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RFC 1943 - Building an X.500 Directory Service in the US


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Network Working Group                                        B. Jennings
Request for Comments: 1943                    Sandia National Laboratory
Category: Informational                                         May 1996

             Building an X.500 Directory Service in the US

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Abstract

   This document provides definition and recommends considerations that
   must be undertaken to operate a X.500 Directory Service in the United
   States.  This project is the work performed for the Integrated
   Directory Services Working Group within the Internet Engineering Task
   Force, for establishing an electronic White Pages Directory Service
   within an organization in the US and for connecting it to a wide-area
   Directory infrastructure.

   Establishing a successful White Pages Directory Service within an
   organization requires a collaborative effort between the technical,
   legal and data management components of an organization. It also
   helps if there is a strong commitment from the higher management to
   participate in a wide-area Directory Service.

   The recommendations presented in the document are the result of
   experience from participating in the Internet White Pages project.

Table of Contents

   1.0     Introduction                                            2
   1.1     Purpose of this Document                                2
   1.2     Introduction to Directory Services                      2
   2.0     The X.500 Protocol                                      4
   2.1     Introduction                                            4
   2.2     Directory Model                                         4
   2.3     Information Model                                       5
   2.4     Benefits and Uses for X.500 Directory Service           6
   2.5     Other Applications of X.500                             7
   3.0     Legal Issues                                            8
   3.1     Introduction                                            8
   3.2     Purpose of the Directory                                8
   3.3     User Rights                                             9
   3.4     Data Integrity                                          9

   3.5     Protection of the Data                                 10
   3.6     Conclusions                                            10
   4.0     Infrastructure                                         11
   4.1     Introduction                                           11
   4.2     A Well Maintained Infrastructure                       11
   4.3     DUA Interfaces for End Users                           12
   5.0     Datamanagement & Pilot Projects                        13
   5.1     Simple Internet White Pages Service                    13
   5.2     InterNIC                                               13
   5.3     ESnet                                                  14
   6.0     Recommendations                                        14
   6.1     General                                                14
   6.2     Getting Started                                        14
   6.3     Who are the Customers                                  14
   6.4     What are the Contents of the Directory                 15
   6.5     What are the Rights of the Individuals                 15
   6.6     Data Integrity                                         16
   6.7     Data Security                                          16
   6.8     Data Administration                                    17
   6.9     Conclusion                                             17
   7.0     References                                             18
   8.0     Glossary                                               19
   9.0     Security Considerations                                22
   10.0    Author's Address                                       22

1.0     Introduction

1.1     Purpose of this Document

   This document provides an introduction for individuals planning to
   build a directory service for an organization in the US. It presents
   an introduction to the technical, legal, and organizational aspects
   of a directory service. It describes various options to organizations
   who want to operate an X.500 Directory service and illustrates these
   with examples of current X.500 service providers.

1.2     Introduction to Directory Services

   An electronic directory server is an electronic process that provides
   a list of information provided via electronic access. This
   information is variable in content, however it should be explicitly
   defined by the directory purpose. Information about people,
   organizations, services, network hardware are just a few examples of
   data content that a directory service can provide. The aim of an
   X.500 Directory service is to make using the directory intuitive and
   as easy to use as calling for directory assistance. The X.500
   Directory service is an international standard ratified by the
   International organization for Standardization (IS) and the ITU-T

   International Telecommunication Union formerly (CCITT) in 1988 [1].

   The Directory is intended to be global service comprised of
   independently operated and distributed Directory Service Agents
   (DSAs), that provide information in the form of a White Pages Phone
   Directory.

   Electronic mail communication benefits from the existence of a global
   electronic White Pages to allow network users to retrieve addressing
   information in an intuitive fashion. Manual searching for names and
   addresses, specifically electronic addresses, can take a great deal
   of time. A White Pages directory service can enable network users to
   retrieve the addresses of communication partners in a user friendly
   way, using known variables such as common name, surname, and
   organization to facilitate various levels of searches.

   In order to make global communication over computer networks work
   efficiently, a global electronic White Pages service is
   indispensable. Such a directory service could also contain telephone
   and fax numbers, postal addresses as well as platform type to
   facilitate in translation of documents between users on different
   systems. An electronic White Pages may prove to be useful for
   specific local purposes; replacing paper directories or improving
   quality of personnel administration for example. An electronic
   directory is much easier to produce and more timely than paper
   directories which are often out of date as soon as they are printed.

