Is it possible to show WebRTC peers only from a local network?

Question

It's more of a signaling issue than WebRTC, but is it somehow possible to find computers only within the same local network? E.g. would it be possible to create a service similar to OS X AirDrop, where you could go to page e.g. https://airdrop.com and you would see other computers that also have the same site opened in the browser, but only if they are in the same local network without having to host some kind of signalling server within the local network (i.e. having only one "global" signaling server)?

Answer 1

Assuming all computers in the local network have access to the Internet through a single device, all of them will have the same public IP.

Then, in your server, you only have to look at the IP.