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RTL8811AU Driver Guide (AWUS036ACS)

Quick Summary: The Realtek RTL8811AU is the 1×1 AC433 chipset inside the 55 mm AWUS036ACS — the pocket-sized monitor-mode companion. Like its big brother the RTL8812AU, it needs the community rtl8811au driver via DKMS, but the build is identical.

Concept: same family, one stream​

The RTL8811AU is essentially the 1×1 variant of the RTL8812AU family: one spatial stream, 433 Mbps max on 5 GHz, lower power draw, smaller board. ALFA wraps it in the tiny ACS body with two 5 dBi external antennas — you get the classic ALFA pen-testing behavior in a package that hides in a pencil case.

Driver-wise, nothing changes from the RTL8812AU story: no in-kernel driver with monitor support, so we use the community rtl8811au DKMS driver. Note the driver also covers the RTL8821AU variant, so do not panic if your dkms status shows the same module name on similar dongles.

Prerequisites​

  • Linux (Ubuntu 20.04+ / Kali / Debian)
  • sudo apt install -y build-essential dkms git
  • sudo access
  • AWUS036ACS

Step 1: Clone and build​

cd /opt
sudo git clone https://github.com/aircrack-ng/rtl8811au.git
cd rtl8811au
sudo make dkms_install

Expected output:

DKMS: install completed.

Step 2: Load and verify​

sudo modprobe 8811au
iw dev

Expected output: an Interface wlan0 (or wlan1) line. If the adapter only shows up after re-plug, add the module to auto-load:

echo 8811au | sudo tee /etc/modules-load.d/alfa.conf

Step 3: Monitor mode + injection​

sudo airmon-ng check kill
sudo airmon-ng start wlan0
sudo aireplay-ng --test wlan0mon

Expected output:

PHY	Interface	Driver		Chipset
phy0	wlan0		8811au		Realtek Semiconductor Corp. RTL8811AU
...
12:34:56  Injection is working!
12:34:56  30/30:  100%

Step 4: Back to normal​

sudo airmon-ng stop wlan0mon
sudo systemctl restart NetworkManager

Troubleshooting​

SymptomCauseFix
DKMS build failsMissing headers / too-new kernelsudo apt install linux-headers-$(uname -r); sudo git pull && sudo make dkms_install
Interface only in managed modeKernel stub rtl8811au grabbed itecho "blacklist rtl8811au" | sudo tee /etc/modprobe.d/alfa-8811au.conf; reboot
Injection 0/30Empty channelsudo iw wlan0mon set channel 6; test near an AP
Throughput lower than expected1×1 radio (AC433) — hardware limitNot a bug; expect ~150–250 Mbps real-world on 5 GHz
Not detected after rebootModule not auto-loadedAdd 8811au to /etc/modules-load.d/alfa.conf

References​