like timeliness, update frequency,
correctness, etc. These criteria should be communicated
throughout the organization and contributing entities should
commit to the defined quality levels.
- Existing databases within an organization should be used to
retrieve IWPS and local information, to the greatest extent
possible. An organization should involve the people who
maintain those databases and make sure to get a formal
written commitment from them to use their data source. The
organization should rely on these people, since they have the
experience in management and control of local, available
data.
- The best motivation for an organization to join the IWPS is
that they will have a local database for local purposes at
the same time. A local database may contain more, not
necessarily public, information and serve more purposes than
is requested for in the IWPS. In connecting to the IWPS an
organization must "filter out" the extra local information
and services that is not meant for the public IWPS using the
directory services protocol.
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6. Legal issues
Most countries have privacy laws regarding the publication of
information about people. They range from the relaxed US laws to
the UK requirement that information should be accurate to the
Norwegian law that says that you can't publish unless you get
specific permission from the individual. Every maintainer of IWPS
information should publish data according to the national law of
the country in which the local database which holds the
information resides.
Some of these are documented in [5] and [1].
A maintainer of IWPS information should also follow some common
rules, even when they are not legally imposed:
- Publish only correct information.
- Give people the possibility to view the information stored
about themselves and the right to withhold information or
have information altered.
- Don't publish information "just because it's there". Publish
what is needed and what is thought useful, and no more.
Given the number of data management and legal issues that are
involved in publishing IWPS information, good consulting services
are vital to have smaller companies quickly and efficiently join
the IWPS. Internet service providers are encouraged to provide
such services.
7. Do not charge for lookups
In the current IWPS it believed that due to today's technological
constraints, charging users is harmful to the viability of the
service. There are several arguments for this belief:
- Micropayment technology is not available at the moment.
- Subscription services require either that the customer sign
up to multiple search services or that the services are
linked "behind the scene" with all kinds of bilateral
agreements; both structures have unacceptably high overhead
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costs and increase the entry cost to the service.
- The current directory services protocols do not support
authentication to a level that would seem appropriate for a
service that charges.
Therefore it is strongly recommended that all lookups by users in
the IWPS are for free. This, of course, does not limit in any way
the ability to use the same IWPS dataset to support other services
where charging may be appropriate.
8. Use X.500
The IWPS based on the X.500 protocol has a relatively wide
deployment. The current service contains about 1,5 million entries
of individuals and 3,000 of organizations. It is coordinated by
Dante, an Internet service provider in the UK, and known as
"NameFLOW-Paradise".
Though X.500 is sometimes criticized by the fact that its
functionality is restricted by the hierarchical naming structure
it imposes, it provides a reasonably good functionality as has
been shown in several pilots by organizations [5], [2], [6], [7]
that are now running a production X.500 IWPS. User interfaces also
determine the functionality the X.500 IWPS offers. Usually they
offer lookups in the IWPS based on the following user input:
- The name of a person
- The name of an organization this person can be related to
- The name of a country
As a result they will provide the publicly available information
about the person in question. Most user interfaces offer the
possibility to list organizations in a country and users in an
organization to help users to make their choice for the input. It
may also be possible to use part of the names as input or
approximate names.
Specific user interfaces can provide lookups based on other input,
like e-mail addresses of people or postal addresses of
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organizations. Such possibilities may however violate privacy
laws. Providers of directory services services may then be held
responsible.
The X.500 naming scheme imposes the requirement on an
interconnected IWPS that all entries stored in it must have unique
names (the "naming scheme"). This is most easily fulfilled by
registering all entries in a "naming tree" with a single root;
this is the reason why the totality of information in an X.500
IWPS is sometimes referred to as the "Directory Information Tree"
or DIT.
Organizations are strongly encouraged to use the X.500 protocol
for joining the IWPS. The current service is based on the X.500
1988 standard [8] and some Internet-specific additions to the
protocol that connects the local databases [10] and to the access
protocol [9]. Organizations should use X.500 software based on
these specifications and additionally supports [11] for the
transportation of OSI protocols over the Internet.
Organisations may connect to the NameFLOW-Paradise infrastructure
with 1988 DSAs that don't implement [10], but they will lack
automatic replication of knowledge references. This will be
inconvenient, but not a big problem. The 1993 standard of X.500
includes the functionality from [10], but uses a different
potocol. Hence organisations that connect to the infrastructure
with a 1993 DSA will also encounter this shortcoming. Section 12
"Future developments" explains why the infrastructure doesn't use
the 1993 standard for the moment.
