Denial of Service Attacks

Computer Science: OCR GCSE, topic 1.4.8

Denial of service (DoS) attacks try to prevent a network from functioning by flooding it with useless traffic.

DoS attacks attempt to bring down a server by flooding it with loads of useless requests.
The attack aims to overload the server. This stops the server responding to legitimate requests.

To protect against DoS attacks, a server's firewall can blacklist (ban) any traffic from an IP address which is known to perform DoS attacks.
Firewalls can also monitor traffic in real time. So if a new IP address starts to send too much traffic then traffic limits can be set.

Distributed DoS (DDos) attacks are commonly used to overcome the blacklisting of an IP address because of a high number of requests.
In a DDoS attack, the requests are sent from an army of compromised machines, known as a botnet.
Botnet machines are infected with malware which allows a hacker to send requests from their computer.
The botnet can launch a huge number of simultaneous requests. The owners of the devices in the botnet might not even realise they are taking part.

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