[pixl97]

Lots of enterprise equipment have features where you can mirror traffic off an ethernet port and monitor it, but it is cheap and easy to do if you are poor too. Dig up a 100MB hub, not a switch, and then with another computer plugged into that hub run a program like Wireshark or tcpdump.

This is one reason why I don't run all-in-one router/wireless combos. Most integrated (especially provided by ISP units) devices have no way to tell you what is being sent over the air and then to your ISP.