12-deny-all-non-whitelisted-traffic-from-the-namespace.md

DENY all non-whitelisted traffic from a namespace

💡 Use Case: This is a fundamental policy, blocking all outgoing (egress) traffic from a namespace by default (including DNS resolution). After deploying this, you can deploy Network Policies that allow the specific outgoing traffic.

Consider applying this manifest to any namespace you deploy workloads to (except 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-egress
  namespace: default
spec:
  policyTypes:
  - Egress
  podSelector: {}
  egress: []

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.
• List of egress rules is an empty array: This causes all traffic (including DNS resolution) to be dropped if it’s originating from Pods in default.

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

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

Cleanup

kubectl delete networkpolicy default-deny-all-egress