Instructions for testing DDoS and how to defend against it

Distributed Denial of Service ( DDoS ) attack is an action by which cybercriminals send a large amount of invalid traffic that makes your website exhausted and inaccessible. This causes serious harm to businesses when customers cannot use the website for communication or transaction purposes. The following article will help you understand what DDoS is and how to secure your business against cyber attacks.

1. What is DoS?

DoS (Denial of Service) is a type of cyberattack in which attackers attempt to prevent legitimate users from accessing a server or network. A common DoS method involves flooding a target system with a massive amount of traffic, exhausting the victim's resources. As a result, the website becomes temporarily inaccessible, causing significant disruption and potential financial loss to businesses.

2. Understanding DoS attack methods

DoS attacks often target virtual private servers (VPS) or the web servers of banks and e-commerce platforms. These attacks usually focus on a single system, using a relatively slow attack rate. Since DoS is launched from a single source and IP address, it is easier to detect and mitigate.

During a DoS attack, the hacker can only use one device and a single IP range. Therefore, monitoring and responding to such attacks is generally straightforward and can be resolved quickly.

3. What is DDoS and how to prevent it?

3.1. What is DDoS?

DDoS (Distributed Denial of Service) is an enhanced version of DoS attacks. It involves exploiting Layer 7 of the OSI model—commonly overlooked by ISPs (Internet Service Providers)—to flood the system with high-speed, illegitimate requests. DDoS attacks are far more dangerous because they come from multiple devices, making it difficult to trace and block in time.

Since a server can only handle a limited number of concurrent requests, a DDoS attack overwhelms the system by sending excessive requests simultaneously, depleting server resources. Consequently, the server becomes incapable of processing legitimate user requests, resulting in downtime.

3.2. Common types of protocol-based DDoS attacks

Here are some popular protocol-based DDoS attack types:

Volumetric attacks: These consume all available bandwidth of the target server. For example, if your server has a 15Gbps port, attackers may send traffic exceeding this limit, making it impossible for real users to connect.
SYN floods: Exploiting the TCP handshake, attackers send fake TCP requests. The server responds and waits for confirmation, which never arrives, leading to a buildup of incomplete connections that eventually crash the server.
Smurf DDoS: Malicious software sends spoofed ICMP ping packets that generate endless response loops, temporarily freezing the system.
Zero-day DDoS: These exploit newly discovered and unpatched vulnerabilities in web applications.
Application-level attacks: These target specific vulnerable apps rather than the entire server. Web-based email platforms, WordPress, Joomla, and forum software are typical targets.

3.3. Simulated DDoS attack guide

DDoS attacks not only harm a business but also degrade user experience. When a website is under a DDoS attack, customers can't access it or complete their transactions. Several free tools are available to simulate DDoS attacks, helping developers understand the severity of such threats.

One commonly used tool is LOIC (Low Orbit Ion Cannon), developed by Praetox Technology and used by the infamous hacker group Anonymous for DDoS demonstrations.

Steps to simulate a DDoS attack using LOIC:

Step 1: Download LOIC
You can download LOIC from SourceForge. Be sure to disable your antivirus warnings and extract the ZIP file.

Step 2: Launch LOIC and configure the attack
Open LOIC and configure it with your target’s IP or URL, port, number of threads, and attack speed.

Step 3: Start the attack
Click the button labeled “IMMA CHARGIN MAH LAZER” to begin the attack and observe its effect in real time.

After simulation, your server will consume significant resources handling the flood of fake traffic generated by the DDoS tool.

To prevent service disruptions and minimize damages, it’s essential to invest in a robust DDoS protection solution.

3.4. How to prevent DDoS

Currently, there are three common types of Web Application Firewalls (WAF) used to prevent various forms of DDoS:

Network-based WAF
Host-based WAF
Cloud-based WAF

Host-based WAFs offer advanced customization and can handle strong UDP floods. They are ideal for local networks (e.g., bank intranets). However, they require on-premise servers, regular maintenance, and have limitations in scalability and traffic DDoS handling.

By contrast, cloud-based WAFs are favored by many organizations due to their simplicity, scalability, and cost-effectiveness. They offer flexible resource scaling and are easier to manage and maintain.

VNIS solution – multi-layered protection against all forms of DDoS attacks

VNIS (VNETWORK Internet Security) is a next-generation Cloud WAF platform developed by VNETWORK. It offers robust multi-layer protection with the following highlights:

Two-layer defense model:
- Layer 1: AI Load Balancer + Multi CDN to mitigate volumetric Layer 3/4 attacks at the edge.
- Layer 2: Cloud WAF to detect and prevent Layer 7 DDoS and OWASP Top 10 vulnerabilities.
2,400+ security rule sets, updated monthly, to block the latest threats.
Behavioral analysis: AI-powered traffic monitoring and anomaly detection.
Uptime guarantee of up to 99.99%, ensuring stable performance during peak times or large-scale attacks.
Real-time reporting and interactive dashboards, allowing businesses to monitor protection status and trace attack origins effectively.