Really fascinating work! I enjoyed reading this article.
Do you actually have tunnels between every device? Wondering, how does this scale?
It scales great, not concentrating connections makes it easy. Tunnels are very lightweight and the only machines with lots of tunnels are servers that are already provisioned for talking to lots of machines.
(Tailscale co-founder)
Additionally, we rotate keys. For security sensitive users we can rotate these keys daily.