draft-ietf-tram-turnbis-04.txt   draft-ietf-tram-turnbis-05.txt 
TRAM WG T. Reddy, Ed. TRAM WG T. Reddy, Ed.
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track A. Johnston, Ed. Intended status: Standards Track A. Johnston, Ed.
Expires: October 17, 2015 Avaya Expires: January 7, 2016 Avaya
P. Matthews P. Matthews
Alcatel-Lucent Alcatel-Lucent
J. Rosenberg J. Rosenberg
jdrosen.net jdrosen.net
April 15, 2015 July 6, 2015
Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Using Relays around NAT (TURN): Relay Extensions to Session
Traversal Utilities for NAT (STUN) Traversal Utilities for NAT (STUN)
draft-ietf-tram-turnbis-04 draft-ietf-tram-turnbis-05
Abstract Abstract
If a host is located behind a NAT, then in certain situations it can If a host is located behind a NAT, then in certain situations it can
be impossible for that host to communicate directly with other hosts be impossible for that host to communicate directly with other hosts
(peers). In these situations, it is necessary for the host to use (peers). In these situations, it is necessary for the host to use
the services of an intermediate node that acts as a communication the services of an intermediate node that acts as a communication
relay. This specification defines a protocol, called TURN (Traversal relay. This specification defines a protocol, called TURN (Traversal
Using Relays around NAT), that allows the host to control the Using Relays around NAT), that allows the host to control the
operation of the relay and to exchange packets with its peers using operation of the relay and to exchange packets with its peers using
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 17, 2015. This Internet-Draft will expire on January 7, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview of Operation . . . . . . . . . . . . . . . . . . . . 5 2. Overview of Operation . . . . . . . . . . . . . . . . . . . . 5
2.1. Transports . . . . . . . . . . . . . . . . . . . . . . . 8 2.1. Transports . . . . . . . . . . . . . . . . . . . . . . . 8
2.2. Allocations . . . . . . . . . . . . . . . . . . . . . . . 9 2.2. Allocations . . . . . . . . . . . . . . . . . . . . . . . 9
2.3. Permissions . . . . . . . . . . . . . . . . . . . . . . . 11 2.3. Permissions . . . . . . . . . . . . . . . . . . . . . . . 11
2.4. Send Mechanism . . . . . . . . . . . . . . . . . . . . . 11 2.4. Send Mechanism . . . . . . . . . . . . . . . . . . . . . 11
2.5. Channels . . . . . . . . . . . . . . . . . . . . . . . . 13 2.5. Channels . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6. Unprivileged TURN Servers . . . . . . . . . . . . . . . . 15 2.6. Unprivileged TURN Servers . . . . . . . . . . . . . . . . 15
2.7. Avoiding IP Fragmentation . . . . . . . . . . . . . . . . 16 2.7. Avoiding IP Fragmentation . . . . . . . . . . . . . . . . 16
2.8. RTP Support . . . . . . . . . . . . . . . . . . . . . . . 17 2.8. RTP Support . . . . . . . . . . . . . . . . . . . . . . . 17
2.9. Discovery of Servers . . . . . . . . . . . . . . . . . . 17 2.9. Discovery of TURN server . . . . . . . . . . . . . . . . 17
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.9.1. TURN URI Scheme Semantics . . . . . . . . . . . . . . 17
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 18
4. General Behavior . . . . . . . . . . . . . . . . . . . . . . 19 4. General Behavior . . . . . . . . . . . . . . . . . . . . . . 19
5. Allocations . . . . . . . . . . . . . . . . . . . . . . . . . 22 5. Allocations . . . . . . . . . . . . . . . . . . . . . . . . . 22
6. Creating an Allocation . . . . . . . . . . . . . . . . . . . 23 6. Creating an Allocation . . . . . . . . . . . . . . . . . . . 23
6.1. Sending an Allocate Request . . . . . . . . . . . . . . . 23 6.1. Sending an Allocate Request . . . . . . . . . . . . . . . 23
6.2. Receiving an Allocate Request . . . . . . . . . . . . . . 25 6.2. Receiving an Allocate Request . . . . . . . . . . . . . . 25
6.3. Receiving an Allocate Success Response . . . . . . . . . 29 6.3. Receiving an Allocate Success Response . . . . . . . . . 29
6.4. Receiving an Allocate Error Response . . . . . . . . . . 30 6.4. Receiving an Allocate Error Response . . . . . . . . . . 30
7. Refreshing an Allocation . . . . . . . . . . . . . . . . . . 32 7. Refreshing an Allocation . . . . . . . . . . . . . . . . . . 32
7.1. Sending a Refresh Request . . . . . . . . . . . . . . . . 32 7.1. Sending a Refresh Request . . . . . . . . . . . . . . . . 32
7.2. Receiving a Refresh Request . . . . . . . . . . . . . . . 33 7.2. Receiving a Refresh Request . . . . . . . . . . . . . . . 33
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some special support for older versions of RTP. some special support for older versions of RTP.
