Configuration Guide 567
Configuring Network Security DoS Defend Configuration
5
DoS Defend Configuration
5.1 Using the GUI
Choose the menu Network Security > DoS Defend > DoS Defend to load the following page.
Figure 5-1 Dos Defend
Follow these steps to configure DoS Defend:
1) In the Configure section, enable DoS Protection.
2) In the Defend Table section, select one or more defend types according to your needs.
The following table introduces each type of DoS attack.
Land Attack The attacker sends a specific fake SYN (synchronous) packet to the destination
host. Because both of the source IP address and the destination IP address of
the SYN packet are set to be the IP address of the host, the host will be trapped
in an endless circle of building the initial connection.
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.
Xmascan The attacker sends the illegal packet with its TCP index, FIN, URG and PSH field
set to 1.
NULL Scan 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
control fields set to 0 are considered illegal.
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