Hostapd Multicast Group Key Issue on PowerPC vs x86

Damon Southworth damon
Fri May 1 15:15:50 PDT 2009


I have been chasing a problem over the last week regarding multicast
messages not getting through a WPA set-up with Hostapd and
Wpasupplicant. The configuration is using a straight forward WPA-PSK
encryption configuration using the madwifi 0.9.4 drivers.

The system is PowerPC based and to try and identify which component was
causing the problem I created the same setup on an x86 platform.
Surprisingly this x86 set-up worked without problem.

The problem is related to the group key as when the connection is
authenticated multicast messages come straight through on the x86 box
but do not come through on the PowerPC box until a group key re-key
takes place which is 600 seconds by default. A dirty workaround would be
to drop the group re-key time but there is still a delay and the side
affect of constant group re-keying.

I can supply config files/debug logs if the problem rings any bells with
anyone although both x86 and powerpc logs looking identical (except for
the encryption) to me so far.

Recent versions of the main components were used:
	Hostapd 0.6.9
	Wpasupplicant 0.6.4
	madwifi 0.9.4

For off the shelf multicast components to exhibit the problem mdns-scan
and bonjour/avahi can be used.



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