gistfile1.txt

#!/storage/xbin/bash

# This script should help forward VPN over any tethered connection on a Android device. 
# Turn on tethering, then enable VPN, then run this script.

# Inital variable setup
tethering=0

# Setup iptables before forwarding VPN
iptables -A POSTROUTING -o tun0 -j MASQUERADE -t nat

# Check if bluetooth is tethered, if so forward VPN
blue=$(/system/bin/ifconfig bt-pan 2>/dev/null | grep "UP" | wc -l)
blueIP=$(ifconfig bt-pan | grep "inet addr" | cut -d":" -f2 | cut -d' ' -f1 | cut -d'.' -f1-3)

if [[ "$blue" -gt 0 ]];
 then
  iptables -A FORWARD -i tun0 -o bt-pan -m state --state RELATED,ESTABLISHED -j RETURN
  iptables -A FORWARD -i bt-pan -o tun0 -m state --state INVALID -j DROP
  iptables -A FORWARD -i bt-pan -o tun0 -j RETURN
  ip rule add from $blueIP.0/24 lookup 61
  ip route add default dev tun0 scope link table 61
  ip route add $blueIP.0/24 dev bt-pan scope link table 61
  ip route add broadcast 255.255.255.255 dev bt-pan scope link table 61
  blueTethered=1
  tethering=1
  echo "Set up VPN on Bluetooth sucessfully"
 else
  blueTethered=0
  echo "Not tethering on Bluetooth"
fi

# Check if USB is tethered, if so forward VPN
usb=$(/system/bin/ifconfig rndis0 2>/dev/null | grep "UP" | wc -l)
usbIP=$(ifconfig rndis0 | grep "inet addr" | cut -d":" -f2 | cut -d' ' -f1 | cut -d'.' -f1-3)

if [[ "$usb" -gt 0 ]];
 then
  iptables -A FORWARD -i tun0 -o rndis0 -m state --state RELATED,ESTABLISHED -j RETURN
  iptables -A FORWARD -i rndis0 -o tun0 -m state --state INVALID -j DROP
  iptables -A FORWARD -i rndis0 -o tun0 -j RETURN
  ip rule add from $usbIP.0/24 lookup 61
  ip route add default dev tun0 scope link table 61
  ip route add $usbIP.0/24 dev rndis0 scope link table 61
  ip route add broadcast 255.255.255.255 dev rndis0 scope link table 61
  usbTethered=1
  tethering=1
  echo "Set up VPN on USB successfully"
  usbTethered=0
  echo "Not tethering on USB"
fi

# Check if WIFI is tethered, if so forward VPN 
wifi=$(dumpsys wifi | grep curState=TetheredState | wc -l)
wifiIP=$(ifconfig wlan0 | grep "inet addr" | cut -d":" -f2 | cut -d' ' -f1 | cut -d'.' -f1-3)

if [[ "$wifi" -gt 0 ]];
 then
  iptables -A FORWARD -i tun0 -o wlan0 -m state --state RELATED,ESTABLISHED -j RETURN
  iptables -A FORWARD -i wlan0 -o tun0 -m state --state INVALID -j DROP
  iptables -A FORWARD -i wlan0 -o tun0 -j RETURN
  ip rule add from $wifiIP.0/24 lookup 61
  ip route add default dev tun0 scope link table 61
  ip route add $wifiIP.0/24 dev wlan0 scope link table 61
  ip route add broadcast 255.255.255.255 dev wlan0 scope link table 61
  wifiTethered=1
  tethering=1
  echo "Set up VPN on WIFI successfully"
 else
  wifiTethered=0
  echo "Not tethering on WIFI"
fi

# Clean up if no tethering is occuring
if [[ "$tethering" -eq 0 ]];
 then
  iptables -D POSTROUTING -o tun0 -j MASQUERADE -t nat
   if [[ "$blueTethered" -gt 0 ]];
    then
     iptables -D FORWARD -i tun0 -o bt-pan -m state --state RELATED,ESTABLISHED -j RETURN
     iptables -D FORWARD -i bt-pan -o tun0 -m state --state INVALID -j DROP
     iptables -D FORWARD -i bt-pan -o tun0 -j RETURN
     ip rule delete from $blueIP.0/24 lookup 61
     ip route delete default dev tun0 scope link table 61
     ip route delete $blueIP.0/24 dev bt-pan scope link table 61
     ip route delete broadcast 255.255.255.255 dev bt-pan scope link table 61
   fi
   if [[ "$usbTethered" -gt 0 ]];
     iptables -D FORWARD -i tun0 -o rndis0 -m state --state RELATED,ESTABLISHED -j RETURN
     iptables -D FORWARD -i rndis0 -o tun0 -m state --state INVALID -j DROP
     iptables -D FORWARD -i rndis0 -o tun0 -j RETURN
     ip rule delete from $usbIP.0/24 lookup 61
     ip route delete default dev tun0 scope link table 61
     ip route delete $usbIP.0/24 dev rndis0 scope link table 61
     ip route delete broadcast 255.255.255.255 dev rndis0 scope link table 61
   fi
   if [[ "$wifiTethered" -gt 0 ]];
     iptables -D FORWARD -i tun0 -o wlan0 -m state --state RELATED,ESTABLISHED -j RETURN
     iptables -D FORWARD -i wlan0 -o tun0 -m state --state INVALID -j DROP
     iptables -D FORWARD -i wlan0 -o tun0 -j RETURN
     ip rule delete from $wifiIP.0/24 lookup 61
     ip route delete default dev tun0 scope link table 61
     ip route delete $wifiIP.0/24 dev wlan0 scope link table 61
     ip route delete broadcast 255.255.255.255 dev wlan0 scope link table 61
   fi
  echo "Cleaned up iptables rules since we are not tethering"
 else
  echo "Sucessfully forwarding VPN over tethering"
fi