wpa-supplicant for adhoc network with more than 2 nodes ?

Ly Hong Ly
Mon May 22 06:56:07 PDT 2006

Hi Jouni

Thanks for the quick answer. 

>>wpa_supplicant does not do any per-STA processing in IBSS mode for 
>>WPA-None, so I would be surprised if this were the case. Which driver 
>>are you using?

For your information: I am using the madwifi-driver (Madwifi-old) and I
have the 
following configuration for wpa_supplicant:



        ssid="test adhoc"
        psk="secret passphrase"

Sorry if I sound a little bit pedantic: What does your above answer
mean? Should WPA-NONE in IBSS mode work with more than two hosts or not?
The question arises from the observation that two hosts work just fine
while a third host can't connect at all.

Could you elaborate on your response that "wpa_supplicant does not do
any per-STA processing in IBSS mode"? Is this a missing piece in
wpa_supplicant or simply not needed at all?

>>This would be IEEE 802.11i IBSS, not WPA. You are talking
>>about WPA TK,
>>so I'm assuming this is indeed WPA-None, not IEEE 802.11i
>>IBSS. Anyway,
>>wpa_supplicant does not currently support IEEE 802.11i IBSS.

Since the standard 802.11i described clearly what is happening in IBSS 
mode. For example:

1. 4-Way Handshake for generation the session-key from the PSK-> each
adhoc link has different session-key
2. The session-key is used as input for data encryption for TKIP

If wpa_supplicant does not support 802.11i IBSS mode, how does WPA-None
work ?

For example, Is there any 4-Way-handshake for generation the 
session-key from the PSK?

>>WPA-None is sharing the same key with all clients..

But TKIP needs amongst others 2 keys (MIC-key and Temporal-Key) as input
for data encryption. 
So these two keys I guess must being somehow derived from the shared key

If there is no 4 Way-handshake implemted in wpa_supplicant in IBSS 
mode, then the 2 Keys must be somehow derived from the shared key

Correct ?

In this case all adhoc-link have the same key like WEP in IBSS mode.

Correct ?

So, if my experiment doesn't fail because of the key management, what
could be the reason? Has anybody ever tried this? On what hardware?

Thanks in advance for your patience
and kind regards

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