|
In computing, a denial-of-service (DoS) attack is an attempt to make a machine or network resource unavailable to its intended users, such as to temporarily or indefinitely interrupt or suspend services of a host connected to the Internet. A distributed denial-of-service (DDoS) is where the attack source is more than one–and often thousands of-unique IP addresses. Criminal perpetrators of DoS attacks often target sites or services hosted on high-profile web servers such as banks, credit card payment gateways; but motives of revenge, blackmail or activism can be behind other attacks. ==Symptoms== The United States Computer Emergency Readiness Team (US-CERT) defines symptoms of denial-of-service attacks to include: * Unusually slow network performance (opening files or accessing web sites) * Unavailability of a particular web site * Inability to access any web site * Dramatic increase in the number of spam emails received—(this type of DoS attack is considered an e-mail bomb) * Disconnection of a wireless or wired internet connection * Long term denial of access to the web or any internet services Denial-of-service attacks can also lead to problems in the network 'branches' around the actual computer being attacked. For example, the bandwidth of a router between the Internet and a LAN may be consumed by an attack, compromising not only the intended computer, but also the entire network or other computers on the LAN.〔 (PDF)〕 If the attack is conducted on a sufficiently large scale, entire geographical regions of Internet connectivity can be compromised without the attacker's knowledge or intent by incorrectly configured or flimsy network infrastructure equipment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Denial-of-service attack」の詳細全文を読む スポンサード リンク
|