(v.) To fool. In networking, the term is used to describe a variety of ways in which hardware and software can be fooled. IP spoofing, for example, involves trickery that makes a message appear as if it came from an authorized IP address. Also see e-mail spoofing.
Spoofing is also used as a network management technique to reduce traffic. For example, most LAN protocols send out packets periodically to monitor the status of the network. LANs generally have enough bandwidth to easily absorb these network management packets. When computers are connected to the LAN over wide-area network (WAN) connections, however, this added traffic can become a problem. Not only can it strain the bandwidth limits of the WAN connection, but it can also be expensive because many WAN connections incur fees only when they are transmitting data. To reduce this problem, routers and other network devices can be programmed to spoof replies from the remote nodes. Rather than sending the packets to the remote nodes and waiting for a reply, the devices generate their own spoofed replies.