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Yes; vaguely... there was some (string) message format that you could manually stitch together with the right IP and port, etc, and basically tell the browser's WebRTC implementation "other client is on this IP and port". I seem to have deleted this code unfortunately, the only thing I saved is this link:

https://github.com/cjb/serverless-webrtc/

EDIT:

Aha! I based my code on: https://github.com/js-platform/node-webrtc/blob/develop/exam...

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Yup, the format is called SDP. It's an old, crufty, and mostly effective way to specify not only the port and IP, but also whether a TCP fallback is being used, video and audio formats, and other things you can mostly ignore when just using data channels. See the "answer" section of 5.2.3 of [1], for details of some of the other magic numbers (which your JS library should handle for you). You can also check out about:webrtc to see SDPs made by other websites, like the Janus demo page.

[1] https://tools.ietf.org/html/draft-ietf-rtcweb-sdp-03

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