Re: Sniffing/Protocol problems

From: Jouni Malinen (
Date: 2002-07-24 19:52:27 UTC

On Wed, Jul 24, 2002 at 10:28:24AM -0700, Omesh Tickoo wrote:

> 3. When I replace the STA card with Cisco aironet card
> and use the airo_cs driver, I see that "iwconfig eth0"
> does not report an access point (or it reports
> 44:44:44:44:44:44 for the access point) if the WEP
> keys dont match with the HostAP running on a nearby
> laptop.

Cisco card is probably using shared key authentication, which used WEP to generate challenge-response style authentication.

> The behavior is different when I use Linksys cards
> with hostap_cs in managed mode for the STA. Regardless
> of whether the WEP keys match or not, the STA reports
> the HostAP MAC as its access point. Of course, I can
> ping between the two machines only if the WEP keys are
> same. Any ideas about which of the two behaviors is
> correct? The Cisco card with airo_cs or the Linksys
> card with hostap_cs.

hostap_cs.o uses the default authentication mode as a station. It is open system authentication that does not use WEP at all. It is thus able to authenticate and associate with the AP even with incorrect WEP keys. Host AP in Master mode allows both authentication algorithms as default, but it is also possible to configure it to accept only open system or shared key authenticationi (prism2_param wlan0 ap_auth_algs <val>).

Jouni Malinen                                            PGP id EFC895FA

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