Comparison of Different NAT Traversal Techniques for Media Controlled by the Real-Time Streaming Protocol (RTSP)
RFC 7604

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Internet Engineering Task Force (IETF)                     M. Westerlund
Request for Comments: 7604                                      Ericsson
Category: Informational                                          T. Zeng
ISSN: 2070-1721                                         PacketVideo Corp
                                                          September 2015

            Comparison of Different NAT Traversal Techniques
    for Media Controlled by the Real-Time Streaming Protocol (RTSP)

Abstract

   This document describes several Network Address Translator (NAT)
   traversal techniques that were considered to be used for establishing
   the RTP media flows controlled by the Real-Time Streaming Protocol
   (RTSP).  Each technique includes a description of how it would be
   used, the security implications of using it, and any other deployment
   considerations it has.  There are also discussions on how NAT
   traversal techniques relate to firewalls and how each technique can
   be applied in different use cases.  These findings were used when
   selecting the NAT traversal for RTSP 2.0, which is specified in a
   separate document.

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/rfc7604.

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Copyright Notice

   Copyright (c) 2015 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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   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Network Address Translators . . . . . . . . . . . . . . .   5
     1.2.  Firewalls . . . . . . . . . . . . . . . . . . . . . . . .   6
     1.3.  Glossary  . . . . . . . . . . . . . . . . . . . . . . . .   7
   2.  Detecting the Loss of NAT Mappings  . . . . . . . . . . . . .   8
   3.  Requirements on Solutions . . . . . . . . . . . . . . . . . .   9
   4.  NAT-Traversal Techniques  . . . . . . . . . . . . . . . . . .  10
     4.1.  Stand-Alone STUN  . . . . . . . . . . . . . . . . . . . .  11
       4.1.1.  Introduction  . . . . . . . . . . . . . . . . . . . .  11
       4.1.2.  Using STUN to Traverse NAT without Server
               Modifications . . . . . . . . . . . . . . . . . . . .  11
       4.1.3.  ALG Considerations  . . . . . . . . . . . . . . . . .  14
       4.1.4.  Deployment Considerations . . . . . . . . . . . . . .  14
       4.1.5.  Security Considerations . . . . . . . . . . . . . . .  15
     4.2.  Server Embedded STUN  . . . . . . . . . . . . . . . . . .  16
       4.2.1.  Introduction  . . . . . . . . . . . . . . . . . . . .  16
       4.2.2.  Embedding STUN in RTSP  . . . . . . . . . . . . . . .  16
       4.2.3.  Discussion on Co-located STUN Server  . . . . . . . .  17
       4.2.4.  ALG Considerations  . . . . . . . . . . . . . . . . .  17
       4.2.5.  Deployment Considerations . . . . . . . . . . . . . .  18
       4.2.6.  Security Considerations . . . . . . . . . . . . . . .  19
     4.3.  ICE . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
       4.3.1.  Introduction  . . . . . . . . . . . . . . . . . . . .  19
       4.3.2.  Using ICE in RTSP . . . . . . . . . . . . . . . . . .  20
       4.3.3.  Implementation Burden of ICE  . . . . . . . . . . . .  21
       4.3.4.  ALG Considerations  . . . . . . . . . . . . . . . . .  22
       4.3.5.  Deployment Considerations . . . . . . . . . . . . . .  22
       4.3.6.  Security Considerations . . . . . . . . . . . . . . .  23

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RFC 7604          Evaluation of NAT Traversal for RTSP    September 2015

     4.4.  Latching  . . . . . . . . . . . . . . . . . . . . . . . .  23
       4.4.1.  Introduction  . . . . . . . . . . . . . . . . . . . .  23