Denial of Service (DoS) Attack

What is DoS Attack ?

A DoS (Denial-of-Service) attack is a type of cyber attack that aim to make a website, server, or network unavailable to its intended users by overwhelming it with a flood of traffic or requests.

The attacker achieves this by either sending a large number of requests to the target system or by exploiting vulnerabilities in the target system's software to cause it to crash or become unresponsive.


Here are some common types of DoS attacks:

1. Ping of Death

This type of attack involves sending a packet of data that is larger than the maximum size allowed by the protocol. This causes the receiving system to crash or become unresponsive.

2. Teardrop

In a Teardrop attack, the attacker sends fragmented packets with overlapping offsets and payloads to the target computer. When the victim computer tries to reassemble the packets, it becomes confused and may crash or freeze.

3. SYN Flood

A SYN Flood Attack exploits the vulnerability in the TCP/IP handshake process by sending a large number of connection requests to the target system. The target system tries to respond to each request, but the attacker does not respond to the target system's response. As a result, the target system's resources are exhausted, and it becomes unresponsive.

4. Land Attack

The Land attack involves sending spoofed packets to the victim computer, with the source IP address and port number set to that of the victim itself. This causes the victim computer to try to establish a connection with itself, resulting in a loop that can cause the computer to become unresponsive or crash.

5. Smurf Attack

In a Smurf Attack, the attacker sends a large number of ICMP echo requests to a network's broadcast address, which is then sent to all devices on the network. The devices on the network then send ICMP echo replies back to the broadcast address, overwhelming the target server with traffic and causing it to become unavailable.

6. UDP Flood

This type of attack involves sending a large number of UDP (User Datagram Protocol) packets to the target system, overwhelming it with traffic and causing it to become unresponsive.

7. HTTP Flood

This type of attack involves sending a large number of HTTP requests to a web server, which can overwhelm the server's resources and cause it to become unresponsive.

8. Slowloris Attack

This type of attack involves sending a large number of HTTP requests to a web server, but slowly and over a long period of time. This ties up the server's resources, preventing it from responding to other requests.


Preventing DoS attacks requires a multi-layered approach that includes both technical and procedural measures.

Here are some ways to prevent DoS attacks:

  1. Deploy a Web Application Firewall (WAF)
  2. Deploy an Intrusion Detection System (IDS)
  3. Use Content Delivery Network (CDN)
  4. Implement Rate Limiting
  5. Continuous Monitoring and Analysis of Network Traffic


The main goal of a DoS attack is to disrupt the normal functioning of the target system, causing it to become unavailable to its legitimate users. This can lead to loss of revenue, reputation damage, and other negative impacts on the target organization. It's important for organizations to have measures in place to detect and mitigate DoS attacks.

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