start-mon.sh

#!/bin/bash

SCRIPT_NAME="start-mon.sh"
SCRIPT_VERSION="20230305"


# Purpose: Start and configure monitor mode on the provided wifi interface

# Usage: $ sudo ./start-mon.sh [interface]


clear


# check to ensure sudo was used to start the script
if [ "$(id -u)" -ne 0 ]; then
	echo "You must run this script with superuser (root) privileges."
	echo "Try: \"sudo ./${SCRIPT_NAME}\""
	exit 1
fi


# check to ensure iw is installed
if ! command -v iw >/dev/null 2>&1; then
	echo "A required package is not installed."
	echo "Please install the following package: iw"
	echo "Once the package is installed, please run \"sudo ./${SCRIPT_NAME}\""
	exit 1
fi


# check to ensure ip is installed
if ! command -v ip >/dev/null 2>&1; then
	echo "A required package is not installed."
	echo "Please install the following package: ip"
	echo "Once the package is installed, please run \"sudo ./${SCRIPT_NAME}\""
	exit 1
fi


# select option to set automatic (1) or manual (2) interface name capture mode
#
# option 1: if you only have one wlan interface (automatic detection)
#iface0=$(iw dev | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
#
# option 2: if you have more than one wlan interface
iface0=${1}


# assign default channel
chan="6"


# set iface0 down
ip link set dev "$iface0" down
RESULT=$?
# if interface was successfully taken down, continue
if [ "$RESULT" = "0" ]; then
#	disable interfering processes
	PROCESSES="wpa_action\|wpa_supplicant\|wpa_cli\|dhclient\|ifplugd\|dhcdbd\|dhcpcd\|udhcpc\|NetworkManager\|knetworkmanager\|avahi-autoipd\|avahi-daemon\|wlassistant\|wifibox\|net_applet\|wicd-daemon\|wicd-client\|iwd"
#	unset match
#	match="$(ps -A -o comm= | grep ${PROCESSES} | grep -v grep | wc -l)"
	# shellcheck disable=SC2009
	badProcs=$(ps -A -o pid=PID -o comm=Name | grep "${PROCESSES}\|PID")
	# shellcheck disable=SC2009
	for pid in $(ps -A -o pid= -o comm= | grep ${PROCESSES} | awk '{print $1}'); do
		command kill -19 "${pid}"
#				(-19 = STOP)
	done
	clear
	echo
	echo ' The following processes have been stopped:'
	echo
	echo "${badProcs}"
	echo
	echo ' Note: The above processes can be returned'
	echo ' to a normal state at the end of this script.'
	echo
	read -p " Press any key to continue... " -n 1 -r


# display interface settings
	clear
	echo
	echo ' --------------------------------'
	echo -e "    ${SCRIPT_NAME} ${SCRIPT_VERSION}"
	echo ' --------------------------------'
	echo '    WiFi Interface:'
	echo '             '"$iface0"
	echo ' --------------------------------'
	iface_name=$(iw dev "$iface0" info | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
	echo '    name  - ' "$iface_name"
	iface_type=$(iw dev "$iface0" info | grep 'type' | sed 's/type //' | sed -e 's/^[ \t]*//')
	echo '    type  - ' "$iface_type"
	iface_state=$(ip addr show "$iface0" | grep 'state' | sed 's/.*state \([^ ]*\)[ ]*.*/\1/')
	echo '    state - ' "$iface_state"
	iface_addr=$(iw dev "$iface0" info | grep 'addr' | sed 's/addr //' | sed -e 's/^[ \t]*//')
	echo '    addr  - ' "$iface_addr"
	echo ' --------------------------------'
	echo


# set addr (has to be done before renaming the interface)
	iface_addr_orig=$iface_addr
	read -p " Do you want to set a new addr? [y/N] " -n 1 -r
	echo
	if [[ $REPLY =~ ^[Yy]$ ]]
	then
		read -p " What addr do you want? ( e.g. 12:34:56:78:90:ab ) " -r iface_addr
		re="^([a-fA-F0-9]{2}:){5}[a-fA-F0-9]{2}$"
		while [[ ! "$iface_addr" =~ $re ]]
		do
			read -p " Invalid addr format, try again: " -r iface_addr
		done
		ip link set dev "$iface0" address "$iface_addr"
		# shellcheck disable=SC2181
		while [[ $? -ne 0 ]]
		do
			read -p " Setting addr failed, try again: " -r iface_addr
			while [[ ! "$iface_addr" =~ $re ]]
			do
				read -p " Invalid addr format, try again: " -r iface_addr
			done
			ip link set dev "$iface0" address "$iface_addr"
		done
	fi


# set monitor mode
#	iw dev <devname> set monitor <flag>
#		Valid monitor flags are:
#		none:     no special flags
#		fcsfail:  show frames with FCS errors
#		control:  show control frames
#		otherbss: show frames from other BSSes
#		cook:     use cooked mode
#		active:   use active mode (ACK incoming unicast packets)
#		mumimo-groupid <GROUP_ID>: use MUMIMO according to a group id
#		mumimo-follow-mac <MAC_ADDRESS>: use MUMIMO according to a MAC address
	iw dev "$iface0" set monitor none


