Проблема с `sudo airmon-ng start wlan0`

У меня Ubuntu 14.04 на Macbook Pro. Я пытался запустить:

sudo airmon-ng start wlan0

тогда результат был:

Found 5 processes that could cause trouble.
If airodump-ng, aireplay-ng or airtun-ng stops working after
a short period of time, you may want to kill (some of) them!

PID Name
899 avahi-daemon
904 avahi-daemon
978 NetworkManager
1298    wpa_supplicant
4408    dhclient

Process with PID 4408 (dhclient) is running on interface wlan0

Interface        Chipset                    Driver
wlan0             **Unknown**   wl - [phy0]mon0: ERROR while getting interface flags: No such device
                (monitor mode enabled on mon0)