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RE: draft-ietf-locate-00.txt
Resubmitting with correct dates.
thanks,
Michael (brain suffering from Y2K glitch)
-----Original Message-----
From: rweltman@netscape.com [mailto:rweltman@netscape.com]
Sent: Wednesday, September 08, 1999 1:12 PM
To: Michael Armijo (Exchange)
Cc: 'ietf-ldapext@netscape.com'
Subject: Re: draft-ietf-locate-00.txt
Michael,
The draft says: "Expires March, 1999".
Rob
"Michael Armijo (Exchange)" wrote:
> Please publish this draft for the LDAPEXT WG.
>
> Attached is the updated "Discovering LDAP Services with DNS" draft.
>
> thanks,
> Michael
>
> <<draft-ietf-ldapext-locate-00.txt>>
>
>
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> Name:
draft-ietf-ldapext-locate-00.txt
> draft-ietf-ldapext-locate-00.txt Type: Plain Text (text/plain)
> Encoding: quoted-printable
INTERNET-DRAFT Michael P. Armijo
<draft-ietf-ldapext-locate-00.txt> Levon Esibov
September, 1999 Paul Leach
Expires: March, 2000 Microsoft Corporation
Discovering LDAP Services with DNS
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet- Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Distribution of this memo is unlimited. It is filed as <draft-
ietf-ldapext-locate-00.txt>, and expires on March 8, 2000.
Please send comments to the authors.
1. Abstract
This draft defines a way that native Internet LDAP servers can make
use of the DNS's knowledge base to provide clients a method to
resolve LDAP services for a given domain.
2. Introduction
The LDAPv3 protocol [RFC 2251] is designed to be a
lightweight access protocol for directory services supporting X.500
models. This may be the X.500 directory itself, but the LDAP
specification explicitly allows it to be a different directory.
Let us define a "native LDAP server" to be one that is not a front
end to the X.500 directory service. Let us further define an "Internet
based organization" as one that has a domain name, and an "Internet
LDAP server" to be one containing a directory entries for such an
organization.
This draft defines a way that native Internet LDAP servers can make
use of the DNS's knowledge base to perform the same function, while
still supporting integration with the X.500 directory.
This draft builds [RFC 2247] to define a mechanism by which collections
of native Internet LDAP servers can be integrated to create a directory
service. That work supports this cause by defining a mapping from an
LDAP DN to a DNS name that can be resolved to the address of a server
holding the entry corresponding to the DN. For example, the DN
"CN=Fred,OU=Eng,DC=example,DC=net" maps to the DNS name "example.net".
In an Internet context, many of the names about which users seek
information are DNS names, or include DNS names. A native LDAP based
directory service for the Internet should make it convenient to
process such names -- there is a huge social investment spanning two
decades to get to the point where names like
"john.doe@somewhere.example" and "http://www.example.net" can
appear in newspaper articles, TV commercials, and on billboards
and millions of people understand what to do with them. As a result,
we assume that Internet based organizations wish to preserve this
investment, yet also want to deploy directory services.
Widespread use of, and dependence on, LDAP services will require that
they are robust and scalable. Both of these features are typically
supported by replicated servers. Use of SRV records to locate LDAP
servers supports clients' use of replicated servers.
3. Locating LDAP servers through DNS
LDAP server location information is to be stored using DNS SRV record
specified in [6]. Such SRV record contains the DNS name of the
server that provides the LDAP service, corresponding Port number, and
parameters that enable the client to choose an appropriate server
according to the algorithm described in [6] in case of multiple
LDAP servers, servicing the same domain. The name of this record
always has the following format:
_Service._Proto.Domain
where Service name is always "ldap", Proto is a protocol that can be
either "udp" or "tcp", and Domain is the ldap domain that this record
refers to.
Presence of such records enables clients to find the LDAP servers
(that support required protocol in specified domain) using standard
DNS query [3].
As an example, a client that searches for an LDAP server in the
example.net domain that supports TCP protocol will submit a DNS
query for a set of SRV records with owner name _ldap._tcp.example.net.
The client will receive the list of SRV records published in DNS that
satisfy the requested criteria. The following is an example of such
record:
_ldap._tcp.example.net. IN SRV 0 0 389 phoenix.example.net.
The set of returned records may contain multiple records in the case
where multiple LDAP servers serve the same domain. Combination with
the A resource records, such as
phoenix.example.net. IN A 10.0.0.1
enables clients to directly contact the LDAP servers.
4. Security Considerations
This document describes a method that uses DNS SRV records to
discover LDAP servers. All security considerations related to DNS
SRV records are inherited by this document. See the security
considerations section in [6] for more details.
5. References
[1] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access
Protocol(v3)". RFC 2251, December 1997.
[2] S. Kille, M. Wahl, "Using Domains in LDAP/X.500 Distinguished
Names". RFC 2247, January 1998.
[3] P. Mockapetris, RFC 1034, DOMAIN NAMES - CONCEPTS AND FACILITIES,
November, 1987.
[4] P. Mockapetris, RFC 1035, DOMAIN NAMES - IMPLEMENTATION AND
SPECIFICATION, November, 1987.
[5] T. Howes, M. Smith, "The LDAP URL Format". RFC 2255 December 1997.
[6] A. Gulbrandsen, P. Vixie, "A DNS RR for specifying the location of
services (DNS SRV)". http://www.ietf.org/internet-drafts/draft-ietf-
dnsind-rfc2052bis-02.txt, January 1999.
6. Authors' Addresses
Michael P. Armijo
One Microsoft Way
Redmond, WA 98052
micharm@microsoft.com
Paul Leach
One Microsoft Way
Redmond, WA 98052
paulle@microsoft.com
Levon Esibov
One Microsoft Way
Redmond, WA 98052
levone@microsoft.com
Expires March, 2000