Cilium

Cilium is an open-source, industry-standard networking, security, and observability platform engineered specifically for containerized workloads and Kubernetes clusters, powered by extended Berkeley Packet Filter (eBPF) technology in the Linux kernel. Traditional Linux networking and iptables firewalls struggle to keep up with the ephemeral scale of modern Kubernetes environments, where thousands of pods spin up and down dynamically, introducing severe CPU overhead and latency. Cilium bypasses these bottlenecks by injecting eBPF bytecode programs directly into the Linux kernel data path, routing network packets and enforcing security policies at native kernel speeds without modifying application containers. Cilium provides high-performance Container Network Interface (CNI) networking, dynamic multi-cluster mesh connectivity, and Layer 3 to Layer 7 network security policy enforcement based on container identity and cryptographic labels rather than unstable IP addresses. Security engineers can inspect and enforce HTTP, gRPC, and DNS communication policies, restricting container communication to authorized endpoints and blocking unauthorized external data transfers. Integrated with transparent IPsec and WireGuard encryption, Cilium secures all inter-pod communications automatically. By eliminating traditional iptables table bottlenecks and embedding security directly at the kernel boundary, Cilium delivers unmatched scale, minimal latency, and robust Zero Trust defense for modern cloud-native architectures.