Reverse-Engineering

Posts that look at how popular implementations are put together

I logged into YouTube on Tuesday and noticed this new camera icon in the upper right corner, with a “Go Live (New)” option, so I clicked on it to try. It turns out you can now live stream directly from the browser. This smelled a lot like WebRTC, so I loaded up chrome://webrtc-internals to see and sure enough, it was WebRTC. We are always curious here to see how large scale deployments are implemented, so I immediately asked WebRTC reverse engineering master Philipp “Fippo” Hancke to investigate deeper. The rest here is his analysis. ...

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Tsahi discovered Hangouts on Firefox started working again and quickly called Fippo to investigate

As the year 2017 comes to an end, there was a small present. Hangouts started to support Firefox with WebRTC instead of rejecting access – plugin access had been unavailable since Firefox 53 removed NPAPI in April 2017. While it had been public for a while that the Firefox WebRTC team had been testing this, it was a nice Christmas present to see this shipped. Tsahi Levent-Levi was one of the first people to notice.
This comes at a time where other Google teams are being criticized for promoting Chrome-only experiences. Kudos to the Hangouts team for showing that you still care about the web as an open platform! ...

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Long have WebRTC developers waited for the day Apple would come around to WebRTC. It has not been simple for web developers and Apple due to their policy that requires web browsing functionality to use the WebKit engine along with Safari. This meant no WebRTC in Safari; no Firefox or Chrome WebRTC on iOS, no native WebView with WebRTC or iOS API’s (but plenty of 3rd party ones). Despite community efforts and active development inside the WebKit project, it was not entirely clear when there would be at launch. That changed earlier this month when Apple announced a WebRTC-enabled WebKit based on the Google-backed webrtc.org engine was coming to both High Sierra – the next version of OSX – and iOS 11. Even better, WebRTC is available today as part of the free Safari Technology Preview. ...

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Earlier this month Fippo published a post analyzing Slack’s new WebRTC implementation. He did not have direct access or a team account to do a thorough deep dive – not to mention he is supposed to be taking some off this month. That left many with some open questions? Is there more to the TURN network? How does multi-party calling work? How exactly is Slack using the Janus gateway? Fortunately WebRTC has an awesomely active and capable community that quickly picked up the slack (pun intended). ...

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Chrome, Firefox, and Edge are all on the same party line. Image from Pillow Talk (1959)

For the first time, Chrome, Firefox and Edge can “talk” to each other via WebRTC and ORTC. Check the demo on Microsoft’s modern.ie testdrive.

tl;dr: don’t worry, audio works. codec interop issue…

Feature Interoperability Notes
ICE yes Edge requires end-of-candidate signaling
DTLS yes
audio yes using G.722, Opus or G.711 codecs
video no standard H.264 is not supported in Edge yet
DataChannels no Edge does not support dataChannels

As a reader of this blog, you probably know what WebRTC is but let me quote this:

WebRTC is a new set of technologies that brings clear crisp voice, sharp high-definition (HD) video and low-delay communication to the web browser.

In order to succeed, a web-based communications platform needs to work across browsers. Thanks to the work and participation of the W3C and IETF communities in developing the platform, Chrome and Firefox can now communicate by using standard technologies such as the Opus and VP8 codecs for audio and video, DTLS-SRTP for encryption, and ICE for networking. ...

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This is the next decode and analysis in Philipp Hancke’s Blackbox Exploration series conducted by &yet in collaboration with Google. Please see our previous posts covering WhatsApp, Facebook Messenger and FaceTime for more details on these services and this series. {“editor”: “chad hart“}

Wire is an attempt to reimagine communications for the mobile age. It is a messaging app available for Android, iOS, Mac, and now web that supports audio calls, group messaging and picture sharing. One of it’s often quoted features is the elegant design. As usual, this report will focus on the low level VoIP aspects, and leave the design aspects up for the users to judge. ...

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ny times stylized

So the New York times uses WebRTC to gather your local ip addresses… Tsahi describes the non-technical parts of the issue in his blog. Let’s look at the technical details… it turns out that the Javascript code used is very clunky and inefficient.

First thing to do is to check chrome://webrtc-internals (my favorite tool since the hangouts analysis). And indeed, nytimes.com is using the RTCPeerConnection API. We can see a peerconnection created with the RtpDataChannels argument set to true and using stun:ph.tagsrvcs.com as a STUN server.
Also, we see that a data channel is created, followed by calls to createOffer and setLocalDescription. That pattern is pretty common to gather IP addresses. ...

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This is the next decode and analysis in Philipp Hancke’s Blackbox Exploration series conducted by &yet in collaboration with Google. Please see our previous posts covering WhatsApp and Facebook Messenger for more details on these services and this series. {“editor”: “chad hart“}

FaceTime is Apple’s answer to video chat, coming preinstalled on all modern iPhones and iPads. It allows audio and video calls over WiFi and, since 2011, 3G too. Since Apple does not talk much about WebRTC (or anything else), maybe we can find out if they are using WebRTC behind the scenes? ...

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Two weeks ago Philipp Hancke,  lead WebRTC developer of Talky and part of the &yet‘s WebRTC consulting team, started a series of posts about detailed examinations he is doing on several major VoIP deployments to see if and how they may be using WebRTC. Please see that post on WhatsApp for some background on the series and below for another great analysis – this time on Facebook Messenger. {“editor”: “chad hart“}

Last week, Facebook announced support for video chats in their Messenger app. Given that Messenger claims to account for 10% of global mobile VoIP traffic, this made in a very interesting target for further investigation. As part of the series of deconstructions, the full analysis (another fifteen pages, using the full range of analysis techniques demonstrated earlier) is available for download here, including the wireshark dumps. ...

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One of our first posts was a Wireshark analysis of Amazon’s Mayday service to see if it was actually using WebRTC. In the very early days of WebRTC, verifying a major deployment like this was an important milestone for the WebRTC community. More recently, Philipp Hancke – aka Fippo – did several great posts analyzing Google Hangouts and Mozilla’s Hello service in Firefox. These analyses validate that WebRTC can be successfully deployed by major companies at scale. They also provide valuable insight for developers and architects on how to build a WebRTC service. ...

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