   The Internet White Pages Project provides many companies in the US
   with an opportunity to pilot X.500 in their organizations.
   Operating as a globally distributed directory service, this project
   allows organizations in a wide variety of industry type to make
   themselves known on the Internet and to provide access to their staff
   as desired.

   Some organizations, such as ESnet agreed to manage directory
   information for other organizations. ESnet maintains data at their
   site for all the national laboratories. They provide assistance to
   organizations in defining their directory information tree (DIT)
   structure. They also provide free access to the X.500 Directory via
   Gopher, WWW, DUAs, whois and finger protocols.

   The InterNIC is another directory services provider on the Internet.
   To date [June 1995] they hold X.500 directory data for 52
   organizations and provide free access to this data via various
   protocols: X.500 DUA, E-Mail, whois, Gopher and WWW.

   To find the most current listing of X.500 providers see RFC 1632 -
   Catalog of Available X.500 Implementations [2].

2.0     The X.500 Protocol

2.1     Introduction

   This chapter provides the basic technical information necessary for
   an organization to begin deploying an X.500 Directory Service. It
   provides a brief introduction to the X.500 protocol and the
   possibilities that X.500 offers.

2.2     The Directory Model

   X.500 Directory Model is a distributed collection of independent
   systems which cooperate to provide a logical data base of information
   to provide a global Directory Service. Directory information about a
   particular organization is maintained locally in a Directory System
   Agent (DSA). This information is structured within specified
   standards. Adherence to these standards makes the distributed model
   possible. It is possible for one organization to keep information
   about other organizations, and it is possible for an organization to
   operate independently from the global model as a stand alone system.
   DSAs that operate within the global model have the ability to
   exchange information with other DSAs by means of the X.500 protocol.

   DSAs that are interconnected form the Directory Information Tree
   (DIT). The DIT is a virtual hierarchical data structure. An X.500
   pilot using QUIPU software introduced the concept of a "root" DSA
   which represents the world; below which "countries" are defined.
   Defined under the countries are "organizations". The organizations
   further define "organizational units" and/ or "people". This DIT
   identifies the DIT for the White Pages X.500 services.

   Each DSA provides information for the global directory. Directories
   are able to locate in the hierarchical structure discussed above,
   which DSA holds a certain portion of the directory. Each directory
   manages information through a defined set of attributes and in a
   structure defined as the Directory Information Base (DIB).

   A DSA is accessed by means of a Directory User Agent (DUA). A DUA
   interacts with the Directory by communicating with one or more DSAs
   as necessary to respond to a specific query. DUAs can be an IP
   protocol such as whois or finger, or a more sophisticated application
   which may provide Graphical User Interface (GUI) access to the DSA.
   Access to a DSA can be accomplished by an individual or automated by
   computer application.

2.3     The Information Model

   In addition to the Directory Model, the X.500 standard defines the
   information model used in the Directory Service. All information in
   the Directory is stored in "entries", each of which belong to at
   least one "object class". In the White Pages application of X.500
   object classes are defined as country, organization, organizational
   unit and person.

   The object classes to which an entry belongs defines the attributes
   associated with a particular entry. Some attributes are mandatory
   others are optional. System administrators may define their own
   attributes and register these with regulating authorities, which will
   in turn make these attributes available on a large scale.

   Every entry has a Relative Distinguished Name (RDN), which uniquely
   identifies the entry. A RDN is made up of the DIT information and the
   actual entry.

   The Directory operates under a set of rules know as the Directory
   schema.  This defines correct utilization of attributes, and ensures
   an element of sameness throughout the global Directory Service.

   Under the White Pages object class "Person" there are three mandatory
   attributes:

        objectClass     commonName      surName

   These attributes along with the DIT structure above, define the RDN.

   An example of an entry under Sandia National Laboratory is shown
   here: @c=US@o=Sandia National Laboratory@ou=Employees@cn=Barbara
   Jennings

                                   root
                                   /  \
                                  /    \
                                c=US    c=CA
                                /  \
                               /    \
                  o=Sandia National   o=ESnet
                    Laboratory
                   /   \
                  /     \
            ou=Employees  ou=Guests
              /                \
             /                  \
     cn=Barbara Jennings        cn=Paul Brooks

   Organizations may define the best structure suited for their DIT.
   Typically an organizations DIT will look very much like the
   organizations structure itself. A DIT structure is determined by
   naming rules and as such, becomes the elements unique Relative
   Distinguished Name (RDN). The DIT structure may also be dependent on
   whether the DSA information is administered by a flat file or a
   database. Extra consideration to designing of the DIT structure
   should be taken when using flat files versus a database, as it takes
   longer to search through a flat file if the tree structure becomes
   too complex or intricate. To obtain information on recommended schema
   for DIT structuring see RFC1274 [3].

