Each item (entry) in the X.500 directory describes one object (e.g. a person, a network resource, an organization) and has a unique identifier called a Distinguished Name (DN). The entry consists of a collection of attributes (e.g. for a person this might be last name, organization name, e-mail address). The entries are found by navigating through a Directory Information Tree (DIT). At the top of the tree is the World, which is subdivided at the next level into countries, and at the next into organizations. Information on people, resources, etc., is stored within organizations.
While most of the information available today via X.500 is about people and organizations, the design of the X.500 directory is also suitable for storing information about other entities (or objects), such as network resources, applications or hardware. Several projects utilize these directory capabilities (e.g. the Internet RFCs (Request For Comments) are listed in the global directory).
X.500 is an OSI (Open System Interconnection) protocol, named after the
number of the CCITT (International Telegraph and Telephone Consultative
Committee) Recommendation document containing its specification. The
Paradise project aims to encourage the use of X.500 in European
Who can use X.500
Although X.500 is part of the OSI standard definition, OSI access is
not necessary to use the directory services. Many X.500 services are
available both on the Internet, and by electronic mail. See the
section Using X.500 below for details.
How to get to X.500
There are three ways to access the X.500 services: via a local client,
via an interactive session (Telnet or X.25 access) to a remote client,
or by electronic mail. Each type of access is described below in the
Using X.500 section.
In addition, network tools such as WWW and Gopher provide access to X.500 directory services through gateways.
Public access to an X.500 client via Telnet or X.25 is an easy way to start querying the X.500 directory. Public access user interfaces are available at:
Telnet (login) Public X.25 Country
jethro.ucc.su.oz.au (fred) Australia sun1.iihe.ac.be (dua) 222100611 Belgium x500.denet.dk (de) Denmark login.dkuug.dk (ds) Denmark nic.funet.fi (dua) Finland x500.tu-chemnitz.de (x500) Germany ashe.cs.tcd.ie (de) Ireland x500.ieunet.ie (de) 272432590024 Ireland jolly.nis.garr.it (de or fred) 22225010083212 Italy zoek.nic.surfnet.nl (no login) Netherlands elc1.mat.torun.edu.pl (de or dish) Poland chico.rediris.es (directorio) 2142160234013 Spain hypatia.umdc.umu.se (de) 240374810306 Sweden nic.switch.ch (dua) 22847971014540 Switzerland dir.ulcc.ac.uk (dua) UK paradise.ulcc.ac.uk (dua) 23421920014853 Paradise
In the following, angle brackets (<>) indicate an optional parameter; a vertical bar (|) indicates a choice of parameters.
Using a local client
In the X.500 world, a local client is called a Directory User Agent (DUA). Public domain and commercial DUAs are available for numerous platforms ranging from mainframes to personal computers. They range from simple command-line based clients to clients based on sophisticated graphical user interfaces which require a pointing device. For a comprehensive list of DUAs, their description and where to find them, consult the Internet document RFC 1292 / FYI 11 - A Catalog of Available X.500 Implementations.
Using Telnet or X.25
DUAs provided by remote sites may have line-oriented, menu-driven or X Window System based user interfaces; examples of each are given below:
Novice users are recommended to try de (directory enquiries) since it has a very simple user interface. de was designed as a public access DUA and is accessible from any kind of terminal. It supports the basic X.500 functions: read, search, and list. Users who are new to querying the X.500 directory should use de's Simple query mode.
The four fields to be filled in are:
Using electronic mail
The Norwegian networking organization (UNINETT) offers an e-mail interface to X.500. To use it, send a mail message to: Directory@UNINETT.NO with the word find in the Subject: field. The body part contains the search request, one per message. A help file is returned if the message body contains the word help.
The format of the search request is:
find <person-name> <: org-name <; country-name>> | <;country-name>
"*" (asterisk) is the wildcard character and can replace any other characters in any name. It can appear anywhere in the name.
The result of the query is sent back in a mail message. The search is
Note: To avoid overloading the directory service, users are
not allowed to search for a person without selecting an organization.
you can search
for the Anthropology
department of the University College, London, United
Kingdom, with the following request:
Person's name, q to quit, * to browse, ? for help :- Department name, * to browse, ? for help :- a* Organisation name, * to browse, ? for help :- ucl Country name, * to browse, ? for help :- ukA few entries match the selected department, all are listed for further selection:
United Kingdom University College London Got the following matches. Please select one from the list by typing the number corresponding to the entry you want. United Kingdom University College London 1 A.U.T. Office 2 Academic Enterprise and Training Unit 3 Anatomy and Developmental Biology 4 Anthropology 5 Audio Visual Centre Department name, * to browse, ? for help :- 4 United Kingdom University College London Anthropology Telephone Number +44 71-387-7050 x2455 fax +44 71 380 7728If you are looking for Erik Lawaetz from UNI-C in Denmark, you can enter the following request:
Person's name, q to quit, * to browse, ? for help :- law* Department name, * to browse,One entry matches the selected criteria, details are displayed:
to search all depts, ? for help :- Organisation name, * to browse, ? for help :- uni-c Country name, * to browse, ? for help :- dk
Denmark UNI-C Erik Lawaetz surname Lawaetz postalAddress UNI-C DTH Bygning 305 DK-2800 Lyngby Post Code DK-2800 Telephone Number +45 45 93 83 55 +45 42 88 39 99 x2018 fax +45 45 93 02 20 electronic mail Erik.Lawaetz@uni-c.dkIf you send mail to Directory@UNINETT.NO with the request:
find geir ped* : *oslo ; noyou'll get the following result:
This message is in response to your request to the directory to find geir ped* : *oslo ; no This is interpreted as a request to find a person with a name matching "geir ped*" in an organisation with name matching "*oslo" in a country with a name matching "no". There were 8 organisations with a name matching the organizational name you specified. Within those organisations there were 7 persons that had a name matching the personal name you specified. Directory information for the located persons is shown below. Geir Pedersen : Universitetet i Oslo ; Norway Alternate Geir Kenneth Pedersen Alternate Geir K. Pedersen E-Mail (RFC) Geir.Pedersen@usit.uio.no E-Mail (X.400) /G=geir/S=pedersen/OU=usit/O=uio/PRMD=uninett/ ADMD= /C=no/ Postal Address Postboks 1059 - Blindern 0316 Oslo 3 NORWAY Phone +47-22-852478 Phone +47-22-852470 (front-office) Fax-phone +47-22-852730 Description Project leader for UNINETTs X.500 projects User ID geirp Favorite Drink Farris Street Address Gaustadalleen 23 Home Address Gaustadveien 17A 0372 Oslo 3 NORWAY See also Geir Pedersen : UNINETT ; Norway Entry updated Tue Jun 15 11:51:31 1993