Subject: [BEHAVE] DNS Service name in draft-ietf-behave-nat-behavior-discovery-05

From: "Alfred E. Heggestad" <[email-masked]>
Date: Wed, 12 Nov 2008 09:43:19 +0100

Hi

I have a question regarding DNS Service name for the
draft-ietf-behave-nat-behavior-discovery-05, compared with
service names for STUN and TURN. It looks like the former has
a different way of specifying this, and I think this needs
clarification why it is not specified in the same way as
STUN or TURN.

 From draft-ietf-behave-nat-behavior-discovery-05:

5.1. Discovery

   "For the Behavior Discovery Usage the service name is "stun-behavior".
    The protocol can be "udp", "tcp" or "tls".  Other aspects of handling
    failures and default ports are followed as described in STUN
    [RFC5389]."

 From draft-ietf-behave-turn-11:

Section 6.1:

   "The client then uses the DNS
    procedures described in [RFC5389], but using an SRV service name of
    "turn" (or "turns" for TURN over TLS) instead of "stun" (or "stuns").

in summary this means:

   STUN over UDP:    _stun._udp
   STUN over TCP:    _stun._tcp
   STUN over TLS:    _stuns._tcp
   TURN over UDP:    _turn._udp
   TURN over TCP:    _turn._tcp
   TURN over TLS:    _turns._tcp
   NATBD over UDP:   _stun-behavior._udp
   NATBD over TCP:   _stun-behavior._tcp
   NATBD over TLS:   _stun-behavior._tls

Can you please clarify why the NATBD over TLS DNS Service name is
using "tls" and not "_stun-behaviors._tcp" (or similar) ?

thanks

/alfred
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---

From: "Bruce Lowekamp" <[email-masked]>
Date: Wed, 12 Nov 2008 08:39:32 -0500

Alfred,

Purely historical.  3489bis used to specify _tls, and we didn't notice
the change and keep behavior-discovery in sync.  I think it would be
best to adopt _stun-behaviors._tcp to keep everything in sync.

It's interesting that IANA didn't generate a list of SRV entries for
5389.  That seems unfortunate to me since there isn't a clear registry
to add to.  (While looking at this, I also noticed that 3263 has a
hypothetical example reference to rfc5766, which will exist soon.)

I've written the following text:

For the Behavior Discovery Usage the service name is "stun-behavior"
   for UDP and TCP.  The service name is "stun-behaviors" for TLS over
   TCP.  Only "tcp" is defined as a protocol for "stun-behaviors".
   Other aspects of handling failures and default ports are followed as
   described in STUN [RFC5389].

and added a new section to IANA considerations:

10.3.  SRV Registry

   This specification defines the "stun-behavior" and "stun-behaviors"
   SRV service names. "stun-behavior" may be used with SRV protocol
   specifiers "udp" and "tcp". "stun-behaviors" may only be specified
   with "tcp".  Thus, the allowable SRV queries are:
   _stun-behavior._udp            UDP
   _stun-behavior._tcp            TCP
   _stun-behaviors._tcp           TLS over TCP

I'm not quite sure what should be in that section.  There seems to be
no consistent format for IANA SRV entries, and many times (like with
5389) it seems that the issue is ignored entirely.

Bruce

---

From: Andrew Sullivan <[email-masked]>
Date: Wed, 12 Nov 2008 09:09:23 -0500

On Wed, Nov 12, 2008 at 08:39:32AM -0500, Bruce Lowekamp wrote:

> to add to.  

For what it's worth, there is work afoot to create an underscore
registry.

A

-- 
Andrew Sullivan
[email-masked]
Shinkuro, Inc.