2.4     Benefits and Uses for X.500 Directory Service

   The nature of the X.500 Directory makes it suitable for independently
   operated segments that can be expanded to global distribution. The
   benefits for local directory use are:

   - with the distributed nature of the service, an organization may
   separate the responsibility for management of many DSAs and still
   retain the overall structure;

   - the robustness of this service allows it to provide information to a
   wide range of applications. Whereas globally integrated projects must
   conform to a specific DIT, independent X.500 operations may define
   unique DITs, object classes and attributes as per their specific
   needs;

   - X.500 is a good alternative for paper directories, offering the
   ability to update and modify in an interactive mode. This allows a
   company to provide the most current information with less cost and
   effort;

   - because of the electronic base of X.500, other electronic
   applications may interact with the application without human
   intervention.

   The benefits for global directory use are:

   - the distributed nature of X.500 is well suited for large global
   applications such as the White Pages Directory. Maintenance can be
   performed in a distributed manner;

   - X.500 offers good searching capabilities from any level in the DIT.
   Also with "User Friendly Naming" in place, searches are very
   intuitive;

   - there are DUA interfaces for the White Pages service available for
   all types of workstations. For an overview of X.500 software reference
   RFC1632.

   - X.500 is an international standard. Using such a standard ensures
   interoperability within the worldwide base.

2.5     Other Applications of X.500

   In addition to the White Pages, X.500 can be used as a source for any
   type of information that needs a distributed storage base.

   The University of Michigan is using X.500 for electronic mail
   routing. Any mail coming to the university domain, umich.edu; gets
   expanded out to a local address that is stored in the rfc822Mailbox
   attribute. The University also operates a standard X.500 name server
   which provides name lookup service of over 200,000 names. They use
   the Lightweight Directory Access Protocol (LDAP) [11].

   An implementation of the X.500 Standard directory service has been
   incorporated into the Open Software Foundation (OSF) Distributed
   Computing Environment (DCE). This component, known as the Global
   Directory Service (GDS), provides an area where distributed
   application clients can find their application servers. The GDS, in
   response to requests made by other clients, provides the unique
   network address for a particular DCE resource.  Because it is based
   on a international standard, GDS can offer access to resources among
   users and organizations worldwide. This scalable service can be
   performed in DCE environments that range in size from the very small
   to the very large.

   Lookup services can be implemented into a variety of applications.
   Cambridge University in Great Britain implemented the X.500 directory
   service into an employee locator application. Based on badge sensors
   at strategic locations, this application can determine the
   whereabouts of an employee on the campus. As the individual moves
   about, the sensors register their location in an X.500 Directory.

   Digital Signature Service (DSS) and Privacy Enhanced Mail (PEM) work
   on the principal of a directory key server which generates and
   provide users with "public" codes that match previously registered
   "private" codes. Only the recipient can decipher messages sent in
   this fashion. The X.509 [4] standard for key certificates easily fits
   within the structure of the X.500 Directory Service.

3.0     Legal Issues

3.1     Introduction

   Currently in the United States, there are no specific legal rules for
   the information that is provided via an electronic directory service.
   Various organizations and groups associated with usage of the
   Internet, noting a need to address privacy and data integrity issues,
   have prepared directives to address this issue. Two such areas
   addressed are those of the rights of registrants included in the
   directory and the responsibility of administrators to guarantee the
   integrity of such data.

   Registries containing information that is related to an individual is
   freely transferred and unregulated in the US, unless the provider of
   the data is an agency or an holder of sensitive information as
   defined by federal legislation and further may differ for each state.
   An agency is defined as: any executive department, military
   department, Government corporation, Government controlled
   corporation, or other establishment in the executive branch of the
   Government (including the Executive Office of the President), or any
   independent regulatory agency. Sensitive data can be financial
   records, medical records, and certain legal documents. As previously
   noted, each state has their own legislation on sensitive or private
   data.The registered persons have little recourse to control list
   information short of filing a lawsuit against the information
   provider.

   For individuals who transfer data across country boundaries, it is
   important to understand that other countries may have legislation to
   regulate data. Prior to requesting list information from these
   countries, an administrator should review applicable legislation and
   have some mechanism in place to ensure how data will be handled once
   it is crosses the border. Policy Statements for some countries have
   been prepared and are provided for via Code of Conduct papers.

