W3C home > Mailing lists > Public > public-webrtc@w3.org > January 2014

Re: What is missing for building "real" services?

From: Eric Rescorla <ekr@rtfm.com>
Date: Wed, 8 Jan 2014 20:02:50 -0800
Message-ID: <CABcZeBMn7adkikUzMw+DO3hjr6K0yC23SW_jqf5J-0e7aScN+Q@mail.gmail.com>
To: cowwoc <cowwoc@bbs.darktech.org>
Cc: "public-webrtc@w3.org" <public-webrtc@w3.org>
On Wed, Jan 8, 2014 at 7:52 PM, cowwoc <cowwoc@bbs.darktech.org> wrote:
> Remind me again, what was wrong with this approach?

It doesn't enable essentially any screen sharing scenario that
people want.


> Enable screensharing without a flag/plugin.
> Prompt the user for permission.
> Allow screensharing for a single browser tab (can't capture the general
> screen or foreign processes).
> Prevent pages that use screensharing from issuing requests to foreign hosts
> (i.e. Same Origin policy minus any exceptions).
> Lets start with something that is fairly restrictive (but doesn't require a
> flag/plugin which kills traction), enable *some* use-cases, and built up
> from there.
> Gili
> On 08/01/2014 9:03 PM, Eric Rescorla wrote:
> On Wed, Jan 8, 2014 at 5:53 PM, piranna@gmail.com <piranna@gmail.com> wrote:
> I'm not ccomparing both in the way I accept whatever of both, but instead in
> the way both (plugins and flags) are equally bad ideas. Screen and
> application sharing should be included and enabled on browsers by default,
> and not hidden behind a flag or whatever other method.
> For the reasons described in:
> http://tools.ietf.org/html/draft-ietf-rtcweb-security-05#section-4.1.1
> The browser vendors don't think this is that great an idea.
> If you think that screen sharing should be available by default, you
> should perhaps suggest some security mechanisms which would
> make the threats described here less severe.
> -Ekr
> Send from my Samsung Galaxy Note II
> El 09/01/2014 02:42, "Alex Gouaillard" <alex.gouaillard@temasys.com.sg>
> escribió:
> @ piranha.
> while I agree with you for social users and most of the population out
> there, the difference between clicking a flag and installing a plugin
> is the process required by IT teams to accept the product and deploy
> it in an enterprise environment. Everything needs to validated
> beforehand, including (especially?) plugins. They have a very long
> list of products to screen and maintain, and are very reluctant to add
> yet another one. Moreover, google's chrome start with a higher
> credibility than any small or medium sized company's plugin.
> On Thu, Jan 9, 2014 at 8:54 AM, Silvia Pfeiffer
> <silviapfeiffer1@gmail.com> wrote:
> On Thu, Jan 9, 2014 at 10:10 AM, Randell Jesup <randell-ietf@jesup.org>
> wrote:
> On 1/7/2014 8:50 PM, Alexandre GOUAILLARD wrote:
> here are a few proposition on things that are really biting us, and how
> to
> (perhaps) make it easier:
> - bandwidth control
> 1. It seems that the number one sdp munging cause is the now infamous
> B=AS:
> line to put a cap on bandwidth. Since that capacity exists in the
> underlying
> code, it would be great to have an API that can help us put caps,
> either on
> each stream, and/or on the full call.
> yes.
> 2. I also see that there is a "auto-mute" feature being implemented
> that
> depend on an arbitrary threshold. It might be interested (but
> overkill?), to
> give user the capacity to set that limit (currently 50k I guess)
> somehow.
> Pointer to this auto-mute implemetation?
> 3. Additionally, and perhaps not unrelated, we would alike to be able
> to
> decide what happen when bandwidth goes down. Right now it feels like
> the
> video has the priority over the audio. We would like to be able to
> explicitly set the audio priority higher than the video in the
> underlying
> system, as opposed to implement a stats listener, which triggers
> re-negotiation (with the corresponding O/A delay) when bandwidth goes
> below
> a certain threshold.
> Right now they have the same "priority", but really audio is typically
> fixed, so the video reacts to changes in the apparent level of
> delay/buffering.  What you may be seeing is better (or less-obvious)
> error
> control and recovery in the video; the eye is often less sensitive to
> things
> like dropped frames than the ear.
> I'd love to see a trace/packet-capture/screen-scrape-recording where
> you see
> that apparent behavior.
> - call controls like mute / hold
> Right now, you can mute a local stream, but it does not seem to be
> possible
> to let the remote peers know about the stream being muted. We ended up
> implementing a specific off band message for that, but we believe that
> the
> stream/track could carry this information. This is more important for
> video
