Network Working Group                                   H. Alvestrand
Request for Comments: 2148                                    UNINETT
BCP: 15                                                       P. Jurg
Category: Best Current Practice                               SURFnet
                                                       September 1997

             Deployment of the Internet White Pages Service

Status of this Memo

   This document specifies an Internet Best Current Practices for the
   Internet Community, and requests discussion and suggestions for
   improvements.  Distribution of this memo is unlimited.

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.

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     (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

     (3)   All interested parties SHOULD make sure there exists a core
           X.500 name space in the world, and that all names in this
           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

   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

   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.

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   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. 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

   -    The individual is employed by the maintainer's organization

   -    The individual is enrolled in the university/school that
        maintains the data

   -    The individual is a (personal) subscriber of the maintainer's
        Internet service

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   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

   -    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

   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 individual's phone number

       -    The individual's fax number

       -    The individual's postal address

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       -    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

   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

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.

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   -    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

   -    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 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.

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   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

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
        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-

   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

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   -    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

   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. 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

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   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 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

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 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)

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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 [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

   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) 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.

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13.  Security considerations

   The security implications of having a directory are many.

   -    People will have a standard way to access the information

   -    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

   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

   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.

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14.  Acknowlegdements

   The authors wish to thank the following people for 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

   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] Jeunik, E. and E. Huizer. Directory Services and Privacy
     Issues. Proceedings of Joint European Networking Conference
     1993, Trondheim,

[2]  Jennings, B. Building an X.500 Directory Service in the US,
     RFC1943, May 1996.

[3]  Barker, P., S. Kille, T. Lenggenhager, Building Naming and
     Structuring Guidelines for X.500 Directory Pilots, P.  Barker,
     S. Kille, T. Lenggenhager, RFC1617

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[4]  The COSINE and Internet X.500 Schema. P. Barker & S. Kille,

[5]  Introducing a Directory Service, SURFnet report 1995 (see

[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

[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,

[16] A Common Schema for the Internet White Pages Service, T.
     Genovese, B. Jennings, Work In  Progress.

[17] Key words for use in RFCs to Indicate Requirement Level, S.
     Bradner, RFC 2119,

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17.  Authors address

   Harald Tveit Alvestrand
   P.O.Box 6883 Elgeseter

   +47 73 59 70 94

   Peter Jurg
   P.O.Box 19035

   +31 30 2305305

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