3.2     Purpose of the Directory

   The operational intent including presentation data and list
   registrants and access rights must be clearly defined and stated.
   Initially this provides the skeleton of the DIT. Eventually a
   statement such as this may provide a basis legally justifying the
   directory.

   All data presented must be defined in the purpose. If for example, a
   directory is for the sole purpose of providing professional
   addressing information - an entry would include name, postal address,
   office telephone, facsimile number, electronic mail address and

   company name.  Private address information listing the home address
   or phone would be prohibited as would any other information not
   directly related to addressing.

3.3     User Rights

   The North American Directory Forum (NADF) has published a document
   that defines the User Bill of Rights [5]. This document defines an
   individuals rights regarding the public release of personal or
   private information.  Among other issues stated, the user has the
   right to be notified regarding the inclusion of their information in
   a data registry as well as the right to examine and have incorrect
   information changed.

   This paper is specifically written for the North American Directory
   Forum and recommends compliance with US or Canadian laws regulating
   privacy and access information.

   Although current US legislation does not include all the suggestions
   in this document, it is the responsibility of the controller of the
   data to respect the rights of the individuals. These recommended
   rules can be seen as respect for the individual and the considerate
   controller will follow these guidelines within any boundaries that
   they may be mandated by.

3.4     Data Integrity

   An information provider has the responsibility to guarantee the data
   that they make available to users. The integrity of a data source is
   heavily weighted by the accuracy and timeliness of the contents.
   Interoperable data sources must have concurrence of these factors as
   well. The degree to which an information provider can guarantee the
   validity of the data that they present, reflects on the validity of
   the provider in general. RFC 1355 [6], suggests that a data source
   enable accuracy statements describing the process that the individual
   NIC will use to maintain accuracy in the database.

   In the European community, it is a legal requirement that the
   information provider guarantee accurate data.

   The controller of the information needs to be certain of the primary
   source of data. When possible, the controller should develop routines
   of random checks to validate the registry data for correctness.

3.5     Data Security

   A Directory Service with non-authenticated access from the Internet
   is difficult to protect from unauthorized use. Unauthorized use being
   defined by each organization within the directory purpose statement.
   Typical misuse being by individuals who attempt to duplicate the
   directory for unauthorized purposes. Other security measures include:
   Access Control Lists (ACLs), limitations on number of entries
   returned to a query, and time to search flags. The result of such
   controls will affect the legitimate user as well as the user they are
   intended to block.

   An alternative that may provide protection from misuse is to create
   and display an attribute with each entry stating non-approved usage.
   This feature will also provide evidence of restricted use in the
   event that a legal case is necessary to stop unauthorized access.

   The responsibility again falls on the data provider/implementor of
   the directory service. Astute programmers will create or make use of
   existing tools to protect against data destruction, falsification,
   and misuse.

3.6     Conclusions

   User Rights, Data Integrity and Protection of data should not be
   considered merely in an effort to abide by legal rulings; they should
   be the intention of a good data source. A successful Directory
   Service must be aware of the requirements of those individuals
   inclusive in the list as well as those of the directory users.

   In general, at the minimum the following conditions should be
   observed:

        1. Define the purpose of the Directory.
        2. Initially inform all registrants of their inclusion in
           a Directory.
        3. Prevent the use of data beyond the stated purpose.
        4. Limit the attributes associated to an entry within
           boundaries of the purpose.
        5. Work towards a suitable level of security.
        6. Develop a mechanism to correct/remove faulty data
           or information that should not be in the Directory.

4.0     Infrastructure

4.1     Introduction

   The White Pages Project, currently operated by Performance Systems
   International (PSI) provides a reliable QUIPU infrastructure for
   sites wishing to provide their own X.500 directory. Started in 1989
   as the NYSERNet White Pages Pilot Project it was the first
   production-quality field test of the Open Systems Interconnection
   (OSI) technology running on top of TCP/IP suite of protocols [7].
   This pilot X.500 Directory, provided a real-time testbed for a
   variety of administrative and usage issues that arise. Today, more
   than 30 countries participate in the globally distributed project
   with over 1 million entries. The White Pages pilot is one of 37 other
   pilots cooperating to provide information in the Nameflow-PARADISE
   directory; an European project.

   Initially the software was public domain, QUIPU X.500 [8]. This
   "shareware" application in conjunction with administrative services
   provided free of charge by PSI, allowed for a truly distributed X.500
   Directory Service to operate.

   In keeping with the Internet rules of operation, the lack of the US
   regulations, the suggestions of North American Directory Forum and
   the Internet Engineering Task Force (IETF), the complications that
   arise from multi-distributed data as a service can be overwhelming.
   PSI took on the challenge to provide such a service, and continues to
   ensure operations today.

