Definitions for "Smurf Attack"
Keywords:  icmp, ping, spoofed, denial, echo
This is a network based attack where the attacker(s) send out false ICMP echo requests that appear to originate from the IP address of the machine or network under attack. This type of attack can be used to flood a network or device with "responses" to the false ICMP requests.
A type of Denial of Service attack. If a "ping" is sent directly to a broadcast or multicast address on a network, the routers may forward the pings on to all of the hosts on the network, all of those hosts may respond. If they do, then an attacker can create many times more traffic on your network than they sent to it. Basically, this attack uses the broadcast address to magnify or amplify the amount of traffic the attack sends.
A maliciously sent PING request sent to an Internet broadcast address, where it can be replicated up to 255 times. Since the attacker's address appears to be the address of the victim, all PING request replies come to the victim's address instead of the real sender's address. A single attacker sending thousands of these PING messages per second can bring an entire ISP network down by filling its T-1 or T-3 with PING replies. The Computer Emergency Response Team at Carnegie Mellon University said Smurf attacks went up from 3 percent of reported incidents in January 1998 to 10 percent by December 1998.
a method of denying service on an IPconnection