Understanding Kubernetes Network Security: Cilium Network Policy Deep Dive eBook

Kubernetes network security is a complex challenge, and network policies are at the heart of securing workloads at scale. But understanding how to implement them effectively can be daunting. That’s why we’ve created Cilium Network Policy Deep Dive, a comprehensive guide designed to help platform engineers, security teams, and SREs operate Cilium network policies with confidence.

Previously, we released “Kubernetes Network Policies Done the Right Way”, focused on the theory and practical implementation of Kubernetes Network Policies using Cilium. 
Today we release a follow up guide, covering a technical deep dive of the Cilium Network Policy engine. This is a must read guide for any Network Administrator and Kubernetes Platform Owner.

Why Kubernetes Network Policies Matter

As Kubernetes adoption grows, so does the need for robust network security. Traditional Kubernetes network policies provide a foundation for securing workloads, but they often fall short in modern, dynamic environments. Cilium enhances network policies by introducing identity-based security, deep observability, and extended control over both L3/L4 and L7 traffic.

A mature network policy practice isn’t just about security, it’s also about governance. Organizations operating in regulated industries must demonstrate strict control over data flows and application communications. Cilium’s fine-grained policy enforcement and observability tools support compliance initiatives like SOC 2, ISO 27001, and PCI DSS by enabling auditable and enforceable controls.

This eBook explores why enterprises need more than just basic Kubernetes network policies and how Cilium provides the flexibility, performance, and security required for cloud-native environments.

How Does the Isovalent Enterprise Platform Make Network Policies Easier?

Implementing and managing network policies in Kubernetes can be complex. The Isovalent Enterprise Platform, built on a hardened version of Cilium, simplifies this process by offering tools designed to enhance the entire network policy lifecycle. Key features include the Hubble UI, which provides real-time network flow visibility and a built-in Network Policy Editor that allows you to create and manage policies directly from observed traffic patterns. Additionally, Isovalent offers enterprise-level support, ensuring that your network policies are robust, compliant, and tailored to your organization’s needs.

Isovalent Enterprise for Cilium: Connectivity Visibility with Hubble

This lab provides an introduction to Isovalent Enterprise for Cilium capabilities focuses on Hubble Flow events that provide label-aware, DNS-aware, and API-aware visibility for network connectivity within a Kubernetes environment using Cilium and Hubble Enterprise.

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What’s Inside the eBook?

This 50+ page guide takes a deep dive into:

• Label-Based Security Identities: How Cilium uses identity-based enforcement instead of traditional IP-based rules.
• Multi-Tenancy and Policy Scoping: Best practices for defining policies in complex, multi-tenant environments.
• Real-World Policy Implementations: Practical YAML examples demonstrating how to apply and troubleshoot Cilium network policies.
• Scaling and Observability: Leveraging tools such as Hubble for policy visibility and continuous security monitoring.
• Advanced Security Strategies: Implementing Zero Trust, securing external access, and using Cilium’s L7 capabilities for application-aware security.

Readers will gain a solid grasp of Cilium’s modeling of Security Identity, how those Identities are associated with workloads and expressed in network policy artifacts, and how to monitor the operation of Cilium’s network policy enforcement in production environments.

Who Is This Guide For?

Whether you’re securing a small Kubernetes deployment or managing multi-cluster enterprise environments, this guide is designed for:

• Platform Engineers & SREs: Learn how to build scalable, secure network policies with Cilium.
• Security Architects: Implement Zero Trust principles and gain deeper insights into Kubernetes networking.
• DevOps & Cloud Teams: Understand how to optimize network policies for performance and security.

By combining hands-on examples with deep technical insights, this guide provides actionable steps to enhance Kubernetes security in real-world environments.

Insights Backed by Experience, From the Team Who Built Cilium

This isn’t just another generic Kubernetes guide. As the creators of Cilium, our engineers Joe Stringer and Nicholas Lane have written this book to share real-world experience that only comes from maintaining and advancing the project used by some of the world’s most demanding enterprises. Isovalent engineers sit at the heart of the Cilium open source community and support mission-critical deployments every day. 

Joe is one of the key architects behind Cilium, working on the project since 2017. As a contributor to open source projects ranging from Open vSwitch to Cilium and the Linux kernel, Joe has built critical components to enforce stateful firewalling and security policies across both cloud and traditional environments.

Nicholas has over a decade of experience as a customer success engineer, helping users adopt cloud native technologies. Throughout his career, Nicholas has focused on enabling users to start using new technologies with as little friction as possible, not only as a former member of the Kubernetes release team, but also with experience across CoreOs, Heptio and now Isovalent. From financial services and telcos to global SaaS providers, our teams help platform and security engineers solve complex problems in production, whether that’s implementing Zero Trust, troubleshooting observability gaps, or managing multi-tenant networks at scale. The insights in this eBook come directly from that front-line experience.

A Visual Sneak Peek Inside

To give you a taste of what’s inside, we’ve included a selection of preview pages showcasing the level of technical depth covered in the eBook.

Excerpts From the Book

Below is a summary of the section “Operating Cilium with Network Policies”.

Operating Cilium with Network Policies

At this point you should have a solid grasp of the core network policy model in Cilium from a high level. This chapter intends to expand on these concepts from a more practical perspective, describing how to write network policies, troubleshooting live environments, and understanding the way that the network policies affect your environment at scale. This will cover how to monitor and observe your environment, but it will not comprehensively break down each network policy use case or way that all Cilium features interact with the network policy engine. Rather, this chapter should provide insight into common usage patterns and give you the tools to be able to further explore Cilium’s capabilities through production usage.

Writing Network Policies

Cilium’s network policy engine provides a range of capabilities through the KNP, CNP and CCNP APIs, which are typically written in YAML and managed through a central control plane in the cluster. This section provides an overview of the structure and semantics of these policies, and discusses the way that these rules may interact with external systems. For more specific examples to write network policies for your environment, see the Isovalent labs for security.

Key Components of a Rule

Network policy identifies the peers involved in network communication and how the policy intends for that communication to be managed – for instance, to allow or deny the traffic. In practice, Cilium identifies four key areas that reflect this intent in order to implement the network policies: the enforcement point, defined by the subject selector; the default deny posture for the subject of the policy; a set of rules under an ingress or egress stanza which identify specific traffic that should be allowed or denied; and finally, an optional rules statement that subjects the traffic to deeper inspection. The following figure highlights these four important components of a common network policy:

Get Your Free Copy Now!

If you’re responsible for securing Kubernetes workloads, optimizing traffic flows, or enforcing compliance at scale, Cilium Network Policy Deep Dive is a must-read. Download your free copy today and take your Kubernetes security knowledge to the next level.

If you want to talk to the experts behind the book directly and discuss how we can help you with your Kubernetes Network Policy challenges today, reach out to us!