Alfa AWUS036ACH is an external WiFi adapter with a USB 3.0 interface. Its most remarkable features are the high power it has and its ability to inject packets. It’s a great device for security tests on wireless networks.
I wonder if this device has out of the box support with package injection in the latest kernels, but on Ubuntu 18.04 it’s necessary to install the driver, as it is not recognized by default. In this post we will see how this is done using the driver in the GitHub repository of aircrack-ng, which also includes support for the mentioned package injection. I did this work on my current GNU/Linux distribution, KDE Neon, which is based on Ubuntu 18.04.
Make sure you have dkms and wireless-tools packages installed before following this post:
Let’s connect the device and run dmesg to check the device detection:
$ dmesg
[ 3026.834346] usb 7-1.3: new high-speed USB device number 7 using xhci_hcd
[ 3026.948882] usb 7-1.3: New USB device found, idVendor=0bda, idProduct=8812, bcdDevice= 0.00
[ 3026.948885] usb 7-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3026.948887] usb 7-1.3: Product: 802.11n NIC
[ 3026.948889] usb 7-1.3: Manufacturer: Realtek
[ 3026.948890] usb 7-1.3: SerialNumber: 123456
Well. It’s detected, so let’s retrieve the source code of the driver using git.
$ git clone https://github.com/aircrack-ng/rtl8812au.git
Now we build and install the driver in the right place using DKMS. You can also install it as traditionally with make, but I prefer to use dkms to keep the kernel modules up-to-date automatically. This post gives a nice approach to the pros and contras of using DKMS.
Change to the new directory and run the dkms-install.sh script:
$ cd rtl8812au/
$ sudo ./dkms-install.sh
Enable your WiFi device adding the driver module to the kernel:
$ sudo modprobe 88XXau
Check the status of your wireless interface:
$ iwconfig
A new device should appear with the name wlx************ where stars are replaced by the mac address, for example, wlcCAFECAFECAFE:
wlcCAFECAFECAFE unassociated Nickname:"<WIFI@REALTEK>"
Mode:Managed Frequency=5.24 GHz Access Point: Not-Associated
Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Power Management:off
Link Quality=0/100 Signal level=0 dBm Noise level=0 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
And that’s it. Now you can connect to the wireless network you want with the CLI or GUI tools of your choice, or you can also have a little fun with aircrack-ng. Good winds Buccaneer!