Enforcing HTTPS and HTTP Strict Transport Security (HSTS) with Nginx

# Nginx configuration for enforcing HTTPS and HSTS

# HTTP server block: Redirects all HTTP traffic to HTTPS
server {
    listen 80;
    listen [::]:80;
    server_name example.com www.example.com; # Replace with your domain

    # Permanent redirect to HTTPS
    return 301 https://$host$request_uri;
}

# HTTPS server block
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name example.com www.example.com; # Replace with your domain

    # SSL certificate paths (replace with your actual paths)
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    # Recommended SSL/TLS settings for security
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers 'TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384';
    ssl_prefer_server_ciphers off;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 1d;
    ssl_session_tickets off;
    ssl_stapling on; # Requires valid OCSP responder
    ssl_stapling_verify on;
    resolver 8.8.8.8 8.8.4.4 valid=300s; # Google DNS or your preferred DNS resolver
    resolver_timeout 5s;

    # HSTS Header: Tells browsers to only connect via HTTPS for a specified duration
    # 'max-age' is in seconds (e.g., 1 year = 31536000).
    # 'includeSubDomains' applies the policy to all subdomains.
    # 'preload' allows inclusion in browsers' HSTS preload lists (requires submission).
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;

    # Other security headers (optional but recommended)
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "DENY" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "no-referrer-when-downgrade" always; # Or more restrictive

    root /var/www/html; # Your web root
    index index.html index.htm;

    location / {
        try_files $uri $uri/ =404;
    }

    # Optional: Proxy pass to a backend application
    # location /api/ {
    #     proxy_pass http://localhost:3000;
    #     proxy_set_header Host $host;
    #     proxy_set_header X-Real-IP $remote_addr;
    #     proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    #     proxy_set_header X-Forwarded-Proto $scheme;
    # }
}