The original arpspoof utility (part of dsniff) provides an easy way to send forged ARP packets. The normal use for this utility is to intercept traffic between two hosts, such as a user and the gateway.
As part of an upcoming project I needed a way to redirect traffic from one host to another host under my control. The arpspoof utility however only allows the user to directly intercept the traffic in question. In order to address this issue I modified the arpsniff utility to enable new functionality which I call ‘spoofing onto a peer’.
In order to use this new functionality the commad line switch -s is used in conjunction with the other command line parameters. For example the command line below would intercept the traffic from host 192.168.1.1 and redirect it to the mac address 12:34:56:78:9a:bc.
arpspoof -s 12:34:56:78:9a:bc 192.168.1.1