> than audio, as a muted video stream is displayed as a black square,
> while a
> muted audio as no audible consequence. We believe that this mute / hold
> scenario will be frequent enough, that we should have a standardized
> way of
> doing it, or interop will be very difficult.
> There is no underlying standard in IETF for communicating this; it's
> typically at the application level.  And while we don't have good ways
> in
> MediaStream to do this yet, I strongly prefer to send an fixed image
> when
> video-muted/holding.  Black is a bad choice....
> It would be nice if browsers sent an image, such as "video on hold" -
> just like they provide default 404 page renderings. This is a quality
> of implementation issue then. Maybe worth registering a bug on
> browsers. But also might be worth a note in the spec.
> - screen/application sharing
> We are aware of the security implications, but there is a very very
> strong
> demand for screen sharing. Beyond screen sharing, the capacity to share
> the
> displayed content of a given window of the desktop would due even
> better.
> Most of the time, users only want to display one document, and that
> would
> also reduce the security risk by not showing system trays.
> Collaboration
> (the ability to let the remote peer edit the document) would be even
> better,
> but we believe it to be outside of the scope of webRTC.
> yes, and dramatically more risky.  Screen-sharing and how to preserve
> privacy and security is a huge problem.  Right now the temporary kludge
> is
> to have the user whitelist services that can request it (via extensions
> typically)
> Yeah, I'm really unhappy about the screen sharing state of affairs,
> too. I would much prefer it became a standard browser feature.
> Cheers,
> Silvia.
>    Randell
> - NAT / Firewall penetration feedback - ICE process feedback
> Connectivity is a super super pain to debug, and the number one cause
> of
> concern.
> 1. The 30s time out on chrome generated candidate is biting a lot of
> people.
> The time out is fine, but there should be an error message that
> surfaces
> (see 5)
> 2. Turn server authentication failure does not generate an error, and
> should
> (see 5)
> 3. ICE state can stay stuck in "checking" forever even after all the
> candidate have been exhausted
> 4. Not all ICE states stated in the spec are implemented (completed?
> fail?)
> 5. It would due fantastic to be able to access the list of candidates,
> with
> their corresponding status (not checked, in use, failed, ….) with the
> cause
> for failure
> 6. In case of success, it would be great to know which candidate is
> being
> used (google does that with the googActive thingy) but also what is the
> type
> of the candidate. Right now, on client side, at best you have to go to
> chrome://webrtc-internals, get the active candidate, and look it up
> from the
> list of candidates. When you use a TURN server as a STUN server too,
> then
> the look up is not an isomorphism.
> right now, the only way to understand what's going on is to have a
> "weaponized" version of chrome, or a native app, that gives you access
> to
> the ICE stack, but we can not expect clients to deploy this, nor to
> automate
> it. Surfacing those in an API would allow one to:
> - adapt the connection strategy on the fly in an iterative fashion on
> client
> side.
> - report automatically the problems and allow remote debug of failed
> calls,
> On Tue, Jan 7, 2014 at 2:15 AM, Eric Rescorla <ekr@rtfm.com> wrote:
> On Mon, Jan 6, 2014 at 10:10 AM, piranna@gmail.com <piranna@gmail.com>
> wrote:
> That's not really going to work unless you basically are on a
> public
> IP address with no firewall. The issue here isn't the properties of
> PeerConnection but the basic way in which NAT traversal algorithms
> work.
> I know that the "IP and port" think would work due to NAT, but
> nothing
> prevent to just only need to exchange one endpoint connection data
> instead of both...
> I don't know what you are trying to say here.
> A large fraction of NATs use address/port dependent filtering which
> means that there needs to be an outgoing packet from each endpoint
> through their NAT to the other side's server reflexive IP in order to
> open the pinhole. And that means that each side needs to provide
> their address information over the signaling channel.
> I strongly recommend that you go read the ICE specification and
> understand the algorithms it describes. That should make clear
> why the communications patterns in WebRTC are the way they
> are.
> -Ekr
> --
> Randell Jesup -- rjesup a t mozilla d o t com
Received on Thursday, 9 January 2014 04:03:58 UTC

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