sudo airmon-ng start wlan0 sudo airodump-ng wlan0mon | Problem | Solution | |----------------------------------|-----------------------------------------------| | No interface shown in iwconfig | Plug in a compatible USB Wi-Fi adapter | | Interface exists but Fern fails | Run sudo airmon-ng check kill + manual monitor mode | | Still not working | Use Wifite or aircrack-ng instead of Fern | | Internal card only | Buy a supported external adapter (~$20–40) | Final Note Fern WiFi Cracker is old and less maintained. Many modern Kali users skip it in favor of Wifite (simpler) or aircrack-ng (more control). If you’re learning Wi-Fi penetration testing, focus on those instead.
For other chipsets, check:
sudo apt update sudo apt install realtek-rtl88xxau-dkms Then reboot.
| Chipset | Example Adapter | Monitor Mode | Packet Injection | |---------------|--------------------------------|--------------|------------------| | | Alfa AWUS036ACH | Yes | Yes | | RTL8187 | Alfa AWUS036H (legacy) | Yes | Yes | | AR9271 | TP-Link TL-WN722N (v1 only) | Yes | Yes | | MT7612U | Panda Wireless PAU09 | Yes | Yes | Kali Linux Fern Wifi Cracker No Wireless Interface Was Found
Avoid TP-Link TL-WN722N v2/v3 – they use a different chipset with poor Linux support. 6. Install/update drivers for your adapter If using an RTL88x2AU or RTL8812AU chipset:
sudo airmon-ng check kill This kills processes like NetworkManager , wpa_supplicant , etc.
If you see nothing, your adapter is either not connected or not recognized. NetworkManager and other services can block the interface. sudo airmon-ng start wlan0 sudo airodump-ng wlan0mon |
sudo fern-wifi-cracker Or if using the GUI launcher, make sure it runs as root. If you still get the error, your internal card likely won’t work. Recommended adapters (chipset must be supported):
ip a Look for wlan0 , wlan1 , or similar.
After running Fern, you can restart networking with: For other chipsets, check: sudo apt update sudo
iwconfig Or:
sudo systemctl restart NetworkManager Sometimes Fern fails to switch the card to monitor mode automatically. Do it manually:
sudo airmon-ng start wlan0 # Replace wlan0 with your interface name This creates a monitor interface like wlan0mon .