Session Traversal Utilities for NAT (STUN) Usage for Consent Freshness
draft-ietf-rtcweb-stun-consent-freshness-16

[Ballot discuss]


Apologies that these discuss points are maybe asking
fairly fundamental questions.  That could be that this
is really the first of the new security things required
by rtcweb to get to the IESG.  Or maybe I'm misreading
stuff here, if so, sorry;-)

(1) Why call this "consent?" That term is (ab)used in
many ways on the web, and adding another variation
without a definition that distinguishes this from "click
ok to my 200 page anti-privacy policy" or "remember that
example.com is allowed use my camera/mic" seems like a
terrible idea. I also don't see how this can ever be
something to which a normal person can "consent" (i.e.
consciously agree while fully understanding) so the term
is IMO very misleading, and will I fear be used to
mislead further.  (See also some of the comments below -
I do not think we ought be as fast and loose with this
aleady terribly badly used term.) To summarise: I'd love
if you did s/consent/anything-else/g but if not, please
define consent here in a way that clearly and
unambiguously distinguishes this usage from other abuses
of the term.

(2) WebRTC does not require STUN or TURN servers for
some calls, even if it does for many. Why is it ok to
require such a server be present in all calls (which I
think this means) espcially when that means exposing
additional meta-data (calling parties in a case where
the servers weren't needed and call duration in all
cases) to those servers when that is not always
necessary?

(3) (end of p5) You have a MUST NOT here that is
depenedent on current browser implementations. Why is
that an IETF thing and not a W3C thing? But more
interestingly, can one securely use this protocol
without the kind of JS vs. browser sandboxing etc that's
needed in the web? If the answer is "no" then don't you
need to say that this protocol can only safely be used
for such implementations? (In section 2, which almost
but not quite says that.)

(4) Cleared.

(5) Cleared.

[Ballot comment]

(Was discuss point#4)
"Section 8: Where are these 96 bits defined? I think
this "requires..." statement needs a precise reference
to the place in some ICE/TURN/STUN RFC where it's
defined. (And I forget where that is, sorry:-) This
should be an easy fix."
Alissa gave me the reference [1] sothat's grand. It
might be an idea to make that clearer if it wasn't
just me missing it as I read, which is very possible;-)

[1] https://tools.ietf.org/html/rfc5389#section-6

- abstract: why is only sending "media" mentioned here?
What about data channels?  And the body of the document
in fact says this all applies to any non-ICE data and
not only media.

- intro: "initial consent to send by performing STUN" I
do not find the word consent in either rfc5245 or 3489,
but perhaps it is used somewhere else. Where?  And with
what meaning?

- section 4, 2nd last para - I think the conclusion is
bogus.  An implementation knows when the keying it's
using can not involve >1 (nominally operating) party.

- 5.1, 3rd para: "Explicit consent to send is
obtained..." is misleading. That is not a concept that
an implementation of STUN will embody.

- 5.1, What is the "Note" about TCP for? Why is this
needed?

[Ballot discuss]


Apologies that these discuss points are maybe asking
fairly fundamental questions.  That could be that this
is really the first of the new security things required
by rtcweb to get to the IESG.  Or maybe I'm misreading
stuff here, if so, sorry;-)

(1) Why call this "consent?" That term is (ab)used in
many ways on the web, and adding another variation
without a definition that distinguishes this from "click
ok to my 200 page anti-privacy policy" or "remember that
example.com is allowed use my camera/mic" seems like a
terrible idea. I also don't see how this can ever be
something to which a normal person can "consent" (i.e.
consciously agree while fully understanding) so the term
is IMO very misleading, and will I fear be used to
mislead further.  (See also some of the comments below -
I do not think we ought be as fast and loose with this
aleady terribly badly used term.) To summarise: I'd love
if you did s/consent/anything-else/g but if not, please
define consent here in a way that clearly and
unambiguously distinguishes this usage from other abuses
of the term.

(2) WebRTC does not require STUN or TURN servers for
some calls, even if it does for many. Why is it ok to
require such a server be present in all calls (which I
think this means) espcially when that means exposing
additional meta-data (calling parties in a case where
the servers weren't needed and call duration in all
cases) to those servers when that is not always
necessary?

(3) (end of p5) You have a MUST NOT here that is
depenedent on current browser implementations. Why is
that an IETF thing and not a W3C thing? But more
interestingly, can one securely use this protocol
without the kind of JS vs. browser sandboxing etc that's
needed in the web? If the answer is "no" then don't you
need to say that this protocol can only safely be used
for such implementations? (In section 2, which almost
but not quite says that.)

(4) Section 8: Where are these 96 bits defined? I think
this "requires..." statement needs a precise reference
to the place in some ICE/TURN/STUN RFC where it's
defined. (And I forget where that is, sorry:-) This
should be an easy fix.

