How To Stop A DDoS Attack: The Complete Guide

In the increasingly wide spectrum of modern cyber attacks, distributed denial-of-service (DDoS) attacks are among the most detrimental to digital networks. These aggressive attacks paralyze a network by overloading it with traffic; this throws the network’s functionality into flux, jeopardizes legitimate usability, and potentially paves a path for further attacks. These characteristics make DDoS attacks a particularly critical aspect of network security. Fortunately, stopping DDoS attacks is more than possible with preemptive knowledge and preventative action.

Read on for a complete guide on how to stop DDoS attacks, including how to fix DDoS attacks that have taken place and how to identify and mitigate future ones.

What Is A DDoS Attack?

A DDoS attack is a malicious, coordinated disruption of a network, service, or website that leverages and weaponizes an excessive amount of traffic. This attack typically stems from a large number of compromised computers, often known as “bots” or “zombies,” which are often part of a botnet controlled by a single attacker or a group. The main objectives of a DDoS attack are to render the targeted system unavailable to its intended users and cause a disruption in services.

In a DDoS attack, the attacker first establishes control over a network of compromised devices, forming what is known as a botnet. These compromised devices are infected with malware and become unwitting participants in the attack. The attacker then uses command and control servers to manage this botnet, instructing the compromised devices to generate a massive volume of traffic.

This flood of traffic aims at the target system, which can be a website, server, or any online service. The overwhelming volume of requests and data packets sent by the compromised devices saturates the target’s resources, such as bandwidth, processing capacity, or memory. As a result, the targeted system becomes unresponsive, rendering it unavailable to genuine users. DDoS attacks vary in scale and duration, with some lasting only a short period and others continuing for extended periods, causing significant downtime and potential financial losses. To defend against DDoS attacks, organizations employ various strategies, such as using DDoS mitigation services, load balancing, and firewalls. DDoS attacks continue to evolve, becoming more sophisticated and harder to thwart, emphasizing the importance of proactive cybersecurity measures to protect online services and infrastructure.

Different Types & Classifications

In understanding how to stop DDoS attacks, it helps to identify the various forms such activity can take. Each type of DDoS attack has its unique characteristics and requires tailored defense mechanisms. Organizations often employ a combination of intrusion detection systems, traffic monitoring, rate limiting, and security best practices to protect against these threats.

Volumetric Attacks

Volumetric DDoS attacks aim to flood the target system with a massive volume of data packets or requests, overwhelming its network bandwidth and resources. These attacks often utilize botnets consisting of thousands to millions of compromised devices, creating a deluge of traffic. Common techniques include UDP flooding and ICMP (Ping) floods. Defending against volumetric attacks usually involves traffic filtering and rate limiting.

Application Layer Attacks

Application layer DDoS attacks, or Layer 7 attacks, target specific vulnerabilities in applications or web servers. Attackers send seemingly legitimate requests that require substantial processing power to complete, such as HTTP GET or POST requests. These attacks are harder to detect because they mimic legitimate user behavior. Protecting against application layer attacks requires robust web application firewalls and traffic inspection.

Protocol Attacks

Protocol attacks focus on exploiting weaknesses in network protocols and services, causing resource exhaustion on the target server. Examples include SYN/ACK, TCP/IP, or DNS amplification attacks. Mitigating protocol attacks involves refining protocol configurations and implementing rate-limiting measures.

Fragmentation Attacks

Fragmentation attacks exploit vulnerabilities in a system’s ability to reassemble fragmented packets. Attackers send fragmented packets with deceptive information, causing excessive resource consumption as the system struggles to piece them together. Effective protection against fragmentation attacks involves packet inspection and proper packet reassembly.

Reflective/Amplification Attacks

Reflective attacks use third-party servers to amplify the attack traffic. Attackers send requests to open services like DNS or NTP servers with the source address spoofed as the victim’s. These servers unwittingly respond to the victim, amplifying the traffic significantly. Protecting against reflective attacks involves securing and rate-limiting open services.

Low-and-Slow Attacks

Low-and-slow attacks aim to evade detection by sending legitimate-looking, low-frequency requests, preventing the target from recognizing a malicious attack. These attacks slowly consume server resources and require more sophisticated detection mechanisms to identify. Effective defense includes anomaly detection and rate-based monitoring.

Botnet-Based Attacks

In botnet-based DDoS attacks, a remotely controlled network of compromised devices targets a victim. The diversity and geographic dispersion of these bots make them challenging to combat. Mitigation involves tracking and disrupting botnet command and control infrastructure.

How To Stop DDoS Attacks

Stopping and preventing DDoS attacks requires an effective blend of insight and preemptive fortification. Such tactics may include:

1. Deploying Strong Network Security Measures

One of the primary strategies for thwarting DDoS attacks is to fortify your network’s security infrastructure; this involves implementing a robust suite of protective measures. Intrusion detection systems (IDS) and intrusion prevention systems (IPS) are pivotal in safeguarding your network. These systems continuously monitor incoming traffic and can discern suspicious patterns indicative of a DDoS attack. By identifying these patterns in real-time, IDS and IPS solutions can thwart malicious traffic, ensuring your network remains operational. It’s vital to keep these security tools updated and finely tuned to stay resilient against evolving attack strategies. DDoS attackers continually adapt, and your security measures must evolve in tandem to counter their efforts effectively.

