arpspoof

arpspoof, part of dsniff, forges ARP replies on a local IPv4 network to redirect a selected host's packets intended for another LAN host (usually its gateway) through the operator's system. It establishes an adversary-in-the-middle position; it does not itself capture application payloads. Kernel IP forwarding or an equivalent forwarder must already be enabled if redirected traffic is expected to continue to its destination.