The Address Resolution Protocol (ARP) is a network protocol used by a router to map layer three IP addresses to layer two MAC addresses for systems communicating on the network. The records stored by the router are held in the form of a table (ARP table) that allows the router to more quickly identify where to send network traffic. Given the inherent trust a system will place in network equipment and the information provided by it, the ARP protocol can be used by an attacker to manipulate the network traffic sent between system.