Another point that hasn't been mentioned in this thread is that this type of attack is very easy to track down, since all the echo-reply packets will have addresses in the same subnet. A good portion of the problem with smurf attacks is not so much the attack itself as the painful process of tracking it to it's source.
By the time you trace the packets, identify the subnet, and convince the Network Administrator to detach the compromized system from the network, the victim's router might have crashed. Especially, when there are more than one DDoS agents are compromized over different networks, the victim site may loose several hours of business! Vipul
Brandon Ross 404-522-5400 VP Engineering, NetRail http://www.netrail.net AIM: BrandonNR ICQ: 2269442 Read RFC 2644! Stop Smurf attacks! Configure your router interfaces to block directed broadcasts. See http://www.quadrunner.com/~chuegen/smurf.cgi for details.