A denial-of-service attack (DoS), happens when legitimate users are unable to use network services because the host has crashed or been flooded with illegitimate requests by a malicious party, with the intent to disrupt normal service. A DoS attack comes from one computer, but a DDos (distributed denial-of service) attack comes from multiple computers.
In a DoS attack, a prankster decides to call you multiple times, placing fake orders that are never intended to be collected. By the time you realize what’s happening, you’ve wasted time and unrecoverable resources. To make it stop, you call your phone company and get the prankster’s number blocked.
In a DDoS attack, this prankster decides to launch a large-scale ordering prank attack and gets all of his friends involved. You start receiving fake calls from multiple numbers, so it appears legitimate at first. Then, pizzas are piling up, but you don’t know which callers are real clients or pranksters. Eventually your perfect pizza ordering system is overwhelmed, and you’re forced to take the phone off the hook. You’ve wasted time and money and lost real customers. While it’s possible to block out the new pranksters, it’s going to take more time to weed them out.
DoS Attack Types
DoS attacks either flood or crash a service. Flooding is more common and occurs when a system is overwhelmed by traffic and stops working because it is unable to handle the volume of requests. Attacks can be divided into volume-based attacks, protocol attacks, and application layer attacks. There are over 35 different DoS attacks, here are some common examples:
How DoS Attacks Succeed
A DoS attack relies on a weak link in the way networks communicate. When you, as a consumer access a website, your computer sends a small packet of information to the site you want to reach. This packet essentially says, “Hi! Can I come in?” The server of the website you are trying to reach replies with another packet of information which says, “Are you real?” Your computer responds with an enthusiastic “Yes!” and so your connection is established, and you can access the site.
A DoS attack is the same “Hi! Can I come in?” The server asks if it is real and after a minute of not receiving a response, closes the connection. Thousands of illegitimate requests later, the server becomes overwhelmed and slows down or crashes.
How to Prevent a DoS Attack
There is no sure-fire way to prevent becoming a target, but proactive steps can be taken to reduce the effects.
If you experience an attack, be sure to keep a close eye on other parts of your network. This attack could be a distraction technique from another secondary target.
Remember, the earlier that an attack can be identified, the quicker damage to your infrastructure can be mitigated.