Reverse Tether - Samsung Galaxy Player 4.0, 5.0

I currently run Paranoid Android on my SG5, which works well enough for my tastes. One thing I've wanted to play with is reverse tethering. Since I charge my player via the computer's usb connection, I figured it'd make sense to disable wifi and save a little power to speed up the slow usb charging and just use the pc's internet connection via usb. I also have a few apps like calibre and the compantion app which don't work correctly when I'm on a wifi connection that's been firewalled to prevent devices from communicating with each other. This bypasses the wifi connection and gives me a nice secure connection between devices.
I got it working ... mostly. I don't expect many people to find this useful, but I thought it might be an entertaining hack to poke at.
The following script sits on my linux netbooks' ~/bin directory as reverse-tether.sh
Code:
#!/bin/sh
# We need root on the host to mess with networking
if [[ $(whoami) != "root" ]]; then
echo "You must be root to run this script!"
exit 1
fi;
# We need root on the Player to mess with networking
echo 'Enabling adb root access...'
adb -d root
# Turn on usb networking
echo 'Enabling usb network interface on the Galaxy Player...'
adb -d shell 'sh /storage/sdcard0/reverse_tether.sh up &'
# adb disconnects, so we wait for the network on the player to settle before continuing on.
sleep 2
# Rename device interface as ArchLinux has annoying device names (becomes player)
IF=`ifconfig -a | grep "enp" | cut -d ':' -f 1`
ip link set dev $IF down
/usr/sbin/ifrename -i $IF -n player
ip link set dev player up
echo 'Setting Computer IP Address ...'
ifconfig player 192.168.200.1 netmask 255.255.255.0
ifconfig player up
echo 'Enabling NAT and IP Forwarding on Computer...'
# Start forwarding and nat (use existing default gw)
iptables -F -t nat
iptables -A POSTROUTING -t nat -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward
echo 'Starting dnsmasq on Computer...'
dnsmasq --interface=player --no-dhcp-interface=player
echo
echo 'Connection is ready! Press any key to shutdown.'
echo
read
echo 'Shutting down reverse tethering'
# SSH server is always running on player, with public rsa key imported for passwordless logins
# This hackery is required as adb seems to be disabled with rndis active.
# I use dropbear server II, but any of the ssh servers would probably work.
ssh [email protected] 'sh /storage/sdcard0/reverse_tether.sh down &'
killall dnsmasq
ifconfig player down
iptables -F -t nat
echo 0 > /proc/sys/net/ipv4/ip_forward
And the following script is simply stashed on the sdcard of the player. as /storage/sdcard0/reverse_tether.sh
Code:
#!/system/bin/sh
if [ "$1" = "up" ]; then
echo 1 > /sys/class/usb_composite/rndis/enable
ip addr add 192.168.200.2/24 dev usb0
ip link set usb0 up
ip route delete default
ip route add default via 192.168.200.1
setprop net.dns1 192.168.200.1
fi
if [ "$1" = "down" ]; then
sleep 2
ip route delete default
ip link set usb0 down
echo 0 > /sys/class/usb_composite/rndis/enable
fi
When I finish, sometimes I need to restart wifi on the player to get networking to work again.
The only real problem I've had is that some apps require or want wifi/3g active in order to fully function. For example, the play store works fine until you try and download an actual update. Google Maps works fine, although you get lots of warnings about having wifi turned off. I have no idea how to "emulate" 3g or wifi which I think would solve that problem.
This was fun getting running. Hope you enjoyed...

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I know this is an old thread but I found this really really useful. Going to give it a try after work today. Great job.
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