draft-ietf-mmusic-rtsp-nat-evaluation-11.txt   draft-ietf-mmusic-rtsp-nat-evaluation-12.txt 
Network Working Group M. Westerlund Network Working Group M. Westerlund
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Informational T. Zeng Intended status: Informational T. Zeng
Expires: July 27, 2014 Expires: July 27, 2014
January 23, 2014 January 23, 2014
The Evaluation of Different Network Address Translator (NAT) Traversal The Evaluation of Different Network Address Translator (NAT) Traversal
Techniques for Media Controlled by Real-time Streaming Protocol (RTSP) Techniques for Media Controlled by Real-time Streaming Protocol (RTSP)
draft-ietf-mmusic-rtsp-nat-evaluation-11 draft-ietf-mmusic-rtsp-nat-evaluation-12
Abstract Abstract
This document describes several Network Address Translator (NAT) This document describes several Network Address Translator (NAT)
traversal techniques that were considered to be used for establishing traversal techniques that were considered to be used for establishing
the RTP media flows controlled by the Real-time Streaming Protocol the RTP media flows controlled by the Real-time Streaming Protocol
(RTSP). Each technique includes a description of how it would be (RTSP). Each technique includes a description of how it would be
used, the security implications of using it and any other deployment used, the security implications of using it and any other deployment
considerations it has. There are also discussions on how NAT considerations it has. There are also discussions on how NAT
traversal techniques relate to firewalls and how each technique can traversal techniques relate to firewalls and how each technique can
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applicable to other protocols as long as they have similar applicable to other protocols as long as they have similar
properties. properties.
The resulting ICE-based RTSP NAT traversal mechanism is specified in The resulting ICE-based RTSP NAT traversal mechanism is specified in
"A Network Address Translator (NAT) Traversal mechanism for media "A Network Address Translator (NAT) Traversal mechanism for media
controlled by Real-Time Streaming Protocol (RTSP)" controlled by Real-Time Streaming Protocol (RTSP)"
[I-D.ietf-mmusic-rtsp-nat]. [I-D.ietf-mmusic-rtsp-nat].
1.1. Network Address Translators 1.1. Network Address Translators
We begin by reviewing what "Network Address Translation (NAT) We begin by reviewing two quotes from Section 3 in "Network Address
Behavioral Requirements for Unicast UDP" [RFC4787] states about NATs Translation (NAT) Behavioral Requirements for Unicast UDP" [RFC4787]
and their Terminology in Section 3: concering NATs and their terminology:
"Readers are urged to refer to "IP Network Address Translator (NAT) "Readers are urged to refer to [RFC2663] for information on NAT
Terminology and Considerations" [RFC2663] for information on NAT
taxonomy and terminology. Traditional NAT is the most common type of taxonomy and terminology. Traditional NAT is the most common type of
NAT device deployed. Readers may refer to "Traditional IP Network NAT device deployed. Readers may refer to [RFC3022] for detailed
Address Translator (Traditional NAT)" [RFC3022] for detailed
information on traditional NAT. Traditional NAT has two main information on traditional NAT. Traditional NAT has two main
varieties -- Basic NAT and Network Address/Port Translator (NAPT). varieties -- Basic NAT and Network Address/Port Translator (NAPT).
