Microservices Security: Protecting Your API Mesh

The Expanded Attack Surface of Microservices

A monolithic application has one entry point. A microservices architecture has dozens — each service exposes its own API endpoints. Securing this distributed mesh requires a fundamentally different approach than traditional perimeter security.

Mutual TLS (mTLS)

Standard TLS authenticates the server to the client. Mutual TLS (mTLS) authenticates both parties. Every service must present a valid certificate before communication is allowed. This prevents a compromised internal service from making unauthorised calls to other services.

# Kubernetes: enforce mTLS via Istio PeerAuthentication
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default
  namespace: production
spec:
  mtls:
    mode: STRICT

API Gateway as Security Perimeter

All external traffic should enter through a single API gateway that handles authentication, rate limiting, and input validation before forwarding requests to internal services.