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As the above figure shown, the attacker sends the fake ARP packets with a forged Gateway 
address to the normal Host, and then the Host will automatically update the ARP table after 
receiving the ARP packets. When the Host tries to communicate with Gateway, the Host will 
encapsulate this false destination MAC address for packets, which results in a breakdown of 
the normal communication. 
  Cheating Gateway 
The attacker sends the wrong IP address-to-MAC address mapping entries of Hosts to the 
Gateway, which causes that the Gateway  cannot  communicate with the legal terminal Hosts 
normally.  The ARP Attack implemented by cheating Gateway is illustrated in the following 
figure. 
 
Figure 12-10 ARP Attack – Cheating Gateway 
As the above figure shown, the attacker sends the fake ARP packets of Host A to the Gateway, 
and then the Gateway will automatically update its ARP table after receiving the ARP packets. 
When the Gateway tries to communicate with Host A in LAN, it will encapsulate this false 
destination MAC address for packets, which results in a breakdown of the normal 
communication. 
  Cheating Terminal Hosts 
The attacker sends the false IP address-to-MAC address mapping entries of terminal 
Host/Server to another terminal Host, which causes that the two terminal Hosts in the same 
network segment cannot communicate with each other normally. The ARP Attack implemented 
by cheating terminal Hosts is illustrated in the following figure.