Query: can wpa_supplicant set up an ad-hoc network

Dan Williams dcbw
Wed Oct 21 10:58:39 PDT 2009

On Tue, 2009-10-20 at 14:03 +0800, Soh Kam Yung wrote:
> On Mon, Oct 19, 2009 at 11:14 AM, Soh Kam Yung <sohkamyung at gmail.com> wrote:
> >
> > It's more of trying to understand how an ad-hoc network works.  Thanks
> > for the info.
> >
> > One more question: if the initial scan does not reveal an existing
> > IBSS and one is created instead by wpa_supplicant, how is the RF
> > channel selected?  Is this at random or are there specific rules that
> > determine which channel will be used?
> >
> > Is there a wpa_supplicant option to configure the channel to be used for a IBSS?
> >
> One more question (besides the one in the quote above): in the sample
> wpa_supplicant configurations for ad-hoc supplied by Dan in an earlier
> mail, there is this one:
> network={
>        ssid="my WPA ad-hoc network"
>        mode=1
>        key_mgmt=WPA-NONE
>        proto=WPA
>        pairwise=NONE
>        group=TKIP
>        psk="blahblahblahblahblah"
> }
> Is this the only WPA secured configuration supported for ad-hoc?  Must
> key_mgmt be WPA-NONE and pairwise be NONE?

Correct.  There is no key management because there is no central entity
(ie, an AP) to perform that key management.  Ad-Hoc has no central

> I checked the IEEE Std. 802.11-2007 document and Section 5.8.3 (IBSS
> functional model description) describes an IBSS where pairwise traffic
> is also encrypted and exchanged.

Jouni would be more likely to know about that than I :)

> The example also uses the 4-way handshake to exchange the transmit
> keys between each station that wants to communicate in the IBSS.  Does
> wpa_supplicant remember all of this key information?

I don't believe this mode is supported in the linux kernel 802.11 stack
at this time.


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