No beacon activity

Lara Deek laradeek
Wed Feb 9 15:19:28 PST 2011

Thank you for your reply Jouni.

> Date: Sun, 6 Feb 2011 13:13:12 +0200
> From: Jouni Malinen <j at>
> Subject: Re: No beacon activity
> To: hostap at
> On Thu, Feb 03, 2011 at 10:53:50AM -0800, Lara Deek wrote:
> > 1) I am running a sniffer on the same machine A that is running hostapd.
> The
> > sniffer does not capture beacon messages (only captures probe request and
> > response packets, both broadcast and unicast). I ran a sniffer from
> another
> > machine B (with a different card) in monitor mode, and B does in fact
> > capture beacon messages (but never from A). Is there any reason why I do
> not
> > sniff beacon frames on A? How can I fix this?
> The actual Beacon frame transmission is not done by mac80211 and there
> is no mechanism for the driver to indicate that a Beacon frame was
> transmitted since this is not normally needed for anything. What would
> you be using the Beacon frames for in the local sniffer?
The beacons I would like machine A to capture are those of its neighboring
APs, to identify which APs can potentially conflict with it if they are on
the same channel. A does not capture any beacons, but only captures probe
request (broadcast) and response messages.

> > 2) I understand that hostapd only configures mac80211 with a template and
> > beacon interval, but does not actually send beacons. Is enabling beacon
> > transmission related to the firmware or driver? I have an AirMagnet C1060
> PC
> > card with an an Atheros, ath9k support, chipset that is not sending
> beacon
> > messages. How should enable beacon transmission?
> The driver is responsible for configuring Beacon frame transmissions.
> How exactly did you verify that the card is not sending out Beacon
> frames? Have you used another device in monitor mode to check that?
Yes, I have used another device in monitor mode (with an Ubiquiti SRC
802.11a/b/g MCX card with an AR5004 chipset), which captures beacons from
sources but never from A. A has an AirMagnet
has an AR5416+AR5133 ath9k supported chipset. I am not sure whether
the issues I am facing are actually due to limitations of the 802.11n PC
card I am using. Unfortunately, the card has no online support.

Otherwise, I am correctly configuring hostapd on A to run in master mode.
After running hostapd, running iwconfig on A indicates that it is in master
mode. The only problem is that there is no beacon activity. I would
appreciate any insight on what the problem could be.

Thank you,

> --
> Jouni Malinen                                            PGP id EFC895FA
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