(5) Why is it ok to approve this while the
rtcweb-security-arch and rtcweb-security are still
developing? There are section-specific references here
along the lines of: "doing this is ok because of section
x.x" of both of those drafts. Why is it ok to approve
this now, when the underlying architecture and overall
security model on which this depends are still in-flux?
I'm not asking about editorial changes here nor about
timing, but about why it's ok to approve this when the
basic security concepts have yet to undergo IETF last
call, and so could change significantly. I do not think
it would be acceptable for a comment/discuss on the
security documents to be received with "yes, but you
approved consent-freshness and so we implemented and
deployed that so you're too late to make that
comment/discuss and expect some change."

[Ballot comment]

- abstract: why is only sending "media" mentioned here?
What about data channels?  And the body of the document
in fact says this all applies to any non-ICE data and
not only media.

- intro: "initial consent to send by performing STUN" I
do not find the word consent in either rfc5245 or 3489,
but perhaps it is used somewhere else. Where?  And with
what meaning?

- section 4, 2nd last para - I think the conclusion is
bogus.  An implementation knows when the keying it's
using can not involve >1 (nominally operating) party.

- 5.1, 3rd para: "Explicit consent to send is
obtained..." is misleading. That is not a concept that
an implementation of STUN will embody.

- 5.1, What is the "Note" about TCP for? Why is this
needed?

[Ballot comment]
This looks good overall. I have a few minor comments:

-- General:

After re-reading this, and the relevant parts of rtcweb-security-architecture, I think a novice reader might find the meaning of "consent" a bit vague, especially in terms of how it might differ from "reachability". Can you offer an example of when an otherwise reachable peer might choose to withdraw consent?

-- section 1, first paragraph:

I think readers are going to stumble over why we think a device that plans to attack a peer is going to worry about consent. This makes more sense in section 2. It might be helpful to move (or copy) the bit about "... deployments of WebRTC..." and "... malicious javascript" forward to the intro.

- 4, 3rd paragraph:

Should the reader infer that the receipt of a package that is strongly assured to have come from a party implies consent from that party? If so, it might be worth an explicit mention.

-- 5.1, first paragraph:

The normative MUST feels wrong here, (and is probably redundant with other normative language further down in the section.) For example, could a sender just choose to stop sending?

-- 5.1, 5th paragraph:

From the next paragraph, I infer that you mean consent expires after 30 seconds when you have been sending binding request every few seconds, not 30 seconds after sending any particular binding request. If that's correct it might be helpful to add a few words to that effect.

-- 5.1, 6th paragraph:

Does the "MUST NOT" refer to the general interval between checks prior to randomization, or to the specific interval between a pair of checks after randomization?

Nits:

-- 2, 2nd paragraph: "verify peer's consent"

Missing article (or "verify peer consent")

-- 5.1, paragraph 3:

s/sending an stun binding/sending a stun binding

-- 5.1, 7th paragraph: "Each STUN binding request for consent MUST use a new STUN transaction
  identifier for every consent binding request..."

That's sort of redundant. I suggest something to the effect of "each consent binding request MUST use a new stun transaction identifier. "

[Ballot comment]
A couple of very minor comments only:

FWIW, I think rtcweb-security-arch need only be an informative reference; it seems only explanatory.  I also think that about RFC 6263.

-- Section 5.1 --

  A full ICE implementation obtains consent to send using ICE.  After
  ICE concludes on a particular candidate pair and whenever the
  endpoint sends application data on that pair consent MUST be
  maintained following the procedure described in this document.

I don't understand the "MUST" here, given that Section 4 says this is "an optional extension".  Why "MUST", then, rather than "can be"?

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-rtcweb-stun-consent-freshness-15, which is currently in Last Call, and has the following comments:

We understand that,  upon approval of this document, there are no IANA Actions that need completion.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, IANA does not object.

If this assessment is not accurate, please respond as soon as possible.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (STUN Usage for Consent Freshness) to Proposed Standard


The IESG has received a request from the Real-Time Communication in
WEB-browsers WG (rtcweb) to consider the following document:
- 'STUN Usage for Consent Freshness'
  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@ietf.org mailing lists by 2015-07-16. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

This document was previously last called on May 1 and has been updated as a result of comments submitted during that last call.

Abstract


  To prevent WebRTC applications, such as browsers, from launching
  attacks by sending media to unwilling victims, periodic consent to
  send needs to be obtained from remote endpoints.

