The Smurf attack is one of the most popular and frightening DoS attacks in use today.

The hacker sends spoofed broadcast pings to many amplifying networks. This can cause every host on every network involved to send an Internet Control Message Protocol (ICMP) echo reply back to the victim's host.

With fast amplifying networks, a hacker can completely saturate a T1 line using only a 56K dial-up connection. When done across the Internet, this attack is virtually untraceable.