Security Kubernetes Security Primitives

Hello, and welcome to this lesson on Kubernetes security primitives. In this article, we explore the foundational security measures required for running production-grade applications on Kubernetes. Understanding these security components is essential for maintaining a robust and secure cluster.

The image features the text "Security-Kubernetes Security Primitives" on a blue background with a network design.

Securing the Underlying Hosts

Before diving into Kubernetes-specific features, it is vital to secure the physical or virtual hosts that form the cluster. Ensure all host access is protected by:

Disabling root access
Disabling password-based authentication
Enforcing SSH key-based authentication
Implementing other critical security measures

A compromise at this level can jeopardize the entire infrastructure.

The image illustrates "Secure Hosts" with three outlined devices and notes on disabling password authentication and using SSH key-based authentication.

Kubernetes-Specific Security Measures

Focusing specifically on Kubernetes, the core component is the kube-apiserver. This component is the central point of contact for operations, whether accessed via the kubectl utility or directly through its API. Its security is paramount, so consider these key questions:

Who can access the cluster?
What actions can they perform once access is granted?

The image discusses securing Kubernetes, focusing on the "kube-apiserver" and questioning who can access it.

Authentication

Access to the API server is managed through robust authentication mechanisms. Methods include:

Static files with user IDs and passwords
Tokens and certificates
External authentication providers (e.g., LDAP)
Machine-to-machine interactions managed through service accounts

The image lists authentication methods: username/password, username/tokens, certificates, LDAP, and service accounts, under the question "Who can access?"

Authorization

Once authenticated, the system determines valid actions through authorization. Kubernetes primarily uses Role-Based Access Control (RBAC), where permissions are assigned based on roles or group memberships. Additional methods include Attribute-Based Access Control (ABAC) and webhooks for extended flexibility.

The image is a slide titled "Authorization" with options for RBAC and ABAC Authorization.

Secure Communication Within the Cluster

All communications between essential cluster components—such as the etcd cluster, kube-controller-manager, scheduler, API server, and nodes (kubelet and kube-proxy)—are secured with TLS encryption. This ensures that every interaction within the cluster remains confidential and tamper-proof.

TLS Encryption

An entire section of Kubernetes documentation is dedicated to configuring TLS certificates. These certificates secure intra-cluster communication, safeguarding sensitive data exchanged between:

Kube ApiServer
ETCD Cluster
Kubelet
Additional components

The image illustrates the use of TLS certificates in a Kubernetes architecture, showing connections between components like Kube ApiServer, ETCD Cluster, Kubelet, and others.

Network Policies

By default, pods within the cluster can communicate freely. However, to tighten security, you can implement network policies, which restrict communication between pods and enhance overall cluster security.

The image illustrates network policies with four smartphone-like icons, each containing colored circles and interconnected by dashed lines and pentagons.

This high-level overview has introduced the key security primitives in Kubernetes. In the upcoming sections, we will explore each component in greater depth to help you build a secure and resilient Kubernetes cluster.

For additional insights, consider exploring the following resources:

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