  This document describes a consent mechanism using a new Session
  Traversal Utilities for NAT (STUN) usage.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-rtcweb-stun-consent-freshness/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-rtcweb-stun-consent-freshness/ballot/


No IPR declarations have been submitted directly on this I-D.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Proposed Standard is requested, and standards track is noted in the
header.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

  In WebRTC contexts, peers send media traffic to each other.
  To prevent attacks on peers, endpoints have to ensure the remote
  peer is willing to receive traffic.  This is performed both when the
  session is first established to the remote peer and periodically
    for the duration of the session.  This document defines a method
    for confirming consent using a new STUN usage.

Working Group Summary

  Was there anything in WG process that is worth noting? For
  example, was there controversy about particular points or
  were there decisions where the consensus was particularly
  rough?

One of the consistent issues within the WebRTC ecosystem is
the extent to which requirements from deployed systems impact
the working of the protocol.  In this context, discussion of how
ICE-lite entities should behave consumed a good bit of time, but
I believe that the document represents the WG's general understanding.

After a set of external reviews by directorates the documented was
updated and a new working group last call issued.  No new issues
were identified during the final working group last call.


Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

The document was reviewed by a number of implementors
and implementations are planned or under way.    This document did
not require expert review of the type mentioned above, but Christer
Holmberg's review is called out in the document for its thoroughness.


Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Ted Hardie is the Document Shepherd; Richard Barnes is the
Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

The document was re-reviewed and the mailing list traffic from the working
group last call forward reviewed to ensure that issues raised were addressed.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed? 

No conerns.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

Because this describes a security mechanism, additional review
would be welcome, but a number of security folks are authors or
reviewers.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No specific concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

No disclosures have been filed.

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

Consensus appears general.


(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

There are no threatened appeals or other discontent of which I am
aware.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

This document passes ID-nits, with only one warning of an unused reference.
This can be removed by the RFC Editor, I believe, and need not hold
the document.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

As noted above, these reviews do not apply to this document.

(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

All normative references are at appropriate levels for advancement.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

None needed for this document.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

It will not change the status of any existing RFC.


(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

This document makes no requests of IANA.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.


This document makes no requests of IANA.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

This document does not use a formal grammar.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-rtcweb-stun-consent-freshness-11, which is currently in Last Call, and has the following comments:

We understand that, upon approval of this document, there are no IANA Actions that need completion.

While it is helpful for the IANA Considerations section of the document to remain in place upon publication, if the authors prefer to remove it, IANA doesn't object.

If this assessment is not accurate, please respond as soon as possible.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (STUN Usage for Consent Freshness) to Proposed Standard


The IESG has received a request from the Real-Time Communication in
WEB-browsers WG (rtcweb) to consider the following document:
- 'STUN Usage for Consent Freshness'
  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@ietf.org mailing lists by 2015-05-15. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  To prevent sending excessive traffic to an endpoint, periodic consent
  needs to be obtained from that remote endpoint.

  This document describes a consent mechanism using a new Session
  Traversal Utilities for NAT (STUN) usage.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-rtcweb-stun-consent-freshness/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-rtcweb-stun-consent-freshness/ballot/


No IPR declarations have been submitted directly on this I-D.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Proposed Standard is requested, and standards track is noted in the
header.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

  In WebRTC contexts, peers send media traffic to each other.
  To prevent attacks on peers, endpoints have to ensure the remote
  peer is willing to receive traffic.  This is performed both when the
  session is first established to the remote peer and periodically
    for the duration of the session.  This document defines a method
    for confirming consent using a new STUN usage.

Working Group Summary

  Was there anything in WG process that is worth noting? For
  example, was there controversy about particular points or
  were there decisions where the consensus was particularly
  rough?

One of the consistent issues within the WebRTC ecosystem is
the extent to which requirements from deployed systems impact
the working of the protocol.  In this context, discussion of how
ICE-lite entities should behave consumed a good bit of time, but
I believe that the document represents the WG's general understanding.


Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

The document was reviewed by a number of implementors
and implementations are planned or under way.    This document did
not require expert review of the type mentioned above, but Christer
Holmberg's review is called out in the document for its thoroughness.


Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Ted Hardie is the Document Shepherd; Richard Barnes is the
Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

The document was re-reviewed and the mailing list traffic from the working
group last call forward reviewed to ensure that issues raised were addressed.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed? 

No conerns.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

Because this describes a security mechanism, additional review
would be welcome, but a number of security folks are authors or
reviewers.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No specific concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

No disclosures have been filed.

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

Consensus appears general.


(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

There are no threatened appeals or other discontent of which I am
aware.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

This document passes ID-nits, with only one warning of an unused reference.
This can be removed by the RFC Editor, I believe, and need not hold
the document.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

As noted above, these reviews do not apply to this document.

(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

All normative references are at appropriate levels for advancement.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

None needed for this document.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

It will not change the status of any existing RFC.


(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

This document makes no requests of IANA.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.


This document makes no requests of IANA.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

This document does not use a formal grammar.