eBPF for Kubernetes Security: Beyond Traditional Network Policies

\n## 🐝 eBPF: Security at the Kernel Level

Traditional Kubernetes security operates at the API level — network policies, RBAC, admission webhooks. eBPF operates at the kernel level, giving you visibility and enforcement that higher-level tools simply can’t provide.

What eBPF Enables

• Runtime process monitoring: See every process execution, even inside containers
• Network flow visibility: L3/L4/L7 traffic without sidecars
• File access auditing: Track every file open/read/write in real-time
• Syscall filtering: Block specific system calls per workload

Cilium Tetragon: Runtime Security

Tetragon provides kernel-level security observability:

apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
  name: detect-privilege-escalation
spec:
  kprobes:
  - call: "security_file_open"
    syscall: false
    args:
    - index: 0
      type: "file"
    selectors:
    - matchArgs:
      - index: 0
        operator: "Prefix"
        values:
        - "/etc/shadow"
        - "/etc/passwd"
    - matchActions:
      - action: Sigkill  # Kill the process immediately
      - action: NotifyEnforcer

  - call: "__x64_sys_setuid"
    syscall: true
    selectors:
    - matchActions:
      - action: Post
        rateLimit: "1m"

This policy detects and kills any container process trying to read /etc/shadow — something network policies can’t do.

Beyond Network Policies

Traditional NetworkPolicy:

# Can only filter by IP/port
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: api-policy
spec:
  podSelector:
    matchLabels:
      app: api
  ingress:
  - from:
    - podSelector:
        matchLabels:
          app: frontend
    ports:
    - port: 8080

Cilium Network Policy (L7-aware):

# Can filter by HTTP method, path, headers
apiVersion: cilium.io/v2
kind: CiliumNetworkPolicy
metadata:
  name: api-l7-policy
spec:
  endpointSelector:
    matchLabels:
      app: api
  ingress:
  - fromEndpoints:
    - matchLabels:
        app: frontend
    toPorts:
    - ports:
      - port: "8080"
        protocol: TCP
      rules:
        http:
        - method: "GET"
          path: "/api/v1/.*"
        - method: "POST"
          path: "/api/v1/orders"
          headers:
          - 'X-Auth-Token: .*'

Practical Use Cases

1. Detect cryptominer processes: Monitor for suspicious CPU-intensive processes in containers
2. Prevent container escapes: Block mount syscalls and privilege escalation attempts
3. DNS monitoring: Track all DNS queries from pods without modifying applications
4. Forensics: Complete audit trail of all process executions and network connections

Getting Started

# Install Cilium with Tetragon
cilium install --version 1.16 --set tetragon.enabled=true

# View security events
kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | \
  tetra getevents -o compact

eBPF-based security is no longer experimental. If you’re running Kubernetes in production, it should be part of your security stack.

Want to implement eBPF-based security? I help teams design defense-in-depth strategies for Kubernetes. Let’s connect.\n