For those curious, the packet-sniffing software they are using in that demonstration is Ettercap, available for free.
In my case, all I need to do is
$ sudo apt-get install ettercap aircrack-ng
and suddenly my innocent Ubuntu netbook is converted into a hacker's wet dream. Something like that, anyway.
There's tons and tons of them out there. If you're looking to do this from a windows environment, I'd say go grab cain & abel and just read its online help file- its pretty self explanatory.
Alternatively, ettercap for a linux environment also has a pretty intuitive ncurses interface and pretty decent man page entry.
Happy hacking :)
Your computer tells another computer on the network, that your computer (or any other computer) is the way to the internet. But instead of forwarding the traffic to the internet, you can just drop anything they send. http://en.wikipedia.org/wiki/ARP_spoofing http://ettercap.sourceforge.net/
http://ettercap.sourceforge.net/
Unless anyone can link a better, more modern tool (works great for me :P).
Screenshots if anyone is interested in simply checking out what it looks like.
Use at your own risk, and only on networks you own. I can't promise that your job/school doesn't have an IDS; don't get fired/expelled/incarcerated.