4.2     A Well Maintained Infrastructure

   This distributed information service involves the cohesive effort of
   all of the participating organizations. The ISO Development
   Environment (ISODE) implementation of the OSI Directory, provided the
   attributes and uniformity to facilitate this effort.

   The primary DSA for the PSI Project is named Alpaca. Operating on a
   Sun Sparc 10 with 120 megabytes of memory, this host serves as the
   Master for the DSAs of 117 organizations under c=US. Redundancy for
   Alpaca is provided by two sources, Fruit Bat operated by PSI and Pied
   Tamarin operated by the InterNIC. Slave updates to this host are
   provided on a nightly basis from the individual DSAs.

   The data presentation is hierarchical in nature and emulates the
   common white pages telephone book. The information provided contains
   at minimum: a common name, voice phone listing, and electronic mail
   addressing. Each entry has a uniqueness associates with it; the
   relative distinguished name which is comprised of the entire

   directory information tree. The DITs may vary slightly, but each must
   contain an organization, and a person. The nature of the directory
   and the structure of the actual organization for whom the directory
   is being provided contribute to the overall DIT structure. The
   following is a list of commonly used attributes:

commonName      physicalDeliveryOfficeName      stateOrProvinceName
description     photo                           streetAddress
userid          postOfficeBox                   surname
favouriteDrink  postalAddress                   telephoneNumber
title           rfc822Mailbox                   facsimileTelephoneNumber

4.3     DUA Interfaces for End Users

   There are a variety of user interfaces on the market today that will
   provide Directory User Agent access to the X.500 Directory. Standard
   protocols such as fred, whois, whois++, finger, are used widely.
   Interfaces are also available via World-wide Web browsers and
   electronic mail.

   Vendors providing DUAs include ISODE Consortium, NeXor, and Control
   Data Corporation. These applications operate in conjunction with the
   vendor provided DSAs.

   Historically DUA interfaces were difficult to implement and required
   the entire OSI stack. Implementing such a product on a PC or Apple
   platform required skillful programming. The executable for these
   platforms were usually very large. The IETF has since defined and
   standardized the Lightweight Directory Access Protocol (LDAP) [11]; a
   protocol for accessing on-line Directory services which offers
   comparable functionality to the Directory Access Protocol (DAP). It
   runs directly over TCP and is used by nearly all X.500 clients. LDAP
   does not have the overhead of the various OSI layers and runs on top
   of TCP/IP.

   The functionality varies by specific DUA. Each offers access to the
   X.500 Directory. Most offer the ability to make modifications to
   entries. There are a few that offer Kerberos authentication.

   Further information on LDAP clients for specific platforms can be
   found on the University of Michigan WWW server:
   http://www.umich.edu/~rsug/ldap.

   Another interface that has been tested and recommended for users by
   our Dutch (Surfnet) colleagues is Directory Enquiry (DE). Originally
   developed by University College London for the Paradise project in
   Europe, the engineers at Surfnet have selected DE as the best
   interface for "dumb" terminals. They have also translated the

   interface into Dutch for their local users [12].

   Ideally, users should be able to access X.500 directly from their
   electronic mail applications. Vendors (other than the ones mentioned
   above) have been slow to incorporate the X.500 Standards into their
   electronic mail applications.

5.0     Datamanagement & Pilot Projects

5.1     Simple Internet White Pages Service

   A wide variety of directory services retrieval protocols has emerged
   in the time since the original Internet White Pages was begun in
   1989. To ensure that decentralized implementations will have
   interoperability with other providers, the IETF Integrated Directory
   Services Working Group, is working to create a draft focusing on the
   common information and operational modeling issues to which all
   Internet White Pages Services (IWPS) must conform to.

   Utilizing current information servers, the conceptual model described
   includes issues regarding naming, schema, query and response issues
   for a narrowly defined subset of directory services. The goal of this
   paper is to establish a simple set of information objects, coupled
   with a basic set of process requirements that will form a basis which
   can lead to ubiquitous IWPS. With this goal in mind, it will be
   easier to proved a consistent User view of the various directory
   services.

5.2     InterNIC

   The InterNIC [9] is a collaborative project of two organizations
   working together to offer the Internet community a full scope of
   network information services. Established in January 1993 by the
   National Science Foundation, the InterNIC provides registration
   services and directory and database services to the Internet.
   (Internet a global network of more than 13,000 computers networks,
   connecting over 1.7 million computers and used by an estimated 13
   million people.) In keeping up with the exponential growth of the
   Internet, the InterNIC provides a guide to navigate the maze of
   available resources.

