⚖️ How SSL/TLS Works with AWS Load Balancers
🔐 What is SSL/TLS?
- SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols used to encrypt data in transit.
- TLS is the modern, secure replacement for SSL (SSL is deprecated).
- In AWS, TLS is used to provide HTTPS for web applications via Load Balancers.
⚖️ How SSL/TLS Works with AWS Load Balancers
AWS Load Balancers terminate SSL/TLS at the load balancer level (called SSL offloading), meaning:
- Clients connect to the Load Balancer over HTTPS
- The Load Balancer decrypts the traffic
- The Load Balancer then forwards traffic to backend EC2s over HTTP or HTTPS
✅ This offloads the encryption/decryption load from your EC2 instances, improving performance.
🧩 Supported Load Balancers + SSL/TLS
| Load Balancer | SSL/TLS Support | Notes |
|---|---|---|
| ALB (Application LB) | ✅ Yes | Layer 7 – supports SNI, HTTPS listeners |
| NLB (Network LB) | ✅ Yes | Layer 4 – supports TLS listeners (v2 feature) |
| CLB (Classic LB) | ✅ Yes | Basic HTTPS/SSL support, less flexible |
⚙️ SSL/TLS Setup Workflow
🔹 1. Obtain an SSL/TLS Certificate
- Use AWS Certificate Manager (ACM) (free public certs for use with ELB)
- Or import your own certificate
🔹 2. Attach Certificate to Load Balancer
- For ALB/NLB, create an HTTPS listener
- Choose or attach an ACM certificate to the listener
🔹 3. Configure Listener Rules
- ALB: Use path-based or host-based routing rules (e.g.,
/api,blog.example.com) - Forward traffic to target groups (EC2, Lambda, etc.)
🔹 4. Optional: Encrypt EC2 traffic
- Backend EC2s can also use HTTPS, if end-to-end encryption is required
📦 Example Architecture
🔐 SSL/TLS Key Features via ELB
| Feature | Supported |
|---|---|
| SSL termination | ✅ |
| SNI (Server Name Indication) | ✅ ALB/NLB |
| ACM integration | ✅ |
| HTTP to HTTPS redirection | ✅ ALB (via listener rules) |
| Cipher policy selection | ✅ |
🧠 Tips & Best Practices
- Use ACM for free, auto-renewed public certificates
- Use HTTPS redirection from port 80 to 443
- Keep backend traffic encrypted if you're handling sensitive data
- Regularly update your TLS policies to remove weak ciphers
✅ Summary
| Feature | Value |
|---|---|
| Purpose | Encrypt traffic (HTTPS) |
| Termination Point | Load Balancer |
| Cert Management | AWS Certificate Manager (ACM) |
| ELB Types Supporting SSL/TLS | ALB, NLB, CLB |
| Encryption to backend | Optional |
| Use Case | Web apps, APIs, secure data transmission |