Hijacking DNS Port 53 with eBPF & XDP for Remote K8s Access - Misha Bragin

This talk explores the challenges of running a local DNS resolver on a non-standard port, particularly when attempting to alter the default DNS port 53. The speaker, Misha Bragin, discusses the development of NetBird's DNS feature that facilitates secure access to internal resources and private Kubernetes clusters without public exposure. The presentation details the innovative combination of Go, eBPF, and XDP techniques that allowed the NetBird team to enable multiple DNS resolvers to use the standard port while leveraging a peer-to-peer WireGuard network. The session demonstrates practical examples of eBPF and XDP in action, showcasing smart DNS handling on Linux systems.