Old versions of RTP [RFC3550] required that the RTP stream be on an Old versions of RTP [RFC3550] required that the RTP stream be on an
even port number and the associated RTP Control Protocol (RTCP) even port number and the associated RTP Control Protocol (RTCP)
stream, if present, be on the next highest port. To allow clients to stream, if present, be on the next highest port. To allow clients to
work with peers that still require this, TURN allows the client to work with peers that still require this, TURN allows the client to
request that the server allocate a relayed transport address with an request that the server allocate a relayed transport address with an
even port number, and to optionally request the server reserve the even port number, and to optionally request the server reserve the
next-highest port number for a subsequent allocation. next-highest port number for a subsequent allocation.
2.9. Discovery of Servers 2.9. Discovery of TURN server
Methods of TURN server discovery, including using anycast, are Methods of TURN server discovery, including using anycast, are
described in [I-D.ietf-tram-turn-server-discovery]. described in [I-D.ietf-tram-turn-server-discovery]. The syntax of
the "turn" and "turn" URIs are defined in Section 3.1 of [RFC7065].
2.9.1. TURN URI Scheme Semantics
The "turn" and "turns" URI schemes are used to designate a TURN
server (also known as a relay) on Internet hosts accessible using the
TURN protocol. The TURN protocol supports sending messages over UDP,
TCP, TLS-over-TCP or DTLS-over-UDP. The "turns" URI scheme MUST be
used when TURN is run over TLS-over-TCP or in DTLS-over-UDP, and the
"turn" scheme MUST be used otherwise. The required <host> part of
the "turn" URI denotes the TURN server host. The <port> part, if
present, denotes the port on which the TURN server is awaiting
connection requests. If it is absent, the default port is 3478 for
both UDP and TCP. The default port for TURN over TLS and TURN over
DTLS is 5349.
3. Terminology 3. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Readers are expected to be familiar with [RFC5389] and the terms Readers are expected to be familiar with [RFC5389] and the terms
defined there. defined there.
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and the server. The transport protocol MUST be one of UDP, TCP, TLS- and the server. The transport protocol MUST be one of UDP, TCP, TLS-
over-TCP or DTLS-over-UDP. Since this specification only allows UDP over-TCP or DTLS-over-UDP. Since this specification only allows UDP
between the server and the peers, it is RECOMMENDED that the client between the server and the peers, it is RECOMMENDED that the client
pick UDP unless it has a reason to use a different transport. One pick UDP unless it has a reason to use a different transport. One
reason to pick a different transport would be that the client reason to pick a different transport would be that the client
believes, either through configuration or by experiment, that it is believes, either through configuration or by experiment, that it is
unable to contact any TURN server using UDP. See Section 2.1 for unable to contact any TURN server using UDP. See Section 2.1 for
more discussion. more discussion.
The client also picks a server transport address, which SHOULD be The client also picks a server transport address, which SHOULD be
done as follows. The client receives (perhaps through configuration) done as follows. The client uses the procedures described in
a domain name for a TURN server. The client then uses the DNS
procedures described in [RFC5389], but using an SRV service name of [I-D.ietf-tram-turn-server-discovery] to discover a TURN server and
"turn" (or "turns" for TURN over (D)TLS) instead of "stun" (or TURN server resolution mechanism defined in [RFC5928] to get a list
"stuns"). For example, to find servers in the example.com domain, of server transport addresses that can be tried to create a TURN
the client performs a lookup for '_turn._udp.example.com', allocation.
'_turn._tcp.example.com', and '_turns._tcp.example.com' if the client
wants to communicate with the server using UDP, TCP, TLS-over-TCP, or
DTLS-over-UDP, respectively.
The client MUST include a REQUESTED-TRANSPORT attribute in the The client MUST include a REQUESTED-TRANSPORT attribute in the
request. This attribute specifies the transport protocol between the request. This attribute specifies the transport protocol between the
server and the peers (note that this is NOT the transport protocol server and the peers (note that this is NOT the transport protocol
that appears in the 5-tuple). In this specification, the REQUESTED- that appears in the 5-tuple). In this specification, the REQUESTED-
TRANSPORT type is always UDP. This attribute is included to allow TRANSPORT type is always UDP. This attribute is included to allow
future extensions to specify other protocols. future extensions to specify other protocols.
