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⎈ Secure Network Boundaries using NSP

🙌 Overview​

As you have seen in some of the scenarios and in general Kubernetes comes with a flat networking schema. This means if you wanted to create network boundaries, you will need to create something called a Network Policy with the help of CNI. In this scenario, we will be looking at a simple use case of how you can create a Network Policy to restrict traffic and create network security boundaries between Kubernetes resources.

By the end of the scenario, you will understand and learn the following:

  1. You will learn to work with Network Policies in Kubernetes Cluster
  2. Understand and work with basic Kubernetes kubectl commands and interact with pods & services
  3. Creating and destroying Kubernetes resources and restricting the traffic using NSPs

⚡️ The story​

This scenario is to deploy a simple Network Security Policy for Kubernetes resources to create security boundaries.

info

To get started with this scenario, please ensure you are using a networking solution that supports NetworkPolicy

🎯 Goal​

tip

Create a Network Policy to drop the access to the website service to complete this scenario.

🪄 Hints & Spoilers​

✨ What is NSP and how to learn?
Let's look at official docs Network Policies. Also there is a detailed explanation of NSP with examples by Ahmet Alp Balkan here🙌

🎉 Solution & Walkthrough​

🎲 Method 1​

note

Refer to https://github.com/ahmetb/kubernetes-network-policy-recipes for more recipes and a detailed explanation of Network Security Policies with examples and details.

  • Let's run the Nginx container with app=website labels and expose it via port 80
kubectl run --image=nginx website --labels app=website --expose --port 80
  • Now, let's run a temporary pod to make a simple HTTP request to the website service
kubectl run --rm -it --image=alpine temp -- sh
  • Let's make a simple HTTP request using wget to the website service
wget -qO- http://website

wget output for website

  • So far it works perfectly fine. Now let's create a Network Policy and apply it to the Kubernetes cluster to block/deny any requests.
website-deny.yaml
kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: website-deny
spec:
  podSelector:
    matchLabels:
      app: website
  ingress: []
  • Let's deploy this NSP policy to the cluster by running the following command:
kubectl apply -f website-deny.yaml
  • Now, let's retry a HTTP request to our website service
kubectl run --rm -it --image=alpine temp -- sh
  • Let's run the wget query to access the website
wget -qO- --timeout=2 http://website

wget output for website failed

  • As you can see the Network Policy is dropping the traffic and you are not able to access the website now.

  • You can remove all the applied resources and clean up by running the following commands

kubectl delete pod website
kubectl delete service website
kubectl delete networkpolicy website-deny
  • Hooray 🥳 , now you have successfully learned how to implement and work with Network Policies in Kubernetes Clusters!

🔖 References​