Internet DRAFT - draft-schwartz-tram-turnbyname

draft-schwartz-tram-turnbyname







Network Working Group                                        B. Schwartz
Internet-Draft                                                 J. Uberti
Intended status: Standards Track                                  Google
Expires: September 6, 2015                                 March 5, 2015


TURN by name: an extension to TURN for contacting an endpoint by its DNS
                                 name.
                   draft-schwartz-tram-turnbyname-00

Abstract

   When tunneling traffic through TURN, a client may sometimes desire to
   contact a remote endpoint that it knows by its DNS name, not its IP
   address.  This document describes an extension to TURN that allows
   such a client to contact a named endpoint.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 6, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  New Address Family for DNS names  . . . . . . . . . . . . . .   3
   3.  Extension to the XOR-PEER-ADDRESS attribute format  . . . . .   3
   4.  Changes to TURN server behavior . . . . . . . . . . . . . . .   4
     4.1.  Servers that do not support the extension . . . . . . . .   4
     4.2.  Supported attributes  . . . . . . . . . . . . . . . . . .   4
     4.3.  Supported messages  . . . . . . . . . . . . . . . . . . .   4
     4.4.  Name mapping storage  . . . . . . . . . . . . . . . . . .   4
     4.5.  Lookup behavior . . . . . . . . . . . . . . . . . . . . .   5
     4.6.  CreatePermission  . . . . . . . . . . . . . . . . . . . .   6
       4.6.1.  Implications of this permission model . . . . . . . .   6
     4.7.  Send  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.8.  Channel Binding . . . . . . . . . . . . . . . . . . . . .   7
       4.8.1.  Implications of this channel binding model  . . . . .   8
     4.9.  Receiving Data  . . . . . . . . . . . . . . . . . . . . .   9
       4.9.1.  Implications of this data receipt model . . . . . . .   9
   5.  Changes to TURN client behavior . . . . . . . . . . . . . . .  10
     5.1.  When to use this extension  . . . . . . . . . . . . . . .  10
     5.2.  Issuing Send, CreatePermission, and ChannelBind requests
           for DNS names . . . . . . . . . . . . . . . . . . . . . .  10
     5.3.  Receiving Data indications  . . . . . . . . . . . . . . .  10
     5.4.  Handling dynamic addressing . . . . . . . . . . . . . . .  11
     5.5.  Dual-stack behavior . . . . . . . . . . . . . . . . . . .  11
   6.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     10.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   The TURN standard [RFC5766] extends STUN to allow proxying
   connections directly through the server.  Clients send messages to
   the server in order to request the allocation of ports on the server,
   and identify the remote peers with whom they want to exchange
   packets.  These remote peers are identified by an XOR-PEER-ADDRESS
   attribute, which includes the remote peer's IP address and port.

   TURN is most commonly used as a component of an ICE [RFC5245]
   implementation, to allow communication between endpoints that each
   send their own transport address to the other in the form of an ICE
   candidate.  These candidates are typically constructed using STUN, or




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   by direct interrogation of the network interfaces, so they normally
   contain IP addresses, although domain names are also allowed.

   However, TURN is now attracting a wider range of use cases,
   especially on enterprise networks and in conjunction with WebRTC.
   Some use cases employ TURN as an "escape hatch" in an otherwise
   tightly restricted network, with the intention that users would
   tunnel much or all of their UDP traffic through the TURN server.  On
   some restricted networks, DNS access is also restricted, which may
   prevent users from determining the IP address of a domain (e.g. an
   application-specified TURN server, for RETURN
   [I-D.schwartz-rtcweb-return], or an ICE candidate that contains a
   domain name) that they wish to contact through the escape-hatch TURN
   server.

   Extending TURN to support named peers allows TURN to work for clients
   who are attempting to contact an endpoint by name, on networks where
   resolving those names is not otherwise possible.

2.  New Address Family for DNS names

   The Address Family 0x03 is defined to indicate that the specified
   address is a DNS name.  This family is only permitted under certain
   circumstances, detailed below.

