03-deny-all-non-whitelisted-traffic-in-the-namespace.md

DENY all non-whitelisted traffic to a namespace

💡 Use Case: This is a fundamental policy, blocking all cross-pod networking other than the ones whitelisted via the other Network Policies you deploy.

Consider applying this manifest to any namespace you deploy workloads to (anything but kube-system).

💡 Best Practice: This policy will give you a default "deny all" functionality. This way, you can clearly identify which components have dependency on which components and deploy Network Policies which can be translated to dependency graphs between components.

Manifest

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: default-deny-all
  namespace: default
spec:
  podSelector: {}
  ingress: []

Note a few things about this manifest:

• namespace: default deploy this policy to the default namespace.
• podSelector: is empty, this means it will match all the pods. Therefore, the policy will be enforced to ALL pods in the default namespace .
• There are no ingress rules specified. This causes incoming traffic to be dropped to the selected (=all) pods.
  • In this case, you can just omit the ingress field, or leave it empty like ingress:

Save this manifest to default-deny-all.yaml and apply:

$ kubectl apply -f default-deny-all.yaml
networkpolicy "default-deny-all" created

Cleanup

kubectl delete networkpolicy default-deny-all