A Distributed Denial-of-Service (DDoS) attack is one of the most disruptive cyber threats businesses and website owners face. It overwhelms a server, network, or website with excessive traffic, rendering it slow or completely unavailable to legitimate users.
DDoS attacks can harm businesses by causing downtime, loss of revenue, and damage to reputation.
In this guide, we will explore how to stop a DDoS attack and protect your website from future threats. We’ll cover detection, mitigation techniques, security best practices, and long-term prevention strategies.
Table of Contents
What is a DDoS Attack?
A DDoS attack occurs when multiple compromised devices (often part of a botnet) flood a website or network with an overwhelming amount of traffic. This can exhaust server resources, leading to downtime.
Types of DDoS Attacks
1. Volume-Based Attacks
Volume-based DDoS attacks aim to overwhelm a target’s bandwidth by flooding it with massive amounts of data. Attackers use botnets—networks of compromised devices—to send an excessive number of requests, exhausting network resources.
Common examples include UDP floods, which flood random ports with User Datagram Protocol packets, and ICMP floods, which overload the server with ping requests. DNS amplification attacks exploit vulnerable DNS servers to reflect and amplify requests, generating even larger traffic loads.
These attacks are measured in bits per second (bps) and can quickly disrupt online services by consuming all available bandwidth.
2. Protocol Attacks
Protocol attacks, also known as state-exhaustion attacks, target weaknesses in network protocols to overwhelm server resources. These attacks exploit vulnerabilities in protocols like TCP, UDP, and ICMP, consuming processing power rather than just bandwidth.
SYN flood attacks send repeated TCP handshake requests without completing the connection, exhausting a server’s ability to respond. Ping of Death fragments large ping packets to crash a system upon reassembly. Smurf attacks amplify ICMP requests by using spoofed addresses, flooding a target with overwhelming responses.
These attacks are measured in packets per second (pps) and often require deep-packet inspection to mitigate.
3. Application Layer Attacks
Application layer attacks, also called Layer 7 attacks, focus on overloading web applications rather than network infrastructure. Attackers mimic legitimate users by sending seemingly valid requests, making detection difficult.
HTTP floods bombard websites with excessive GET or POST requests, overwhelming web servers. Slowloris attacks keep connections open indefinitely by sending incomplete HTTP requests, consuming all available connections.
Botnet-based attacks use thousands of infected devices to send requests simultaneously. Since these attacks target specific website functions, they often require web application firewalls (WAFs) and rate-limiting techniques to detect and block malicious activity.
How to Detect a DDoS Attack
Before stopping a DDoS attack, you need to recognize the signs:
- Unusual traffic spikes from unknown sources.
- Slow or unresponsive website performance.
- High server load with no legitimate increase in user activity.
- Increased requests from a single IP or geographical location.
- Errors like “503 Service Unavailable” appearing frequently.
Monitoring tools like Google Analytics, server logs, and specialized security software can help detect suspicious traffic patterns.
How to Stop an Ongoing DDoS Attack
1. Identify the Attack Early
The first step in stopping a DDoS attack is recognizing it as soon as possible. Many businesses mistake sudden traffic surges for normal spikes, leading to delayed responses. Use network monitoring tools like Wireshark, Nagios, or SolarWinds to analyze traffic in real-time.
Check for unusual patterns, such as a massive increase in requests from a single IP or region. Look for abnormal server load or users reporting slow access. Implement automated alerts that notify your team when traffic surpasses expected levels.
Early detection allows for quicker mitigation, reducing downtime and minimizing potential damage to your website.
2. Activate DDoS Protection Services
Many content delivery networks (CDNs) and hosting providers offer DDoS protection that can be activated immediately during an attack. Services like Cloudflare, AWS Shield, and Akamai detect malicious traffic and block it before it reaches your server.
These solutions filter out harmful requests while allowing legitimate users to access your site. If you haven’t already, subscribe to a premium DDoS protection plan with automatic mitigation. Some services provide emergency response teams who can step in to neutralize large-scale attacks.
Enabling DDoS protection early ensures that your website remains accessible even under a heavy influx of malicious traffic.
3. Use a Web Application Firewall (WAF)
A Web Application Firewall (WAF) acts as a security barrier between your website and incoming traffic. It detects and blocks malicious requests before they can overwhelm your server. Services like Cloudflare WAF, AWS WAF, and Sucuri use rule-based filtering to differentiate between normal and attack traffic.
Custom WAF rules can be set to block suspicious patterns, such as repeated requests from the same IP address. Some WAFs also use machine learning to recognize evolving threats. Deploying a WAF is a quick and effective way to filter out bad traffic, keeping your site functional during a DDoS attack.
4. Rate Limiting and Traffic Filtering
Rate limiting prevents any single user from overloading your server by capping the number of requests they can make in a set time. Implement rate limiting on login pages, API endpoints, and other high-risk areas to prevent excessive requests.