3.  Extension to the XOR-PEER-ADDRESS attribute format

   STUN/TURN attributes are Type-Length-Value encoded ([RFC5389],
   Section 15).  For both of the existing Families, the attribute's
   encoded length is a known constant, because the length of the address
   is constant.  For the newly defined Family 0x03, the length is
   variable, and the indicated length from the TLV encoding is necessary
   in order to parse the attribute.

   The DNS name is transmitted in the X-Address field, and is encoded by
   the following procedure:

   1.  Define the "legacy transaction ID" as a 128-bit value consisting
       of the 32-bit magic cookie followed by the 96-bit transaction ID.

   2.  Define the DNS name as a standard dot-separated UTF-8 byte-string
       (not null-terminated).

   3.  Compute the encoded address (X-Address) by XOR'ing each byte of
       the DNS name with the corresponding byte of the legacy
       transaction ID.





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       *  If the DNS name is longer than 128 bits, the corresponding
          byte with which to XOR wraps around to the beginning of the
          legacy transaction ID.

   This procedure is an extension of the encoding for families 0x01 and
   0x02, so all three XOR-PEER-ADDRESS families can be encoded and
   parsed by a single procedure, without any special cases.

4.  Changes to TURN server behavior

4.1.  Servers that do not support the extension

   Servers are NOT REQUIRED to support this extension.  No change is
   required to servers that do not support the extension.  Upon
   receiving a message containing an XOR-PEER-ADDRESS attribute with
   Family 0x03, existing compliant servers MUST reply with Error 440
   (Address Family not Supported).

   Servers that do support this extension MUST comply with the
   requirements that follow in this section.

4.2.  Supported attributes

   Address Family 0x03 is only permitted in the context of the XOR-PEER-
   ADDRESS attribute.  All other attributes that use address families
   remain restricted to families 0x01 and 0x02.  The server MUST respond
   with Error 440 (Address Family not Supported) when encountering this
   address family in an attribute where it is not supported.

4.3.  Supported messages

   The XOR-PEER-ADDRESS attribute may only have family 0x03 in the
   context of a CreatePermission, Send, Data, or ChannelBind message.
   If the server encounters this address family in the context of any
   other message type, it MUST respond with Error 440 (Address Family
   not Supported).

   If a TURN server supports address family 0x03 in one of these
   messages, it MUST support it in all of these messages.

4.4.  Name mapping storage

   Baseline TURN servers must store two kinds of state for each
   Allocation: Permissions and Channel Bindings.  This extension adds a
   third kind of state: Name Mappings.  Each DNS Name Mapping consists
   of:

   o  a DNS name



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   o  an IP address

   o  a reference count, which is always either 1 or 2

   Name Mappings do not have an expiration time, but the server MUST
   delete them if their reference count falls to zero.  Like Permissions
   and Channel Bindings, Name Mappings are scoped to a single
   Allocation.

   Each IP address appears in only one Name Mapping for an Allocation.
   The requirements for CreatePermission and ChannelBind are structured
   to maintain this invariant.

   Server implementations SHOULD implement Name Mappings in a way that
   enables fast bidirectional lookup.

4.5.  Lookup behavior

   When a DNS name lookup is required, the server's behavior depends on
   the current Allocation.  Each supported message is associated with an
   Allocation, whose address family is IPv4, IPv6 [RFC6156], or Both
   (via ADDITIONAL-ADDRESS-FAMILY [I-D.ietf-tram-turnbis]).

   If the address family is IPv4, then the server MUST search for an A
   record for the name, and similarly if the address family is IPv6, the
   server MUST search for a AAAA record.  The server MUST handle errors
   as follows:

   o  If resolution fails due to a server error (e.g.  DNS SERVFAIL),
      reply with error code 500 (Server Error).

   o  If the resolution fails because there is no record of the required
      type (e.g.  DNS NOERROR), respond with error code 443 (Peer
      Address Family Mismatch).

   o  For all other DNS errors, return error code 447 (Connection
      timeout or failure).