For recommendations on which attributes to use in X.500 and how to
use them (either for public IWPS information or additional local
information the reader is referred to [3] and [4]. For specific
non-public local purposes also new attributes (and object classes)
may be defined. Generally it should be recommended to use as much
as possible the multi-valuedness of attributes in X.500 as this
will improve the searching functionality of the service
considerably. For example, the organizationalName attribute which
holds the name of an organization or the commonName attribute
which holds the name of a person should contain all known aliases
for the organization or person. In particular it is important to
add "readable" variants of all attributes that people are expected
to search for, if they contain national characters.
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Another recommendation that can be made is that replication of
data [10] between local databases is used in order to improve the
performance of the service. Since replicating all entries of a
part of the IWPS from one local database in another may violate
local privacy laws, it is recommended to restrict replication to
country and organizational entries and knowledge references (which
tell where to go for which part of the IWPS). Of course privacy
laws are not violated when the replicating database is managed by
the same organization as the one that masters the information. So
local replication between two databases within the same
organization is highly recommended.
In general replication within one country will usually be less a
legal problem than across country borders.
Recommendations for the operation of a database in the X.500
infrastructure can be found in [12].
X.500 is not recommended to be used for:
- A Yellow Pages service with a large scope. See [5].
- Searching outside the limited patterns listed here, in
particular searching for a person without knowing which
organization he might be affiliated to.
- Publishing information in other character sets than ASCII,
some of the Latin-based European scripts and Japanese (the
T.61 character sets). While support for these character sets
is available in revised versions of X.500, products that
support the revision aren't commonly available yet.
9. Use the global name space
Some people, for instance when using Novell 4 servers, have
decided that they will use X.500 or X.500-like services as an
internal naming mechanism, without coordinating with an outside
source.
This suffers from many of the same problems as private IP
addresses, only more so: your data may need significant
restructuring once you decide to expose them to the outer world.
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A globally accessible X.500 service requires a globally connected
X.500 name space. See [3] and [4] for recommendations on how
create a local part of the global name space.
Though the standard is not very clear about this and the most
recent version (93) appears not to support it, in practice the
X.500 name space is only manageable if there is a single root
context operated under a cooperative agreement. However, one can
be sure that there will be turf battles over it's control.
If those turf battles aren't decided outside the actual running
service, the effect on the service quality will be ruinous.
This document appeals to all players in the field to let existing
practice alone until a better system is agreed and is ready to go
into place; at the moment, the root context of the day is operated
by the Dante NameFLOW-Paradise service.
More information on the Dante NameFLOW-Paradise service is found
at the URL
http://www.dante.net/nameflow.html
10. Use LDAP
At the moment, LDAP as documented in [9] is the protocol that
offers the most X.500 functionality in places where it is not
feasible to implement the full OSI stack.
It is implemented on a lot of platforms, including several PC-type
platforms, and is popular in a multitude of commercial offerings.
A concerted effort to make LDAP available is the publication
method that gives the widest access to the data.
In addition, X.500 DSAs must implement the necessary linkages to
make sure they are properly integrated into the naming/referral
tree; in most cases, this will mean that they should implement the
X.500 DSP protocol at least.
(The question of whether one gateways LDAP to DAP or DAP to LDAP
is irrelevant in this context; it may be quite appropriate to
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store data on an LDAP-only server and make it available to the
DAP/DSP-running world through a gateway if the major users all use
LDAP)
11. Make services available
The technical investment in running an X.500 service is not
enormous, see for example [5].
12. Future developments
Today [October 1996] there are several enhancements to be expected
with respect to IWPS technology.
The most important one to be mentioned here is the creation of a
"Common Indexing Protocol" that must enable the integration of
X.500, Whois++ and protocols that use stand-alone databases. Such
a protocol would not only enable integration but would offer at
the same time the possibility to explore yellow pages services and
enhanced searches, even if used for X.500 only.
In the context of the Common Indexing Protocol the stand-alone
LDAP servers should be mentioned that are announced by several
software developers. These are stand-alone address databases that
can be accessed by LDAP. Currently also a public domain version is
available from the University of Michigan. Also announced is an
LDAP-to-DAP gateway that can integrate a stand-alone LDAP server
in an X.500 infrastructure.
Other improvements include defining a common core schema for
multiple White Pages services, leading to the possibility of
accessing data in multiple services through a single access
protocol.
The 1993 version of the X.500 standard has already been
implemented in several products. It is an enhancement over the
1988 standard in several ways, but has not been implemented in the
NameFLOW-Paradise infrastructure yet. The main reason is that the
standard doesn't recognize the existence of a single root DSA, but
assumes that the managers of first-level DSAs (the country DSA's)
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make bilateral contracts for interconnection. In the case of
NameFLOW-Paradise such a situation would be unmanageable. In [13]
an enhancement of the 1993 standard is proposed that makes a
single root possible. As soon as implementations of [13] are
available, NameFLOW-Paradise will experiment with 1993 DSAs. This
is expected in 1997.