# assign monitor mode interface name
#	info:	Realtek out-of-kernel drivers have problems when trying to rename
#		interfaces on some systems.
#	info:	The above may be corrected by turning off the following:
#		PREDICTABLE NETWORK INTERFACE NAMES
#	more info: https://wiki.debian.org/NetworkInterfaceNames#initrd
#	info:	Realtek out-of-kernel drivers do not handle deleting or adding
#		interface names. There is no virtual interface support.
#	info:	In-kernel drivers do not have the above problems.
#
	iface0mon="$iface0"
	if [ "$iface0mon" = "wlan0" ]; then
		iface0mon="wlan0mon"
	fi
	if [ "$iface0mon" = "wlan1" ]; then
		iface0mon="wlan1mon"
	fi
	ip link set dev "$iface0" name $iface0mon


# bring the interface up
	ip link set dev "$iface0mon" up


# set channel to default
	iw dev "$iface0mon" set channel "$chan"


# display interface settings
	clear
	echo
	echo ' --------------------------------'
	echo -e "    ${SCRIPT_NAME} ${SCRIPT_VERSION}"
	echo ' --------------------------------'
	echo '    WiFi Interface:'
	echo '             '"$iface0"
	echo ' --------------------------------'
	iface_name=$(iw dev "$iface0mon" info | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
	echo '    name  - ' "$iface_name"
	iface_type=$(iw dev "$iface0mon" info | grep 'type' | sed 's/type //' | sed -e 's/^[ \t]*//')
	echo '    type  - ' "$iface_type"
	iface_state=$(ip addr show "$iface0mon" | grep 'state' | sed 's/.*state \([^ ]*\)[ ]*.*/\1/')
	echo '    state - ' "$iface_state"
	iface_addr=$(iw dev "$iface0mon" info | grep 'addr' | sed 's/addr //' | sed -e 's/^[ \t]*//')
	echo '    addr  - ' "$iface_addr"
	iface_chan=$(iw dev "$iface0mon" info | grep 'channel' | sed 's/channel //' | sed -e 's/^[ \t]*//')
	echo '    chan  - ' "$iface_chan"
	echo ' --------------------------------'
	echo


# set channel
#	Documentation:
#	iw dev <devname> set channel <channel> [NOHT|HT20|HT40+|HT40-|5MHz|10MHz|80MHz]
#	iw dev <devname> set freq <freq> [NOHT|HT20|HT40+|HT40-|5MHz|10MHz|80MHz]
#	iw dev <devname> set freq <control freq> [5|10|20|40|80|80+80|160] [<center1_freq> [<center2_freq>]]
	read -p " Do you want to set the channel? [y/N] " -n 1 -r
	echo
	if [[ $REPLY =~ ^[Yy]$ ]]
	then
		read -p " What channel do you want to set? " -r chan
#	Select one or modify as required:
		iw dev "$iface0mon" set channel "$chan" HT20
#		iw dev "$iface0mon" set channel "$chan" HT40-
#		iw dev "$iface0mon" set channel "$chan" 80MHz
	fi


# display interface settings
	clear
	echo
	echo ' --------------------------------'
	echo -e "    ${SCRIPT_NAME} ${SCRIPT_VERSION}"
	echo ' --------------------------------'
	echo '    WiFi Interface:'
	echo '             '"$iface0"
	echo ' --------------------------------'
	iface_name=$(iw dev "$iface0mon" info | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
	echo '    name  - ' "$iface_name"
	iface_type=$(iw dev "$iface0mon" info | grep 'type' | sed 's/type //' | sed -e 's/^[ \t]*//')
	echo '    type  - ' "$iface_type"
	iface_state=$(ip addr show "$iface0mon" | grep 'state' | sed 's/.*state \([^ ]*\)[ ]*.*/\1/')
	echo '    state - ' "$iface_state"
	iface_addr=$(iw dev "$iface0mon" info | grep 'addr' | sed 's/addr //' | sed -e 's/^[ \t]*//')
	echo '    addr  - ' "$iface_addr"
	iface_chan=$(iw dev "$iface0mon" info | grep 'channel' | sed 's/channel //' | sed -e 's/^[ \t]*//')
	echo '    chan  - ' "$iface_chan"
	iface_txpw=$(iw dev "$iface0mon" info | grep 'txpower' | sed 's/txpower //' | sed -e 's/^[ \t]*//')
	echo '    txpw  - ' "$iface_txpw"
	echo ' --------------------------------'
	echo


# set txpw
	read -p " Do you want to set the txpower? [y/N] " -n 1 -r
	echo
	if [[ $REPLY =~ ^[Yy]$ ]]
	then
		echo " Notes: Some USB WiFi adapters will not allow the txpw to be set."
		echo "        Be careful to not increase power to the point that you overheat the adapter."
		echo
		read -p " What txpw setting do you want to attempt to set? ( e.g. 2300 = 23 dBm ) " -r iface_txpw
		iw dev "$iface0mon" set txpower fixed "$iface_txpw"
	fi