NAPT is by far the most commonly deployed NAT device. NAPT allows NAPT is by far the most commonly deployed NAT device. NAPT allows
multiple internal hosts to share a single public IP address multiple internal hosts to share a single public IP address
simultaneously. When an internal host opens an outgoing TCP or UDP simultaneously. When an internal host opens an outgoing TCP or UDP
session through a NAPT, the NAPT assigns the session an external IP session through a NAPT, the NAPT assigns the session a public IP
address and port number, so that subsequent response packets from the address and port number, so that subsequent response packets from the
external endpoint can be received by the NAPT, translated, and external endpoint can be received by the NAPT, translated, and
forwarded to the internal host. The effect is that the NAPT forwarded to the internal host. The effect is that the NAPT
establishes a NAT mapping to translate the (private IP address, establishes a NAT session to translate the (private IP address,
private port number) tuple to a (external IP address, external port private port number) tuple to a (public IP address, public port
number) tuple, and vice versa, for the duration of the session. The number) tuple, and vice versa, for the duration of the session. An
external IP address is commonly a public one, but might be of other issue of relevance to peer-to-peer applications is how the NAT
type if the NAT is in itself in a private address domain. An issue behaves when an internal host initiates multiple simultaneous
of relevance to peer-to-peer applications is how the NAT behaves when sessions from a single (private IP, private port) endpoint to
an internal host initiates multiple simultaneous sessions from a multiple distinct endpoints on the external network. In this
single (private IP, private port) endpoint to multiple distinct specification, the term "NAT" refers to both "Basic NAT" and "Network
endpoints on the external network. In this specification, the term Address/Port Translator (NAPT)"."
"NAT" refers to both "Basic NAT" and "Network Address/Port Translator
(NAPT)".
This document uses the term "address and port mapping" as the "This document uses the term "address and port mapping" as the
translation between an external address and port and an internal translation between an external address and port and an internal
address and port. Note that this is not the same as an "address address and port. Note that this is not the same as an "address
binding" as defined in RFC 2663." binding" as defined in RFC 2663."
Note: In the above it would be more correct to use external
instead of public in the above text. The external IP address is
commonly a public one, but might be of other type if the NAT's
external side is in a private address domain.
In addition to the above quote there exists a number of address and In addition to the above quote there exists a number of address and
port mapping behaviors described in more detail in Section 4.1 of port mapping behaviors described in more detail in Section 4.1 of
"Network Address Translation (NAT) Behavioral Requirements for "Network Address Translation (NAT) Behavioral Requirements for
Unicast UDP" [RFC4787] that are highly relevant to the discussion in Unicast UDP" [RFC4787] that are highly relevant to the discussion in
this document. this document.
NATs also have a filtering behavior on traffic arriving on the NATs also have a filtering behavior on traffic arriving on the
external side. Such behavior affects how well different methods for external side. Such behavior affects how well different methods for
NAT traversal works through these NATs. See Section 5 of "Network NAT traversal works through these NATs. See Section 5 of "Network
Address Translation (NAT) Behavioral Requirements for Unicast UDP" Address Translation (NAT) Behavioral Requirements for Unicast UDP"
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[I-D.ietf-mmusic-rfc2326bis] [I-D.ietf-mmusic-rfc2326bis]
Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M., Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
and M. Stiemerling, "Real Time Streaming Protocol 2.0 and M. Stiemerling, "Real Time Streaming Protocol 2.0
(RTSP)", draft-ietf-mmusic-rfc2326bis-39 (work in (RTSP)", draft-ietf-mmusic-rfc2326bis-39 (work in
progress), January 2014. progress), January 2014.
[I-D.ietf-mmusic-rtsp-nat] [I-D.ietf-mmusic-rtsp-nat]
Goldberg, J., Westerlund, M., and T. Zeng, "A Network Goldberg, J., Westerlund, M., and T. Zeng, "A Network
Address Translator (NAT) Traversal mechanism for media Address Translator (NAT) Traversal mechanism for media
controlled by Real-Time Streaming Protocol (RTSP)", draft- controlled by Real-Time Streaming Protocol (RTSP)", draft-
ietf-mmusic-rtsp-nat-17 (work in progress), November 2013. ietf-mmusic-rtsp-nat-18 (work in progress), January 2014.
[NICE] "Libnice - The GLib ICE implementation, [NICE] "Libnice - The GLib ICE implementation,
http://nice.freedesktop.org/wiki/", May 2013. http://nice.freedesktop.org/wiki/", May 2013.
[PJNATH] "PJNATH - Open Source ICE, STUN, and TURN Library, [PJNATH] "PJNATH - Open Source ICE, STUN, and TURN Library,
http://www.pjsip.org/pjnath/docs/html/", May 2013. http://www.pjsip.org/pjnath/docs/html/", May 2013.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980. August 1980.
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