Some time ago I a wrote a small tool in C for WiFi deauthentication that uses the libpcap library as a means to inject packets. Because it may be useful to someone, I published it on GitHub.

Simply run the automated installation script ./install.sh or look at the commands inside and run them manually. The script works on macOS and Linux distributions that use the package manager apt. On macOS, Homebrew has to be installed.

CDeauth (WiFi deauthentication in C) - (C) by Dustin Born 2016-2019 :

Usage: ./CDeauth [-c client] [-a access_point] [-n number]
                 [-i interface] [-h]

-a access point   :  MAC address of access point
-c client         :  MAC address or target client
-h                :  Print this help screen
-i interface      :  The interface on which to send the packets on
-n number         :  A integer specifying how many packets to send
                     (-1 for unlimited)
A client MAC, an access point MAC and an interface has to be specified.

Example: ./CDeauth -c AA:BB:CC:DD:EE:FF -a FF:EE:DD:CC:BB:AA -i wlan0

Note: The specified interface has to be in monitor mode and CDeauth may have to be run as root user.

Let <interface> be your WiFi interface. To put it into monitor mode, run:

sudo ifconfig <interface> down
sudo iwconfig <interface> mode monitor
sudo ifconfig <interface> up

Important: In case this does not work, you may have to make sure that the interface is not connected to a network prior to running these commands.

Alternatively you can use airmon-ng from the aircrack-ng suite.

CDeauth is licensed under the MIT license, see here.