For those who dont know smurfing is a DOS (denial of service) attack that is much more effective then the old style "SYN flood" attacks
How it works
A smurf begins when a single malicious user sends a stream of Internet Control Message Protocol, or ping, packets - used to determine if a machine is alive - to a target network's central "directed broadcast" address, which is rarely used, but easily obtained. This address pings all the machines - often 255 boxes or more - on the target network.
Each of the hundreds of hosts on that target network will dutifully respond with a "yes, I'm here faggit
There is alot more to it but i dont feel like explaining atm