Internet Protocol (IP) is a connection protocol that exists at the Network layer (layer 3) of the Open Systems Interconnection (OSI) reference model. Internet protocol is used to assist routers or any layer 3 devices to forward packets to their corresponding destinations. One main characteristic of internet protocol is its nature of being a connectionless protocol, which means it provides delivery using best effort and is not guaranteed to be delivered to the recipient. Since IP is said to be connectionless, it depends on the upper layers to assist with the delivery of data. The layer above the Network layer is known as the Transport layer. There are two sub protocols, which are used primarily for delivery; these are known as the User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP). An IP packet contains the following: source and destination IP addresses, version (IPv4 or IPv6), Time to Live (TTL) value, protocol (TCP, UDP, or ICMP), and flags.

It is through the forging of this source address that hackers are able to break into the network and mislead communication between the source and the destination. Almost all networks use routers as intermediate devices for the transmission of data. When the data is sent via routers, they identify the destination IP address from the header of the IP datagram to forward the packets to that destination. The source address is ignored by the routers. The source address is used only by the destination machine when a reply is sent back for the received packets.