MAC address change

Jouni Malinen jkmaline at
Tue Jun 1 00:13:04 EDT 2004

On Wed, May 26, 2004 at 12:29:58PM -0400, Mustafa C. Kuscu wrote:

> When I change the wireless NIC's MAC address using SIOCSIFHWADDR 
> ioctl(), the card associates to the AP using the new MAC (but it does 
> not send disassociation).
> Is this because of the hostap driver, or the firmware? More 
> specifically, to what extent can I control the procedure that the 
> ioctl() initiates such that those excessive associations can be 
> eliminated?

In theory, the firmware could send deauthentication in such a case, but
since changing the own MAC address is not really that common operation,
I would not be too surprised if the firmware would not be prepared for
disconnecting the old address. I do not see this as very common case
either, so I'm not likely to use much time on it. Anyway, you might be
able to force the driver to send out a deauthentication frame manually
by using the same MLME request ioctl (hostapd ioctl, sub-type
PRISM2_HOSTAPD_MLME) I use in wpa_supplicant. See
wpa_supplicant/driver_hostap.c for an example.

Jouni Malinen                                            PGP id EFC895FA

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