   The TURN server implementation MAY use a high-level DNS resolution
   API, such as gethostbyname or getaddrinfo, to perform the lookup.

   If the Allocation has both address families, then it MUST look for an
   IPv6 address, and fall back to IPv4 only if a AAAA record is not
   found.







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4.6.  CreatePermission

   In baseline TURN, each CreatePermission message creates or renews a
   Permission to send and receive messages to some specified IP address.
   With this extension, a Permission may indicate either an IP address
   or a DNS name.  Both types of Permissions are subject to the same
   expiration policy.

   At any given time, there is at most one Permission that specifies any
   IP address, or any DNS name, but there may be a Permission specifying
   a DNS name that resolves to an IP address that is specified in
   another Permission.

   Upon receiving a CreatePermission message on an Allocation, the
   server MUST perform these steps:

   1.  If the CreatePermission message contains a peer address of family
       0x01 or 0x02, create or update a Permission for the given
       address.  (No change from baseline.)

   2.  If the CreatePermission message contains peer address of family
       0x03:

       A.  Look for an existing Permission with the given DNS name.  If
           one exists, refresh its expiration time and return success.

       B.  Otherwise, check if there is a Name Mapping for the DNS name.

           i.    If one exists, increment its reference count.

           ii.   Otherwise, perform a DNS lookup for the name.  If it
                 succeeds, add a DNS name mapping for the name and the
                 resolved address, with reference count 1.

       C.  Install a new permission for the DNS name.

   When a Permission containing a DNS name expires, the server MUST
   decrement the reference count on the Name Mapping for this DNS name,
   and delete the Name Mapping if its reference count falls to zero.

4.6.1.  Implications of this permission model

   As long as a permission is regularly refreshed with the same DNS
   name, the effective IP address will not change.

   Permission refreshes for an IP address do not extend the lifetime of
   DNS resolutions to that address.




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   Permission requests for an IP address are not sufficient to allow
   Send requests to a DNS name that resolves to that IP address, and
   vice versa.

4.7.  Send

   Upon receiving a Send message on an Allocation, the server MUST
   perform these steps:

   1.  If the Send message contains a peer address of family 0x01 or
       0x02, check for a Permission that indicates that IP address.
       (There will be at most one.)  If a Permission matches, send the
       packet; otherwise silently drop it.  (No change from baseline.)

   2.  If the Send message contains a peer address of family 0x03, check
       if there is a Permission for the given DNS name.  (There will be
       at most one.)  If one exists, send the packet to the IP address
       indicated for that DNS name in its Name Mapping; otherwise
       silently drop it.

4.8.  Channel Binding

   In baseline TURN, each ChannelBind message creates or renews a
   channel binding, which consists of a transport ID, a peer's IP
   address, and a port on that address.  It also creates or renews a
   permission for the peer's IP address, exactly as if a
   CreatePermission message had been received for that IP address.

   In this extension, each channel binding includes either an IP address
   or a DNS name.

   Upon receiving a ChannelBind message on an Allocation, the server
   MUST perform these steps:

   1.  If the ChannelBind indicates a peer address of family 0x01 or
       0x02

       A.  If a binding already exists with the specified transport ID,
           IP address, and port, refresh the binding.

       B.  If a binding already exists for the specified transport ID
           with a different or unspecified IP address or port, report
           Error 400 (Bad Request).

       C.  If a binding already exists with this port and this IP
           address, or a DNS name that maps to this IP address, report
           Error 400 (Bad Request) and include a CHANNEL-NUMBER




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           attribute that indicates the number of the conflicting
           channel.

       D.  Otherwise, create a binding.

       E.  Install or refresh a permission for the originally indicated
           peer IP address.

   2.  If the ChannelBind indicates a peer address of family 0x03

       A.  If a binding already exists with the specified transport ID,
           DNS name, and port, refresh the binding, including the IP
           address.

