#747: LLC Header changed when capturing packets using monitor mode
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Reporter: feuerhahn[at]tkn.tu-berlin.de | Owner:
Type: defect | Status: new
Priority: major | Milestone:
Component: madwifi: other | Version:
Resolution: | Keywords: monitor mode
Patch_attached: 0 |
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Comment (by [EMAIL PROTECTED]):
Hi,
I've been battling with this problem as well, as I have been trying to
write an 802.11 decoder. It turns out that 802.11e (multimedia extensions)
adds 2 octets to the end of the MAC header, before the payload. Normally
these two bytes represent the ethertype of the payload, however with WME
they represent QoS bits and the payload (with ethertype) starts two octets
later. This is why some packets are OK but others arent.
You can tell if a data frame has these QoS bits by looking at the subtype
in the frame control field. The IEEE 802.11e-2005 document lists the new
subtypes on page 21.
Hope that helps,
--
Ticket URL: <http://madwifi.org/ticket/747>
MadWifi <http://madwifi.org/>
Multiband Atheros Driver for Wireless Fidelity
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