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rfc:rfc2148

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.

Alvestrand & Jurg Best Current Practice [Page 1] RFC 2148 Internet White Pages Service September 1997

   (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
         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.

Alvestrand & Jurg Best Current Practice [Page 2] RFC 2148 Internet White Pages Service September 1997

 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
 cases:
  1. The individual is employed by the maintainer's organization
  1. The individual is enrolled in the university/school that

maintains the data

  1. The individual is a (personal) subscriber of the maintainer's

Internet service

Alvestrand & Jurg Best Current Practice [Page 3] RFC 2148 Internet White Pages Service September 1997

 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:
  1. The individual's name
  1. The individual's e-mail address, in RFC-822 format; if not

present, some other contact information is to be included

  1. 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 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:
  1. The individual's phone number
  1. The individual's fax number
  1. The individual's postal address

Alvestrand & Jurg Best Current Practice [Page 4] RFC 2148 Internet White Pages Service September 1997

  1. 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:
  1. The URL of the organizations home page on the Web
  1. Postal address
  1. Fax numbers
  1. Internet domain
  1. 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 larger
 organizations. The following recommendations can be made with respect
 to these issues:
  1. 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.
  1. 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.

Alvestrand & Jurg Best Current Practice [Page 5] RFC 2148 Internet White Pages Service September 1997

  1. 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.
  1. 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.
  1. 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:
  1. Publish only correct information.
  1. Give people the possibility to view the information stored

about themselves and the right to withhold information or

      have information altered.
  1. Don't publish information "just because it's there". Publish

what is needed and what is thought useful, and no more.

Alvestrand & Jurg Best Current Practice [Page 6] RFC 2148 Internet White Pages Service September 1997

 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:
  1. Micropayment technology is not available at the moment.
  1. 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.
  1. 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:
  1. The name of a person
  1. The name of an organization this person can be related to

Alvestrand & Jurg Best Current Practice [Page 7] RFC 2148 Internet White Pages Service September 1997

  1. 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. 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

Alvestrand & Jurg Best Current Practice [Page 8] RFC 2148 Internet White Pages Service September 1997

 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:
  1. A Yellow Pages service with a large scope. See [5].
  1. Searching outside the limited patterns listed here, in

particular searching for a person without knowing which

       organization he might be affiliated to.
  1. 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.

Alvestrand & Jurg Best Current Practice [Page 9] RFC 2148 Internet White Pages Service September 1997

 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 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)

Alvestrand & Jurg Best Current Practice [Page 10] RFC 2148 Internet White Pages Service September 1997

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) 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.

Alvestrand & Jurg Best Current Practice [Page 11] RFC 2148 Internet White Pages Service September 1997

13. Security considerations

 The security implications of having a directory are many.
  1. People will have a standard way to access the information

published.

  1. 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).
  1. 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.
  1. 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 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.

Alvestrand & Jurg Best Current Practice [Page 12] RFC 2148 Internet White Pages Service September 1997

14. Acknowlegdements

 The authors wish to thank the following people for their constructive
 contributions to the text in this document:
       Peter Bachman <peterb@suport.psi.com>
       David Chadwick <D.W.Chadwick@iti.salford.ac.uk>
       William Curtin <curtinw@ncr.disa.mil>
       Patrik Faltstrom <paf@swip.net>
       Rick Huber <rvh@att.com>
       Thomas Lenggenhager <lenggenhager@switch.ch>
       Sri Saluteri <sri@qsun.ho.att.com>
       Mark Wahl <M.Wahl@critical-angle.com>

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,
   http://www.surfnet.nl/surfnet/diensten/x500/privacy.html

[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

Alvestrand & Jurg Best Current Practice [Page 13] RFC 2148 Internet White Pages Service September 1997

[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

[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.

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

   Bradner, RFC 2119,

Alvestrand & Jurg Best Current Practice [Page 14] RFC 2148 Internet White Pages Service September 1997

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

Alvestrand & Jurg Best Current Practice [Page 15]

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