draft BCP for the Internet White Pages Service September 96
Best Current Practice for the Internet White Pages Service
Tue Sep 24 15:29:10 MET DST 1996
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 author.
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The file name of this version is draft-ietf-ids-ds-bcp-01.txt
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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) The organization MUST do this in accordance with the laws
of the country in which it resides, and SHOULD also follow
the recommendations of [1]
(3) The preferable way for publishing the information is by
using X.500 as its data structure and naming scheme. 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 supporting an LDAP server for
those 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
single X.500 name space in the world, and that all names in
this name space are resolvable.
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The rest of this document is justification and details for this
recommendation.
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 others 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
todays experience, todays protocols, todays products and todays
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 exists 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
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. Inter connection of databases however,
is highly recommended for an IWPS, since it ensures that data can
be found. Hence ph as such is not considered to be a good
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candidate for an IWPS, but future developments may change this
situation (see section 13).
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. When
such technology becomes available and experiments show that they
work, this document will be updated.
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 8-12 discuss X.500
specific issues. In section 13 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. IWPS- information of 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 maintainers organization
- The individual is enrolled in the university/school that
maintains the data
- The individual is a (personal) subscriber of the maintainers
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 dont
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
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organization the information relates to.
4. What kind of information should be published?
The information to be published about an individual should at
least include:
- The individuals name
- The individuals e-mail address, in RFC-822 format; if not
present, some other contact information is to be included
- Some indication of the individuals 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
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 individuals phone number
- The individuals fax number
- The individuals postal address
- The URL of the individuals home page on the Web
In the near future it will be a good idea to also store public key
information. 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
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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 1st component of the domain name.
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 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
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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.
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 cant 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.
- Dont publish information "just because its there". Publish
whats needed and whats 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.
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7. Do not charge for lookups
A very common question with respect to the IWPS is how it has to
be financed. In the current IWPS it believed that due to todays
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
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 3,5 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:
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- 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
organizations. Such possibilities may however violate privacy
laws.
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.
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.
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
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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 fo the operation of a database in the in 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). ISO is revising X.500, but products
that support the revision arent 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.
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
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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 its control.
If those turf battles arent 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 project.
More information on DANTE NameFlow 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, 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)
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11. Make services available
The technical investment in running an X.500 service is not
enormous, see for example [5].
12. Future developments
Today [September 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.
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 change is
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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
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. 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
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[5] Introducing a Directory Service, SURFnet report 1995
[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
[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
15. 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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