Having trouble with device or resource busy error in aircrack-ng; raspberry pi 3, raspbian

Question

I was using my raspberry pi 3 today trying to launch a deauth attack using aircrack-ng(Don't worry the network is mine). But I'm not here to talk about hacking I actually need help with setting up wlan0 and mon0. When I type in the following command this is what happens:

    sudo iwconfig wlan0 channel 11
    Error for wireless request "Set Frequency" (8B04) :
    SET failed on device wlan0 ; Device or resource busy.

Now I've heard there is a daemon that prevents the usage of this command; ifplugd, but when I try to stop the service it does this...

    sudo service ifplugd stop
    ifplugd: unrecognized service

So that doesn't work...but I think it should; when I go to the etc directory ifplugd is right there it even has its own sub-directory, I don't know what's wrong someone please help...

Answer 1

ifplugd has nothing to do with WiFi. If you want to get exclusive access to a wireless adapter, you should rather run

sudo service wpa_supplicant stop

Answer 2

To stop offending processes, as root airmon-ng check kill. It is usually something automagic, like dhclient or wpa_supplicant, and it may try to restart, so begin your aireplay-ng session immediately after doing this.