Prevention Techniques (cont’d)
How to prevent being a “bounce site” in a “Smurf” or “Fraggle” attack:
Turn off directed broadcasts to networks:
Cisco: Interface command “no ip directed-broadcast”
As of 12.0, this is default (CSCdj31162)
Proteon: IP protocol configuration “disable directed-broadcast”
Bay Networks: Set a false static ARP address for bcast address
3Com: SETDefault -IP CONTrol = NoFwdSubnetBcast
Use access control lists (if necessary) to prevent ICMP echo requests from entering your network
Configure host machines to not reply to broadcast ICMP echos