#2 Inconsistent response to Probe Request

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nobody
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5
2006-03-29
2006-03-29
Rick Farrington
No

Using a wireless monitor, I have seen that the AP
does not consistently respond to probe requests. I
am attaching a log file in Ethereal format which
demonstrates this behavior.

1. probe requests (broadcast ssid) at: pkts 118-123,
125-128, 154-156, 158-162, 177-183

2. probe response at: pkts 184-197
** THREE seconds after initial request, two
responses, neither is ACK'd)

3. probe request (broadcast ssid) at: pkt 199
** almost TWO seconds later probe responses at: pkt
217 (no ACK until pkt 251)

4. probe request (broadcast ssid) at: pkt 282
** NO response

In this case the client associated; however in MOST
other cases, it will not. I have noticed that the
longer the AP has been running, the less likely that
probe responses will be issued. Also; this is not
isolated to one client - I have seen this behavior
with five different clients:

1. Dell Inspiron w/integrated IPW2915
2. Dell Inspiron w/Cisco a/b/g cardbus
3. HP iPaq
4. Toshiba laptop w/integrated IPW2200
5. Toshiba laptop w/integrated Atheros b/g

Since the probe requests are handled by the firmware,
I tried changing the settings of both
the 'respond_to_probe' and 'respond_to_bc' members of
the probe_response_control structure. I also
experimented with setting 4 basic rates (1,2,5.5 &
11) instead of the 2 basic rates (1 & 2) that are in
the code now. However, none of these changes made
any difference in the behavior of the anomaly.

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