Nebula by Defined Networking is a managed overlay networking solution designed to provide fast, secure, and scalable connectivity. It utilizes a peer-to-peer mesh VPN architecture to overcome traditional VPN availability and performance bottlenecks. Nebula creates encrypted UDP-based Layer 3 tunnels on-demand, offering a decentralized approach to networking. It uses certificate-based authentication and public key infrastructure (PKI) to establish trust between hosts, encrypting and routing network traffic for secure connectivity across distributed environments. Nebula employs the NoiseIX protocol, a variant of the Noise protocol framework, for mutual authentication and encryption of tunnels. The system is built to handle large-scale networks with hundreds of thousands of hosts, providing resilience through its decentralized architecture. Nebula allows direct peer-to-peer connections between hosts in an overlay network, regardless of their location on the same LAN or across the internet, and includes a built-in firewall similar to AWS Security Groups for network-wide security management.