# display interface settings
	clear
	echo
	echo ' --------------------------------'
	echo -e "    ${SCRIPT_NAME} ${SCRIPT_VERSION}"
	echo ' --------------------------------'
	echo '    WiFi Interface:'
	echo '             '"$iface0"
	echo ' --------------------------------'
	iface_name=$(iw dev "$iface0mon" info | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
	echo '    name  - ' "$iface_name"
	iface_type=$(iw dev "$iface0mon" info | grep 'type' | sed 's/type //' | sed -e 's/^[ \t]*//')
	echo '    type  - ' "$iface_type"
	iface_state=$(ip addr show "$iface0mon" | grep 'state' | sed 's/.*state \([^ ]*\)[ ]*.*/\1/')
	echo '    state - ' "$iface_state"
	iface_addr=$(iw dev "$iface0mon" info | grep 'addr' | sed 's/addr //' | sed -e 's/^[ \t]*//')
	echo '    addr  - ' "$iface_addr"
	iface_chan=$(iw dev "$iface0mon" info | grep 'channel' | sed 's/channel //' | sed -e 's/^[ \t]*//')
	echo '    chan  - ' "$iface_chan"
	iface_txpw=$(iw dev "$iface0mon" info | grep 'txpower' | sed 's/txpower //' | sed -e 's/^[ \t]*//')
	echo '    txpw  - ' "$iface_txpw"
	echo ' --------------------------------'
	echo
	echo ' DORMANT = up but inactive.'
	echo


# interface ready
	echo " Ready for Monitor Mode use."
	echo
	echo ' You can place this terminal in'
	echo ' the background while you run any'
	echo ' applications you wish to run.'
	echo
	read -p " Press any key to exit... " -n 1 -r
	echo


# return the adapter to original settings or not
	read -p " Do you want to return the adapter to original settings? [Y/n] " -n 1 -r
	if [[ $REPLY =~ ^[Nn]$ ]]
	then
#	display interface settings
		clear
		echo
		echo ' --------------------------------'
		echo -e "    ${SCRIPT_NAME} ${SCRIPT_VERSION}"
		echo ' --------------------------------'
		echo '    WiFi Interface:'
		echo '             '"$iface0"
		echo ' --------------------------------'
		iface_name=$(iw dev "$iface0mon" info | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
		echo '    name  - ' "$iface_name"
		iface_type=$(iw dev "$iface0mon" info | grep 'type' | sed 's/type //' | sed -e 's/^[ \t]*//')
		echo '    type  - ' "$iface_type"
		iface_state=$(ip addr show "$iface0mon" | grep 'state' | sed 's/.*state \([^ ]*\)[ ]*.*/\1/')
		echo '    state - ' "$iface_state"
		iface_addr=$(iw dev "$iface0mon" info | grep 'addr' | sed 's/addr //' | sed -e 's/^[ \t]*//')
		echo '    addr  - ' "$iface_addr"
		echo ' --------------------------------'
		echo
		exit 0
	else
		ip link set dev "$iface0mon" down
		ip link set dev "$iface0mon" address "$iface_addr_orig"
		iw "$iface0mon" set type managed
		ip link set dev "$iface0mon" name "$iface0"
		ip link set dev "$iface0" up
#	enable interfering processes
		# shellcheck disable=SC2009
		for pid in $(ps -A -o pid= -o comm= | grep ${PROCESSES} | awk '{print $1}'); do
			command kill -18 "${pid}"   # -18 = CONT
		done
#	display interface settings
		clear
		echo
		echo ' --------------------------------'
		echo -e "    ${SCRIPT_NAME} ${SCRIPT_VERSION}"
		echo ' --------------------------------'
		echo '    WiFi Interface:'
		echo '             '"$iface0"
		echo ' --------------------------------'
		iface_name=$(iw dev "$iface0" info | grep 'Interface' | sed 's/Interface //' | sed -e 's/^[ \t]*//')
		echo '    name  - ' "$iface_name"
		iface_type=$(iw dev "$iface0" info | grep 'type' | sed 's/type //' | sed -e 's/^[ \t]*//')
		echo '    type  - ' "$iface_type"
		iface_state=$(ip addr show "$iface0" | grep 'state' | sed 's/.*state \([^ ]*\)[ ]*.*/\1/')
		echo '    state - ' "$iface_state"
		iface_addr=$(iw dev "$iface0" info | grep 'addr' | sed 's/addr //' | sed -e 's/^[ \t]*//')
		echo '    addr  - ' "$iface_addr"
		echo ' --------------------------------'
		echo
		exit 0
	fi
else
	clear
	echo
	echo " ERROR: Please provide an existing interface as parameter!"
	echo -e " Usage: $ sudo ./$SCRIPT_NAME [interface]"
	echo " Tip:   $ iw dev"
	echo
	exit 1
fi