Have you ever found yourself waiting impatiently for the online release of a product, one that you’re eagerly waiting to purchase? You keep refreshing the page, waiting for that moment when the product will go live. Then, as you press F5 for the last time, the page shows an error: “Service Unavailable.” The server must be overloaded!
There are indeed cases like these where a website’s server gets overloaded with traffic and simply crashes, sometimes when a news story breaks. But more commonly, this is what happens to a website during a DoS attack, or denial-of-service, a malicious traffic overload that occurs when attackers over flood a website with traffic. When a website has too much traffic, it’s unable to serve its content to visitors.
A DoS attack is performed by one machine and its internet connection, by flooding a website with packets and making it impossible for legitimate users to access the content of flooded website. Fortunately, you can’t really overload a server with a single other server or a PC anymore. In the past years it hasn’t been that common if anything, then by flaws in the protocol.
A DDoS attack, or distributed denial-of-service attack, is similar to DoS, but is more forceful. It’s harder to overcome a DDoS attack. It’s launched from several computers, and the number of computers involved can range from just a couple of them to thousands or even more.
Since it’s likely that not all of those machines belong to the attacker, they are compromised and added to the attacker’s network by malware. These computers can be distributed around the entire globe, and that network of compromised computers is called botnet.
Since the attack comes from so many different IP addresses simultaneously, a DDoS attack is much more difficult for the victim to locate and defend against.
