implementing-ddos-mitigation-with-cloudflare

# Implementing DDoS Mitigation with Cloudflare ## Overview Cloudflare provides multi-layer DDoS protection across its global network of over 300 data centers with 477+ Tbps of capacity. The platform protects against L3/4 volumetric attacks (SYN floods, UDP amplification, DNS reflection), protocol attacks (Ping of Death, Smurf), and L7 application-layer attacks (HTTP floods, Slowloris, cache-busting). Cloudflare's autonomous detection systems identify and mitigate attacks within approximately 3 seconds using traffic profiling, machine learning, and adaptive rulesets. This skill covers configuring Cloudflare's DDoS protection stack including managed rulesets, WAF rules, rate limiting, Bot Management, and origin server hardening. ## Prerequisites - Cloudflare account (Pro plan minimum for WAF, Enterprise for Advanced DDoS) - Domain with DNS delegated to Cloudflare nameservers - Origin server IP address(es) - Understanding of normal traffic patterns and peak volumes - Cloudflare API token for automation ## Core Concepts ### DDoS Attack Categories | Layer | Attack Type | Examples | Cloudflare Protection | |-------|------------|----------|----------------------| | L3/4 | Volumetric | SYN flood, UDP flood, DNS amplification | Network-layer DDoS managed rules | | L3/4 | Protocol | Ping of Death, Smurf, IP fragmentation | Advanced TCP Protection | | L7 | Application | HTTP flood, Slowloris, cache busting | HTTP DDoS managed rules, WAF, Rate Limiting | | DNS | DNS-specific | DNS query flood, NXDOMAIN attack | Advanced DNS Protection | ### Cloudflare Protection Stack ``` Internet Traffic │ ▼ ┌─────────────────────────┐ │ Cloudflare Edge (PoP) │ │ ┌───────────────────┐ │ │ │ L3/4 DDoS Mgd Rules│ │ ← Volumetric/Protocol mitigation │ └───────────────────┘ │ │ ┌───────────────────┐ │ │ │ IP Access Rules │ │ ← Country/ASN/IP blocks │ └───────────────────┘ │ │ ┌───────────────────┐ │ │ │ Bot Management │ │ ← Bot score, JS challenge │ └───────────────────┘ │ │ ┌───────────────────┐ │ │ │ WAF Managed Rules │ │ ← OWASP, Cloudflare, Custom │ └───────────────────┘ │ │ ┌───────────────────┐ │ │ │ Rate Limiting │ │ ← Request rate enforcement │ └───────────────────┘ │ │ ┌───────────────────┐ │ │ │ HTTP DDoS Mgd Rules│ │ ← L7 flood detection │ └───────────────────┘ │ └─────────────────────────┘ │ ▼ Origin Server ``` ## Implementation Steps ### Step 1: Onboard Domain to Cloudflare ```bash # Add domain via API curl -X POST "https://api.cloudflare.com/client/v4/zones" \ -H "Authorization: Bearer $CF_API_TOKEN" \ -H "Content-Type: application/json" \ --data '{ "name": "example.com", "type": "full", "plan": {"id": "enterprise"} }' # Update DNS records (proxy enabled for DDoS protection) curl -X POST "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/dns_records" \ -H "Authorization: Bearer $CF_API_TOKEN" \ -H "Content-Type: application/json" \ --data '{ "type": "A", "name": "example.com", "content": "203.0.113.50", "proxied": true, "ttl": 1 }' ``` ### Step 2: Configure DDoS Managed Rulesets **HTTP DDoS Attack Protection override:** ```bash # List HTTP DDoS managed ruleset curl -X GET "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/rulesets/phases/ddos_l7/entrypoint" \ -H "Authorization: Bearer $CF_API_TOKEN" # Override HTTP DDoS sensitivity and action curl -X PUT "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/rulesets/phases/ddos_l7/entrypoint" \ -H "Authorization: Bearer $CF_API_TOKEN" \ -H "Content-Type: application/json" \ --data '{ "rules": [{ "action": "execute", "action_parameters": { "id": "4d21379b4f9f4bb088e0729962c8b3cf", "overrides": { "rules": [{ "id": "fdfdac75430c4c47a422bdc024aab531", "sensitivity_level": "medium", "action": "block" }], "sensitivity_level": "high" } }, "expression": "true" }] }' ``` **Network-layer DDoS Protection override:** ```bash curl -X PUT "https://api.cloudflare.com/client/v4/accounts/$ACCOUNT_ID/rulesets/phases/ddos_l4/entrypoint" \ -H "Authorization: Bearer $CF_API_TOKEN" \ -H "Content-Type: application/json" \ --data '{ "rules": [{ "action": "execute", "action_parameters": { "id": "3b64149bfa6e4220bbbc2bd6db7c867e", "overrides": { "sensitivity_level": "high" } }, "expression": "true" }] }' ``` ### Step 3: Configure Rate Limiting Rules ```bash # Create rate limiting rule for login endpoint curl -X POST "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/rulesets/phases/http_ratelimit/entrypoint" \ -H "Authorization: Bearer $CF_API_TOKEN" \ -H "Content-Type: application/json" \ --data '{ "rules": [ { "description": "Rate limit login attempts", "expression": "(http.request.uri.path eq \"/api/login\")", "action": "block", "ratelimit": { "characteristics": ["cf.colo.id", "ip.src"], "period": 60, "requests_per_period": 10, "mitigation_timeout": 600 } }, { "description": "Rate limit API endpoints", "expression": "(http.request.uri.path matches \"^/api/\")", "action": "managed_challenge", "ratelimit": { "characteristics": ["cf.colo.id", "ip.src"], "period": 60, "requests_per_period": 100, "mitigation_timeout": 300 } }, { "description": "Global rate limit per