Posted 24 October 2011 - 11:48
he could always send traffic to other computers, but as to sniffing -- without flooding the switch to have it fail open and send all packets to a every port the only traffic he would see while sniffing is broadcast traffic, arps, multicast traffic. He would not for example see your traffic between your machine and neowin.net
But sure he could for example do a arp spoof of the routers mac and have your machine think his machine is the gateway and send all traffic to his machine.
A switch normally keeps someone from sniffing all the traffic, but an "attacker" can do things to change this yes - its not 100% protection against sniffing.
And you will see all the broadcast traffic, which can be very useful info -- I really suggest you grab wireshark, and do a bit of sniffing to see what kind of traffic you see, etc.