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Mac80211 is the new wireless stack of the Linux kernel. It is included in the kernel since 2.6.22, but drivers are only included since 2.6.24.
The following drivers use mac80211 (not all have been tested to work with aircrack-ng):
In general, these drivers will mostly work with aircrack-ng, but there may be exceptions. Here is a list of drivers (with appropriate patches) that people have reported as working successfully with the aircrack-ng suite:
Mac80211 introduced changes to monitor mode to support the Radiotap standard. Radiotap is a new packet header format, similar to the Prism header. As mac80211 requires all injected packets to have a Radiotap header, which is not supported in aircrack-ng 0.9, injection requires at least aircrack-ng 1.0-rc1.
The mac80211 stack supports injection natively. However, to use any fragmentation attacks with a mac80211 driver, you need to patch the mac80211 stack.
Depending on what you are using, here are the patching instructions:
Airmon-ng supports mac80211's interface management features (nl80211) using a tool called iw (not to be confused with iwconfig). iw is called automatically by the airmon-ng script, or you might also call it directly to set up monitor interfaces.
Iw is not part of the aircrack-ng suite. You can download it from here. Choose the latest version, or at least 0.9.5. Iw requires a recent version of libnl (1.0-pre8 minimum, 1.1 recommended).
When running airodump-ng or aireplay-ng's test attack, you can notice PWR readings in the range 150~250. This is due to mac80211 returning the signal strength values in dBm, which is almost always a negative number, and aircrack-ng treats the negative reading incorrectly. This is fixed in the latest SVN trunk, where airodump-ng shows signal strength correctly in dBm.
Workaround: Try an SVN trunk build.