Assuming each node is on a different WAN, how can these nodes find each other, using neither: an intermediary STUN, TURN or other server; nor an explicit DNS | IP address?
|node 0|------|node 1|
\ /
\ /
\ /
\---|node 2|---/
My use-case is to connect multiple smartphones together without Bluetooth, infrared, wired-connection, or having them join the same network. I've seen some NAT or other hole-punch tech. Is that the right approach? - I could generate a QR code but it's unclear what information to expose there (e.g., the public IP address isn't correct).