draft-ietf-tram-alpn-01.txt   draft-ietf-tram-alpn-02.txt 
TRAM P. Patil TRAM P. Patil
Internet-Draft T. Reddy Internet-Draft T. Reddy
Intended status: Standards Track G. Salgueiro Intended status: Standards Track G. Salgueiro
Expires: March 14, 2015 Cisco Expires: March 20, 2015 Cisco
M. Petit-Huguenin M. Petit-Huguenin
Impedance Mismatch Impedance Mismatch
September 10, 2014 September 16, 2014
Application Layer Protocol Negotiation (ALPN) for Session Traversal Application Layer Protocol Negotiation (ALPN) labels for Session
Utilities for NAT (STUN) and Traversal Using Relays around NAT (TURN) Traversal Utilities for NAT (STUN) and its Usages
draft-ietf-tram-alpn-01 draft-ietf-tram-alpn-02
Abstract Abstract
Application Layer Protocol Negotiation (ALPN) labels for the Session Application Layer Protocol Negotiation (ALPN) labels for Session
Traversal Utilities for NAT (STUN) and Traversal Using Relays around Traversal Utilities for NAT (STUN) and its usages, such as Traversal
NAT (TURN) are defined in this document to allow the application Using Relays around NAT (TURN) and NAT discovery, are defined in this
layer to negotiate STUN, TURN within the Transport Layer Security document to allow an application layer negotiate STUN and its usages
(TLS) connection. The STUN ALPN protocol identifier and TURN ALPN within the Transport Layer Security (TLS) connection. ALPN protocol
identifier applies to both TLS and Datagram Transport Layer Security identifiers defined in this document apply to both TLS and Datagram
(DTLS). Transport Layer Security (DTLS).
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 14, 2015. This Internet-Draft will expire on March 20, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 3. ALPN Labels . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
STUN can be securely transported using TLS-over-TCP (referred to as STUN can be securely transported using TLS-over-TCP (referred to as
TLS [RFC5246]), as specified in [RFC5389], or TLS-over-UDP (referred TLS [RFC5246]), as specified in [RFC5389], or TLS-over-UDP (referred
to as DTLS [RFC6347]), as specified in [I-D.ietf-tram-stun-dtls]. to as DTLS [RFC6347]), as specified in [RFC7350].
ALPN [RFC7301] enables an endpoint to positively identify STUN ALPN [RFC7301] enables an endpoint to positively identify an
protocol and TURN in TLS/DTLS and distinguish them from other TLS/ application protocol in TLS/DTLS and distinguish it from other TLS/
DTLS protocols. With ALPN, the client sends the list of supported DTLS protocols. With ALPN, the client sends the list of supported
application protocols as part of the TLS/DTLS ClientHello message. application protocols as part of the TLS/DTLS ClientHello message.
The server chooses a protocol and sends the selected protocol as part The server chooses a protocol and sends the selected protocol as part
of the TLS/DTLS ServerHello message. The application protocol of the TLS/DTLS ServerHello message. Application protocol
negotiation can thus be accomplished within the TLS/DTLS handshake, negotiation can thus be accomplished within the TLS/DTLS handshake,
without adding network round-trips, and allows the server to without adding network round-trips.
associate a different certificate with each application protocol, if
desired.
TURN ALPN is useful in the following scenarios: A STUN protocol identifier and its associated usages, such as TURN,
can be used to identify the purpose of a flow without initiating a
session. This capability is useful and adds efficiency, as shown in
the following scenarios.
1. Consider an Enterprise network that deploys a TURN server in a 1. Consider an Enterprise network that deploys a TURN server in a
DeMilitarized Zone (DMZ) to audit all media sessions from inside DeMilitarized Zone (DMZ) to audit all media sessions from inside
the Enterprise premises to any external peer. In this the Enterprise premises to any external peer. In this
deployment, an Enterprise firewall could use the TURN ALPN deployment, an Enterprise firewall could use the TURN ALPN
identifer to detect, and act accordingly, the use of a TURN identifier to detect the use of a TURN server that is outside the
server outisde the Enterprise domain (i.e., a TURN server Enterprise domain (i.e., a TURN server provided by an application
provided by an application server, access network etc). server, access network, etc).
2. If a firewall is configured to block all outgoing traffic except 2. If a firewall is configured to block all outgoing traffic except
for TCP traffic to specific ports (e.g., 443 for HTTPS), a TURN for TCP traffic to specific ports (e.g., 443 for HTTPS), a TURN
server listening on its default ports (3478 for TCP/UDP, 5349 for server listening on its default ports (3478 for TCP/UDP, 5349 for
TLS) would not be reachable. However, despite the restrictions TLS) would not be reachable. However, despite the restrictions
imposed by the firewall, the TURN server can still be reached on imposed by the firewall, a TURN server can still be reached on
the allowed HTTPS port if the TURN ALPN identifier is used to the allowed HTTPS port if the TURN ALPN identifier is used to
establish usage of TURN as part of the TLS handshake. In this establish usage of TURN as part of the TLS handshake.
case, the TURN ALPN identifier sent by the client will be used by
the server to identify that the client intends to make a TURN
request and it must act as a TURN server to relay the traffic to
and from the remote peer.
3. If a TURN server is in a resource exhausted state then it could
use the TURN ALPN identifier sent by the client to identify that
the connection will be used to allocate resouces, which the
server cannot accommodate, and hence reject the (D)TLS handshake
with a fatal error.
