Understanding Cilium: An Introductory Guide
As technology evolves and computer systems become more advanced, the need for network security is becoming increasingly critical. Newer software architectures such as microservices and containerization can create unique issues when it comes to securing the network, since traditional security approaches may not be adequate in defending against emerging threats. Cilium offers an effective solution to these problems, with its high-speed, low-latency security and networking features that can be implemented in contemporary distributed systems.
What is Cilium?
Cilium is a modern, open-source networking and security solution for containerized environments. It provides a high-level of visibility and control over network traffic and offers advanced security features, including encryption, network policy enforcement, and more. Cilium uses eBPF (Extended Berkeley Packet Filter) to provide high-performance networking and security, and it is designed to work with container orchestration systems like Kubernetes.
eBPF (extended Berkeley Packet Filter): The eBPF technology is a Linux kernel bytecode interpreter used for packet filtering, socket filters, packet mangling, forwarding, and more. The in-kernel verifier ensures safety while the JIT compiler enables native execution efficiency. eBPF programs can run at various hooking points in the kernel. Cilium detects available kernel features and uses them as needed.
One of the key features of Cilium is its ability to enforce security policies at the network layer, allowing for fine-grained control over traffic between services. Cilium can also provide encryption and authentication for network traffic, ensuring that data is transmitted securely.
In addition to its security features, Cilium also offers a number of networking capabilities that are particularly useful in containerized environments. For example, Cilium can provide load balancing and service discovery, allowing services to be accessed by other services in a simple and scalable manner.
Hubble, built on Cilium and eBPF, offers distributed networking and security observability with deep visibility into services and network infrastructure. It provides dynamic and programmable visibility with minimized overhead and is designed to leverage eBPF.
Overall, Cilium is a powerful and flexible solution for securing and networking modern, distributed systems. Its use of eBPF technology and focus on network-level security make it particularly well-suited for containerized environments where traditional security and networking solutions may not be sufficient.
Cilium Architecture:
Cilium is a network security and observability solution designed for cloud-native environments such as Kubernetes. It is built on top of a new Linux kernel technology called eBPF, which enables the dynamic insertion of security, visibility, and networking control logic into the Linux kernel.
The architecture of Cilium consists of a few primary components:
Agent
The agent runs on each node of a Kubernetes cluster and is responsible for establishing connections with the Kubernetes API server and maintaining network and security policies. It uses eBPF to insert security and networking policies into the Linux kernel.
Operator
Cilium Operator manages cluster duties for the entire cluster and is not critical for network policy decisions. Unavailability can cause delays in IP Address Management and kvstore unhealthiness leading to agent restarts.
Cilium CLI
The command-line interface (CLI) is used to interact with the Cilium API server and manage Cilium’s policies and configuration.
CNI Plugin
CNI(Container Networking Interface) plugin is activated by Kubernetes during pod scheduling or termination on a node. It communicates with the node’s Cilium API to initiate the required datapath configuration for networking, load-balancing, and network policies for the pod.
Cilium’s architecture is highly scalable and can handle complex network topologies. It provides several features such as multi-cluster and multi-cloud capabilities, advanced load balancing, transparent encryption, and extensive network security capabilities. With eBPF at its core, Cilium can achieve high-performance and low-latency networking and security for modern distributed systems.
How Cilium works:
As mentioned earlier, Cilium is a powerful network tool that operates at the network layer and provides advanced security features for Kubernetes clusters. At a high level, Cilium works by intercepting and analyzing network traffic between Kubernetes pods and using this information to enforce security policies.
When a packet is sent between two pods, Cilium’s data plane intercepts the packet and inspects its source and destination. It then determines whether the packet is allowed to be transmitted based on a set of security policies defined by the cluster administrator. These policies can be based on a variety of factors, such as the identity of the source and destination pods, their labels or annotations, and the type of traffic being transmitted.
Cilium’s policy enforcement relies on eBPF, a virtual machine that allows complex security policies to run directly in the Linux kernel for efficient processing of network traffic. This enables Cilium to enforce policies without requiring any changes to the application code or network configuration.
Cilium offers several advanced networking features that can enhance the reliability and performance of Kubernetes clusters in addition to policy enforcement. Among other things, Cilium can conduct load balancing and traffic routing between pods, as well as provide network traffic visibility using advanced monitoring and tracing tools.
Cilium’s service mesh architecture, on the other hand, utilizes eBPF programs inserted into the Linux kernel to enable transparent policy enforcement and in-depth visibility into network traffic. This capability empowers Cilium to enforce identity-based policies to ensure secure service communication and conduct comprehensive visibility and network flow analysis to enhance security and observability.
Use cases for Cilium:
Cilium is a versatile tool that can be used in a variety of scenarios to provide network security and connectivity for containerized environments. Here are some examples of how Cilium can be used:
Networking
Service Load Balancing: Cilium provides robust and secure load balancing through BGP, XDP, and eBPF, operating at the kernel layer and enabling intelligent workload connection decisions, while also improving performance and eliminating the need for kube-proxy.
Scalable Kubernetes CNI: Cilium is designed for large-scale cloud environments with dynamic workloads, optimized control plane up to 5K nodes, data plane uses eBPF for efficient load-balancing, and supports IPv6.
