Lighthouse

Lighthouses are responsible for keeping track of all of the other hosts and helping them find each other within a Managed Nebula network, anywhere in the world. A lighthouse is the only node in a Managed Nebula network whose IP should not change.

A lighthouse learns where each host can be reached on the internet. It plays no part in the encrypted handshake between two hosts and holds none of their key material, so it cannot read or modify the traffic between them. By default a network's lighthouses also serve as relays, forwarding traffic between hosts that cannot connect to each other directly. This feature can be disabled in the network settings, at which point only hosts marked as dedicated relays will be used.

Lighthouses can be managed by Defined Networking or self-hosted. Every Managed Nebula network includes a managed lighthouse automatically, so most networks need no lighthouse infrastructure of their own. See Managed lighthouses.

You can also run your own lighthouse when you want more control over your network infrastructure. Running one requires very few compute resources, and you can easily use the least expensive option from a cloud hosting provider, on a server with a stable public IP. A UDP port (default 4242, configurable when creating the lighthouse) should be opened to the internet so that hosts can communicate with the lighthouse. See Enrolling a lighthouse.