2. Leveraging Content Delivery Networks (CDNs)

Another effective technique for countering DDoS attacks is the deployment of Content Delivery Networks (CDNs). CDNs are distributed systems of servers positioned in various geographic locations. They serve as intermediaries between your website or services and end-users. During a DDoS attack, CDNs can absorb a substantial portion of the malicious traffic, ensuring your primary servers remain accessible. This distribution of traffic across multiple servers is instrumental in maintaining a consistent user experience even in the face of a massive DDoS assault. By filtering out malicious traffic and only forwarding legitimate requests to your origin servers, CDNs can act as a significant protective shield.

3. Implementing Rate Limiting

Rate limiting is a powerful mechanism to curtail the number of requests or connections established from a single source within a specified time frame. By setting predefined limits, you restrict the volume of requests that can flood your network. This measure is particularly useful in preventing attackers from overwhelming your resources with excessive requests – a common tactic in DDoS attacks. However, it’s crucial to strike a balance when configuring rate limits. Set them too low, and you risk impeding legitimate users from accessing your services. Thus, the key is to find an equilibrium where you can effectively deter attackers while ensuring genuine users can access your resources without hindrance. Rate limiting forms an integral part of a multi-layered defense strategy against DDoS threats.

4. Harnessing Anycast Routing

Anycast routing is a sophisticated networking technique that can be a valuable asset against DDoS attacks; it directs incoming traffic to the nearest available server within a network of geographically dispersed servers. This dispersion of traffic across multiple nodes is highly effective in minimizing the impact of a DDoS attack. This method allows you to scatter the incoming traffic, making it significantly more challenging for attackers to concentrate their efforts on a single target. Anycast routing effectively distributes the load and diverts traffic away from the primary server under attack, thereby mitigating the risk of service disruption.

5. Implementing Traffic Filtering with Access Control Lists (ACLs)

Access Control Lists (ACLs) are invaluable tools for filtering incoming network traffic and blocking requests originating from known malicious IP addresses. ACLs enable you to create rules that define which traffic is permitted and which should be denied. By maintaining an updated list of blacklisted IP addresses and configuring ACLs to block traffic from these sources, you can prevent a significant portion of malicious requests from reaching your network. This proactive approach in traffic filtering adds a layer of protection against DDoS attacks, as it reduces the volume of harmful traffic that needs to be handled by your network infrastructure, thereby mitigating the impact of an attack.

6. Utilizing Load Balancers

Load balancers are an essential component in your DDoS mitigation strategy. These devices distribute incoming network traffic evenly across a cluster of servers or resources. By doing so, load balancers ensure that no single server becomes overwhelmed, making it difficult for attackers to target one specific entry point. Load balancers operate as traffic managers, optimizing resource utilization and enhancing your network’s overall performance and resilience. This distribution of traffic effectively dilutes the impact of a DDoS attack, safeguarding the availability of your services even during a high-intensity attack. It’s vital to deploy load balancers that can detect and mitigate DDoS attacks in real time, providing another layer of protection to your infrastructure.

7. Using Web Application Firewalls (WAFs)

Web Application Firewalls (WAFs) are specialized security solutions that protect web applications from various online threats, including DDoS attacks. These firewalls employ various techniques, such as signature-based filtering, behavioral analysis, and rate limiting, to identify and block malicious traffic. WAFs can filter out DDoS-related traffic patterns and employ challenge-response mechanisms to distinguish between genuine users and attackers. By implementing a WAF, you can significantly bolster your network’s resilience to DDoS attacks, safeguarding your web applications and services from disruptions.

8. Employing Intrusion Detection Systems (IDS)

Intrusion Detection Systems (IDS) are crucial elements in identifying and thwarting DDoS attacks. These systems continuously monitor your network for suspicious activities and traffic patterns that could indicate a DDoS attack in progress. IDS solutions can trigger alerts or take automated actions when they detect anomalies, helping you respond swiftly to emerging threats. Deploying IDS as part of your DDoS defense strategy provides an additional layer of visibility and protection, allowing you to detect and mitigate attacks early on, reducing their impact on your network.

9. Enabling Rate-Based Traffic Shaping

Rate-based traffic shaping is a strategic approach to managing incoming network traffic by regulating the flow of packets based on their rate. It involves setting predefined thresholds for the rate at which packets can enter the network. By employing rate-based traffic shaping, you can effectively manage and throttle incoming traffic during a DDoS attack, preventing network congestion and service disruptions. This approach allows you to ensure a more equitable distribution of resources, making it challenging for attackers to saturate your network with malicious traffic. However, it’s essential to carefully configure rate limits to avoid false positives or unintentionally affecting legitimate users.

10. Distributing Your DNS Infrastructure

Distributing your Domain Name System (DNS) infrastructure across multiple geographically diverse locations is a strategic move to enhance your DDoS resilience. By doing so, you reduce the risk of a single point of failure in your DNS services. Anycast DNS, in particular, allows you to route DNS requests to the nearest available DNS server in the network; this ensures that your DNS services remain available, even when facing a DDoS attack that attempts to overwhelm your DNS servers. Effective DNS distribution is a critical part of maintaining overall service availability during DDoS attacks, as it makes it difficult for attackers to disrupt your DNS resolution process and, subsequently, your entire online presence.


Stopping DDoS attacks is arguably one of the most important aspects of modern cybersecurity, considering these attacks’ far-reaching impact on networks. Therefore, when undergoing cybersecurity auditing, your organization should emphasize DDoS mitigation and prevention protocol; this could make a world of difference for your network’s safety and integrity. Contact our team for any questions!