The glossary below contains many of the terms you will find in common use throughout the Symantec Security Response website. Please refer to this list to find definitions of terms and answers to other Internet security-related questions.

Smurf DoS attack

Ping is a software tool that is available on most operating systems and commonly used to check if a specified computer is reachable. When the ping tool is executed, an ICMP echo request packet is sent to the destination computer. If the destination computer receives the TCP packet, it replies to confirm the ping request. In the case of a Smurf denial-of-service attack, the ping's packet return IP address is forged with the IP of the targeted computer. The ping is issued to the entire IP broadcast address. This technique causes every computer to respond to the bogus ping packets and reply to the targeted computer, which floods it. This technique is called a Smurf attack because the DoS tool that is used to perform the attack is called Smurf. One way to reduce risk of this attack is to disable IP-directed broadcast, which is often not used or needed. Some operating systems are configured to prevent the computer from responding to ICMP packets.