I recently acquired a Fujitsu Lifebook T2010 tablet for use as my work machine (finally giving me the opportunity to put aside a very tired Dell Dimension 4700). This tablet has an Intel Pro/Wireless 4965 wireless card. I'd used the 3945 before on a Dell Inspiron with minimum fuss (install the firmware, make a wpa_supplicant.conf, Bob's your uncle), so I figured I'd have a similar situation.

Well. What a drama. I initially installed Debian Lenny on it. Everything worked fantastic (note: I haven't bothered to try to get the stylus to work yet), except the wireless. I installed firmware-iwlwifi, made sure all relevant modules were enabled including mac80211, and even when running an ifconfig, the wlan0 device was definitely present and detected.

So what wasn't working? Well, I simply could *not * get it to communicate properly with the wireless router. It knew it was there, assumably could authenticate, but could not retrieve a DHCP lease from it or the server behind it. I knew nothing was wrong with the wireless router because I use it on other machines frequently with the same settings.
This is the sort of thing I'd see in syslog after an ifup wlan0: just a timeout essentially:

Oct 19 14:52:26 diveli NetworkManager: <WARN>  nm_device_802_11_wireless_scan(): (wlan0): could not trigger wireless scan: Network is down
Oct 19 14:54:28 diveli NetworkManager: <WARN>  nm_device_802_11_wireless_scan(): (wlan0): could not trigger wireless scan: Network is down
Oct 19 14:54:42 diveli dhclient: Listening on LPF/wlan0/00:13:e8:da:19:8d
Oct 19 14:54:42 diveli dhclient: Sending on   LPF/wlan0/00:13:e8:da:19:8d
Oct 19 14:54:42 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 8
Oct 19 14:54:42 diveli dhclient: receive_packet failed on wlan0: Network is down
Oct 19 14:54:50 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 9
Oct 19 14:54:59 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 15
Oct 19 14:55:14 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 17
Oct 19 14:56:05 diveli dhclient: Listening on LPF/wlan0/00:13:e8:da:19:8d
Oct 19 14:56:05 diveli dhclient: Sending on   LPF/wlan0/00:13:e8:da:19:8d
Oct 19 14:56:13 diveli dhclient: Listening on LPF/wlan0/00:13:e8:da:19:8d
Oct 19 14:56:13 diveli dhclient: Sending on   LPF/wlan0/00:13:e8:da:19:8d
Oct 19 14:56:13 diveli dhclient: receive_packet failed on wlan0: Network is down
Oct 19 14:56:14 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
Oct 19 14:56:19 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 10
Oct 19 14:56:29 diveli dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 11
Oct 19 14:56:30 diveli NetworkManager: <WARN>  nm_device_802_11_wireless_scan(): (wlan0): could not trigger wireless scan: Network is down

I tried with a static IP setting, but no luck. It would apparently connect but I couldn't ping to even other local machines. Something was definitely not right.

I googled around for a few hours and got a vague sort of gist that something was buggy either with the firmware or more specifically, that driver and that kernel combination (or kernels from about 2.6.24 and up).

I tried compiling the driver myself, but that didn't help either. I even installed Ubuntu (gark!) - in which very initially at the first time I booted up after install, it worked flawlessly, but after an apt-get upgrade (which incidentally brought in an update to the kernel), it stopped working again.

I tried on Etch hoping an older kernel might in fact save me. No luck, even more troubles compiling because mac80211 wasn't part of the 2.6.18 kernel or something.

Finally back on Lenny after doing some more googling related to this output of 'iwlist scan':

debian:/home/diveli# iwlist scan
lo		Interface doesn't support scanning
 
eth0		Interface doesn't support scanning
 
wmaster0	Interface doesn't support scanning
 
wlan0		Interface doesn't support scanning

I came across this forum post on Debian-FR, in which a user mentioned that to get this problem sorted, he had to (of all things!) install a GUI network manager called 'wicd'.

I didn't really believe it could make a difference, but I added the wicd repository to my sources.list:

deb http://apt.wicd.net lenny extras

And

apt-get install wicd

(then may as well give it a reboot or you may get errors about NetworkManager applet pop up (some sort of legacy from the old version I suspect))

This program removed the existing default NetworkManager and its gnome support package and replaced it with its own. I can't believe it, but using this GUI, it somehow manages to communicate with my wireless router properly, authenticates and gets me a DHCP lease. I know it 'just works', because I'm writing this blog post on the same tablet :)

Bizarre! But since everyone seems so vague about it online (I *really* hate bug reports where people say 'nevermind I got it fixed' or simply go silent with the developer asking 'did you manage to get it fixed?' without ever getting a response ), I thought I'd document here what I did to get things going (not everyone gets lucky by understanding what's on a French debian forum :) What a drama!

I hope this helps someone! If someone can tell me why this program made a difference, let me know!