Cilium eBPF L7 Network Security & Transparent Egress Governance | AgentRules.org

Rules Stacks Clients Auditor Pruner Self-Heal RFCs Benchmark CLI CI/CD Authors Submit

This specification is maintained by the AgentRules Working Group. Have enhancements or want to claim maintainership?Submit Specification →

devopscritical PriorityID: cilium-ebpf-network-security-policy

Cilium eBPF L7 Network Security & Transparent Egress Governance

Cloud-native Kubernetes network governance standard for Cilium eBPF. Enforces granular CiliumNetworkPolicy for L7 HTTP/DNS egress filtering, replaces bloated iptables sidecars with kernel-level eBPF acceleration, and mandates default-deny pod network isolation.

Prohibited Anti-Pattern: AI provisions Kubernetes pods with open egress (0.0.0.0/0), allowing compromised pods to query external malicious command-and-control servers or exfiltrate cloud metadata.

Export Ready-to-Drop Configuration

Select format below to copy code or download file directly.

---
description: Cilium eBPF L7 Network Security & Transparent Egress Governance - Cloud-native Kubernetes network governance standard for Cilium eBPF. Enforces granular CiliumNetworkPolicy for L7 HTTP/DNS egress filtering, replaces bloated iptables sidecars with kernel-level eBPF acceleration, and mandates default-deny pod network isolation.
globs: **/cilium-policy*.yaml, **/network-policy*.yaml, **/k8s/**/*.yaml
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/cilium-ebpf-network-security-policy"
---

# Cilium eBPF L7 Network Security & Transparent Egress Governance

> **Severity**: CRITICAL | **Category**: devops
> **Anti-Pattern Warning**: AI provisions Kubernetes pods with open egress (0.0.0.0/0), allowing compromised pods to query external malicious command-and-control servers or exfiltrate cloud metadata.

## System Constraints
You are a Kubernetes Zero-Trust and eBPF Network Security Engineer. NEVER leave Kubernetes workloads with unrestricted egress or un-isolated ingress. Always write CiliumNetworkPolicy with explicit L7 DNS filtering rules and strict default-deny postures.

## Strict Guidelines
- Enforce a default-deny ingress and egress posture for all production application namespaces.
- Use CiliumNetworkPolicy with toFQDNs rules to allow egress ONLY to explicitly whitelisted DNS domains (e.g. api.stripe.com).
- Block access to the Cloud Provider Instance Metadata Service (169.254.169.254/32) across all standard application pods.
- Specify L7 HTTP match rules (e.g. method: GET, path: /healthz) to restrict pod-to-pod API reachability.
- Verify eBPF socket load balancing without iptables kube-proxy overhead to reduce pod network latency.

## Bad vs Good Implementations
### CiliumNetworkPolicy with L7 FQDN Egress Whitelist & Cloud Metadata Blocking

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: An open egress policy permits compromised containers to exfiltrate database records, download external malware payloads, or steal cloud IAM role credentials from the AWS/GCP metadata endpoint.
```yaml
# FATAL: Default open egress allows data exfiltration to any internet IP
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-all-egress
spec:
  podSelector: {}
  egress:
  - {} # Allows ANY outbound traffic including C2 servers and 169.254.169.254 metadata!
```

#### Production Standard (Correct)
> **Standard**: Implements kernel-level eBPF egress filtering with Cilium. Outbound connections are locked down strictly to kube-dns and verified FQDN api.stripe.com; all other IP destinations (including cloud metadata) are instantly dropped.
```yaml
apiVersion: cilium.io/v2
kind: CiliumNetworkPolicy
metadata:
  name: payment-service-strict-egress
  namespace: production
spec:
  endpointSelector:
    matchLabels:
      app: payment-service
  # 1. Ingress: Only from API Gateway
  ingress:
  - fromEndpoints:
    - matchLabels:
        app: api-gateway
    toPorts:
    - ports:
      - port: "8080"
        protocol: TCP
  # 2. Egress: Strict DNS + FQDN whitelist only (blocks 169.254.169.254)
  egress:
  - toEndpoints:
    - matchLabels:
        k8s:io.kubernetes.pod.namespace: kube-system
        k8s-app: kube-dns
    toPorts:
    - ports:
      - port: "53"
        protocol: UDP
      rules:
        dns:
        - matchPattern: "*"
  - toFQDNs:
    - matchName: "api.stripe.com"
    toPorts:
    - ports:
      - port: "443"
        protocol: TCP
```

Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Cilium Hubble Observability MCP

Inspects real-time eBPF network flows and identifies dropped or unauthorized packet trajectories.

Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

askills: Cilium eBPF Policy Hardener

Generates least-privilege CiliumNetworkPolicies with DNS FQDN filtering and metadata shielding.

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Cilium eBPF L7 Network Security & Transparent Egress Governance

Cilium eBPF L7 Network Security & Transparent Egress Governance defines an industrial-grade behavioral standard for devops engineering. Cloud-native Kubernetes network governance standard for Cilium eBPF. Enforces granular CiliumNetworkPolicy for L7 HTTP/DNS egress filtering, replaces bloated iptables sidecars with kernel-level eBPF acceleration, and mandates default-deny pod network isolation. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: AI provisions Kubernetes pods with open egress (0.0.0.0/0), allowing compromised pods to query external malicious command-and-control servers or exfiltrate cloud metadata. Without an explicit system instruction file, developers spend hours debugging silent failures.

Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	AI provisions Kubernetes pods with open egress (0.0.0.0/0), allowing compromised pods to query external malicious command-and-control servers or exfiltrate cloud metadata.	Critical	Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production. Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture Inconsistency	AI assistants produce mixed paradigms across files, creating fragmented codebase conventions.	Medium	Increases cognitive load during code reviews and leads to maintenance debt across engineering teams. Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.

Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Enforce a default-deny ingress and egress posture for all production application namespaces.

Enforce a default-deny ingress and egress posture for all production application namespaces.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

2

Use CiliumNetworkPolicy with toFQDNs rules to allow egress ONLY to explicitly whitelisted DNS domains (e.g. api.stripe.com).

Use CiliumNetworkPolicy with toFQDNs rules to allow egress ONLY to explicitly whitelisted DNS domains (e.g. api.stripe.com).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

3

Block access to the Cloud Provider Instance Metadata Service (169.254.169.254/32) across all standard application pods.

Block access to the Cloud Provider Instance Metadata Service (169.254.169.254/32) across all standard application pods.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

4

Specify L7 HTTP match rules (e.g. method

Specify L7 HTTP match rules (e.g. method: GET, path: /healthz) to restrict pod-to-pod API reachability.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

5

Verify eBPF socket load balancing without iptables kube-proxy overhead to reduce pod network latency.

Verify eBPF socket load balancing without iptables kube-proxy overhead to reduce pod network latency.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.

Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.

Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Cilium eBPF L7 Network Security & Transparent Egress Governance critical for AI coding assistants?

Cloud-native Kubernetes network governance standard for Cilium eBPF. Enforces granular CiliumNetworkPolicy for L7 HTTP/DNS egress filtering, replaces bloated iptables sidecars with kernel-level eBPF acceleration, and mandates default-deny pod network isolation. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (AI provisions Kubernetes pods with open egress (0.0.0.0/0), allowing compromised pods to query external malicious command-and-control servers or exfiltrate cloud metadata.) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

Open Specification · CC BY 4.0·Free for Personal, Team & Commercial In-Repo Use

Citation & Open Source Attribution Guidelines

This specification is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You are completely free to adapt and share this rule in your workspace. If citing, including in public AI benchmark datasets, or redistributing, attribution to AgentRules.org is required.

Related DEVOPS Rules

View all rules →

Kubernetes Gateway API v1 HTTPRoute Canary and ReferenceGrant Invariants

Enforces strict conformance to Kubernetes Gateway API v1 specifications during migration from legacy Ingress controllers. Mandates explicit ReferenceGrant resources for cross-namespace routing, strict relative integer weighting for HTTPRoute canary releases, and explicit backendRef port declarations.

ArgoCD ApplicationSet Matrix Generator Invariants & Cascade Deletion Guards

Enforces strict structural constraints on ArgoCD ApplicationSet Matrix generators combining cluster selectors and Git directories. Prevents catastrophic multi-cluster cascade pruning, accidental secret exposure through parameter interpolation, and runaway Application CR explosion via explicit sync policies, preservation finalizers, and parameter validation.

Karpenter Resilient Topology, Interruption Queue, and Consolidation Budget Standard

Enforces deterministic disruption budgets, multi-instance-type diversification, and event-driven SQS interruption queue handling across Karpenter NodePools and EC2NodeClasses. Eliminates cascading eviction loops, instance starvation, and availability downtime during AWS Spot rebalances and underutilized node consolidation.

1 Rule in Stack

Cilium