SKILL.md
mTLS Configuration
Comprehensive guide to implementing mutual TLS for zero-trust service mesh communication.
Do not use this skill when
- The task is unrelated to mtls configuration
- You need a different domain or tool outside this scope
Instructions
- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
Use this skill when
- Implementing zero-trust networking
- Securing service-to-service communication
- Certificate rotation and management
- Debugging TLS handshake issues
- Compliance requirements (PCI-DSS, HIPAA)
- Multi-cluster secure communication
Core Concepts
1. mTLS Flow
┌─────────┐ ┌─────────┐
│ Service │ │ Service │
│ A │ │ B │
└────┬────┘ └────┬────┘
│ │
┌────┴────┐ TLS Handshake ┌────┴────┐
│ Proxy │◄───────────────────────────►│ Proxy │
│(Sidecar)│ 1. ClientHello │(Sidecar)│
│ │ 2. ServerHello + Cert │ │
│ │ 3. Client Cert │ │
│ │ 4. Verify Both Certs │ │
│ │ 5. Encrypted Channel │ │
└─────────┘ └─────────┘
2. Certificate Hierarchy
Root CA (Self-signed, long-lived)
│
├── Intermediate CA (Cluster-level)
│ │
│ ├── Workload Cert (Service A)
│ └── Workload Cert (Service B)
│
└── Intermediate CA (Multi-cluster)
│
└── Cross-cluster certs
Templates
Template 1: Istio mTLS (Strict Mode)
# Enable strict mTLS mesh-wide
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
name: default
namespace: istio-system
spec:
mtls:
mode: STRICT
---
# Namespace-level override (permissive for migration)
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
name: default
namespace: legacy-namespace
spec:
mtls:
mode: PERMISSIVE
---
# Workload-specific policy
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
name: payment-service
namespace: production
spec:
selector:
matchLabels:
app: payment-service
mtls:
mode: STRICT
portLevelMtls:
8080:
mode: STRICT
9090:
mode: DISABLE # Metrics port, no mTLS
