One document matched: draft-ietf-asid-ldapv3-tls-01.txt
Differences from draft-ietf-asid-ldapv3-tls-00.txt
ASID Working Group Jeff Hodges, Stanford
INTERNET-DRAFT RL "Bob" Morgan, Stanford
Mark Wahl, Critical Angle Inc.
June, 1997
Lightweight Directory Access Protocol (v3):
Extension for Transport Layer Security
draft-ietf-asid-ldapv3-tls-01.txt
1. Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working docu-
ments 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.''
To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).
2. Abstract
This document defines the "Start Transport Layer Security (TLS) Opera-
tion" for LDAP [LDAPv3, TLS]. This operation provides for TLS establish-
ment in an LDAP association and is defined in terms of an LDAP extended
request.
The key words "MUST", "SHOULD", and "MAY" used in this document are to
be interpreted as described in [Bradner97].
3. The Start TLS Operation
3.1. Requesting TLS Establishment
A client may perform a Start TLS operation by transmitting an LDAP PDU
containing an ExtendedRequest [LDAPv3] specifying the OID for the Start
TLS operation:
1.3.6.1.4.1.1466.20037
Hodges, Morgan, Wahl [Page 1]
LDAPv3: Extension for Transport Layer Security June 1997
An LDAP ExtendedRequest is defined as follows:
ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID,
requestValue [1] OCTET STRING OPTIONAL }
A Start TLS extended request is formed by setting the requestName field
to the OID string given above. The requestValue field is absent. The
client MUST NOT send any PDUs on this connection following this request
until it receives a Start TLS extended response.
When a Start TLS extended request is made, the server MUST return an
LDAP PDU containing a Start TLS extended response. An LDAP Exten-
dedResponse is defined as follows:
ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
responseName [0] LDAPOID OPTIONAL,
response [1] OCTET STRING OPTIONAL,
standardResponse [2] LDAPResult }
A Start TLS extended response MUST contain a responseName field which
MUST be set to the same string as that present in the Start TLS extended
request. The response field is absent. The server MUST set the
resultCode of the standardResponse field to either success or one of the
other values outlined in section 3.3.
3.2. "Success" Response
If the standardResponse field contains a resultCode of success, this
indicates that the server is willing and able to negotiate TLS. At this
point the client, which has ceased to transfer LDAP requests on the con-
nection, MUST either begin a TLS negotiation, or close the connection.
In the former case, the client will send PDUs in the TLS Record Protocol
directly over the underlying TCP bytestream to the server.
After the TLS connection is established, both parties MUST individually
decide whether or not to continue based on the privacy level achieved.
Ascertaining the TLS connection's privacy level is implementation depen-
dent, and accomplished by communicating with one's respective local TLS
implementation.
If the client or server decides that the level of authentication or
privacy is not high enough for it to continue, it SHOULD close the TLS
connection immediately after the TLS negotiation has completed, to
disconnect the TLS service and return to an LDAP state (see section 5,
below). This will cause the client's authorization identity to be reset
to anonymous. The client MAY attempt to Start TLS again, or MAY send an
unbind request, or send any other LDAP request.
Hodges, Morgan, Wahl [Page 2]
LDAPv3: Extension for Transport Layer Security June 1997
3.3. Response other than "success"
If the standardResponse field contains a resultCode other than success,
this indicates that the server is unwilling or unable to negotiate TLS.
If the Start TLS extended request was not successful, the resultCode
will be one of:
- operationsError (operations sequencing incorrect; e.g. TLS already
established)
- protocolError (TLS not supported or incorrect PDU structure)
- referral (this server doesn't do TLS, try this one)
- unavailable (e.g. some major problem with TLS, or server is
shutting down)
The server MUST return operationsError if the client violates any of the
Start TLS extended operation sequencing requirements described in sec-
tion 4, below.
If the server does not support TLS (whether by design or by current con-
figuration), it MUST set the resultCode to protocolError (see section
4.1.1 of [LDAPv3]), or to referral. The server MUST include an actual
referral value in the LDAP Result if it returns a resultCode of refer-
ral. The client's current session is unaffected if the server does not
support TLS. The client MAY proceed with any LDAP operation, or it MAY
close the connection.
The server MUST return unavailable if it supports TLS but cannot estab-
lish a TLS connection for some reason, e.g. the certificate server not
responding, it cannot contact its TLS implementation, or if the server
is in process of shutting down. The client MAY retry the StartTLS opera-
tion, or it MAY proceed with any other LDAP operation, or it MAY close
the connection.
4. Sequencing of the Start TLS Operation
The client MAY send the Start TLS extended request at any time after
establishing an LDAP association, except that in the following cases the
client MUST NOT send a Start TLS extended request:
- if TLS is currently established on the connection, or
- during a multi-stage SASL negotiation, or
- if there are any LDAP operations outstanding on the connection.
The result of violating any of these requirements is described above in
section 3.3.
Hodges, Morgan, Wahl [Page 3]
LDAPv3: Extension for Transport Layer Security June 1997
The client MAY have already perfomed a Bind operation when it sends a
Start TLS request, or the client might have not yet bound.
If the client did not establish a TLS connection before sending any
other requests, and the server requires the client to establish a TLS
connection before performing a particular request, the server MUST
reject that request with a confidentialityRequired or strongAuthRequired
result. The client MAY send a Start TLS extended request, or it MAY
choose to close the connection.
