HostAP Digest, Vol 4, Issue 33

Jouni Malinen jkmaline at
Mon Aug 18 22:40:18 EDT 2003

On Mon, Aug 18, 2003 at 01:57:40PM +0000, Haidong Xia wrote:

> Can anyone explain to me how HostAP set up a default wep key ? Since I 
> don't have a hardware manual of prism2 card, I am a little confused, when I 
> read the code of WEP key setting under HostAP.

You don't need a hardware manual for this.. IEEE 802.11 standard might
be more useful ;-).

> The basic question is: When HostAP sets up a default wep key, a WinXP 
> client automatically detects this access point has a default wep key. How a 
> WinXP client know an Access Point has a WEP key, right after association?

Actually, it already knows it before association. The AP includes a
Privacy bit in the capability info field of the beacons.

> I am doing an experiment to allow both of clients using Wep key, or not 
> using wep key to get access to an Access point. But WinXP client keeps 
> saying there is a wep key, and just wants to use a Wep key, even I didn't 
> set up a key for it.

Yes, many WinXP clients do not really like the Privacy bit in the
beacons (or probe responses) if you are trying to use unencrypted

> Is there a way to set up a default wep key in HostAP, but WinXP client will 
> not detect it?  So that a user can configure the client freely with or with 
> WEP key?   Of course, at hostAP side, it can detect a
> frame is encrypted or not, and deal with it correspondingly.

This depends a bit on the client implementation. In other words, you
might get it working with some drivers, but not with all.. I don't
remember whether Prism2 changes the capability information contents
based on "exclude unencrypted" configuration. If it does, you try
setting up the WEP keys with 'open' option of the iwconfig (iwconfig
wlan0 key s:abcde open).

Jouni Malinen                                            PGP id EFC895FA

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