Some comments on this STUN draft and the TURN one:
1) The ABNF in these drafts leaves no room for future extension such as adding
parameters. Was that intentional?
2) Why do both of these docs repeat a lot of ABNF from RFC 3986, instead of
just referencing it? It says in the appendix some ABNF was repeated because
RFC 3986 "are for hierarchical URIs". I'm not exactly sure what that means
other than you don't have a path component, but as far as I can tell the copied
ABNF components in these STUN/TRUN drafts are verbatim copies of RFC 3986, all
the way down to their final expansion.
For example, 'IP-literal' and all of its sub-defined parts ('IPv6address',
'IPvFuture', 'h16', 'ls32') appear identical to those in RFC 3986. In fact, so
is 'stun-host' and 'turn-host' - it's just RFC 3986 'host' by another name. Am
I missing something?
Why not just have this:
stunURI = scheme ":" stun-host [ ":" stun-port ]
scheme = "stun" / "stuns"
stun-host = host ;see section 3.2.2 of [RFC3986]
stun-port = port ;see section 3.2.3 of [RFC3986]
Not a big deal, but it just seems simpler and cleaner to me to not repeat ABNF
from other RFCs, especially when the RFC in question is the one for general URI
syntax and you're defining a specific URI syntax based on it.
-hadriel
On Aug 12, 2013, at 6:14 PM, Graham Klyne <GK(_at_)ninebynine(_dot_)org> wrote:
From: The IESG <iesg-secretary(_at_)ietf(_dot_)org>
To: IETF-Announce <ietf-announce(_at_)ietf(_dot_)org>
Reply-To: ietf(_at_)ietf(_dot_)org
Sender: <iesg-secretary(_at_)ietf(_dot_)org>
Subject: Last Call: <draft-nandakumar-rtcweb-stun-uri-05.txt> (URI Scheme
for Session Traversal Utilities for NAT (STUN) Protocol) to Proposed Standard
The IESG has received a request from an individual submitter to consider
the following document:
- 'URI Scheme for Session Traversal Utilities for NAT (STUN) Protocol'
<draft-nandakumar-rtcweb-stun-uri-05.txt> as Proposed Standard
The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf(_at_)ietf(_dot_)org mailing lists by 2013-08-16. Exceptionally,
comments may be
sent to iesg(_at_)ietf(_dot_)org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.
Abstract
This document is the specification of the syntax and semantics of the
Uniform Resource Identifier (URI) scheme for the Session Traversal
Utilities for NAT (STUN) protocol.
The file can be obtained via
http://datatracker.ietf.org/doc/draft-nandakumar-rtcweb-stun-uri/
IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-nandakumar-rtcweb-stun-uri/ballot/
No IPR declarations have been submitted directly on this I-D.
As IANA designated expert for reviewing URI scheme registrations, I've been
asked to approve this scheme for registration. If there is IETF consensus to
publish this document, it is clear to me that the scheme should be registered.
But, in a personal capacity, not as designated reviewer, I have to ask *why*
this needs to be a URI. As far as I can tell, it is intended for use only in
very constrained environments, where there seems to be little value in having
an identifier that can appear in all the contexts where a URI may be
recognized.
The criteria for new URI schemes in http://tools.ietf.org/html/rfc4395
include:
"New URI schemes SHOULD have clear utility to the broad Internet community,
beyond that available with already registered URI schemes."
-- http://tools.ietf.org/html/rfc4395#section-2.1
This "utility to the broader community" is not clear to me, but I don't fully
understand the intended scope of this protocol, so I could be missing
something. So, in declaring consensus for this specification, I would
request that this aspect at least be considered.
...
Further, according to http://tools.ietf.org/html/rfc5389 it appears that
there are security considerations with regard to the STUN protocol that it
should not be used in isolation:
[[
Classic STUN also had a security vulnerability -- attackers could
provide the client with incorrect mapped addresses under certain
topologies and constraints, and this was fundamentally not solvable
through any cryptographic means. Though this problem remains with
this specification, those attacks are now mitigated through the use
of more complete solutions that make use of STUN.
For these reasons, this specification obsoletes RFC 3489, and instead
describes STUN as a tool that is utilized as part of a complete NAT
traversal solution.
]]
-- http://tools.ietf.org/html/rfc5389#section-2
It seems to me that creating a URI for STUN could encourage its use in
environments outside the "more complete solutions that make use of STUN".
This seems to be further reason that STUN[S] should not be a URI scheme.
I have also suggested that, if registered, the URI scheme registration should
carries a "health warning" to this effect, and that it is not suitable for
general use that is not part of a "complete NAT traversal solution". But I
also recognize that I do not fully grasp the security implications, and that
if those that do know better can agree that there is no potential for
creating security risks here, this suggestion may be unnecessary.
#g
--