Denial of Service Attacks
Definition: Denial of Service. A cracker attack that overloads a server to the point that it no longer responds or shuts down completely. To flood a network or individual server with huge amounts of data packets.
How it Works
In a typical connection, the user sends a message asking the server to authenticate it. The server returns the authentication approval to the user. The user acknowledges this approval and then is allowed onto the server. In a denial of service attack, the user sends several authentication requests to the server, filling it up. All requests have false return addresses, so the server can't find the user when it tries to send the authentication approval. The server waits, sometimes more than a minute, before closing the connection. When it does close the connection, the attacker sends a new batch of forged requests, and the process begins again--tying up the service indefinitely.
Types of Attacks
I. Operating System Attacks
These attacks exploit bugs in a specific operating system, which is the basic software that your computer runs, such as Windows 98 or MacOS. In general, when these problems are identified, they are promptly fixed by the company such as Microsoft. So as a first step, always make sure you have the very latest version of your operating system, including all bug fixes. All Windows users should regularly visit Microsoft's Windows update site, which automatically checks to see if you need any updates.
II. Networking Attacks
These attacks exploit inherent limitations of networking to disconnect you from the IRC server or your ISP, but don't usually cause your computer to crash. Sometimes it doesn't even matter what kind of operating system you use, and you cannot patch or fix the problem directly. The attacks on Yahoo and Amazon were large scale networking attacks, and demonstrate how nobody is safe against a very determined attacker. Network attacks include ICMP flood (ping flood) and ‘smurf’ which are outright floods of data to overwhelm the finite capacity of your connection, spoof unread/redirect a.k.a. ‘click’ which tricks your computer into thinking there is a network failure and voluntarily breaking the connection, and a whole new generation of distributed denial of service attacks (although these are seldom used against individuals).
III. SYN Attack
When a session is initiated between the TCP client and server in a network, a very small buffer space exists to handle the usually rapid "hand-shaking" exchange of messages that sets up the session. The session-establishing packets...