In a smurf attack, or smurfing, and a denial of service, or DOS attack, a hacker targets an Internet service provider (ISP) and floods it with so much garbage traffic that none of the ISP's customers can use the service. Smurf attacks have become one of the most popular kinds of hacker attacks on the Internet. The attack starts when a hacker sends a series of ping (Packet Internet Groper) packets to a network attached to the Internet. Ping uses the Internet Control Message Protocola widely used protocol for, among other things, determining whether a particular computer is attached to the Internet and working properly. The network being pinged is not the target of the attack. Instead, it will be used as a way to attack the ISP.
