Cilium Architecture
You set up cilium architecture by running an agent on each Linux node. This agent loads eBPF programs into the kernel to route packets and check rules. Teams often deploy this setup to replace older network tools in Kubernetes clusters. When teams write broad network rules, pods can talk to every database or service. Overly wide roles also let too many users change cluster routing rules. How cilium architecture works in the kernel The core of cilium architecture relies on eBPF inside the Linu
Zero Trust Architecture + Cilium Network Policies: the complete guide
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You set up cilium architecture by running an agent on each Linux node. This agent loads eBPF programs into the kernel to route packets and check rules. Teams often deploy this setup to replace older network tools in Kubernetes clusters. When teams write broad network rules, pods can talk to every database or service. Overly wide roles also let too many users change cluster routing rules.
How cilium architecture works in the kernel
The core of cilium architecture relies on eBPF inside the Linux kernel. An agent runs as a daemon on every node in your cluster. This agent watches the Kubernetes API for new pods, services, and network rules. When a pod starts, the agent compiles small eBPF programs for that pod. It attaches those programs straight to the Linux network data path.
Old network tools check every packet against long lists of IP rules. That old method slows down as your cluster grows to thousands of pods. Cilium skips those long IP lists and uses workload identities instead. It gives each group of pods a shared numeric identity based on labels. The kernel checks this number in a fast hash table before sending data.
A cluster operator tool also runs alongside the node agents. The operator handles cluster tasks like IP address allocation and cloud router updates. It makes sure one node does not repeat work done by another node. For viewing network logs, a separate tool named Hubble reads kernel events. Hubble shows teams which pods talk to each other and which packets drop.
How identity rules control pod traffic
In old networks, security rules depend on pod IP addresses and ports. Pod IP addresses change every time a deployment restarts or scales up. Tracking changing IP addresses across many nodes creates mistakes and security holes. Identity rules fix this by tying security to pod labels instead of IPs.
When a pod sends a packet, the kernel marks it with the sender identity. The receiving node reads that mark and checks its local policy map. If the rule allows that identity, the packet goes straight to the pod. If the rule blocks it, the kernel drops the packet right away. The system can also parse HTTP calls to block specific web paths.
Zero Trust Architecture + Cilium Network Policies: architecture patterns and best practices
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What native network rules solve and what they miss
This kernel setup solves pod-to-pod routing and load balancing at high speed. It removes the need for extra sidecar containers on every single pod. Teams get clear flow logs and strong network boundaries between different apps. It stops rogue pods from scanning the internal network or reaching random hosts.
Still, network rules only check which pod or host sends the traffic. They do not know which human engineer or admin runs a command inside. Once an allowed pod or user opens a database session, network rules stop watching. The kernel cannot read SQL queries or stop a user from reading private data. It also cannot rewrite sensitive fields like emails or card numbers in flight. Teams still need a way to inspect individual commands and mask sensitive results.
Govern statements and responses across databases and APIs
Good config and scoped roles are needed setup. They do not check single queries in flight or mask sensitive fields in returned rows. Across Postgres, MySQL, SQL Server, MongoDB, ClickHouse, Kubernetes APIs, SSH, and internal HTTP endpoints, hoop.dev runs beside each supported service as an open-source proxy, a sidecar for your database or API.
First, hoop.dev guardrails block banned queries before they run. Then hoop.dev data masking rewrites matched sensitive values in responses in memory. The audit trail records every statement and verdict per resource. Furthermore, hoop.dev holds SOC 2 Type II and is open source on GitHub.
Frequently asked questions
What does eBPF do in a Kubernetes cluster?
It lets the Linux kernel run safe, fast programs when network events happen. This handles routing, load balancing, and security checks without changing kernel source code.
How does Cilium differ from standard iptables networking?
Standard iptables checks rules in a slow list that grows with every service. Cilium uses kernel hash tables so lookups stay fast at any cluster size.
Do I still need kube-proxy when running this setup?
No, the node agent can replace kube-proxy by handling service routing with eBPF. This removes duplicate rule processing and speeds up network traffic across nodes.