----- 2022-01-25 ## Monitor Mode Purpose: Provide information and tools for testing and using monitor mode with the following Realtek drivers: ``` https://github.com/morrownr/8812au-20210629 https://github.com/morrownr/8821au-20210708 https://github.com/morrownr/8821cu-20210118 https://github.com/morrownr/88x2bu-20210702 https://github.com/morrownr/8814au ``` Note: This document and the `start-mon.sh` script will work with adapters that use in-kernel drivers but it is not necessary as the use of any of the many guides that are available should work fine as the in-kernel drivers work in the textbook, standards compliant manner. Please submit corrections or additions via Issues. Monitor mode, or RFMON (Radio Frequency MONitor) mode, allows a computer with a wireless network interface controller (WNIC) to monitor all traffic received on a wireless channel. Monitor mode allows packets to be captured without having to associate with an access point or ad hoc network first. Monitor mode only applies to wireless networks, while promiscuous mode can be used on both wired and wireless networks. Monitor mode is one of the eight modes that 802.11 wireless cards and adapters can operate in: Master (acting as an access point), Managed (client, also known as station), Ad hoc, Repeater, Mesh, Wi-Fi Direct, TDLS and Monitor mode. Note: This document and the `start-mon.sh` script have been tested on the following: ``` Kali Linux Raspberry Pi OS Linux Mint Ubuntu ``` ----- ## Steps to start/test monitor mode #### Install USB WiFi adapter and driver per instructions. #### Update system ``` sudo apt update ``` ``` sudo apt full-upgrade ``` ----- #### Ensure WiFi radio is not blocked ``` sudo rfkill unblock wlan ``` ----- #### Install aircrack-ng (optional) ``` sudo apt install -y aircrack-ng ``` ----- #### Check wifi interface information ``` iw dev ``` ----- #### Information The wifi interface name `wlan0` is used in this document but you will need to substitute the name of your wifi interface while using this document. ----- #### Enter and check monitor mode A script called `start-mon.sh` is available in the driver directory. It will automate much of the following. Usage: ``` sudo ./start-mon.sh [interface:wlan0] ``` Note: If you want to do things manually, continue below. ----- #### Disable interfering processes (see note about `start-mon.sh` below) ``` sudo airmon-ng check kill ``` Note: `start-mon.sh` is capable of disabling interfering processes. It uses a different method than airmon-ng. Airmon-ng kills the processes whereas `start-mon.sh` simply stops the processes and restarts them when the script terminates. Stopping the processes seems to have some advantages over killing them. Advantage 1: When killing the very clever interfering processes, you may find that interfering processes are able to spawn new processes that will continue to interfer. Stopping the interfering processes does not seem to trigger the spawning of new processes. Advantage 2: If you use more than one wifi adapter/card in the system, and if you need one of the adapter/cards to stay connected to the internet, killing the processes may cause your internet connection to drop. Stopping the processes does not cause your internet connection to drop. Advantage 3: Stopping the processes allows the processes to be restarted. The `start-mon.sh` script can put your interface in monitor mode, properly configured, and then return your system, including stopped processes and interface to original settings. This can reduce reboots that sometimes might have been needed to reset things to normal operation. #### Change to monitor mode Option 1 (the airmon-ng way) Note: This option may not work with some driver/adapter combinations (I'm looking at you Realtek). If this option does not work, you can use Option 2 or the `start-mon.sh` script that was previously mentioned. ``` sudo airmon-ng start ``` Option 2 (the manual way) Check the wifi interface name and mode ``` iw dev ``` Take the interface down ``` sudo ip link set down ``` Set monitor mode ``` sudo iw set monitor control ``` Bring the interface up ``` sudo ip link set up ``` Verify the mode has changed ``` iw dev ``` ----- ### Test injection Option for 5 GHz and 2.4 GHz ``` sudo airodump-ng --band ag ``` Option for 5 GHz only ``` sudo airodump-ng --band a ``` Option for 2.4 GHz only ``` sudo airodump-ng --band g ``` Set the channel of your choice ``` sudo iw dev set channel [NOHT|HT20] ``` ``` sudo aireplay-ng --test ``` ----- ### Test deauth Option for 5 GHz and 2.4 GHz ``` sudo airodump-ng --band ag ``` Option for 5 GHz only ``` sudo airodump-ng --band a ``` Option for 2.4 GHz only ``` sudo airodump-ng --band g ``` ``` sudo airodump-ng --bssid --channel ``` Option for 5 GHz: ``` sudo aireplay-ng --deauth 0 -c -a -D ``` Option for 2.4 GHz: ``` sudo aireplay-ng --deauth 0 -c -a ``` ----- ### Revert to Managed Mode Check the wifi interface name and mode ``` iw dev ``` Take the wifi interface down ``` sudo ip link set down ``` Set managed mode ``` sudo iw set type managed ``` Bring the wifi interface up ``` sudo ip link set up ``` Verify the wifi interface name and mode has changed ``` iw dev ``` ----- ### Change the MAC Address before entering Monitor Mode Check the wifi interface name, MAC address and mode ``` iw dev ``` Take the wifi interface down ``` sudo ip link set dev down ``` Change the MAC address ``` sudo ip link set dev address ``` Set monitor mode ``` sudo iw set monitor control ``` Bring the wifi interface up ``` sudo ip link set dev up ``` Verify the wifi interface name, MAC address and mode has changed ``` iw dev ``` ----- ### Change txpower ``` sudo iw dev set txpower fixed 1600 ``` Note: 1600 = 16 dBm ----- ### Information airodump-ng can receive and interpret key strokes while running. ``` The following list describes the currently assigned keys and supported actions: a Select active areas by cycling through these display options: AP+STA; AP+STA+ACK; AP only; STA only d Reset sorting to defaults (Power) i Invert sorting algorithm m Mark the selected AP or cycle through different colors if the selected AP is already marked o Enable colored display of APs and their stations. p Disable colored display. q Quit program. r (De-)Activate realtime sorting - applies sorting algorithm every time the display will be redrawn s Change column to sort by, which currently includes: BSSID; PWR level; Beacons; Data packets; Packet rate; Channel; Max. data rate; Encryption; Strongest Ciphersuite; Strongest Authentication; ESSID ``` -----