What do you mean by USB device for internet connection? Are you using a dongle with a SIM card? If so then those dongles need their respective software to connect to PC which are (in most cases) only available for Windows.
If that is not the case, try these steps.
In a terminal, type:
sudo vi /etc/init.sh
add 4 lines below to init.sh
netcfg eth0 dhcp
echo nameserver <ip> > /etc/resolv.conf
setprop net.dns1 126.96.36.199