Internet over USB on android devices

#!/system/bin/sh
# Config
USBWAN="rndis0"
USBIPNET="192.168.0.150/24"
USBGW="192.168.0.1"
# stuff
echo "Starting IoUSB configurator"
case $USER in
        root)
                if [ "$(getprop sys.usb.config)" = 'rndis,adb' ]; then
                        echo "RNDIS enable"
                else
                        setprop sys.usb.config 'rndis,adb'
                        echo "RNDIS enable"
                fi
                ip address add $USBIPNET brd + dev $USBWAN >/dev/null 2>&1
                ip link set dev $USBWAN up >/dev/null 2>&1
                mobile_mark=$(ip ru |grep ccmni0 | head -1 | awk '{print $5}')
                wlan_mark=$(ip ru |grep wlan0 | head -1 | awk '{print $5}')
                echo "Replacing routes"
                if [ -n $mobile_mark ]; then
                        mark=$mobile_mark
                        ip route replace default via $USBGW dev $USBWAN table ccmni0 >/dev/null 2>&1
                        ip route delete default dev ccmni0 table ccmni0 >/dev/null 2>&1
                elif [ -n $wlan_mark ]; then
                        mark=$wlan_mark
                        ip route replace default via $USBGW dev $USBWAN table wlan0 >/dev/null 2>&1
                        ip route delete default dev wlan0 table wlan0 >/dev/null 2>&1
                else
                        echo "Abort! Enable Mobile or Wifi connetction!"
                        exit 0
                fi
                ip route delete default >/dev/null 2>&1
                iptables -t mangle -I INPUT -i $USBWAN -j MARK --set-mark $mark >/dev/null 2>&1
                iptables -I bw_INPUT -i $USBWAN -j ACCEPT >/dev/null 2>&1
                iptables -A bw_OUTPUT -o $USBWAN -j ACCEPT >/dev/null 2>&1
                ip route add default via $USBGW dev $USBWAN >/dev/null 2>&1
                echo "Done! IoUSB enabled"
        ;;
        *)
                echo "Abort! You are get permissions!"
        ;;
esac

exit $?