IP", "expression": "true", "action": "managed_challenge", "ratelimit": { "characteristics": ["ip.src"], "period": 10, "requests_per_period": 50, "mitigation_timeout": 60 } } ] }' ``` ### Step 4: Configure WAF Custom Rules ```bash # Block known attack patterns curl -X POST "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/rulesets/phases/http_request_firewall_custom/entrypoint" \ -H "Authorization: Bearer $CF_API_TOKEN" \ -H "Content-Type: application/json" \ --data '{ "rules": [ { "description": "Block requests from known bad ASNs", "expression": "(ip.geoip.asnum in {12345 67890})", "action": "block" }, { "description": "Challenge requests without User-Agent", "expression": "(not http.user_agent ne \"\")", "action": "managed_challenge" }, { "description": "Block high-risk countries for admin paths", "expression": "(http.request.uri.path contains \"/admin\" and not ip.geoip.country in {\"US\" \"CA\" \"GB\"})", "action": "block" }, { "description": "Block oversized request bodies", "expression": "(http.request.body.size gt 10000000)", "action": "block" } ] }' ``` ### Step 5: Configure Origin Protection Ensure the origin server only accepts traffic from Cloudflare: ```bash # Get Cloudflare IP ranges curl https://api.cloudflare.com/client/v4/ips # Configure origin server firewall (iptables) # Allow only Cloudflare IPs for ip in $(curl -s https://www.cloudflare.com/ips-v4); do iptables -A INPUT -p tcp --dport 443 -s $ip -j ACCEPT iptables -A INPUT -p tcp --dport 80 -s $ip -j ACCEPT done # Drop all other HTTP/HTTPS traffic iptables -A INPUT -p tcp --dport 443 -j DROP iptables -A INPUT -p tcp --dport 80 -j DROP # Enable Authenticated Origin Pulls (mutual TLS) # Download Cloudflare origin CA certificate curl -o /etc/ssl/cloudflare-origin-pull.pem \ https://developers.cloudflare.com/ssl/static/authenticated_origin_pull_ca.pem # Nginx configuration for authenticated origin pulls # ssl_client_certificate /etc/ssl/cloudflare-origin-pull.pem; # ssl_verify_client on; ``` ### Step 6: Enable Under Attack Mode Automation ```python #!/usr/bin/env python3 """Auto-enable Cloudflare Under Attack Mode based on traffic anomalies.""" import requests import time import sys CF_API_TOKEN = "your-api-token" ZONE_ID = "your-zone-id" HEADERS = { "Authorization": f"Bearer {CF_API_TOKEN}", "Content-Type": "application/json", } BASE_URL = f"https://api.cloudflare.com/client/v4/zones/{ZONE_ID}" NORMAL_RPS_THRESHOLD = 5000 # Requests per second threshold CHECK_INTERVAL = 30 # Seconds between checks def get_current_security_level(): """Get current security level setting.""" resp = requests.get( f"{BASE_URL}/settings/security_level", headers=HEADERS ) return resp.json()["result"]["value"] def set_security_level(level: str): """Set security level (off, essentially_off, low, medium, high, under_attack).""" resp = requests.patch( f"{BASE_URL}/settings/security_level", headers=HEADERS, json={"value": level} ) result = resp.json() if result["success"]: print(f"[+] Security level set to: {level}") else: print(f"[-] Failed to set security level: {result['errors']}") return result["success"] def get_traffic_analytics(): """Get recent traffic data from Cloudflare analytics.""" query = """ query { viewer { zones(filter: {zoneTag: "%s"}) { httpRequests1mGroups(limit: 1, orderBy: [datetime_DESC]) { sum { requests threats } dimensions { datetime } } } } } """ % ZONE_ID resp = requests.post( "https://api.cloudflare.com/client/v4/graphql", headers=HEADERS, json={"query": query} ) return resp.json() def monitor_and_respond(): """Monitor traffic and auto-enable under attack mode.""" current_level = get_current_security_level() print(f"[*] Current security level: {current_level}") print(f"[*] Monitoring traffic (threshold: {NORMAL_RPS_THRESHOLD} RPS)...") attack_mode_active = False consecutive_normal = 0 while True: try: analytics = get_traffic_analytics() zones = analytics.get("data", {}).get("viewer", {}).get("zones", []) if zones and zones[0].get("httpRequests1mGroups"): data = zones[0]["httpRequests1mGroups"][0]["sum"] rps = data["requests"] / 60 threats = data["threats"] print(f"[*] Current RPS: {rps:.0f}, Threats: {threats}") if rps > NORMAL_RPS_THRESHOLD and not attack_mode_active: print(f"[!] Traffic spike detected: {rps:.0f} RPS") set_security_level("under_attack") attack_mode_active = True consecutive_normal = 0 elif rps <= NORMAL_RPS_THRESHOLD and attack_mode_active: consecutive_normal += 1 if consecutive_normal >= 5: print("[+] Traffic normalized, disabling under attack mode") set_security_level("high") attack_mode_active = False consecutive_normal = 0 except Exception as e: print(f"[-] Error: {e}") time.sleep(CHECK_INTERVAL) if __name__ == "__main__": monitor_and_respond() ``` ## Monitoring and Alerting ### Cloudflare Dashboard Metrics - **Firewall Events** - View blocked requests, challenged requests, rate-limited requests - **DDoS Analytics** - Attack size, duration, type, and mitigation status - **Traffic Analytics** - Request volume, bandwidth, error rates by time - **Bot Analytics** - Bot score distribution, verified bots vs automated threats ### Alert Configuration ```bash # Create notification policy for DDoS attacks