# Cis K8S V200 5.3.2

> Ensure that all Namespaces have Network Policies defined (Manual)

- Skill: `cyberstrikeus/cis-k8s-v200-5-3-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-k8s-v200-5-3-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-k8s-v200-5-3-2/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-k8s-v200-5-3-2

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# 5.3.2 Ensure that all Namespaces have Network Policies defined (Manual)

## Profile Applicability

- Level 2 - Master Node

## Description

Use network policies to isolate traffic in your cluster network.

## Rationale

Running different applications on the same Kubernetes cluster creates a risk of one compromised application attacking a neighboring application. Network segmentation is important to ensure that containers can communicate only with those they are supposed to. A network policy is a specification of how selections of pods are allowed to communicate with each other and other network endpoints.

Network Policies are namespace scoped. When a network policy is introduced to a given namespace, all traffic not allowed by the policy is denied. However, if there are no network policies in a namespace all traffic will be allowed into and out of the pods in that namespace.

## Impact

Once network policies are in use within a given namespace, traffic not explicitly allowed by a network policy will be denied. As such it is important to ensure that, when introducing network policies, legitimate traffic is not blocked.

## Audit

Run the below command and review the `NetworkPolicy` objects created in the cluster.

```bash
kubectl get networkpolicy --all-namespaces
```

Ensure that each namespace defined in the cluster has at least one Network Policy.

## Remediation

Follow the documentation and create `NetworkPolicy` objects as you need them.

## Default Value

By default, network policies are not created.

## References

1. https://kubernetes.io/docs/concepts/services-networking/networkpolicies/
2. https://octetz.com/posts/k8s-network-policy-apis
3. https://kubernetes.io/docs/tasks/configure-pod-container/declare-network-policy/