Draytek 2950 User Guide

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Vigor2950 Series User’s Guide 
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As a sub-functionality of IP Filter/Firewall, there are 15 types of detect/ defense function in 
the DoS Defense setup. The DoS Defense functionality is disabled for default. 
Click Firewall and click DoS Defense to open the setup page. 
 
Enable Dos Defense 
Check the box to activate the DoS Defense Functionality. 
Enable SYN flood 
defense
 
Check the box to activate the SYN flood defense function. Once 
detecting the Threshold of the TCP SYN packets from the Internet 
has exceeded the defined value, the Vigor router will start to 
randomly discard the subsequent TCP SYN packets for a period 
defined in Timeout. The goal for this is prevent the TCP SYN 
packets’ attempt to exhaust the limited-resource of Vigor router. 
By default, the threshold and timeout values are set to 50 packets 
per second and 10 seconds, respectively. 
Enable UDP flood 
defense 
Check the box to activate the UDP flood defense function. Once 
detecting the Threshold of the UDP packets from the Internet has 
exceeded the defined value, the Vigor router will start to randomly 
discard the subsequent UDP packets for a period defined in 
Timeout. The default setting for threshold and timeout are 150 
packets per second and 10 seconds, respectively. 
Enable ICMP flood 
defense 
Check the box to activate the ICMP flood defense function. Similar 
to the UDP flood defense function, once if the Threshold of ICMP 
packets from Internet has exceeded the defined value, the router 
will discard the ICMP echo requests coming from the Internet. The 
default setting for threshold and timeout are 50 packets per second 
and 10 seconds, respectively. 
Enable PortScan 
detection 
Port Scan attacks the Vigor router by sending lots of packets to 
many ports in an attempt to find ignorant services would respond. 
Check the box to activate the Port Scan detection. Whenever 
detecting this malicious exploration behavior by monitoring the