DoS – Denial of Service attack
The concept behind the design of DoS attack is interfering in the normal functions of a server, web site, or other resources of a network. The hackers and even the virus writers can use number of ways in order to get this job done. One of the most common methods is flooding a server with heavy traffic from network so that it becomes difficult to control it. As a result of this heavy traffic it is not possible to carry out the normal functions properly and sometimes this can further lead to server crash.
The only difference in case of DDoS attack is that multiple machines are used in order to conduct it. The master and zombie machines are used by hackers or virus writers in order to co-ordinate the attack across the other. These two machines usually exploit an application’s vulnerability on the machine, to install any malicious code like Trojan.
DDoS – Distributed Denial of Service attack
There is not much difference in DDoS attack and DoS attack as both are designed to create hindrance in the normal functions of a server, web site, or other network resources. In case of DDoS attack the attack takes place with the help of multiple machines which makes it different from DoS attack.
Symptoms
Here are the symptoms of denial-of-service attacks:
- The performance of the network becomes unusually slow. Such as web sites access and opening of the files
- A particular web site becomes unavailable
- It becomes difficult to access any web site
- Noticeable increase in the number of spam emails received—such kind of DoS attack is referred to as an e-mail bomb
The problems due to denial-of-service attacks are not limited to the computer that is being attacked but it also causes troubles to the network ‘branches’ around it. Here is an example, the router’s bandwidth between the LAN and the Internet may be consumed by an attack, and this can spread to the whole network.
If the attack takes place on a big scale, then the internet connectivity of the whole geographical region can be affected without the knowledge or intention of attacker and this happens due to incorrect configuration or due to use of weak network infrastructure device.
Picture source: cisco.com
If you need more about DoS and DDoS attacks, consider this: