Which of the following will help prevent smurf attacks?
Allowing necessary UDP packets in and out of the network
Disabling directed broadcast on border routers
Disabling unused services on the gateway firewall
Flash the BIOS with the latest firmware
A smurf attack involves sending PING requests to a broadcast address. Therefore, we can prevent smurf
attacks by blocking broadcast packets on our external routers.
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 T-1 (or even T-3) line
with ping replies, bring the 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.