UDP Transport Layer (UDPTL) over Datagram Transport Layer Security (DTLS)
RFC 7345
Internet Engineering Task Force (IETF) C. Holmberg
Request for Comments: 7345 I. Sedlacek
Category: Standards Track Ericsson
ISSN: 2070-1721 G. Salgueiro
Cisco
August 2014
UDP Transport Layer (UDPTL)
over Datagram Transport Layer Security (DTLS)
Abstract
This document specifies how the UDP Transport Layer (UDPTL) protocol,
the predominant transport protocol for T.38 fax, can be transported
over the Datagram Transport Layer Security (DTLS) protocol, how the
usage of UDPTL over DTLS is indicated in the Session Description
Protocol (SDP), and how UDPTL over DTLS is negotiated in a session
established using the Session Initiation Protocol (SIP).
Status of This Memo
This is an Internet Standards Track document.
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). Further information on
Internet Standards is available in 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/rfc7345.
Copyright Notice
Copyright (c) 2014 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Holmberg, et al. Standards Track [Page 1]
RFC 7345 UDPTL over DTLS August 2014
Table of Contents
1. Introduction ....................................................3
2. Conventions .....................................................5
3. Secure Channel ..................................................5
4. SDP Offerer/Answerer Procedures .................................6
4.1. General ....................................................6
4.2. Generating the Initial Offer ...............................7
4.3. Generating the Answer ......................................7
4.4. Offerer Processing of the Answer ...........................7
4.5. Modifying the Session ......................................7
5. Miscellaneous Considerations ....................................8
5.1. Anonymous Calls ............................................8
5.2. NAT Traversal ..............................................8
5.2.1. ICE Usage ...........................................8
5.2.2. STUN Interaction ....................................8
5.3. Rekeying ...................................................9
5.4. Compatibility with UDPTL over UDP ..........................9
6. Security Considerations .........................................9
7. IANA Considerations ............................................10
8. Acknowledgments ................................................10
9. References .....................................................11
9.1. Normative References ......................................11
9.2. Informative References ....................................12
Appendix A. Examples .............................................13
A.1. General ...................................................13
A.2. Basic Message Flow ........................................13
A.3. Message Flow of T.38 Fax Replacing Audio Media Stream in
an Existing Audio-Only Session ............................20
Holmberg, et al. Standards Track [Page 2]
RFC 7345 UDPTL over DTLS August 2014
1. Introduction
While it is possible to transmit highly sensitive documents using
traditional telephony encryption devices, secure fax on the Public
Switched Telephone Network (PSTN) was never widely considered or
prioritized. This was mainly because of the challenges involved with
malevolent physical access to telephony equipment. As real-time
communications transition to IP networks, where information might
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