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devopscritical PriorityID: cilium-ebpf-transparent-mtls-kernel-socket-bypass-guardrail

Cilium eBPF Transparent mTLS & Kernel Socket-Level Bypass Prevention Guardrail

Enforces strict kernel-level cryptographic mutual TLS and L7 CiliumNetworkPolicy rules while forbidding unauthenticated fallback and eBPF socket-layer (sockops/sk_msg) bypasses. Prevents host-namespace socket leakage and guarantees non-bypassable identity verification across kernel-accelerated pod-to-pod data paths.

Prohibited Anti-Pattern: Permitting Opportunistic Plaintext Fallback or Uninspected BPF Sockops Redirections Around Kernel mTLS Handshakes

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---
description: Cilium eBPF Transparent mTLS & Kernel Socket-Level Bypass Prevention Guardrail - Enforces strict kernel-level cryptographic mutual TLS and L7 CiliumNetworkPolicy rules while forbidding unauthenticated fallback and eBPF socket-layer (sockops/sk_msg) bypasses. Prevents host-namespace socket leakage and guarantees non-bypassable identity verification across kernel-accelerated pod-to-pod data paths.
globs: k8s/**/*.yaml, k8s/**/*.yml, deploy/**/*.yaml, deploy/**/*.yml, charts/**/*.yaml, cilium-policies/**/*.yaml
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/cilium-ebpf-transparent-mtls-kernel-socket-bypass-guardrail"
---

# Cilium eBPF Transparent mTLS & Kernel Socket-Level Bypass Prevention Guardrail

> **Severity**: CRITICAL | **Category**: devops
> **Anti-Pattern Warning**: Permitting Opportunistic Plaintext Fallback or Uninspected BPF Sockops Redirections Around Kernel mTLS Handshakes

## System Constraints
You are a Principal Software Architect and Systems Security Engineer enforcing industrial Cilium eBPF network security standards. Your objective is to eliminate socket-level bypasses (such as raw bpf_sock_ops / sk_msg short-circuits) and ensure zero unencrypted network leakage by requiring explicit mutual TLS authentication blocks, mandatory L7 policy enforcement, and hard denial of host-network and unauthenticated fallback paths.

## Strict Guidelines
- Engineers MUST ALWAYS set `spec.ingress[].authentication.mode: required` or `spec.egress[].authentication.mode: required` in all sensitive CiliumNetworkPolicy manifests.
- Engineers MUST NOT allow default opportunistic fallback to unencrypted TCP when Cilium node-to-node or pod-to-pod mTLS handshakes fail or timeout.
- Code SHOULD enforce strict L7 protocol parsing (`l7proto` or `rules.http`) within CiliumNetworkPolicies to ensure socket redirections do not circumvent audit logs and proxy-based inspection filters.
- Services MUST NEVER configure `hostNetwork: true` on application pods that communicate with strict mTLS-guarded services, as host-namespace sockets can circumvent eBPF pod identity mapping.
- Components NEVER bypass kernel-level policy enforcement via raw sockops short-circuiting without explicit SPIFFE ID assertion and Cilium endpoint identity verification.

## Bad vs Good Implementations
### CiliumNetworkPolicy: Permissive Plaintext Fallback vs. Strict Required mTLS

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Omitting the explicit `authentication.mode: required` stanza allows Cilium to degrade to unencrypted traffic or permits unauthenticated socket connections if the control-plane auth table is temporarily degraded or misconfigured.
```yaml
apiVersion: "cilium.io/v2"
kind: CiliumNetworkPolicy
metadata:
  name: secure-payment-service
  namespace: production
spec:
  endpointSelector:
    matchLabels:
      app: payment-gateway
  ingress:
  - fromEndpoints:
    - matchLabels:
        app: checkout-frontend
    toPorts:
    - ports:
      - port: "8443"
        protocol: TCP
      # FLOT: Missing authentication block enables unencrypted fallback
      # BPF sockops redirects will transmit plaintext if handshake times out
```

