TL;DR
No one is completely immune to a determined Distributed Denial of Service (DDoS) attack. However, you can significantly reduce your risk and impact by using multiple layers of protection, including cloud-based mitigation services, robust network infrastructure, and proactive security measures.
Understanding the Problem
A DDoS attack overwhelms a server or network with traffic from many sources, making it unavailable to legitimate users. The ‘non-DDoSable’ idea is about minimising your surface area for attack and having systems in place to absorb or deflect malicious requests.
Steps to Improve Your DDoS Resilience
- Understand Your Traffic Profile: Before you can defend against attacks, know what normal traffic looks like. Monitor bandwidth usage, request types, geographic origins, and typical user behaviour.
- Use network monitoring tools (e.g., Wireshark, tcpdump) to capture and analyse traffic patterns.
- Establish baseline metrics for your website or service.
- Cloud-Based DDoS Mitigation: This is the most effective defence for many organisations.
- Services like Cloudflare, Akamai, AWS Shield, and Google Cloud Armor act as a reverse proxy, absorbing attack traffic before it reaches your servers.
- They typically offer automatic detection and mitigation of common DDoS attacks.
- Configuration usually involves changing your DNS records to point to the provider’s servers.
ns1.cloudflare.com
- Network Infrastructure: A robust network can handle a larger volume of traffic before becoming overwhelmed.
- Over-Provisioning: Have more bandwidth capacity than you typically need.
- Redundancy: Use multiple internet service providers (ISPs) and load balancers to distribute traffic.
- Firewalls & Intrusion Detection/Prevention Systems (IDS/IPS): Configure firewalls to block malicious IP addresses and suspicious traffic patterns. An IPS can automatically respond to detected attacks.
- Rate Limiting: Limit the number of requests from a single IP address within a given timeframe.
- This prevents attackers from overwhelming your server with rapid-fire requests.
- Implement rate limiting at the web server level (e.g., using Nginx or Apache modules) or through a Web Application Firewall (WAF).
- Example Nginx configuration:
limit_req zone=mylimit burst=5 nodelay;
- Web Application Firewall (WAF): A WAF filters malicious HTTP traffic.
- It can block common attack vectors like SQL injection, cross-site scripting (XSS), and DDoS attacks targeting specific web applications.
- Popular WAFs include ModSecurity, Cloudflare WAF, and AWS WAF.
- Anycast DNS: Distributes your DNS records across multiple servers globally.
- This makes it harder for attackers to target your DNS infrastructure with a DDoS attack.
- Services like Cloudflare and AWS Route 53 offer Anycast DNS.
- Geo-Blocking: Block traffic from countries where you don’t expect legitimate users.
- This can reduce the overall volume of attack traffic, but be careful not to block legitimate users accidentally.
- Keep Software Updated: Regularly update your operating systems, web servers, and applications to patch security vulnerabilities that attackers could exploit.
- Incident Response Plan: Have a plan in place for responding to a DDoS attack.
- Identify key personnel and their roles.
- Establish communication channels.
- Document procedures for escalating the incident.
Important Considerations
No Silver Bullet: There is no single solution that will completely protect you from all DDoS attacks.
Attack Sophistication: Attackers are constantly evolving their techniques. You need to stay informed about the latest threats and adapt your defences accordingly.
Cost: DDoS mitigation services can be expensive, especially for large-scale protection. Balance your risk tolerance with your budget.