Section: Threats and Vulnerabilities
Explanation/Reference:
Explanation:
A smurf attack is a type of network security breach in which a network connected to the Internet is
swamped with replies to ICMP echo (PING) requests. A smurf attacker sends PING requests to an Internet
broadcast address. These are special addresses that broadcast all received messages to the hosts
connected to the subnet. Each broadcast address can support up to 255 hosts, so a single PING request
can be multiplied 255 times. The return address of the request itself is spoofed to be the address of the
attacker's victim. All the hosts receiving the PING request reply to this victim's address instead of the real
sender's address. A single attacker sending hundreds or thousands of these PING messages per second
can fill the victim's Internet connection with ping replies, bringing their entire Internet service to its knees.
Smurfing falls under the general category of Denial of Service attacks -- security attacks that don't try to
steal information, but instead attempt to disable a computer or network.
By disabling IP-directed broadcasts on all routers, we can prevent the smurf attack by blocking the ping
requests to broadcast addresses.