How hostapd get frames from Driver??

Jouni Malinen jkmaline
Sat Feb 10 20:12:17 PST 2007

On Sun, Jan 14, 2007 at 12:45:07PM +1100, Nazeer Khan wrote:

> I just wanted to ask how hostapd get frames from the driver. I am
> interested about wireless (madwifi). I am a bit confused. Is madwifi
> stripping off the 802.11 header and giving the resultant to hostapd or
> hostapd itself stips off the 802.11 header??

In case of madwifi driver, yes, the driver/net80211 is taking care of
802.11 management frames (i.e., hostapd does not receive them) and the
driver converts the 802.11 header in data frames to Ethernet headers.

> I am not sure but wat i understand by looking at the code in "l2_packet.h"
> and "l2_packet_linux.c" is that hostapd deals with ethernet frames not
> 802.11 frames. Am i right??

Yes, l2_packet is used to receive data frames with Ethernet header. In
case of madwifi, this is used to receive EAPOL frames from IEEE
802.1X/WPA authentication.

> I wanted to ask how hostapd is getting frames from the driver. (Whether
> they are ethernet or wireless)

Depends on the driver.. The description above is for madwifi. In case of
Host AP driver and net/d80211 (Devicescape stack), frames are delivered
differently and hostapd is actually receiving them with 802.11 headers.

Jouni Malinen                                            PGP id EFC895FA

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