KubernetesMarch 28, 202614 min read

eBPF & Cilium Deep-Dive: In-Kernel Kubernetes Networking, Zero-Overhead Observability & Tetragon Security

Replacing iptables and kube-proxy with eBPF: kernel-level packet routing, sub-millisecond service mesh latencies, Hubble observability, and real-time Tetragon runtime security.

SA

Sikander Ali

Senior DevOps Architect (CKA, Linux Kernel)

Executive Engineering Summary & Takeaways

  • eBPF programs bypass Linux network stack overhead to route packets directly in the kernel, improving pod throughput by up to 300%.
  • Cilium Hubble provides zero-overhead L3/L4/L7 flow observability without injecting heavy application sidecars.
  • Tetragon executes in-kernel security enforcement, detecting and killing malicious shell spawning or privilege escalation instantaneously.

1. In-Kernel Packet Filtering vs. Legacy iptables

In large Kubernetes clusters with tens of thousands of services, iptables rules grow O(N) sequentially. Every network packet must traverse thousands of sequential filter rules, causing significant CPU overhead and jitter.

Cilium replaces iptables with eBPF hash tables operating directly at the socket layer (sockops) and XDP (eXpress Data Path). Packet lookup becomes O(1) instantaneous.

cilium-helm-values.yamlYAML
kubeProxyReplacement: "true"
k8sServiceHost: "127.0.0.1"
k8sServicePort: "6443"
routingMode: "native"
autoDirectNodeRoutes: "true"
bpf:
  masquerade: "true"
  tproxy: "true"
hubble:
  enabled: true
  relay:
    enabled: true
  ui:
    enabled: true
  metrics:
    enabled:
      - dns
      - drop
      - tcp
      - http
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