I've just installed Debian 7.5.0 amd netinst.
Actually I am trying to install the firmware through aptitude install firmware-linux-nonfree
When I executed ifconfig and ifconfig -a, the output indicates only the loopback no eth0 interface. However the Ethernet card and WLAN card are pretty detected, I checked it through lspci and both cards appear.
I edited /etc/network/interfacesl by adding DHCP but it was in vain.