Votes: 0Posted On: May 23, 2017 01:54:58
Although, there are many forms of DDoS attacks that are used to bring the server offline, some are more effective than others. DDoS attacks can also be planned according to the different layers of the network. For instance, layer 7 attacks concentrate on the application layer of the server. Here are some of the major forms of DDos attacks with their methods of attack and the effect they have on the server.
When a host tries to send or receive data to or from the server under TCP protocol, it does so by establishing a connection first. As TCP is a connection oriented protocol, it establishes connection by a three-way handshaking process. It sends an SYN message to the server which in turn acknowledges by sending a SYN+ACK message to the remote host. The remote host, in return, sends the ACK message completing the handshaking process. In the case of DDOS attacks, the botnets keep sending the SYN messages to the server without responding to server's SYN+ACK message. This results in a large number of open connections depleting the server's bandwidth.
Unlike TCP, UDP is a connectionless protocol. In case of UDP flood attack, the attackers constantly flood UDP packets to the server. The server checks for the application listening to that port but is forced to send ICMP Destination Unreachable packet as the requests are coming from a spoofed IP address.
this type of attack focuses on attacking a web server or application. The attackers flood the server with HTTP GET or POST requests forcing the server to allocate maximum resources resulting in Denial of Service.
Ping of Death
In this case, the attackers send continuous ping requests to the servers each of whose size is 65535 bytes. These packets are divided into packets and then is send to the servers. When these packets are reassembled on the server side, they overflow the memory buffers allocated for the packets.
These were only some of the attacks that are used to perform a DDOS attack. These attacks can cause fatal to a server's performance and even bring it down. Hence, various preventive measures are taken by every large organization around the world to prevent and mitigate these DDOS attacks.