Network Security Fundamentals

Network Security Fundamentals

Kubernetes networking operates on the principle that all pods can communicate with each other by default. While this simplifies application deployment, it creates security risks in multi-tenant environments. Network policies provide the mechanism for implementing network segmentation, controlling traffic flow between pods, namespaces, and external endpoints. Understanding Kubernetes networking architecture is essential for implementing effective network security.

The Container Network Interface (CNI) plugin implements the actual networking data plane. Different CNI plugins offer varying security features, from basic network policies to advanced capabilities like encryption and observability. Choosing the right CNI plugin impacts available security controls and performance characteristics. Popular options like Calico, Cilium, and Weave Net each provide different security capabilities that organizations must evaluate.

Service mesh technologies add another layer of network security through mutual TLS (mTLS) encryption and fine-grained authorization policies. While not part of core Kubernetes, service meshes like Istio, Linkerd, and Consul Connect have become common in production deployments. These technologies provide zero-trust networking within clusters but add operational complexity. Organizations must balance security benefits against operational overhead.