Internet card? I think its Network Interface card... That has a MAC address (The physical address of your network interface card). As far as i know, a modem has no address other than your phone address, But the modem gives your computer an IP address that it gets from your ISP, and a layer 3 switch does have an address if you specify one for it. The MAC address is given to your network card by the manufacturer and you can not change it, but, you can spoof it. You can change your proxy server by telling your computer to use the address of a proxy server that is open for anonymous use. go and Google Proxy server list.