arpspoof redirects packets from a target host (or all hosts)
on the LAN intended for another host on the LAN by forging ARP
replies. This is an extremely effective way of sniffing traffic on a
switch.
Kernel IP forwarding (or a userland program which accomplishes the
same, e.g. fragrouter(8)) must be turned on ahead of time.
OPTIONS
-i interface
Specify the interface to use.
-t target
Specify a particular host to ARP poison (if not specified, all hosts
on the LAN).
host
Specify the host you wish to intercept packets for (usually the local
gateway).