Using Kerberos Version 5 over the Transport Layer Security (TLS) Protocol
RFC 6251
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RFC - Informational
(May 2011; No errata)
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Last updated |
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2015-10-14
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IETF
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plain text
pdf
html
bibtex
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WG state
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(None)
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Document shepherd |
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No shepherd assigned
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IESG state |
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RFC 6251 (Informational)
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Consensus Boilerplate |
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Unknown
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Responsible AD |
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Tim Polk
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IESG note |
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Jeffrey Hutzelman (jhutz@cmu.edu) is the document shepherd.
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(None)
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Internet Engineering Task Force (IETF) S. Josefsson
Request for Comments: 6251 SJD AB
Category: Informational May 2011
ISSN: 2070-1721
Using Kerberos Version 5
over the Transport Layer Security (TLS) Protocol
Abstract
This document specifies how the Kerberos V5 protocol can be
transported over the Transport Layer Security (TLS) protocol in order
to provide additional security features.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6251.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Josefsson Informational [Page 1]
RFC 6251 Protecting Kerberos V5 with TLS May 2011
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction and Background .....................................2
2. Kerberos V5 STARTTLS Extension ..................................3
3. Examples ........................................................4
4. STARTTLS-Aware KDC Discovery ....................................5
5. Server Certificates .............................................6
6. IANA Considerations .............................................7
7. Acknowledgements ................................................7
8. Security Considerations .........................................7
9. References ......................................................8
9.1. Normative References .......................................8
9.2. Informative References .....................................8
1. Introduction and Background
This document describes how a Kerberos V5 [RFC4120] implementation
may upgrade communication between clients and Key Distribution
Centers (KDCs) to use the Transport Layer Security (TLS) [RFC5246]
protocol.
The TLS protocol offers integrity- and privacy-protected exchanges
that can be authenticated using X.509 certificates, OpenPGP keys
[RFC6091], and usernames and passwords via Secure Remote Password
(SRP) [RFC5054].
There are several reasons to use Kerberos V5 over TLS.
o It prevents downgrade attacks affecting, e.g., encryption types
and pre-auth data negotiation. The encryption type field in
KDC-REQ and the METHOD-DATA field with the requested pre-auth
types from the server in KDC_ERR_PREAUTH_REQUIRED errors in
KDC-REP are sent without integrity or privacy protection in
Kerberos V5. This allows an active attacker to replace the
encryption type with a compromised encryption type, e.g., 56-bit
DES, or request that clients should use a broken pre-auth type.
Josefsson Informational [Page 2]
RFC 6251 Protecting Kerberos V5 with TLS May 2011
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