ZyXEL Communications ZyWall USG 2000 User Manual page 536

Chapter 32 ADP
full, the system will ignore all incoming SYN requests, making the system
unavailable for other users.
Figure 374 SYN Flood
LAND Attack
In a LAND attack, hackers flood SYN packets into a network with a spoofed source
IP address of the network itself. This makes it appear as if the computers in the
network sent the packets to themselves, so the network is unavailable while they
try to respond to themselves.
UDP Flood Attack
UDP is a connection-less protocol and it does not require any connection setup
procedure to transfer data. A UDP flood attack is possible when an attacker sends
a UDP packet to a random port on the victim system. When the victim system
receives a UDP packet, it will determine what application is waiting on the
destination port. When it realizes that there is no application that is waiting on the
port, it will generate an ICMP packet of destination unreachable to the forged
source address. If enough UDP packets are delivered to ports on victim, the
system will go down.
Protocol Anomaly Background Information
The following sections may help you configure the protocol anomaly profile screen
(see Section 32.3.5 on page
536
530)
ZyWALL USG 2000 User's Guide