|There is a Modem there somewhere. You cannot transmits data over any distances without one as the connection to the back of your computer will be Ethernet and that is restricted to 100 meters. You don't plug it into the back your CPU, you plug it into the back of your computer. A CPU is a chip on the motherboard, the big one with a fan on it.|
You should be able to use a router and use the connection on as many computer as you like. You may have to clone the MAC address of your computer to the router so the ISP still thinks it is connected to the computer.