Nebula: Slack’s overlay VPN explained

Nebula is the open source mesh VPN that Slack released on November 19, 2019, after running it internally for over two years. Each node holds its own cryptographic identity and connects directly to the others, so traffic never passes through a central server that decrypts it. The project stays active: version 1.10.3 landed on February 6, 2026.

March 10, 2025 6 min 239

Architecture

Cilium and the Future of Container Networking with eBPF

Cilium replaces iptables with eBPF programs loaded directly into the Linux kernel, substituting O(n) linear chains with O(1) hash lookups. Documented benchmarks show up to 50% lower p95 latency, 2-3x more throughput, and 70% less kernel CPU in large Kubernetes clusters.

August 9, 2023 5 min 239 4.5