How to Defend Against DDoS Attacks: Techniques for DevOps and Developers

DDoS (Distributed Denial of Service) attacks are among the most common threats to cloud-native infrastructure and APIs. They can flood your services with traffic, exhausting resources and causing downtime.

In this article, we’ll explore effective strategies to prevent and mitigate DDoS attacks — from rate limiting to cloud-based protections.

1. What Is a DDoS Attack?

A DDoS attack occurs when a network of compromised machines sends overwhelming traffic to a target server or service, aiming to exhaust bandwidth or system resources.

Common types:

• Volume-based (UDP floods, ICMP floods)
• Protocol-based (SYN flood)
• Application layer (HTTP GET/POST flood)

2. Key Strategies to Mitigate DDoS

🔐 2.1. Rate Limiting

Use reverse proxies (e.g., NGINX, Envoy) to limit requests per second per IP:

limit_req_zone $binary_remote_addr zone=req_limit:10m rate=10r/s;

server {
  location /api/ {
    limit_req zone=req_limit burst=20 nodelay;
  }
}

☁️ 2.2. Use Cloud DDoS Protection

Enable services like:

• Cloudflare / AWS Shield / Google Cloud Armor
• CDN caching to reduce backend load

🔥 2.3. Block Bad Traffic with iptables

Basic iptables rule to drop excessive connections:

iptables -A INPUT -p tcp --syn -m limit --limit 10/s --limit-burst 20 -j ACCEPT
iptables -A INPUT -p tcp --syn -j DROP

🧠 2.4. Detect Anomalies

Use tools like:

• Fail2ban
• Netdata or Prometheus with alert rules
• IDS/IPS systems (e.g., Suricata)

🧰 2.5. Kubernetes-Specific Options

• Ingress rate limiting (NGINX Ingress Controller)
• NetworkPolicies to isolate traffic
• Pod-level firewalls (e.g., Cilium)

3. Best Practices

• Always use HTTPS + CDN
• Monitor traffic in real-time
• Combine multiple techniques
• Use autoscaling for mitigation

4. Conclusion

No system is 100% immune to DDoS, but layered defenses drastically improve resilience. Use a mix of rate limiting, traffic monitoring, and cloud protection services to stay ahead.