   InterNIC provides two types of services; InterNIC directory and
   database services and registration services. AT&T provides the
   directory and database services, acting as the pointer to numerous
   resources on the network offering X.500 to help users easily locate
   other users and organizations on the Internet.

5.3     ESnet

   The Energy Sciences Network [10], is a nationwide computer data
   communications network whose primary purpose is support multiple
   program, open scientific research. As part of this support, ESnet
   offers networking services including information access and
   retrieval, directory services, group communications series, remote
   file access services and infrastructure services. As a early member
   of the White-Pages Pilot Project, ESnet continues to be a part of the
   worldwide distributed directory service based on the ISO/OSI X.500
   standard. There are over nineteen ESnet organization represented in
   the directory, comprising over 120,000 entries. ESnet provides access
   to seven other sites via the X.500 DSAs.

6.0     Recommendations

6.1     General

   The X.500 Directory technology is available through several options.
   Vendors can provide consultation for schema design as well as supply,
   install, and support the software to perform the operations required.
   For smaller organizations or companies who do not want to administer
   their own DSA, there are providers available who will maintain the
   DSAs remotely and provide this service to the Internet. Those with
   network and management expertise, can either operate independently or
   join one of several white pages directory projects. Careful
   consideration must be given to the initial investment required and
   the required maintenance process.

6.2     Getting Started

   Successful initialization of a directory service requires a
   systematic approach. The complexity of offering this type of service
   becomes more apparent as implementation progresses. Several aspects
   must be considered as this service becomes a cooperative effort among
   the technical, administrative, organizational, and legal disciplines.
   Procedures must be defined and agreed to at the initial phase of
   implementing an X.500 Directory service [13].  The following are
   issues that should be addressed in these procedures.

6.3     Who are the Customers?

   Defining the customer and the customer requirements will determine
   the scope of service to offer. What is the primary purpose for the
   directory service? A company may find it desirable to do away with a
   paper directory while simultaneously providing the current directory
   information. The directory may be for internal use only or expanded
   to any users with Internet access. Will the customer use the

   directory for e-mail address only or is other locational information
   such as postal address and telephone number a requirement?

   The directory may provide information to electronic customers such as
   distributed computing applications as well. In this case, the data
   must be provided in machine readable format.

   Will the customers extend across country boundaries? Information may
   be considered private by one country and not by another. It is
   necessary to be aware of the legalities and restrictions for the
   locality using the data.  Some counties have published a Code of
   Conduct with the IETF, explicitly stating the legal restrictions on
   directory and list data. Check the archives to determine if the
   country with whom information will be shared has presented such
   information.

6.4     What are the contents of the Directory?

   The information presented in the directory is tightly coupled with
   the purpose. If the purpose is to provide addressing information for
   individuals, then customary information would include: Name, address,
   phone, e-mail address, facsimile number, pager, etc. If the use of
   the directory is to facilitate electronic mail routing then the
   destination mail address needs to be included for each user. No other
   information should be presented in the directory if it is not
   directly related to the purpose.

   If the directory is internal only, it may be desirable to include the
   registrants title as well. Remember that information available on the
   Internet is generally open to anyone who wants to access it.
   Individuals wishing to target a specific market may access
   directories to create customer mailing lists.

   The structure or schema of the X.500 Directory must be an initial
   consideration. Will the hierarchy follow the company structure or is
   a different approach more practical? How many entries will there be
   in the directory five or 50,000? A complex hierarchyfor thousands of
   users may affect the efficiency of queries.

6.5     What are the rights of the individuals?

   The subjects included in the directory shall have well defined
   rights.  These may be mandated by company policy, legal restrictions,
   and the ultimate use of the directory. For a basic Internet White
   Pages Service these rights may include:

        1. the option of inclusion in the directory
        2. the right of access to the information
        3. the right to have inaccurate entries corrected

   The terms and conditions for employees of an organization may affect
   these rights. On becoming an employee of any organization, an
   individual inevitably agrees to forego certain personal privacies and
   to accept restrictions.

   Every organization should develop and publish the "rights" that can
   be expected by the list registrants.

6.6     Data Integrity

   Information that needs to be included in the directory may come from
   various sources. Demographic information may originate from the human
   resources department. Electronic mail addresses may be provided by
   the computer network department. To guarantee data integrity, it is
   advised that the data be identified and maintained as corporate
   information.