       B.  Otherwise, resolve the DNS name to an IP address, using the
           name mapping table if it exists, and performing a DNS lookup
           only if no name mapping exists for this DNS name.

           i.    If a binding already exists for the specified transport
                 ID with a different IP address or port, report Error
                 400 (Bad Request).

           ii.   If a binding already exists with a different transport
                 ID, for this port, and this IP address or a DNS name
                 that is mapped to this IP address, report Error 400
                 (Bad Request) and include a CHANNEL-NUMBER attribute
                 that indicates the number of the conflicting channel.

       C.  Install a channel binding with the specified transport ID,
           DNS name, and port.

       D.  Increment the name mapping's reference count, or Install a
           new name mapping if one does not already exist for this DNS
           name.

       E.  Perform the steps required when receiving a CreatePermission
           message for this DNS name.

   When a channel binding that indicates a DNS name expires, the server
   MUST decrement the reference count on the matching name mapping, and
   delete the mapping if the reference count falls to zero.

4.8.1.  Implications of this channel binding model

   As long as a channel is refreshed before it times out, it will
   continue to resolve to a constant address.





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   There can never be two channels bound to the same remote transport
   address.  If that were possible, it would result in traffic
   amplification (sending each received packet to all matching channels)
   or other strange behaviors (e.g. selecting one arbitrary channel to
   receive the packet).

   Each time a new channel is bound for a DNS name, it checks for a Name
   Mapping before doing any external resolution, so the resolved IP
   address is guaranteed to be consistent with the active Permission for
   this DNS name, if one exists.  As a result, DNS resolution results
   can persist indefinitely within an Allocation, longer than the DNS
   TTL or any individual connection, if they are maintained by
   ChannelBind or CreatePermission calls to different ports on the same
   remote peer that overlap in time.

   If two ChannelBind requests are received for the same port on two
   different DNS names that resolve to the same IP address, the second
   request will fail with a generic error code (400), but will also let
   the client know which existing channel to use instead.  The same is
   true of collisions between IP and DNS channel binding requests.

   Installing a channel binding to a DNS name also enables Send messages
   to the DNS name, but not to the resolved IP address.

4.9.  Receiving Data

   Upon receiving an incoming packet on an Allocation, the server MUST
   perform these steps:

   1.  Check if there is a channel binding to this source port and IP
       address, or a DNS name that is mapped to this IP address.  (There
       will be at most one such channel.)  If there is, let the channel
       handle the packet.

   2.  Otherwise, check if there is any DNS permission that is mapped to
       the source IP address.  If there is, produce a Data message with
       that DNS name.

   3.  Otherwise, check if there is any IP permission that matches the
       source IP address.  If there is, produce a Data message with the
       source IP address; otherwise discard the packet.

4.9.1.  Implications of this data receipt model

   If a name mapping exists for an IP address, all packets received from
   that address will be labeled with the DNS name, not the IP address.
   Clients never learn the IP address for a DNS name unless they provoke
   a conflict, similar to the naming model used by SOCKS5 [RFC1928].



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   If a channel is bound for a port on a peer, all packets from that
   port will be routed to the channel exclusively.

5.  Changes to TURN client behavior

   Clients are NOT REQUIRED to support this extension.  No change is
   required to existing clients.  The requirements in this section only
   apply to clients that opt to support the extension.

5.1.  When to use this extension

   When the client receives a request to contact an endpoint that is
   identified by its DNS name, the client SHOULD attempt to use this
   extension to reach that endpoint, and SHOULD NOT attempt to perform a
   local DNS lookup for the name, so that connections may succeed even
   if the local DNS server fails to return a correct result.

   If the TURN server responds with Error 440 (Address Family Not
   Supported), then the TURN client application SHOULD attempt to
   perform a local DNS lookup for the name, and retry the connection by
   IP address.  (This functionality is logically separable from the TURN
   protocol itself, and might best be implemented by having a TURN
   client library that indicates the error, leaving the DNS lookup to be
   the responsibility of the application that uses the library.)

