I just installed Debian Wheezy on a Toshiba laptop using the netinstall CD.

During installation everything worked fine, ethernet and wireless interfaces were both detected and functional. I actually did the installation using the wireless connection. On the “Task selection” screen I only selected “Laptop” and “Standard system utilities”.

However, after the reboot at the end of the installation, I had no network anymore. Here is what I did to fix it:

Edit /etc/network/interfaces and add this block:

auto eth0
allow-hotplug eth0
iface eth0 inet dhcp

Then run as root:

/etc/init.d/networking start

If the machine is connected via ethernet cable to a router, you should see messages about your network being configured via DHCP, i.e. receiving its local IP address.

If you get error messages, then you might have to install firmware for your network card:

On another computer, download firmware.tar.gz and save it to a USB stick.

Then do the following as root on the new Debian system:

Plug in the USB stick and mount it. You might have to run “dmesg” to see which device file to mount. In my case it was /dev/sdb …

mount /dev/sdb /mnt

Unzip the firmware tarball:

cd /mnt
tar xvzf firmware.tar.gz

Install the core firmware packages:

dpkg -i firmware-linux-*.deb

Install additional firmware packages as necessary. Use the output of the lspci command to identify your network cards. Consult the “Firmware” Debian wiki page to find out what package you have to install.

If you are done installing firmware, restart the system:

shutdown -r now

Hopefully you will have a network connection after the reboot.