WiFi / Intel 3945

This device is an ieee802.11abg wifi card : "Intel PRO/Wireless 3945ABG Network Connection"
(device identifier PCI 8086:4227).

You will need to install the non-free firmware 

in /etc/apt/sources.list
        #Add  "non-free" and "contrib" for ipw3945
        deb http://ftp.debian.org/debian/ etch main contrib non-free

then run the following commands 

apt-get install firmware-ipw3945 ipw3945d ipw3945-modules-$(uname -r)

You have to run "modprobe ipw3945" or to reboot.

Radio Switch

Make sure "radio" switch isn't turn off.

For diagnostic purpose, dmesg will show one of the following messages when you load ipw3945, depending on the radio switch state: 

ipw3945: Intel(R) PRO/Wireless 3945 Network Connection driver for Linux, 1.1.3dmpr
ipw3945: Copyright(c) 2003-2006 Intel Corporation
ipw3945: Detected Intel PRO/Wireless 3945ABG Network Connection

followed by either : 

ipw3945: Radio Frequency Kill Switch is On:
Kill switch must be turned off for wireless networking to work.

or this (if radio is enabled) : 

ipw3945: Detected geography ABG (13 802.11bg channels, 23 802.11a channels)