ZyXEL Communications 2602HWNLI-D7A User Manual

 

All contents copyright (c) 2007 ZyXEL Communications Corporation.   

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In a LAN attack, hackers flood SYN packets to the network with a spoofed source IP address of the 

targeted system. This makes it appear as if the host computer sent the packets to itself, making the system 

unavailable while the target system tries to respond to itself.   

A Brute-force attack, such as 'Smurf' attack, targets a feature in the IP specification known as directed or 

subnet broadcasting, to quickly flood the target network with useless data. A Smurf hacker flood a 

destination IP address of each packet is the broadcast address of the network, the router will broadcast the 

ICMP echo request packet to all hosts on the network. If there are numerous hosts, this will create a large 

amount of ICMP echo request packet, the resulting ICMP traffic will not only clog up the 'intermediary' 

network, but will also congest the network of the spoofed source IP address, known as the 'victim' 

network. This flood of broadcast traffic consumes all available bandwidth, making communications 

impossible.   

Many DoS attacks also use IP Spoofing as part of their attack. IP Spoofing may be used to break into 

systems, to hide the hacker's identity, or to magnify the effect of the DoS attack. IP Spoofing is a 

technique used to gain unauthorized access to computers by tricking a router or firewall into thinking that 

the communications are coming from within the trusted network. To engage in IP Spoofing, a hacker 

must modify the packet headers so that it appears that the packets originate from a trusted host and should 

be allowed through the router or firewall.   

There are two default ACLs pre-configured in the Prestige, one allows all connections from LAN to 

WAN and the other blocks all connections from WAN to LAN except of the DHCP packets.