Configuring IP Teardrop Attack Screen
This topic describes how to configure detection of an IP teardrop attack.
Teardrop attacks exploit the reassembly of fragmented IP packets. In the IP header, one of the field is the fragment offset fields, which indicates the starting position, or offset of the data contained in a fragmented packet, relative to the data of the original unfragmented packet. When the sum of the offset and size of one fragmented packet differs from that of the next fragmented packet, the packets overlap and the server attempting to reassemble the packet might crash.
Configure the security screen option and attach it to the untrustZone as follows:
[edit] user@host# set security screen ids-option untrustScreen ip tear-drop user@host# set security zones security-zone untrustZone screen untrustScreen user@host# set security screen ids-option untrustScreen alarm-without-drop