5.2.  Issuing Send, CreatePermission, and ChannelBind requests for DNS
      names

   When attempting to contact an endpoint by its DNS name, the client
   SHOULD transmit a CreatePermission or ChannelBind request whose XOR-
   PEER-ADDRESS attribute contains family 0x03, conveying the DNS name
   formatted as described above.

   If the server responds with Error 440 (Address family not supported),
   then the client SHOULD abandon all requests using DNS, because the
   server does not support this extension.

   If a ChannelBind request fails with Error 400, but includes a
   CHANNEL-NUMBER attribute, then that channel is already bound to the
   remote transport address.

5.3.  Receiving Data indications

   Clients MAY send CreatePermission requests for both an IP address and
   a DNS name that maps to that IP address, and both requests will
   succeed.  However, all Data messages from the remote peer will be
   marked as being received from the DNS name.  Therefore, clients MUST




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   NOT assume that replies from a Send to an IP address are labeled with
   that IP address.

5.4.  Handling dynamic addressing

   The IP address to which a DNS name resolves is not a constant.  It
   may change occasionally due to address reassignment, or it may even
   change on every lookup, in the case of round-robin DNS.

   The TURN server ensures that the IP address associated with a
   permission or channel binding does not change as long as the
   permission or binding is refreshed before it expires.  Therefore,
   clients that need to send messages to a stable IP address MUST
   refresh their DNS name permissions and channel bindings even while
   they are not in use, to ensure that they do not expire and later
   resolve to a different IP address.

   If the client has previously connected to a DNS name on an
   Allocation, and wishes to connect again to the same DNS name with an
   up-to-date IP address resolution, it SHOULD request a new Allocation,
   and connect to the DNS name on the new Allocation.

5.5.  Dual-stack behavior

   If a specific address family is not indicated for the remote
   endpoint, and the server does not support dual allocation (e.g.
   ADDITIONAL-ADDRESS-FAMILY [I-D.ietf-tram-turnbis]]), then the
   client's behavior is implementation-defined.  For example, when
   processing a request to send the first packet to a DNS name, the
   client MAY use an approach inspired by Happy Eyeballs [RFC6555]:

   o  Create an Allocation for the system's preferred address family
      (e.g.  IPv6).

   o  Attempt to connect to the DNS name on this Allocation using a
      ChannelBind message.

      *  If the server replies with error code 443 (Peer Address Family
         Mismatch), immediately discard the Allocation and try again
         with an Allocation of the other family.

      *  If a response message is received before some timeout (e.g. 300
         ms), use this Allocation

      *  If no response message is received before some timeout (e.g.
         300 ms), attempt to connect using a new Allocation of the other
         address family, and use whichever Allocation receives a
         response first.  Discard the other Allocation.



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6.  Examples

  TURN                                 TURN           Peer          DNS
  client                               server          A          Server
    |                                    |             |             |
    |-- ChannelBind req ---------------->|             |             |
    | (peer-a.example.com to 0x4001)     |             |             |
    |                                    |======= DNS query ========>|
    |                                    |     (peer-a.example.com)  |
    |                                    |<=======DNS result=========|
    |                                    |     (192.0.2.15)          |
    |<---------- ChannelBind succ resp --|             |             |
    |                                    |             |             |
    |-- [0x4001] data ------------------>|             |             |
    |                                    |=== data ===>|             |
    |                                    |             |             |
    |                                    |<== data ====|             |
    |<------------------ [0x4001] data --|             |             |

                Figure 1: Using DNS names with ChannelBind

  TURN                                 TURN           Peer          DNS
  client                               server          A          Server
    |                                    |             |             |
    |----- CreatePermission req -------->|             |             |
    |      (peer-a.example.com)          |             |             |
    |                                    |======= DNS query ========>|
    |                                    |     (peer-a.example.com)  |
    |                                    |<=======DNS result=========|
    |                                    |     (192.0.2.15)          |
    |<-- CreatePermission success resp --|             |             |
    |                                    |             |             |
    |-- Send ind (peer-a.example.com) -->|             |             |
    |                                    |=== data ===>|             |
    |                                    |             |             |
    |                                    |<== data ====|             |
    |<-- Data ind (peer-a.example.com) --|             |             |
    |                                    |             |             |

