# Pehle sab band. Pod compromise ho to wo cluster me idhar-udhar na ja sake.
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: default-deny-all
  namespace: demo-app
spec:
  podSelector: {}
  policyTypes: [Ingress, Egress]
---
# Ab sirf jo chahiye wahi khola: app port par traffic andar, DNS bahar.
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-app
  namespace: demo-app
spec:
  podSelector:
    matchLabels:
      app: demo-app
  policyTypes: [Ingress, Egress]
  ingress:
    - ports:
        - protocol: TCP
          port: 8000
  egress:
    # DNS ke bina kuch bhi kaam nahi karega
    - to:
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: kube-system
      ports:
        - protocol: UDP
          port: 53
        - protocol: TCP
          port: 53
    # Tracing: Tempo host ke bridge IP par sunta hai
    - to:
        - ipBlock:
            cidr: 192.168.124.1/32
      ports:
        - protocol: TCP
          port: 4318