IP addresses can easily be spoofed. The trick of exploiting your current setup, might prove more or less difficult depending on the physical location of the attacker. To put in more plainly - it is trivial for me to send you a packet that will claim it is from any IP address of my choosing. The difficult part would be getting any reply that would then be sent to that IP address. If I were going to attempt such a devious plan - I would physically position myself so that I could either sniff the traffic on your physical wire, or the physical wire of the 'expected' return address. By placing my NIC in promiscuous mode, I would grab all traffic on that wire (including the traffic bound for the address that I spoofed). I hope this is clear. Happy H4K1N
Sincerely,
Captain Weenie