It's a privacy issue. You can use it to fingerprint a user, local IP will give you quite many bits of entropy. <https://coveryourtracks.eff.org/>
Honestly I'm not even sure if I'm surprised, but it's 2022 and we've been having this problem basically since the day WebRTC was introduced. At this point, if you care about privacy, you should probably put it in the same bag as third-party cookies and just block it entirely.
It's a privacy/functionality tradeoff. But most people consider not being able to videocall or do online gaming with someone in the same building to not be acceptable.
This shows how browser developers race to push new features without proper estimation of privacy concerns.
Luckily this was somewhat fixed by using randomized Apple mDNS names instead of IPs. But as a result the browser has to support Apple DNS protocol which can potentially increase attack surface.
I would prefer to disable this feature completely by default and let the minority who needs it enable it via settings.
Settling on a different trade-off then you would like is not the same thing as doing it without consideration.
The "Apple" DNS protocol is standard DNS, over a multicast IP address, on port 5353. You can literally use plain old dig to perform mDNS lookups:
$ dig @224.0.0.251 -p 5353 +short hello.local
192.168.123.45
The DNS names WebRTC generates for this purpose are random, and known only to the signaling participants.
Zoom/Teams with people in the same office? That seems like a rather large user base
Almost all of the “sales/demo/cross company” video calls I’ve been on have been in this bucket
My understanding is Zoom only supports P2P for two person calls.
I can't quite tell from this answer if it is the default or not, but it sounds like it has to be manually enabled:
> Account owners and admins can enable one-on-one meetings to have data routed between two participants (peer-to-peer), rather than going through the cloud or server. Enabling this may improve the quality and connection of one-on-one meetings (depending on how your network prioritizes traffic) by directly sending video and audio between both parties.
https://support.zoom.us/hc/en-us/articles/360061410851-Enabl...
* Controlling Robots (formant.io)
* Security Cameras
* File Sharing
* Game Streaming/VNC
I keep a list of interesting open source WebRTC projects at https://github.com/pion/awesome-pion
There is also WebGL whose main purpose is to provide user's videocard model to advertising companies and governemnt institutions.
I think an opt-in permission seems like the way to go, like the one we already have for microphone/camera permissions, and possibly just merged with these (i.e. grant WebRTC permissions together with A/V permissions).
There are quite a few interesting non-A/V WebRTC applications around – these could be handled via an explicit prompt, similarly to how newer iOS versions handle local network permissions.
I don't buy it: You have to block IPv6 as well, and that's becoming harder to do.
If the user is trying to protect their "privacy" from their ISP by using a VPN (for example), and are attempting to prevent the application-level leak of providing a list of all the local interfaces, they really need to configure their system to restrict e.g. their web browsers and other sensitive tools to those specific interfaces, e.g.
https://askubuntu.com/questions/1313755/forcing-chrome-brows...
This should be easier, like maybe a button in the VPN software.