5. Closing a TLS Connection
5.1. Graceful Closure
Either the client or server MAY terminate the TLS connection on an LDAP
association by sending a TLS closure alert. This will leave the LDAP
association intact.
Before closing a TLS connection, the client MUST either wait for any
outstanding LDAP operations to complete, or explicitly abandon them
[LDAPv3].
After the initiator of a close has sent a closure alert, it MUST discard
any TLS messages until it has received an alert from the other party.
It will cease to send TLS Record Protocol PDUs, and following the
reciept of the alert, MAY send and receive LDAP PDUs.
The other party, if it receives a closure alert, MUST immediately
transmit a TLS closure alert. It will subequently cease to send TLS
Record Protocol PDUs, and MAY send and receive LDAP PDUs.
5.2. Abrupt Closure
Either the client or server MAY abruptly close the entire LDAP associa-
tion and any TLS connection established on it by dropping the underlying
TCP connection. A server MAY beforehand send the client a Notice of
Disconnection [LDAPv3] in this case.
6. Effects of TLS Establishment on the Client's Authorization Identity
Upon establishment of the TLS connection onto the LDAP association, the
server MAY base the client's authorization identity on the client's
negotiated TLS credentials, overriding any previously established
credentials and authorization identity. Otherwise, any previously esta-
blished credentials and authorization identity MUST remain in force,
including anonymous cedentials and identity in the case where the client
had not previously bound.
Hodges, Morgan, Wahl [Page 4]
LDAPv3: Extension for Transport Layer Security June 1997
A client MAY explicitly request that its authenticated TLS credentials
be used as the source for its LDAP authorization identity. This is
accomplished after TLS establishment by invoking a Bind request of the
SASL form with a negotiated mechanism name of "EXTERNAL" [SASL]. The
credentials field MAY contain the client's distinguished name (as an
LDAP string), or it MAY be empty. If it does contain a distinguished
name, this name MUST match the authorization identity negotiated by TLS
as the client's identity. It is a matter of local policy what consti-
tutes a match. In the absence of local policy, the default matching pol-
icy compares for equality. The server MUST reject the Bind operation
with an invalidCredentials resultCode in the Bind response if they do
not match.
Closure of the TLS connection MUST cause the LDAP association to move to
an anonymous authentication and authorization state regardless of the
state established over TLS and regardless of the authentication and
authorization state prior to TLS connection establishment.
7. Security Considerations
The goals of using the TLS protocol with LDAP are to ensure connection
confidentiality and integrity, and to optionally provide for authentica-
tion. TLS expressly provides these capabilities, as described in [TLS].
All security gained via use of the Start TLS operation is gained by the
use of TLS itself. The Start TLS operation, on its own, does not provide
any additional security.
The use of TLS does not provide or ensure for confidentiality and/or
non-repudiation of the data housed by an LDAP-based directory server.
Once established, TLS only provides for and ensures confidentiality and
integrity of the operations and data in transit over the LDAP associa-
tion, and only if the implementations on the client and server support
and negotiate it.
The level of security provided though the use of TLS depends directly on
both the quality of the TLS implementation used and the style of usage
of that implementation. Both parties SHOULD independently ascertain and
consent to the privacy level achieved once TLS is established and before
begining use of the TLS connection. For example, the privacy level of
the TLS connection might have been negotiated down to plaintext.
Client and server implementors SHOULD take measures to ensure proper
protection of credentials and other confidential data where such meas-
ures are not otherwise provided by the TLS implementation.
Server implementors SHOULD allow for server administrators to elect
whether and when connection confidentiality is required.
Hodges, Morgan, Wahl [Page 5]
LDAPv3: Extension for Transport Layer Security June 1997
8. Acknowledgements
The authors thank Tim Howes and Paul Hoffman for their contributions to
this document.
9. References
[Bradner97]
Scott Bradner, "Key Words for use in RFCs to Indicate Requirement
Levels", Internet Draft, RFC 2119.
[LDAPv3]
M. Wahl, S. Kille and T. Howes, "Lightweight Directory Access Pro-
tocol (v3)", Internet Draft, February, 1997. Available as draft-
ietf-asid-ldapv3-protocol-04.txt.
[TLS]Tim Dierks, C. Allen, "The TLS Protocol Version 1.0", Internet
Draft, March 1997. Available as draft-ietf-tls-protocol-03.txt
[SASL]J. Myers, "Simple Authentication and Security Layer (SASL)",
Internet Draft, April 1997. Available as draft-myers-auth-sasl-
10.txt
10. Author's Address
Jeff Hodges
Computing & Communication Services
Stanford University
115 Pine Hall
Stanford, CA 94305-4122
USA
Phone: +1-415-723-2452
EMail: Jeff.Hodges@Stanford.edu
RL "Bob" Morgan
Computing & Communication Services
Stanford University
115 Pine Hall
Stanford, CA 94305-4122
USA
Phone: +1-415-723-9711
EMail: Bob.Morgan@Stanford.edu
Mark Wahl
Hodges, Morgan, Wahl [Page 6]
LDAPv3: Extension for Transport Layer Security June 1997
Critical Angle Inc.
4815 W. Braker Lane #502-385
Austin, TX 78759
USA
EMail: M.Wahl@critical-angle.com
Hodges, Morgan, Wahl [Page 7]
| PAFTECH AB 2003-2026 | 2026-04-23 04:24:34 |