Introducing Nebula, the open source global overlay network from Slack

This post introduces Nebula, an open-source global overlay network developed by Slack. It details the problem Nebula solves: securely connecting tens of thousands of computers across multiple cloud providers and locations. The post outlines Nebula's goals: encrypted connections, service provider agnosticism, high-level traffic filtering, strong identity via certificates, performance, and testability. It explains the motivation for building Nebula, stemming from the operational burden and performance impact of IPSec and the limitations of region-siloed security groups. The post highlights the use of the Noise Protocol Framework for encryption and draws inspiration from Tinc for mesh networking concepts. Nebula has been in use at Slack for over two years and has undergone security assessments and is being added to Slack's bug bounty program.