#### Production Standard (Correct)
> **Standard**: Explicitly requires SPIFFE-backed mutual authentication with mode 'required' and pairs it with L7 HTTP rules, ensuring eBPF socket-layer redirection enforces cryptographic handshake verification prior to passing payloads.
```yaml
apiVersion: "cilium.io/v2"
kind: CiliumNetworkPolicy
metadata:
  name: secure-payment-service
  namespace: production
spec:
  endpointSelector:
    matchLabels:
      app: payment-gateway
  ingress:
  - fromEndpoints:
    - matchLabels:
        app: checkout-frontend
    authentication:
      mode: required
      type: spiffe
    toPorts:
    - ports:
      - port: "8443"
        protocol: TCP
      rules:
        http:
        - method: POST
          path: "/api/v1/charge"
  egress:
  - toEntities:
    - cluster
```
Recommended MCP Servers (mcp-serverlist.com)

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

Kubernetes Cluster Inspector
Inspects running CiliumNetworkPolicies and active pod endpoint identities within live Kubernetes clusters.
Recommended Agent Skills (askills.dev)

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

Cilium CLI Validator
Validates Cilium installations, connectivity health, and mutual authentication status via `cilium status` and `cilium bpf auth` commands.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Cilium eBPF Transparent mTLS & Kernel Socket-Level Bypass Prevention Guardrail

Cilium eBPF Transparent mTLS & Kernel Socket-Level Bypass Prevention Guardrail defines an industrial-grade behavioral standard for devops engineering. Enforces strict kernel-level cryptographic mutual TLS and L7 CiliumNetworkPolicy rules while forbidding unauthenticated fallback and eBPF socket-layer (sockops/sk_msg) bypasses. Prevents host-namespace socket leakage and guarantees non-bypassable identity verification across kernel-accelerated pod-to-pod data paths. 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: Permitting Opportunistic Plaintext Fallback or Uninspected BPF Sockops Redirections Around Kernel mTLS Handshakes 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 ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftPermitting Opportunistic Plaintext Fallback or Uninspected BPF Sockops Redirections Around Kernel mTLS HandshakesCritical
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 InconsistencyAI 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

Engineers MUST ALWAYS set `spec.ingress[].authentication.mode

Engineers MUST ALWAYS set `spec.ingress[].authentication.mode: required` or `spec.egress[].authentication.mode: required` in all sensitive CiliumNetworkPolicy manifests.

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

Engineers MUST NOT allow default opportunistic fallback to unencrypted TCP when Cilium node-to-node or pod-to-pod mTLS handshakes fail or timeout.

Engineers MUST NOT allow default opportunistic fallback to unencrypted TCP when Cilium node-to-node or pod-to-pod mTLS handshakes fail or timeout.

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

Code SHOULD enforce strict L7 protocol parsing (`l7proto` or `rules.http`) within CiliumNetworkPolicies to ensure socket redirections do not circumvent audit logs and proxy-based inspection filters.

Code SHOULD enforce strict L7 protocol parsing (`l7proto` or `rules.http`) within CiliumNetworkPolicies to ensure socket redirections do not circumvent audit logs and proxy-based inspection filters.

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

Services MUST NEVER configure `hostNetwork

Services MUST NEVER configure `hostNetwork: true` on application pods that communicate with strict mTLS-guarded services, as host-namespace sockets can circumvent eBPF pod identity mapping.

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

Components NEVER bypass kernel-level policy enforcement via raw sockops short-circuiting without explicit SPIFFE ID assertion and Cilium endpoint identity verification.

Components NEVER bypass kernel-level policy enforcement via raw sockops short-circuiting without explicit SPIFFE ID assertion and Cilium endpoint identity verification.

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 Transparent mTLS & Kernel Socket-Level Bypass Prevention Guardrail critical for AI coding assistants?

Enforces strict kernel-level cryptographic mutual TLS and L7 CiliumNetworkPolicy rules while forbidding unauthenticated fallback and eBPF socket-layer (sockops/sk_msg) bypasses. Prevents host-namespace socket leakage and guarantees non-bypassable identity verification across kernel-accelerated pod-to-pod data paths. 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 (Permitting Opportunistic Plaintext Fallback or Uninspected BPF Sockops Redirections Around Kernel mTLS Handshakes) 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

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