TABLE OF CONTENTS SYN flood attacks
Other single-source DoS attacks
Distributed DoS
Stopping DoS attacks
A denial of service (DoS) attack attempts to prevent legitimate users from accessing a computing resource. DoS attacks can take several forms:
Overwhelm a network: The attack can flood a network with so many packets that legitimate traffic slows to a crawl.
Overwhelm a server: The attack can flood a single server with so much traffic that legitimate users can t access the server.
Bring down a server: The attack can cause a server to crash.
You can t prevent an attacker from launching a DoS attack, but you can detect one in progress and take steps to mitigate its impact. In addition, you can prevent hosts on your network from being unwitting parties to a distributed DoS, a DoS attack in which the source is multiple computers.
The earliest DoS attacks were launched from a single source computer. They are attractive types of attacks to system crackers because they don t require any account access. The attacker launches packets from his or her machine that compromise the victim by taking advantage of the victim s natural behavior to communication requests.
A simple type of DoS attack comes from a single source computer. one of the earliest to appear was the SYN flood attack (see Figure 7.1), which takes advantage of the TCP three-way handshake that we reviewed...
