The Address Resolution Protocol (ARP) is a communication protocol used for discovering the link layer address, such as a MAC address, given an IP address. The ARP protocol is a very simple protocol, and it does not implement any security measure. The ARP cache poisoning attack is a common attack against the ARP protocol. Under such an attack, attackers can fool the victim into accepting forged IP-to-MAC mappings. This can cause the victim's packets to be redirected to the computer with the forged MAC address.
The objective of this lab is for students to gain the first-hand experience on the ARP cache poisoning attack, and learn what damages can be caused by such an attack. In particular, students will use the ARP attack to launch a man-in-the-middle attack, where the attacker can intercept and modify the packets between the two victims A and B.