# Firewall

> Firewall Configuration in the Kubernetes.

---

Site [llms.txt](/llms.txt)

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In Kubernetes, we utilize the [Cilium](https://cilium.io/) firewall. This can be configured using `CiliumNetworkPolicies`. **By default, all incoming and outgoing connections of a pod are dropped**, except for a few exceptions like DNS and Istio sidecars.

Cilium itself provides an [editor](https://editor.networkpolicy.io/) which helps to create these policies. Otherwise comprehensive explanations can be found in the [official documentation](https://docs.cilium.io/en/stable/security/policy/#network-policy).

A small example on a policy allowing traffic from our ingress gateway to port 8080, would be:

```yaml
apiVersion: cilium.io/v2
kind: CiliumNetworkPolicy
metadata:
  name: example
  namespace: example
spec:
  endpointSelector:
    matchLabels:
      k8s:app: example
  ingress:
    - fromEndpoints:
        - matchLabels:
            k8s:app: istio-ingressgateway
            k8s:io.kubernetes.pod.namespace: istio-ingressgateway
            k8s:istio: ingressgateway
            k8s:name: istio-ingressgateway
      toPorts:
        - ports:
            - port: "8080"
              protocol: TCP
```