         Figure 2: Using DNS names with CreatePermission and Send











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  TURN                                 TURN           Peer          DNS
  client                               server          A          Server
    |                                    |             |             |
    |------- CreatePermission req ------>|             |             |
    |        (peer-a.example.com)        |             |             |
    |                                    |======= DNS query ========>|
    |                                    |     (peer-a.example.com)  |
    |                                    |<=======DNS result=========|
    |                                    |     (192.0.2.15)          |
    |<-- CreatePermission success resp --|             |             |
    |                                    |             |             |
    |------- ChannelBind req ----------->|             |             |
    |  (peer-a.example.com to 0x4001)    |             |             |
    |                                    |             |             |
    |<---- ChannelBind succ resp --------|             |             |
    |                                    |             |             |
    |-- Send ind (peer-a.example.com) -->|             |             |
    |                                    |=== data ===>|             |
    |                                    |             |             |
    |                                    |<== data ====|             |
    |<---------- [0x4001] data ----------|             |             |
    |                                    |             |             |

   Figure 3: Sharing DNS names between CreatePermission and ChannelBind

7.  Security Considerations

   TURN servers that implement this specification can be made to parse
   arbitrary DNS records.  They should make sure to use secure, well-
   tested DNS client implementations.

   Clients can cause the TURN server to perform an arbitrary number of
   DNS lookups.  Server implementations MAY limit the rate at which an
   individual client can trigger lookups, and return Error 508
   (Insufficient Capacity) when a client exceeds the limit.

   A malicious server could forward messages to the wrong IP address for
   a specified domain name, but this does not represent a change in
   security relative to the basic TURN standard.

   To provide this functionality, the server is required to store a
   number of DNS Name Mappings that is at most the number of active
   permissions or channels.  Implementers should take care to avoid
   resource leaks in the DNS mapping implementation, to maintain this
   bound.






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8.  IANA Considerations

   This draft adds a new STUN address family, 0x03 (DNS name).

9.  Acknowledgements

   Thanks to Warren Kumari for his early review.

10.  References

10.1.  Normative References

   [I-D.ietf-tram-turnbis]
              Reddy, T., Johnston, A., Matthews, P., and J. Rosenberg,
              "Traversal Using Relays around NAT (TURN): Relay
              Extensions to Session Traversal Utilities for NAT (STUN)",
              draft-ietf-tram-turnbis-02 (work in progress), February
              2015.

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245, April
              2010.

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

   [RFC5766]  Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
              Relays around NAT (TURN): Relay Extensions to Session
              Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.

   [RFC6156]  Camarillo, G., Novo, O., and S. Perreault, "Traversal
              Using Relays around NAT (TURN) Extension for IPv6", RFC
              6156, April 2011.

10.2.  Informative References

   [I-D.schwartz-rtcweb-return]
              Schwartz, B. and J. Uberti, "Recursively Encapsulated TURN
              (RETURN) for Connectivity and Privacy in WebRTC", draft-
              schwartz-return-04 (work in progress), November 2014.

   [RFC1928]  Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and
              L. Jones, "SOCKS Protocol Version 5", RFC 5766, March
              1996.





Schwartz & Uberti       Expires September 6, 2015              [Page 14]

Internet-Draft                TURN-BY-NAME                    March 2015


   [RFC6555]  Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
              Dual-Stack Hosts", RFC 6555, April 2012.

Authors' Addresses

   Benjamin M. Schwartz
   Google, Inc.
   111 8th Ave
   New York, NY  10011
   USA

   Email: bemasc@webrtc.org


   Justin Uberti
   Google, Inc.
   747 6th Street South
   Kirkland, WA  98033
   USA

   Email: justin@uberti.name






























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