Multi-cluster Connectivity: Cluster Mesh enables high-performance cross-cluster connectivity, creating a single zone of connectivity for load-balancing, observability, and security between nodes across multiple clusters.
Observability
Identity-aware Visibility: Cilium leverages eBPF for rich observability in Kubernetes. Its Hubble framework provides API, CLI, and a graphical UI to troubleshoot application and connectivity issues with native understanding of Kubernetes label and DNS identities.
Advanced Self Service Observability: Cilium uses eBPF to enable efficient visibility into L7 proxies such as Envoy, and applications and protocols like HTTP, gRPC, and Kafka, while gathering process context at the kernel layer. This data is available via Cilium’s Hubble framework and includes TLS-interception for HTTPS traffic.
Network Metrics + Policy Troubleshooting: Cilium provides Prometheus compatible L3/L4 and L7 network flow metrics with rich identity context, allowing teams to detect and investigate network and application behavior and faults. Flow and metric data include information on traffic allowed or denied by network policies, simplifying policy troubleshooting.
Security
Transparent Encryption: Cilium provides transparent encryption capabilities for securing data in-flight, using efficient IPsec capabilities built into the Linux kernel. It requires only a single configuration setting, with no application changes or proxying required, for encrypting communications between all workloads within, or between, Kubernetes clusters.
Security Forensics + Audit: Cilium’s Hubble provides identity-aware network flow logs and process context to enable long-term forensics for security in Kubernetes.
Advanced Network Policy: Cilium supports basic, DNS-aware, and application-aware Kubernetes network policies, as well as cluster-wide network policy and host-layer firewalling. Learn more by getting started or watching a video.
Real-world use cases and success stories:
Cilium has been adopted by a number of organizations across a variety of industries and has been used to secure large-scale, mission-critical containerized environments. Here are some examples of real-world use cases and success stories:
- Datadog: Cilium is used by Datadog to secure and monitor the network traffic of their containerized applications running on Kubernetes. They were able to replace their legacy iptables-based solution with Cilium, which improved performance and provided richer observability.
- Arista Networks: Cilium is used by Arista Networks to secure the network traffic of their multi-cloud Kubernetes deployments. They were able to simplify their security posture by using Cilium’s identity-based policies, which provided better visibility and control over network traffic.
- Cloudflare: Cilium is used by Cloudflare to secure the network traffic of their Kubernetes-based Edge Compute platform. They were able to achieve higher performance and scalability by leveraging Cilium’s eBPF-based dataplane and identity-aware policies.
- GitLab: Cilium is used by GitLab to secure the network traffic of their containerized applications running on Kubernetes. They were able to improve the reliability and security of their network traffic by using Cilium’s network policies and observability features.
- OVHcloud: Cilium is used by OVHcloud to secure the network traffic of their Kubernetes-based cloud platform. They were able to achieve better network performance and security by leveraging Cilium’s eBPF-based dataplane and identity-aware policies.
Getting started with Cilium:
In this section, we will provide a step-by-step guide for getting started with Cilium, including the installation and configuration process as well as how to use Cilium to secure your containerized environment.
- Prerequisites: Before getting started with Cilium, you need to have a Kubernetes cluster up and running. Additionally, you need to have the Cilium binary installed on each node of your Kubernetes cluster.
- Installation: There are different ways to install Cilium depending on the type of Kubernetes environment you are running. You can install Cilium with a one-line command using a package manager like Helm or as a Kubernetes operator. You can also install Cilium manually by downloading the binary and running it on each node. The installation process is well-documented in the Cilium documentation.
- Configuration: Once Cilium is installed, you need to configure it to secure your containerized environment. This includes defining network policies, setting up service meshes, and configuring your Kubernetes cluster to work with Cilium. The Cilium documentation provides detailed instructions on how to configure Cilium.
- Using Cilium: After installation and configuration, you can start using Cilium to secure your containerized environment. You can define network policies to restrict traffic between services, set up service meshes to manage traffic, and use Cilium’s visibility features to monitor your network. The Cilium documentation provides detailed instructions on how to use these features.
Cilium has a steep learning curve, but its well-documented installation and configuration process and feature-rich capabilities make it a potent solution for securing containerized environments.
Official installation documentation can be found at this link.
Conclusion:
In conclusion, Cilium is a powerful and flexible solution for securing and managing container networking in modern distributed systems. Its advanced use of eBPF technology, combined with its rich set of features and policies, makes it an ideal choice for organizations seeking to improve the security and performance of their container environments.
Some of the key takeaways from this article include:
- Cilium provides scalable and efficient networking and security for containerized applications.
- Cilium is compatible with a wide range of container orchestration platforms, including Kubernetes and Docker.
- Cilium is highly extensible and customizable, offering a rich set of APIs and integrations with other tools.
Readers are encouraged to explore Cilium further and consider its use in their own environments. A lot can be offered by Cilium, whether it is for securing Kubernetes clusters, improving microservices performance, or simply streamlining container networking.
References:
- Official Documentation: https://docs.cilium.io/
- Kubernetes Documentation: https://kubernetes.io/docs/home/
- Cilium Blog: https://cilium.io/blog/
