I have Ubuntu Server on an old laptop.
It connects to my router via wifi.

/etc/network/interfaces
Code:
auto eth1
iface eth1 inet dhcp
    wpa-ssid <ESSID>
    wpa-psk <password>
It has an Ethernet port (eth0) to which I've connected a Windows 8 box with no internet. I want the internet on the Windows box.

This is easy using Ubuntu or Windows GUI. But how do I achieve this by command line? I've worked on this for three days with no results.