TRAM                                                   M. Petit-Huguenin
Internet-Draft                                        Impedance Mismatch
Intended status: Standards Track                            O. Johansson
Expires: October 25, 2015                                      Edvina AB
                                                            G. Salgueiro
                                                           Cisco Systems
                                                          April 23, 2015


Using DNS-based Authentication of Named Entities (DANE) to validate TLS
certificates for the Session Traversal Utilities for NAT (STUN) protocol
                 draft-petithuguenin-tram-stun-dane-03

Abstract

   This document defines how DNS-based Authentication of Named Entities
   (DANE) can be used to validate TLS certificates with the Session
   Traversal Utilities for NAT (STUN) protocol.

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   This Internet-Draft will expire on October 25, 2015.

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   5
   Appendix B.  Release notes  . . . . . . . . . . . . . . . . . . .   6
     B.1.  Modifications between draft-petithuguenin-tram-stun-
           dane-01 and draft-petithuguenin-tram-stun-dane-02 . . . .   6
     B.2.  Modifications between draft-petithuguenin-tram-stun-
           dane-00 and draft-petithuguenin-tram-stun-dane-01 . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   This document defines how DNS-based Authentication of Named Entities
   [RFC6698] (DANE) can be used to validate TLS certificates with the
   Session Traversal Utilities for NAT [RFC5389] (STUN) protocol.

   STUN [RFC5389] uses Transport Layer Security [RFC5246] (TLS) as a
   secure transport and [RFC7350] subsequently added Datagram Transport
   Layer Security [RFC6347] (DTLS) as a secure transport more suited for
   the originally intended purpose of STUN, which is to support
   multimedia sessions.  Both transports require to have the certificate
   presented by the server validated following the rules established by
   [RFC2818].  Additionally [RFC5389] provides rules on how to use DNS
   SRV Resource Records [RFC2782] to resolve a domain name to a list of
   host name for the purpose of load balancing and increased
   reliability.  These rules were subsequently enhanced to support
   S-NAPTR Resource Records [RFC5928] to add the possibility of
   selecting the preferred transport and redirect between domains.

   DANE [RFC6698] improves the mechanism established by [RFC2818] by
   enabling the administrators of domain names to specify the public
   keys (either in an X.509 certificate or in a SubjectPublicKeyInfo
   structure [RFC5280]) used by the secure servers in their domains.
   The benefits of this approach encompass increasing flexibility,
   getting less reliance on trust anchors, enabling Perfect Forward
   Secrecy (PFS) and much more.




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2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "MAY", and "OPTIONAL"
   in this document are to be interpreted as described in [RFC2119] when
   they appear in ALL CAPS.  When these words are not in ALL CAPS (such
   as "must" or "Must"), they have their usual English meanings, and are
   not to be interpreted as RFC 2119 key words.

   "Source Domain" and "Host Name" are defined in [I-D.ietf-dane-srv].

3.  Operations

   STUN clients that are conform with this specification, and that are
   using one or more DNS lookups to find the server, and that have
   established that all DNS Resource Records from the Source Domain to
   the Host Name are secure according to DNSsec [RFC4033] (i.e. that the
   AD bit is set in all the DNS answers), and that have selected a
   secure protocol (e.g.  TLS or DTLS) MUST lookup for a TLSA Resource
   Record for the protocol, port and Host Name selected.  If the TLSA
   Resource Record is secure then the STUN client MUST use it to
   validate the certificate presented by the STUN server.  If there is
   no TLSA Resource Record or if the Resource Record is not secure, then
   the client MUST fallback to the validation process defined in
   [RFC5389] and [RFC7350].

   Note that only STUN Usages where the connection is the result of a
   DNS lookup are to be used with DANE which, for the list of STUN
   Usages listed in [RFC7350], means these:

      NAT Discovery Usage

      NAT Behavior Discovery Usage

      TURN Usage

4.  Security Considerations

   Using DANE as (D)TLS certificate validation mechanism does not
   introduce any specific security considerations beyond those for STUN
   over TLS detailed in [RFC5389] and those for STUN over DTLS detailed
   in [RFC7350].

5.  IANA Considerations

   This document has no IANA actions.






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6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              February 2000.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements", RFC
              4033, March 2005.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5389]  Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
              "Session Traversal Utilities for NAT (STUN)", RFC 5389,
              October 2008.

