cannot see any AP using iwlist wlan0 scan

dpowers · 08-25-2005, 07:22 PM

I have a Dell Latitude D600 with a Broadcom Corporation BCM4309 802.11a/b/g card in the laptop. I have gone through most of the stuff on the ndiswrapper site, and have gotten to the point where when I

Code:

modprobe ndiswrapper

,
it accepts it. dmesg shows

Code:

wlan0: ndiswrapper ethernet device 00:90:4b:16:cb:67 using driver bcmwl5a
ndiswrapper: driver bcmwl5a (Broadcom,02/17/2004, 3.40.65.0) added

If I ifconfig -a, wlan0 shows up. So I think everything is working fine.

However, my problem comes here:

Code:

dpowers@lappy:~$ sudo iwlist wlan0 scan
Password:
wlan0     No scan results

My AP (Airport Base Station) generally has no problems with when I boot the same laptop with WinXP. But I cannot discover the AP when I boot to Ubuntu.
I have also tried pressing Fn+F2, thinking that maybe I have to turn the wireless on. Nothing worked.

Any thoughts?

-dmp

edit: one additional question, if I have my normal onboard NIC connected and online, should I still be able to at least scan for the AP through wireless, or do I have to bring the onboard connection offline?

dpowers · 08-25-2005, 10:55 PM

Well driverloader works. I'd rather not pay for it, so I have 30 days to figure out why ndiswrapper with the same driver doesn't work.

mpyusko · 08-26-2005, 12:26 PM

did you do?

iwconfig wlan0 essid (your essid here)

you should be:

modprobe ndiswrapper

iwconfig wlan0 essid (blah)

iwconfig wlan0 enc (blah) ---- if necessary

ifconfig wlan0 xxx.xxx.xxx.xxx
or
dhcpd wlan0

try ndiswrapper -l (see if it shows hardware present)

dpowers · 08-26-2005, 05:22 PM

Yes, ndiswrapper -l showed the hardware as being present. I tried iwconfig wlan0 essid 'myssid' but that doesnt work. I believe that if scan fails to see any AP, then there is no use trying to configure the essid anyway, but I may be wrong on that.

I pretty much tried everything. I wonder if compiling from source will do the trick....

mpyusko · 08-27-2005, 10:39 AM

dumb questin but, you do have your AP broadcasting it's essid...right? Scan won't show it if it's not.

Mine is set to broadcast, but it wouldn't light up the card until I put in the Key. I also had a hard time accessing the intrenet once it was configured so I ran ./rc.inet1 and it fixed that problem.

calculator18 · 08-28-2005, 09:36 AM

Hello everyone.

Just to set the record straight, in my experience, that last comment is not entirely correct.
I suffer from a similar issue to the one described above. Showing scan results with iwlist
sometimes works and sometimes doesn't. However, when it does, even access points
not broadcasting their ssid show up in the scans. The ESSID field is "". Additionally,
allowing the access point to broadcast the ssid doesn't resolve the iwlist issue.

A post on another forum suggested reloading the driver/kernel module.
This worked for me once, but not since.

As far as I know, there are two methods for hiding the SSID. The general confusion is
mostly due to their similar names. One method is not sending the SSID with the beacon
frames (not broadcasting it), and the other is not responding to probe requests sent with
the "broadcast SSID" (also known as the empty SSID or default/any SSID), or with any other
SSID that is different than the AP's SSID for that matter. Both these methods are not in the
802.11 standard, so not all access points support them.

The first method prevents passive scanning, which is to listen on each channel for a certain
period of time, trying to detect beacon management frames with SSIDs in them. The second
method prevents active scanning, which is to send probe requests with the "broadcast SSID",
trying to detect the standard responses.

But even using both these methods won't prevent an attacker from finding the SSID, by
deauthenticating a connected client, and waiting for him to reassociate, thus sending the
SSID with his probe request.

Regards,
Calculator.