DoS Attack Type  Description 
Scan SYNFIN  The attacker sends the packet with its SYN field and the FIN field set to 1. 
The SYN field is used to request initial connection whereas the FIN field is 
used to request disconnection. Therefore, the packet of this type is illegal. 
The switch can defend this type of illegal packet. 
Xmascan  The attacker sends the illegal packet with its TCP index, FIN, URG and 
PSH field set to 1. 
NULL Scan Attack  The attacker sends the illegal packet with its TCP index and all the control 
fields set to 0. During the TCP connection and data transmission, the 
packets with all the control fields set to 0 are considered as the illegal 
packets.
 
SYN packet with its source port 
less than 1024 
The attacker sends the illegal packet with its TCP SYN field set to 1 and 
source port less than 1024.
 
Ping Flooding  The attacker floods the destination system with Ping broadcast storm 
packets to forbid the system to respond to the legal communication. 
SYN/SYN-ACK Flooding  The attacker uses a fake IP address to send TCP request packets to the 
Server. Upon receiving the request packets, the Server responds with 
SYN-ACK packets. Since the IP address is fake, no response will be 
returned. The Server will keep on sending SYN-ACK packets. If the attacker 
sends overflowing fake request packets, the network resource will be 
occupied maliciously and the requests of the legal clients will be denied.   
Table 11-1 Defendable DoS Attack Types   
On this page, you can enable the DoS Defend type appropriate to your need. 
Choose the menu Network Security→DoS Defend→DoS Defend to load the following page. 
 
Figure 11-16 DoS Defend 
The following entries are displayed on this screen: 
¾  Config 
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