Kubernetes Network Policies: Control Pod Traffic and Improve Security

Packets hit the cluster and vanish. Without control, they move anywhere. Kubernetes Network Policies change that.

The community version of Kubernetes Network Policies lets you define how Pods talk to each other and to the outside world. It is not about monitoring. It is about enforcing rules at the network layer. You choose which traffic is allowed and which is blocked. This makes workloads safer and more predictable.

A NetworkPolicy resource uses selectors to target Pods. You write rules based on labels, namespaces, and ports. Policies are either ingress, egress, or both. Ingress controls incoming connections. Egress controls outgoing connections. By default, Pods accept all traffic if no policy applies. Once a policy selects a Pod, Kubernetes blocks traffic that is not explicitly allowed.

In the community version, enforcement depends on the CNI plugin. Calico, Cilium, and Weave Net support Network Policies. kube-proxy alone does not. Install a supported CNI to make the rules real. Without it, policies exist only on paper.

Start small. Apply a simple ingress rule that allows traffic from one namespace to another. Verify with kubectl describe networkpolicy. Expand to multi-layer policies using both ingress and egress. Document every policy. Avoid wide 0.0.0.0/0 allowances. Keep selectors tight.

Network security is not a one-time setup. In Kubernetes, deployments change daily. Update policies with every new service, job, or replica set. Audit them regularly. Test what happens when policies are removed. The community version gives you control, but demands discipline to keep it effective.

If you want to see Kubernetes Network Policies in action without building a whole cluster first, try hoop.dev. You can run policies live in minutes—no setup, no waiting.