User:Tanaysaksena

Introduction s

As a IT or computer science students u several times u came accrose this word Dos attack or DDOS attack and some of you may not known about DOS attacks. So today I am giving you some little information on DOS attack. What is DOS Attack? In computing DOS Attack is Denial of service attack is an attempt to make a machine or network resource unavailable for users. Dos attack means pinging or requesting the website or server more number of times it can handle. Suppose there is a website avaiable on a server which has a request limit of 20,000 if request more than 20,000 will be sent it will result in crash of server or unavaiable of website. DOS attack and DDOS attack are hackers best friends  it works maximum numbers of times   Note:   Not every time there are some webservers wqhich have dos attack protection. DDOS Attack means distributed denial of service means where attack is done more then 1 ip or hundreds or thousands of ip. Target of Dos attack may be anything like particular Website, web Servers, Bank Sites, payment gateway, Social networking sites, routers  etc.   There are several times of Dos attacks some of them are:- Teardrop attacks A teardrop attack involves sending mangled IP fragments with overlapping, over-sized payloads to the target machine. This can crash various operating systems because of a bug in their TCP/IP fragmentation re-assembly code. Windows 3.1x, Windows 95 andWindows NT operating systems, as well as versions of Linux prior to versions 2.0.32 and 2.1.63 are vulnerable to this attack.

SYN flood A SYN flood occurs when a host sends a flood of TCP/SYN packets, often with a forged sender address. Each of these packets are handled like a connection request, causing the server to spawn a half-open connection, by sending back a TCP/SYN-ACK packet (Acknowledge), and waiting for a packet in response from the sender address (response to the ACK Packet). However, because the sender address is forged, the response never comes. These half-open connections saturate the number of available connections the server can make, keeping it from responding to legitimate requests until after the attack ends. Etc. Some of the avaiable tools for dos attacks are:- 1. LOIC 2. XOIC 3. HULK 4. HOIC 5. hping ,etc

DDOS attack is much effective than dos attack as there are several ip from different source’s sending requestsand it is also difficult for website or web server admin to block all ip address’s Which are sending so many request. .