spoof

vi. To capture, alter, and retransmit a communication stream in a way that
misleads the recipient. As used by hackers, refers especially to altering
TCP/IP packet source addresses or other packet-header data in order to
masquerade as a trusted machine. This term has become very widespread and is
borderline techspeak. Interestingly, it was already in use in its modern
sense more than a century ago among Victorian telegraphers; it shows up in
Kipling.

