ZyXEL Communications Unified Security Gateway ZyWALL 1000 User Manual page 454

Chapter 30 ADP
30.8.2.5 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.
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ZyWALL USG 1000 User's Guide