One document matched: draft-ietf-tram-alpn-01.xml

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<rfc category="std" docName="draft-ietf-tram-alpn-01" ipr="trust200902">
  <front>
    <title abbrev="ALPN for STUN/TURN">Application Layer Protocol Negotiation
    (ALPN) for Session Traversal Utilities for NAT (STUN) and Traversal Using
    Relays around NAT (TURN)</title>

    <author fullname="Prashanth Patil" initials="P." surname="Patil">
      <organization abbrev="Cisco">Cisco Systems, Inc.</organization>

      <address>
        <postal>
          <street/>

          <street/>

          <city>Bangalore</city>

          <country>India</country>
        </postal>

        <email>praspati@cisco.com</email>
      </address>
    </author>

    <author fullname="Tirumaleswar Reddy" initials="T." surname="Reddy">
      <organization abbrev="Cisco">Cisco Systems, Inc.</organization>

      <address>
        <postal>
          <street>Cessna Business Park, Varthur Hobli</street>

          <street>Sarjapur Marathalli Outer Ring Road</street>

          <city>Bangalore</city>

          <region>Karnataka</region>

          <code>560103</code>

          <country>India</country>
        </postal>

        <email>tireddy@cisco.com</email>
      </address>
    </author>

    <author fullname="Gonzalo Salgueiro" initials="G." surname="Salgueiro">
      <organization abbrev="Cisco">Cisco Systems, Inc.</organization>

      <address>
        <postal>
          <street>7200-12 Kit Creek Road</street>

          <city>Research Triangle Park</city>

          <region>NC</region>

          <code>27709</code>

          <country>US</country>
        </postal>

        <email>gsalguei@cisco.com</email>
      </address>
    </author>

    <author fullname="Marc Petit-Huguenin" initials="M."
            surname="Petit-Huguenin">
      <organization>Impedance Mismatch</organization>

      <address>
        <postal>
          <street/>

          <city/>

          <region/>

          <code/>

          <country>USA</country>
        </postal>

        <email>marc@petit-huguenin.org</email>
      </address>
    </author>

    <date year="2014"/>

    <workgroup>TRAM</workgroup>

    <abstract>
      <t>Application Layer Protocol Negotiation (ALPN) labels for the Session
      Traversal Utilities for NAT (STUN) and Traversal Using Relays around NAT
      (TURN) are defined in this document to allow the application layer to
      negotiate STUN, TURN within the Transport Layer Security (TLS)
      connection. The STUN ALPN protocol identifier and TURN ALPN identifier
      applies to both TLS and Datagram Transport Layer Security (DTLS).</t>
    </abstract>
  </front>

  <middle>
    <section anchor="introduction" title="Introduction">
      <t>STUN can be securely transported using TLS-over-TCP (referred to as
      TLS <xref target="RFC5246"/>), as specified in <xref target="RFC5389"/>,
      or TLS-over-UDP (referred to as DTLS <xref target="RFC6347"/>), as
      specified in <xref target="I-D.ietf-tram-stun-dtls"/>.</t>

      <t>ALPN <xref target="RFC7301"/> enables an endpoint to positively
      identify STUN protocol and TURN in TLS/DTLS and distinguish them from
      other TLS/DTLS protocols. With ALPN, the client sends the list of
      supported application protocols as part of the TLS/DTLS ClientHello
      message. The server chooses a protocol and sends the selected protocol
      as part of the TLS/DTLS ServerHello message. The application protocol
      negotiation can thus be accomplished within the TLS/DTLS handshake,
      without adding network round-trips, and allows the server to associate a
      different certificate with each application protocol, if desired.</t>

      <t>TURN ALPN is useful in the following scenarios:</t>

      <t><list style="numbers">
          <t>Consider an Enterprise network that deploys a TURN server in a
          DeMilitarized Zone (DMZ) to audit all media sessions from inside the
          Enterprise premises to any external peer. In this deployment, an
          Enterprise firewall could use the TURN ALPN identifer to detect, and
          act accordingly, the use of a TURN server outisde the Enterprise
          domain (i.e., a TURN server provided by an application server,
          access network etc).</t>

          <t>If a firewall is configured to block all outgoing traffic except
          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
          TLS) would not be reachable. However, despite the restrictions
          imposed by the firewall, the TURN server can still be reached on the
          allowed HTTPS port if the TURN ALPN identifier is used to establish
          usage of TURN as part of the TLS handshake. In this 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.</t>

          <t>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.</t>
        </list></t>

      <t>This document defines entries ("stun") and ("turn") in the
      "Application Layer Protocol Negotiation (ALPN) Protocol IDs" registry
      established by <xref target="RFC7301"/> to identify the STUN protocol
      and usage of TURN.</t>
    </section>

    <section anchor="term" title="Terminology">
      <t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
      "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
      document are to be interpreted as described in <xref
      target="RFC2119"/>.</t>
    </section>

    <section anchor="iana" title="IANA Considerations">
      <t>The following entry is to be added to the "Application Layer Protocol
      Negotiation (ALPN) Protocol IDs" registry established by <xref
      target="RFC7301"/>.</t>

      <t>The "stun" label identifies STUN over TLS/DTLS:</t>

      <t><list style="empty">
          <t>Protocol: Session Traversal Utilities for NAT (STUN)</t>

          <t>Identification Sequence: 0x73 0x74 0x75 0x6E ("stun")</t>

          <t>Specification: This document (RFCXXXX)</t>
        </list></t>

      <t>The "turn" label identifies TURN over TLS/DTLS:</t>

      <t><list style="empty">
          <t>Protocol: Traversal Using Relays around NAT (TURN)</t>

          <t>Identification Sequence: 0x74 0x75 0x72 0x6E ("turn")</t>

          <t>Specification: This document (RFCXXXX)</t>
        </list></t>
    </section>

    <section anchor="security" title="Security Considerations">
      <t>The ALPN STUN protocol identifier does not introduce any specific
      security considerations beyond those detailed in the TLS ALPN Extension
      specification <xref target="RFC7301"/>. It also does not impact security
      of TLS/DTLS session establishment nor application data exchange.</t>
    </section>

    <section anchor="ack" title="Acknowledgements">
      <t>This work benefited from the discussions and invaluable input by the
      various members of the TRAM working group. These include Simon Perrault,
      Paul Kyzivat, Brandon Williams and Andrew Hutton. Special thanks to
      Martin Thomson and Oleg Moskalenko for their constructive comments,
      suggestions, and early reviews that were critical to the formulation and
      refinement of this document.</t>
    </section>
  </middle>

  <back>
    <references title="Normative References">
      <?rfc include="reference.RFC.2119"?>

      <?rfc include="reference.RFC.5246"?>

      <?rfc include="reference.RFC.5389"?>

      <?rfc include="reference.RFC.6347"?>

      <?rfc include="reference.RFC.7301"?>

      <?rfc include="reference.I-D.ietf-tram-stun-dtls"
?>

      <?rfc include="reference.I-D.mbelshe-httpbis-spdy"?>
    </references>

    <references title="Informative References">
      <?rfc include='reference.RFC.5766'
?>

      <!---->
    </references>
  </back>
</rfc>