   [RFC5928]  Petit-Huguenin, M., "Traversal Using Relays around NAT
              (TURN) Resolution Mechanism", RFC 5928, August 2010.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, January 2012.

   [RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
              of Named Entities (DANE) Transport Layer Security (TLS)
              Protocol: TLSA", RFC 6698, August 2012.

   [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.

   [I-D.ietf-dane-srv]
              Finch, T., Miller, M., and P. Saint-Andre, "Using DNS-
              Based Authentication of Named Entities (DANE) TLSA Records
              with SRV Records", draft-ietf-dane-srv-07 (work in
              progress), July 2014.




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6.2.  Informative References

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC7065]  Petit-Huguenin, M., Nandakumar, S., Salgueiro, G., and P.
              Jones, "Traversal Using Relays around NAT (TURN) Uniform
              Resource Identifiers", RFC 7065, November 2013.

Appendix A.  Examples

   With the DNS RRs in Figure 1 and an ordered TURN transport list of
   {DTLS, TLS, TCP, UDP}, a TURN client conform to this specification
   and using the TURN URI [RFC7065] "turns:example.com" will try first
   to connect to the TURN server at address 192.0.2.1:5389 using DTLS
   and using DANE to verify the certificate subsequently presented by
   the server.

   If this connection does not succeed, the client will then try to
   connect to the TURN server at 192.0.2.1:5000 but will not use DANE
   for the certificate verification even as a TLSA RR is available,
   because the DNSsec validation chain is broken in this case.

   Using a TURN URI of "turns:example.com;transport=udp" bypasses the
   NAPTR lookup, but at the expense of preventing the TLS fallback.

   example.com.
   IN NAPTR 100 10 "" RELAY:turn.tls:turn.dtls "" example.net.
   IN RRSIG NAPTR ...

   _turns._tcp.example.com.
   IN SRV   0 0 5000 a.example.net.

   _turns._udp.example.com.
   IN SRV   0 0 5349 a.example.net.
   IN RRSIG SRV ...

   example.net.
   IN NAPTR 200 10 "" RELAY:turn.tcp:turn.tls "" stream.example.net.
   IN NAPTR 100 10 "" RELAY:turn.udp:turn.dtls "" datagram.example.net.
   IN RRSIG NAPTR ...

   datagram.example.net.
   IN NAPTR 100 10 S RELAY:turn.udp "" _turn._udp.example.net.
   IN NAPTR 100 10 S RELAY:turn.dtls "" _turns._udp.example.net.
   IN RRSIG NAPTR ...



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   stream.example.net.
   IN NAPTR 200 10 S RELAY:turn.tcp "" _turn._tcp.example.net.
   IN NAPTR 200 10 S RELAY:turn.tls "" _turns._tcp.example.net.
   IN RRSIG NAPTR ...

   _turn._udp.example.net.
   IN SRV   0 0 3478 a.example.net.

   _turn._tcp.example.net.
   IN SRV   0 0 5000 a.example.net.

   _turns._udp.example.net.
   IN SRV   0 0 5349 a.example.net.
   IN RRSIG SRV ...

   _turns._tcp.example.net.
   IN SRV   0 0 5000 a.example.net.

   a.example.net.
   IN A     192.0.2.1
   IN RRSIG A ...

   _5389._udp.a.example.net.
   IN TLSA ...
   IN RRSIG TLSA ...

   _5000._tcp.a.example.net.
   IN TLSA ...
   IN RRSIG TLSA ...

                                 Figure 1

Appendix B.  Release notes

   This section must be removed before publication as an RFC.

B.1.  Modifications between draft-petithuguenin-tram-stun-dane-01 and
      draft-petithuguenin-tram-stun-dane-02

   o  DANE can store public keys or certificates.

B.2.  Modifications between draft-petithuguenin-tram-stun-dane-00 and
      draft-petithuguenin-tram-stun-dane-01

   o  Change affiliation.

   o  Update STUN-DTLS reference.




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   o  Nits

Authors' Addresses

   Marc Petit-Huguenin
   Impedance Mismatch

   Email: marc@petit-huguenin.org


   Olle E. Johansson
   Edvina AB
   Runbovaegen 10
   Sollentuna  SE-192 48
   SE

   Email: oej@edvina.net


   Gonzalo Salgueiro
   Cisco Systems
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709
   US

   Email: gsalguei@cisco.com

























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