Traffic filtering allows you to block suspicious IP addresses, particularly those from regions where attacks originate. Many firewalls and CDNs provide automated filtering, but you can also manually blacklist malicious IPs.
If an attack targets a specific section of your website, consider temporarily disabling that feature to reduce server strain while mitigating the attack.
5. Enable Anycast Routing
Anycast is a network routing technique that disperses incoming traffic across multiple servers located in different geographical regions. This distribution helps absorb DDoS attacks by preventing any single server from being overwhelmed.
CDNs like Cloudflare, Fastly, and Akamai use Anycast technology to spread out incoming requests, ensuring attackers can’t concentrate their efforts on one point of failure. If your website infrastructure supports Anycast, enable it to make your network more resilient against attacks.
By dispersing traffic across multiple locations, you significantly reduce the risk of downtime, keeping your website operational even during a high-volume DDoS event.
6. Scale Up Server Resources
If a DDoS attack is consuming your server’s bandwidth and computing power, temporarily increasing resources can help mitigate the impact. Cloud hosting services like AWS, Google Cloud, and Microsoft Azure offer auto-scaling features that expand resources in response to traffic surges.
Deploying additional servers or load balancers helps distribute incoming traffic, reducing stress on any single machine. Although this isn’t a long-term solution, it can keep your website functional while you implement other mitigation strategies.
Be sure to set spending limits on auto-scaling to avoid excessive costs if the attack persists for an extended period.
7. Contact Your Hosting Provider or ISP
If your website is under a large-scale DDoS attack, your hosting provider or Internet Service Provider (ISP) may be able to help. Many hosting companies offer DDoS mitigation services, which can filter or reroute attack traffic before it reaches your server.
Contact their support team immediately and provide details about the attack, such as traffic patterns and affected services. Some providers have specialized anti-DDoS infrastructure that can absorb attack traffic at the network level.
Working with your hosting provider ensures you have additional resources and expertise to counteract even the most persistent attacks.
8. Temporarily Take the Website Offline
If all other mitigation strategies fail and your website is still being overwhelmed, you may need to take it offline temporarily. Deploy a “503 Service Unavailable” maintenance page to inform users that you’re working on resolving technical difficulties.
This prevents further damage while you analyze the attack and strengthen your defenses. If your business relies on online sales or critical services, consider creating a backup site on a different domain or hosting provider.
Once the attack subsides, reintroduce your website with enhanced security measures to prevent the same attack from happening again.
How to Protect Your Website from Future DDoS Attacks
Stopping a DDoS attack is one thing, but preventing future ones is even more critical. Here’s how:
1. Use a DDoS-Resistant Hosting Provider
Choose hosting providers that offer built-in DDoS protection, such as:
- HarmonWeb
- Hostinger
2. Enable a Content Delivery Network (CDN)
A CDN distributes traffic across multiple servers, reducing the risk of overload. Top CDN providers include:
- Cloudflare
- Fastly
- Akamai
- StackPath
3. Set Up Web Application Firewall (WAF) Rules
Customize your WAF rules to detect and block unusual traffic patterns before they impact your site.
4. Implement Rate Limiting
Rate limiting ensures that users can’t send excessive requests in a short time. This helps mitigate bot-driven DDoS attacks.
5. Use Bot Mitigation and CAPTCHA Protection
DDoS attacks often use bots. Protect your login and comment sections with:
- Google reCAPTCHA
- hCaptcha
- Honeypot traps
6. Monitor Traffic Regularly
Use real-time monitoring tools to detect unusual traffic patterns. Some effective tools include:
- Google Analytics (to track traffic sources).
- Cloudflare Analytics (to analyze bot activity).
- Log monitoring tools like ELK Stack or Splunk.
7. Update Software and Security Patches
- Keep your CMS (e.g., WordPress, Joomla, Drupal) and plugins updated.
- Patch vulnerabilities in server software and third-party scripts.
8. Implement Multi-Layered Security Measures
- Use intrusion detection systems (IDS) like Snort or OSSEC.
- Deploy anti-malware solutions to prevent bot infections.
- Harden your server configurations to minimize attack surfaces.
9. Develop an Incident Response Plan
Prepare for potential attacks with a DDoS response strategy, including:
- A contact list of security teams and hosting providers.
- A step-by-step mitigation plan for different attack types.
- A strategy for notifying users during outages.
10. Train Your Team on Cybersecurity Best Practices
Educate employees on:
- Recognizing attack signs.
- Properly handling security incidents.
- Avoiding phishing scams that could infect systems with DDoS malware.
Wrapping Up
DDoS attacks can severely impact your website’s uptime, performance, and security. However, with the right defenses—such as DDoS protection services, firewalls, and proactive monitoring—you can keep your website safe.
At HarmonWeb, we provide DDoS-protected web hosting to ensure your website remains secure and accessible, even under attack. Our advanced security solutions, including firewall protection, CDN integration, and 24/7 monitoring, help mitigate threats before they cause damage.
Whether you run a small business or a large enterprise, HarmonWeb’s reliable hosting ensures you stay online and protected.
