rtl8821cu

Drivers for the rtl8821cu chipset for wireless adapters (D-Link DWA-171 rev C1)

Install driver

requirement

* kernel header

compile the driver

> cd driver
> make

test the driver (require cfg80211 loaded in system)

> sudo insmod 8821cu.ko

install driver

> sudo make install

auto switch from DISK mode to NIC mode

requirement (test with ubuntu 18.04):

1. install usb-modeswitch usb-modeswitch-data

    > sudo apt install usb-modeswitch usb-modeswitch-data

2. install udev

    > sudo apt install udev

install usb-modeswitch setting files

> cd usbswitch
> sudo make install

UEFI Secure Boot - (boot the kernel with signed)

if insmod the module it shows error of "Required key not available", you are using a kernel which is signed Only signed module can be use in this condition.

1. Create signing keys

    openssl req -new -x509 -newkey rsa:2048 -keyout MOK.priv -outform DER -out MOK.der -nodes -days 36500 -subj "/CN=Descriptive name/"

2. Sign the module

    sudo /usr/src/linux-headers-$(uname -r)/scripts/sign-file sha256 ./MOK.priv ./MOK.der /path/to/module

3. Register the keys to Secure Boot

    sudo mokutil --import MOK.der

​ Supply a password for later use after reboot

4. Reboot and follow instructions to Enroll MOK (Machine Owner Key). Here's a sample with pictures. The system will reboot one more time.
5. Confirm the key is enrolled

mokutil --test-key MOK.der