If the client wishes to obtain a relayed transport address of a If the client wishes to obtain a relayed transport address of a
specific address type then it includes a REQUESTED-ADDRESS-FAMILY specific address type then it includes a REQUESTED-ADDRESS-FAMILY
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o More detail on packet translations. o More detail on packet translations.
22. Acknowledgements 22. Acknowledgements
Most of the text in this note comes from the original TURN Most of the text in this note comes from the original TURN
specification, [RFC5766]. The authors would like to thank Rohan Mahy specification, [RFC5766]. The authors would like to thank Rohan Mahy
co-author of orginal TURN specification and everyone who had co-author of orginal TURN specification and everyone who had
contributed to that document. contributed to that document.
Thanks to Justin Uberti, Pal Martinsen, Oleg Moskalenko, Aijun Wang Thanks to Justin Uberti, Pal Martinsen, Oleg Moskalenko, Aijun Wang
and Simon Perreault for their help on SSODA mechanism. and Simon Perreault for their help on SSODA mechanism. Authors would
like to thank Gonzalo Salgueiro for comments and review.
23. References 23. References
23.1. Normative References 23.1. Normative References
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389, "Session Traversal Utilities for NAT (STUN)", RFC 5389,
October 2008. October 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
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[RFC1122] Braden, R., "Requirements for Internet Hosts - [RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989. Communication Layers", STD 3, RFC 1122, October 1989.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011. Algorithm", RFC 6145, April 2011.
[RFC3697] Rajahalme, J., Conta, A., Carpenter, B., and S. Deering, [RFC3697] Rajahalme, J., Conta, A., Carpenter, B., and S. Deering,
"IPv6 Flow Label Specification", RFC 3697, March 2004. "IPv6 Flow Label Specification", RFC 3697, March 2004.
[RFC7065] Petit-Huguenin, M., Nandakumar, S., Salgueiro, G., and P.
Jones, "Traversal Using Relays around NAT (TURN) Uniform
Resource Identifiers", RFC 7065, November 2013.
23.2. Informative References 23.2. Informative References
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
November 1990. November 1990.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981. 1981.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP E. Lear, "Address Allocation for Private Internets", BCP
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June 2002. June 2002.
[I-D.rosenberg-mmusic-ice-nonsip] [I-D.rosenberg-mmusic-ice-nonsip]
Rosenberg, J., "Guidelines for Usage of Interactive Rosenberg, J., "Guidelines for Usage of Interactive
Connectivity Establishment (ICE) by non Session Initiation Connectivity Establishment (ICE) by non Session Initiation
Protocol (SIP) Protocols", draft-rosenberg-mmusic-ice- Protocol (SIP) Protocols", draft-rosenberg-mmusic-ice-
nonsip-01 (work in progress), July 2008. nonsip-01 (work in progress), July 2008.
[I-D.ietf-tram-turn-server-discovery] [I-D.ietf-tram-turn-server-discovery]
Patil, P., Reddy, T., and D. Wing, "TURN Server Auto Patil, P., Reddy, T., and D. Wing, "TURN Server Auto
Discovery", draft-ietf-tram-turn-server-discovery-01 (work Discovery", draft-ietf-tram-turn-server-discovery-03 (work
in progress), January 2015. in progress), May 2015.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness [RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005. Requirements for Security", BCP 106, RFC 4086, June 2005.
[RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using [RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
Relays around NAT (TURN): Relay Extensions to Session Relays around NAT (TURN): Relay Extensions to Session
Traversal Utilities for NAT (STUN)", RFC 5766, April 2010. Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.
[RFC5928] Petit-Huguenin, M., "Traversal Using Relays around NAT
(TURN) Resolution Mechanism", RFC 5928, August 2010.
[Port-Numbers] [Port-Numbers]
"IANA Port Numbers Registry", 2005, "IANA Port Numbers Registry", 2005,
<http://www.iana.org/assignments/port-numbers>. <http://www.iana.org/assignments/port-numbers>.
[Frag-Harmful] [Frag-Harmful]
"Fragmentation Considered Harmful", <Proc. SIGCOMM '87, "Fragmentation Considered Harmful", <Proc. SIGCOMM '87,
vol. 17, No. 5, October 1987>. vol. 17, No. 5, October 1987>.
[Protocol-Numbers] [Protocol-Numbers]
"IANA Protocol Numbers Registry", 2005, "IANA Protocol Numbers Registry", 2005,
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