ARP stands for Address Resolution Protocol. ARP acts as a layer over the Internet Protocol address (IP) and converts it into a Media Access Control address (MAC address) or Ethernet Hardware Address (EHA). Understanding the concept of ARP is very important for a hacker because, a potential hacker will be able to poison the network and steal the information running between two servers. Hence he can execute a ‘Man-In-The-Middle‘ attack using a simple ARP poisoning tool such as Cain & Abel. The function of Cain & Abel is similar to a packet sniffer.