The term "spoofing" is generally regarded as slang, but refers to the act of fooling -- that is, presenting a false truth in a credible way. There are several different types of spoofing that occur, but most relevant to networking is the IP spoof. Most types of spoofing have a common theme: a nefarious user transmits packets with an IP address, indicating that the packets are originating from another trusted machine.

The first step in spoofing is determining the IP address of a host the intended target trusts. After that, the attacker can change the headers of packets to make it seem like the transmissions are originating from the trusted machine.

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