   The required timeliness of the data is unique for each DSA. Updates
   to the data may be a frequent as once a day or once a month. Updates
   to the data must be provided on a regular basis. In cases where data
   is time sensitive, an attribute should be included to display the
   most recent maintenance date.

   A regular check for data accuracy should be included in the directory
   administration. Faulty information may put an organization in breach
   of any data protection laws and possibly render the company as
   unreliable.

6.7     Data Security

   Securing networked information resources is inherently complex.
   Attempts must be made to preserve the security of the data. These may
   include access control lists (ACLs), limiting the number or responses
   allowed to queries, or internal/external access to the directory.

   The 1993 recommendations have added a complex access control model
   that is designed to tightly restrict the access that users may have
   to the information in the Directory. Local protection is configured
   by the implementor. A secure X.500 Directory should provide tools to
   protect against destruction, falsification, and loss of data.

   There is not a tool yet that will protect against the misuse of data.
   There are flags and limits that can be set from within the
   application that will serve somewhat as a barrier to such unwanted

   use. Any restrictions however, also will affect the legitimate users.
   One suggestion is to post a notice of illegitimate use within each
   entry. This of course will only serve as a deterrent and as an asset
   should legal action be required.

   Again, caution must be taken when transferring data between country
   and state borders. In the US data regulations differ from state to
   state.

6.8     Data Administration

   The decentralized nature of the X.500 Directory service means that
   each organization has complete control over the data. As part of a
   global service however, it is important that the operation of the DSA
   be monitored and maintained in a consistent manner. Authorization
   must be given to the local manager of the information and in some
   cases, the subjects included in the directory may also have
   modification privileges.

   Once the service is running, the importance of guaranteed operation
   can not be overstated. Maintenance of the local Directory will be an
   integral part of normal administrative procedures within the
   organization and must be defined and agreed upon in the initial
   stages of development.

6.9     Conclusion

   Establishing a Directory service within an organization will involve
   a great deal of cooperative effort. It is essential to get commitment
   from the integral parties of an organization at the onset.  This
   includes the technical, legal, and data managements components of the
   organization.  Executive level commitment will make it much easier to
   get the cooperation necessary.

   Operational procedures must be clearly defined, as the inclusion in a
   globally distributed service has wide visibility. Adherence to these
   procedures must be maintained to the highest degree possible as
   misinformation may result in unintentional legal violations and
   unreliable access or data can adversely affect on a companys
   reputation.

   An X.500 Directory can be extremely useful for an organization if it
   operates as designed. It may serve as the "hub" of the information
   routing and the basis for several everyday activities. A successful
   service will be one of the most important tools for communication in
   the computer network environment. For people to make use of the
   service, they must be able to rely on consistent and accurate
   information.

References

   1.      CCITT Blue Book, Volume VIII - Fascicle VIII.8, November 1988.

   2.      RFC 1632; A Revised Catalog of Available X.500
           Implementations. A. Getchell; ESnet, S.
           Sataluri; AT&T.

   3.      RFC 1274; The COSINE and Internet X.500 Schema. P. Barker &
           S. Kille.

   4.      CCITT Blue Book, Volume VIII - Fascicle VIII - Rec. X.509,
           November 1988.

   5.      RFC 1295; User Bill of Rights for entries and listing in the
           Public Directory. Networking Working Group; IETF, January
           1992.

   6.      STD 35, RFC 1355; Privacy and Accuracy Issues in Network
           Information Center Databases. Curran, Marine, August 1992.

   7.      RFC 1006, ISO Transport Class 2 Non-use of Explicit Flow
           Control over TCP RFC 1006 extension. Y. Pouffary, June 1995.

   8.      Colin Robbins, NEXOR Ltd., Nottingham, London.
           c.robbins@nexor.co.uk

   9.      InterNIC; Collaborative effort of AT&T and
           Network Solutions; info@internic.net

   10.     ESnet; Managed and funded by the US Department of Energys
           Energy Research Office in Scientific Computing (DOE/ER/OSC).

   11.     RFC 1777; Lightweight Directory Access Protocol, W. Yeong,
           T. Howes, S. Kille, March 1995.

   12.     Building a Directory Service, Final Report test phase SURFnet
           X.500 pilot project, June 1995.

   13.     The X.500 Directory Services: a discussion of the concerns
           raised by the existence of a global Directory, Julia M. Hill,
           Vol.2/No.1 Electronic Networking, Spring 1992.

   14.     Directory Services and Privacy Issues, E. Jeunik and E.
           Huizer.

   15.     The Little Black Book; Mail Bonding with OSI Directory
           Services, Marshall T. Rose, Simon & Schuster Company,
           1992.

