DoS in fact not a Disk Operating System aka DOS
but a coordinated system of actions to turn operators like a disk, so-to-say.
Boycott & Sabotage using public entry over the brim.
Imagine a bookstore selling deviant infos such as 'George Orwell 1984':
There are organized observers and whistleblowers and a pack of instructed hooded activists (as to be experienced on university campus for example).
Upon a signal hundreds of activists storm a bookstore selling literature their masters don't want to be read by people who disagree with their own special economical or political agenda. What will happen?
The bookstore is so crowded that nobody can get in or out anymore.
It was legal entry but in big numbers. The selling of books is stopped.
No more business, no more income. Though no direct violence was done the result is nevertheless destructive and expensive.
A Denial of Service, or DoS as it's often abbreviated, is a malicious attack on a network. This type of attack is essentially designed to bring a network to its knees by flooding it with useless traffic.
Although a DoS attack does not usually result in the theft of information or other security loss, it can cost the target person or company a great deal of time and money. Typically, the loss of service is the inability of a particular network service, such as e-mail, to be available or the temporary loss of all network connectivity and services. A denial of service attack can also destroy programming and files in affected computer systems. In some cases, DoS attacks have forced Web sites accessed by millions of people to temporarily cease operation.
Common forms of denial of service attacks are:
Buffer Overflow Attacks
... send more traffic to a network address than the programmers who planned its data buffers anticipated someone might send
... send a number of connection requests very rapidly and then fail to respond to the reply
... the attacker's IP puts a confusing offset value in the second or later fragment. If the receiving operating system does not have a plan for this situation, it can cause the system to crash.
... lots of ping replies flooding back to the innocent, spoofed host. If the flood is great enough, the spoofed host will no longer be able to receive or distinguish real traffic.
... the victim is not usually specifically targeted but simply a host unlucky enough to get the virus. Depending on the particular virus, the denial of service can be hardly noticeable ranging all the way through disastrous.
Physical Infrastructure Attacks
... snip a fiber optic cable. This kind of attack is usually mitigated by the fact that traffic can sometimes quickly be rerouted.
A Denial of Service (DoS) attack is an attack which attempts to prevent the victim from being able to use all or part of their network connection.
A denial of service attack may target a user, to prevent them from making outgoing connections on the network. A denial of service may also target an entire organization, to either prevent outgoing traffic or to prevent incoming traffic to certain network services, such as the organizations web page.
Denial of service attacks are much easier to accomplish than remotely gaining administrative access to a target system. Because of this, denial of service attacks have become very common on the Internet.