This document defines entries ("stun") and ("turn") in the This document defines entries in the "Application Layer Protocol
"Application Layer Protocol Negotiation (ALPN) Protocol IDs" registry Negotiation (ALPN) Protocol IDs" registry established by [RFC7301] to
established by [RFC7301] to identify the STUN protocol and usage of identify the STUN protocol and its usages.
TURN.
2. Terminology 2. 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 [RFC2119]. document are to be interpreted as described in [RFC2119].
3. IANA Considerations 3. ALPN Labels
The following entry is to be added to the "Application Layer Protocol The document proposes the following ALPN labels to identify the STUN
Negotiation (ALPN) Protocol IDs" registry established by [RFC7301]. protocol and its associated usages.
The "stun" label identifies STUN over TLS/DTLS: 'stun': Generic label to identify STUN over (D)TLS. This label
identifies the STUN protocol or any of currently defined usages
(e.g., "stun.turn", "stun.nat-discovery") as well as any future
usages that may be defined at a later date (e.g., any labels
starting with "stun.").
'stun.turn': Label to identify the specific use of STUN over (D)TLS
for TURN.
'stun.nat-discovery': Label to identify the specific use of STUN
over (D)TLS for NAT discovery.
This document does not explicitly assign ALPN labels for other usages
of STUN, such as NAT Behavior Discovery using STUN ([RFC5780]). All
such usages that do not have a dedicated label are implicitly
identified by the generic "stun" ALPN label.
4. IANA Considerations
The following entries are to be added to the "Application Layer
Protocol Negotiation (ALPN) Protocol IDs" registry established by
[RFC7301].
The "stun" label identifies STUN over (D)TLS:
Protocol: Session Traversal Utilities for NAT (STUN) Protocol: Session Traversal Utilities for NAT (STUN)
Identification Sequence: 0x73 0x74 0x75 0x6E ("stun") Identification Sequence: 0x73 0x74 0x75 0x6E ("stun")
Specification: This document (RFCXXXX) Specification: This document (RFCXXXX)
The "turn" label identifies TURN over TLS/DTLS: The "stun.turn" label identifies TURN usage over (D)TLS:
Protocol: Traversal Using Relays around NAT (TURN) Protocol: Traversal Using Relays around NAT (TURN)
Identification Sequence: 0x74 0x75 0x72 0x6E ("turn") Identification Sequence: 0x73 0x74 0x75 0x6E 0x2E 0x74 0x75 0x72
0x6E ("stun.turn")
Specification: This document (RFCXXXX) Specification: This document (RFCXXXX)
4. Security Considerations The "stun.nat-discovery" label identifies usage of STUN for the
purposes of NAT/behavior discovery over (D)TLS:
Protocol: NAT discovery using Session Traversal Utilities for NAT
(STUN)
Identification Sequence: 0x73 0x74 0x75 0x6E 0x2E 0x6e 0x61 0x74
0x2d 0x64 0x69 0x73 0x63 0x6f 0x76 0x65 0x72 0x79 ("stun.nat-
discovery")
Specification: This document (RFCXXXX)
5. Security Considerations
The ALPN STUN protocol identifier does not introduce any specific The ALPN STUN protocol identifier does not introduce any specific
security considerations beyond those detailed in the TLS ALPN security considerations beyond those detailed in the TLS ALPN
Extension specification [RFC7301]. It also does not impact security Extension specification [RFC7301]. It also does not impact security
of TLS/DTLS session establishment nor application data exchange. of TLS/DTLS session establishment nor application data exchange.
5. Acknowledgements 6. Acknowledgements
This work benefited from the discussions and invaluable input by the This work benefited from the discussions and invaluable input by the
various members of the TRAM working group. These include Simon various members of the TRAM working group. These include Simon
Perrault, Paul Kyzivat, Brandon Williams and Andrew Hutton. Special Perrault, Paul Kyzivat, Brandon Williams and Andrew Hutton. Special
thanks to Martin Thomson and Oleg Moskalenko for their constructive thanks to Martin Thomson and Oleg Moskalenko for their constructive
comments, suggestions, and early reviews that were critical to the comments, suggestions, and early reviews that were critical to the
formulation and refinement of this document. formulation and refinement of this document.
6. References 7. References
7.1. Normative References
6.1. Normative References
[I-D.ietf-tram-stun-dtls]
Petit-Huguenin, M. and G. Salgueiro, "Datagram Transport
Layer Security (DTLS) as Transport for Session Traversal
Utilities for NAT (STUN)", draft-ietf-tram-stun-dtls-05
(work in progress), June 2014.
[I-D.mbelshe-httpbis-spdy]
Belshe, M. and R. Peon, "SPDY Protocol", draft-mbelshe-
httpbis-spdy-00 (work in progress), February 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[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.
[RFC5780] MacDonald, D. and B. Lowekamp, "NAT Behavior Discovery
Using Session Traversal Utilities for NAT (STUN)", RFC
5780, May 2010.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012. Security Version 1.2", RFC 6347, January 2012.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, July 2014. Negotiation Extension", RFC 7301, July 2014.
6.2. Informative References [RFC7350] Petit-Huguenin, M. and G. Salgueiro, "Datagram Transport
Layer Security (DTLS) as Transport for Session Traversal
Utilities for NAT (STUN)", RFC 7350, August 2014.
7.2. Informative References
[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.
Authors' Addresses Authors' Addresses
Prashanth Patil Prashanth Patil
Cisco Systems, Inc. Cisco Systems, Inc.
Bangalore Bangalore
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