   16.     NYSERNet White Pages Pilot Project: Status Report; NYSERNet
           Technical Report #89-12-31-1, Marshall T. Rose, December 1989.

   17.     RFC 1798, Connection-less Lightweight Directory Access
           Protocol, A. Young, June 1995.

   18.     RFC 1781; Using the OSI Directory to Achieve User Friendly
           Naming, S. Kille, March 1995.

   19.     draft-ietf-pds-iwps-design-spec-01.txt, Tony Genovese;
           Microsoft, Work in Progress, July 1995.

   20.     draft-ietf-ids-privacy-00.txt, B. Jennings; Sandia National
           Laboratories, S. Sataluri; AT&T, Work in Progress, November
           1994.

Glossary

   ACL     Access Control List; a mechanism to restrict access to data
           stored in an X.500 Directory Service

   Attribute       A collection of attributes belong to an entry in the
                   Directory Service, and contain information belonging
                   to that entry.

   c=      countryName; Object class definition, specifies a country.
           When used as part of the directory name, it identifies the
           country in which the named object is physically located.

   cn=     commonName; Attribute defining common name for individuals
           included in a directory. In 1988 standards can be up to 64
           characters.

   CCITT   The International Telegraph and Telephone Consultative
           Committee.

   DAP     Directory Access Protocol; the protocol between a DUA and a
           DSA.

   DIB     Directory Information Base; a collection of information
           objects in the Directory.

   DIT     Directory Information Tree; the hierarchy of the distributed
           database that makes up an X.500 service.

   DSA     Directory System Agent; an application that offers the
           Directory service, this is the database for the Directory.

   DUA     Directory User Agent; an application that facilitates User
           access to a DSA.

   E-Mail  Electronic Mail.  Entry A Directory Service contains entries
           on people, organizations, countries, etc. Entries belong to a
           certain class, and information on entries is stored in
           attributes.

   ESnet   Energy Sciences Network; nationwide computer data
           communications network.

   GUI     Graphical User Interface.

   IETF    Internet Engineering Task Force; an internationally
           represented task force charged with solving the short-term
           needs of the Internet

   Internet        A collection of connected networks, international,
                   running the Internet suite of protocols.

   InterNIC        Directory of Directories, a collaborative project
                   between AT&T, and Network Solutions, Inc.

   IP      Internet Protocol; the network protocol offering a
           conectionless-mode network service in the Internet suite of
           protocols.

   ISODE   ISO Development Environment, a research tool developed to
           study the upper-layers of OSI and deploy network applications
           according to the ISO OSI standards and ITU X series of
           recommendations.

   ITU     International Telecommunication Union; formerly the CCITT.

   LDAP    Lightweight Directory Access Protocol, an Internet Standard
           for a lightweight version of DAP running over TCP/IP.

   Object  Entries in a Directory Service belong to an Object Class to
           Class indicate the type and characteristic; e.g. Object Class
           "person".

   OSI     Open Standards Interconnection, An international
           standardization program, facilitated by ISO and ITU to develop
           standards for data networking.

   o=      organization; An attribute defining the company or
           organization that the person works for.

   ou=     organizational unit; An attribute found under organization.
           Denotes the department, division, or other such sub-unit of
           the organization that the person works in.

   PEM     Privacy Enhanced Mail; and Internet Standard for sending
           secure Electronic mail.

   PSI     Performance Systems International, Inc.; operator of the
           Internet White Pages Project

   QUIPU   X.500 Directory implementation developed by Colin Robbins
           while at the University College of London.

   RDN     Relative Distinguished Name; a unique identifier for each list
           subject, defined by the hierarchy of the DSA.

   RFC     Request For Comments; Internet series publications

   sn=     surname; Attribute defining the surname of the person in the
           directory.

   TCP/IP  Transmission Control Protocol and Internet Protocol; two
           internet protocols.

   White-Pages     Electronic directory, accessible via Internet suite of
                   protocols.

   Whois   An Internet standard protocol.

   Whois++ An Internet Directory Services protocol; a possible
           alternative for X.500 WPS

   White Pages Service a Directory Service that contains information on
                       people and organizations.

   X.500   A series of recommendations as defined by the ITU, that
           specify a Directory Services protocol.

9.0 Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   Barbara Jennings
   Sandia National Laboratories
   Scientific Computing Systems
   P.O. Box 5800
   M/S 0807
   Albuquerque, NM  87106
   USA

   Phone:  505-845-8554
   Fax:    505-844-2067
   EMail:  jennings@sandia.gov

 

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