WebRTC URI for remote resource identification and local configuration

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Table of Contents

1. Introduction

The WebRTC framework specifies protocol support for direct interactive rich communication using audio, video, and data between two peers. WebRTC was originally designed with the browser in mind. Usage of WebRTC has extended far beyond that. This WebRTC URI is designed for users outside of the browser. In the browser these behaviors could be achieved with ORTC interfaces.¶

The flexibility of WebRTC's signaling plane has made adoption difficult for some use cases. The signaling plane also presents challenges around security, privacy and operational burden. However WebRTC's media plane is unambiguous. Once two WebRTC Agents have enough details from signaling it is easy to establish rich communication.¶

The signaling plane is only necessary when two clients don't have enough information to establish a session. In some cases signaling is not necessary. If the two WebRTC agents agree on some basic details signaling is not required. The greatest difficulty comes with establishing connectivity between two ICE Agents. [I-D.ietf-ice-rfc5245bis] If these two ICE Agents use mDNS [I-D.cheshire-dnsext-multicastdns] and are in the same network you can establish a Zeroconf session. If one ICE Agent is World Routable connectivity is also easily possible. The WebRTC URI format does not allow connectivity between two ICE Agents that would require STUN or TURN.¶

Multiple sessions can be established using the same set of WebRTC URIs. This document describes a URI that contains these details.¶

Discussion of this work is encouraged to happen on the MMUSIC IETF mailing list mmusic@ietf.org or on the GitHub repository which contains the draft: https://github.com/sean-der/webrtc-uri.¶

2. Use Cases

Please note that this section is informational only.¶

3. The WebRTC URI Scheme

The WebRTC URI takes two possible forms. The only difference is how the authority is handled.¶

webrtc://<ice-user-fragment>:<ice-password>@<mDNS name>?<parameters>

webrtc://<ice-user-fragment>:<ice-password>@<Address/Port>?<parameters>

4. Examples of WebRTC URI Syntax

webrtc://eu6k:cae6@alice.local?local-ice-ufrag=adu3&local-ice-pwd=eew4&datachannel&ice-controlling&dtls-client

webrtc://adu3:eew4@bob.local?local-ice-ufrag=eu6k&local-ice-pwd=cae6&datachannel

webrtc://eu6k:cae6@example.org:5001?local-ice-ufrag=adu3&local-ice-pwd=eew4&datachannel&ice-controlling&dtls-client

5. Sharing URIs

The typical flow for crafting and sharing WebRTC URIs will differ depending on the use case.¶

6. Security, Privacy and Availability Benefits of WebRTC URIs

Without the WebRTC URI a signaling plane is required to establish a WebRTC session.¶

If an attacker is able to modify messages in the signaling plane they could MITM a WebRTC Session. The attacker could replace the candidates and certificate fingerprint with their own. They could then route all traffic through a host they control. The two users would connect to each other and not realize that anything is wrong.¶

If an attacker is able to observe messages they can extract valuable information around a session. The attacker is able to determine when a call is taking place. They are also able to determine how many media tracks are being exchanged.¶

Many times two WebRTC agents are in the same LAN. The signaling plane is usually run on a World Routable server. The WebRTC Agents may have direct connectivity with each other, but not be able to connect to the signaling plane.¶

7. Compatibility with Existing WebRTC Implementations

A WebRTC URI can be parsed and used by a WebRTC implementation that doesn't support URIs. The values in the URI could be expanded to be a SetLocalDescription and SetRemoteDescription. These options could also be handled by a ORTC Implementation.¶

Given the following URI¶

webrtc://eu6k:cae6@example.org:5001?local-ice-ufrag=adu3&local-ice-pwd=eew4&datachannel&ice-controlling&dtls-client

You get this Local Description¶

v=0
o=- 0 1 IN IP4 127.0.0.1
s=-
t=0 0
m=application 9 DTLS/SCTP 5000
c=IN IP4 127.0.0.1
a=ice-ufrag:adu3
a=ice-pwd:eew4
a=setup:actpass
a=mid:0
a=sctpmap:5000 webrtc-datachannel 1024
a=fingerprint:tbd

And this Remote Description¶

v=0
r=- 0 2 IN IP4 127.0.0.1
s=-
t=0 0
m=application 9 DTLS/SCTP 5000
c=IN IP4 127.0.0.1
a=candidate:1966762134 1 udp 2122260223 example.org 5001 typ host
a=ice-ufrag:eu6k
a=ice-pwd:cae6
a=setup:passive
a=mid:0
a=sctpmap:5000 webrtc-datachannel 1024
a=fingerprint:tbd

8. Security Considerations

9. IANA Considerations

10. Acknowledgments

Author's Address