Once these developments reach stability, they may be referenced by
later versions of this BCP document.
13. Security considerations
The security implications of having a directory are many.
- People will have a standard way to access the information
published.
- People will be able to gather parts of the information for
purposes you never intended (like publishing directories,
building search engines, headhunting or making harassing
phone calls).
- People will attempt to access more of the information than
you intended to publish, by trying to break security
functions or eavesdropping on conversations other users have
with the Directory.
- If modification over the Net is possible, people will attempt
to change your information in unintended ways. Sometimes
users will change data by mistake, too; not all undesired
change is malicious.
The first defense for directory security is to limit your
publication to stuff you can live with having publicly available,
whatever happens.
The second defense involves trying to impose access control. LDAP
supports a few access control methods, including the use of
cleartext passwords. Cleartext passwords are not a secure
mechanism in the presence of eavesdroppers; this document
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encourages use of stronger mechanisms if modification is made
available over the open Internet. Otherwise, modification rights
should be restricted to the local intranet.
The third defense involves trying to prevent "inappropriate"
access to the directory such as limiting the number of returned
search items or refuse list operations where they are not useful
to prevent "trolling". Such defenses are rarely completely
successful, because it is very hard to set limits that
differentiate between an innocent user doing wasteful searching
and a malicous data troller doing carefully limited searches.
Future enhancements may include using encrypted sessions, public
key logins and signed requests; such mechanisms are not generally
available today.
14. Acknowlegdements
The authors wish to thank the following people fo their
constructive contributions to the text in this document:
Peter Bachman
David Chadwick
William Curtin
Patrik Faltstrom
Rick Huber
Thomas Lenggenhager
Sri Saluteri
Mark Wahl
15. Glossary
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DAP Directory Access Protocol; protocol used between a DUA and a
DSA to access the Directory Information. Part of X.500.
DSP Directory System Protocol: the protocol used between two DSAs
DSA Directory System Agent - entity that provides DUAs and other
DSAs access to the information stored in the Directory
LDAP Lightweight Directory Access Protocol - defined in RFC 1777
Further terms may be found in RFC 1983.
16. References
[1] Directory Services and Privacy Issues, E. Jeunik and E.
Huizer. Proceedings of Joint European Networking Conference
1993, Trondheim
[2] Building an X.500 Directory Service in the US, B. Jennings,
RFC1943
[3] Building Naming and Structuring Guidelines for X.500
Directory Pilots, P. Barker, S. Kille, T. Lenggenhager,
RFC1617
[4] The COSINE and Internet X.500 Schema. P. Barker & S. Kille,
RFC1274
[5] Introducing a Directory Service, SURFnet report 1995 (see
URL:
http://info.nic.surfnet.nl/surfnet/projects/x500/introducing/)
[6] Paradise International Reports, University College London,
April 1991 - April 1994
[7] Naming Guidelines for the AARNet X.500 Directory Service,
Michaelson and Prior, RFC 1562
[8] CCITT Blue Book, Volume VIII - Fascicle VIII.8, November 1988
[9] Lightweight Directory Access Protocol, W. Yeong, T. Howes, S.
Kille, RFC1777
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[10] Replication and Distributed Operations extensions to provide
an Internet Directory using X.500, S. Kille, RFC1276
[11] ISO transport services on top of the TCP: Version: 3, M.
Rose, D. Cass, RFC1006
[12] Recommendations for an X.500 Production Directory Service, R.
Wright et al., RFC1803
[13] Managing the X.500 Root Naming Context, D. Chadwick, RFCxxxx
[14] A Revised Catalog of Available X.500 Implementations, A.
Getchell, S. Sataluri, RFC1632
[15] A Naming Scheme for c=US, The North American Directory Forum,
RFC1255
[16] A Common Schema for the Internet White Pages Service, T.
Genovese, B. Jennings, Work In Progress [draft-ietf-ids-
iwps-schema-spec-03.txt]
[17] Key words for use in RFCs to Indicate Requirement Level, S.
Bradner, RFC 2119
17. Authors address
Harald Tveit Alvestrand
UNINETT
P.O.Box 6883 Elgeseter
N-7002 TRONDHEIM
NORWAY
+47 73 59 70 94
Harald.T.Alvestrand@uninett.no
Peter Jurg
SURFnet
P.O.Box 19035
NL-3501 DA UTRECHT
THE NETHERLANDS
+31 30 2305305
Peter.Jurg@surfnet.nl
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