Complete Request Flow Diagram works in a web server

User Request
↓
Cloudflare DNS & WAF (Filters basic threats, caches static content)
↓
AWS Security Group (Filters non-HTTP traffic)
↓
CSF (Network-Level Firewall; blocks brute-force attacks, limits requests per IP)
↓
ModSecurity (Application-Level WAF; Blocks SQL Injection, XSS, and other attacks)
↓
Imunify360 (Deep malware scanning, AI-based bot protection)
↓
Apache (Processes Static Content & PHP Requests)
↓
PHP-FPM (Executes PHP Code)
↓
MariaDB (Handles Database Queries)
↓
Response Sent to User

With your Cloudflare DNS, AWS EC2, CSF, Imunify360, Apache, AlmaLinux v9.5, PHP-FPM, MariaDB, and PHP 8.2, the incoming request follows a structured path before serving the response. Below is a step-by-step breakdown:

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1. Incoming Request from User’s Browser

A user accesses https://yourdomain.com, sending an HTTP(S) request.

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2. Cloudflare DNS & CDN Handling

• Cloudflare DNS resolves yourdomain.com to your EC2 public IP.
• If enabled, Cloudflare Proxy (CDN & WAF):
  • Blocks malicious traffic (via Cloudflare WAF).
  • Caches static assets (reducing requests to your server).
  • Forwards allowed requests to your AWS EC2 instance.

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3. AWS Security (EC2 Security Group & Network Layer)

• The request hits AWS Security Groups (firewall).
  • Allowed Ports: 80 (HTTP), 443 (HTTPS), 22 (SSH if needed).
  • Blocked: Unwanted traffic (e.g., non-standard ports).
• AWS Network Firewall rules apply (if configured).

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4. CSF (ConfigServer Firewall) on EC2

• If CSF (ConfigServer Security & Firewall) is active, it:
  • Blocks blacklisted IPs.
  • Restricts login attempts (brute force protection).
  • Filters bad traffic before reaching Apache.
  • Allows whitelisted IPs through.

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5. Imunify360 (Application-Level Security)

• Once past CSF, Imunify360 scans incoming requests:
  • Checks for malware and known attack patterns.
  • Blocks bad bots and known threats.
  • Filters suspicious traffic before Apache processes it.

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6. Apache (Web Server Processing)

• Apache receives the request and:
  • Handles static files (CSS, JS, images).
  • Passes dynamic requests to PHP-FPM.
  • Uses mod_rewrite for URL redirection (e.g., WooCommerce URLs).

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7. PHP-FPM (PHP Processing)

• If the request involves PHP execution (like WordPress/WooCommerce pages):
  • Apache forwards the request to PHP-FPM.
  • PHP-FPM spawns worker processes based on pm.max_children settings.
  • Executes PHP 8.2 scripts (e.g., index.php in WordPress).

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8. MariaDB (Database Query Execution)

• If PHP-FPM needs data (e.g., WooCommerce products), it:
  • Sends SQL queries to MariaDB.
  • MariaDB executes queries and returns results.
  • Slow queries are cached (if Redis/Memcached is used).

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9. Response Back to User

• PHP-FPM sends the processed response back to Apache.
• Apache sends it to Cloudflare.
• Cloudflare caches static content for future requests.
• Final page is delivered to the user’s browser.

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Key Takeaways

✅ Cloudflare filters attacks & caches static content.
✅ CSF blocks unwanted traffic at the OS level.
✅ Imunify360 prevents malware & bad bots.
✅ Apache processes static content & PHP-FPM executes dynamic scripts.
✅ MariaDB serves database queries.
✅ Optimizations at each layer improve performance & security.