Replicant USB Networking¶

This page explains how to connect your Replciant phone to the Internet via an USB connection to a computer connected to the Internet.

What you need¶

• A phone running Replicant (but it should also work on CyanogenMod or Android)
• A computer with USB connectivity and network access running GNU/Linux

Automation scripts¶

Two scripts are necessary: one to run on the host computer and one to run on the device.

Replicant USB Networking - PC¶

Here's the script to run on the computer. Copy the following text to a file named "run_pc.sh" (or any other name, you just need to keep the same name along the process):

#!/bin/sh

# Replicant USB Networking
# ========================                             
# 
# Copyright (C) 2011 Paul Kocialkowski, GPLv3+
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

IPTABLES_CLEAN_RULES=true

USB_IFACE="usb0" 
INTERNET_IFACE="eth0" 

USB_IFACE_IP="192.168.4.200" 

# Clean iptables rules

iptables_rules_clean () {
    if [ $IPTABLES_CLEAN_RULES = false ]
    then
        return
    fi

    iptables --flush
    iptables --table nat --flush
    iptables --delete-chain
    iptables --table nat --delete-chain
}

# Inject iptables forwarding rules

iptables_forward_rules_apply () {
    iptables --table nat --append POSTROUTING --out-interface $INTERNET_IFACE -j MASQUERADE
    iptables --append FORWARD --in-interface $USB_IFACE -j ACCEPT
    echo 1 > /proc/sys/net/ipv4/ip_forward 
}

# Configure network link

usb_networking_configure () {
    ifconfig $USB_IFACE up
    ifconfig $USB_IFACE $USB_IFACE_IP
}

usb_networking_disable () {
    ifconfig $USB_IFACE down
    echo 0 > /proc/sys/net/ipv4/ip_forward 
}

case $1 in
    "start")
        echo "Starting Replicant USB Networking" 
        iptables_rules_clean
        usb_networking_configure
        iptables_forward_rules_apply
    ;;
    "stop")
        echo "Stopping Replicant USB Networking" 
        usb_networking_disable
        iptables_rules_clean
    ;;
    *)
        echo "Usage: sh $0 {start|stop}" 
    ;;
esac

Then, set this file executable: chmod a+x run_pc.sh

Replicant USB Networking - Device¶

Here's the script to run on the device. Copy the following text to a file named "run_dev.sh" (or any other name, you just need to keep the same name along the process):

#!/system/bin/sh

# Replicant USB Networking
# ========================                             
# 
# Copyright (C) 2011 Paul Kocialkowski, GPLv3+
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Enable USB Networking

USB_IFACE="usb0" 

USB_IFACE_IP="192.168.4.202" 
GATEWAY_IP="192.168.4.200" 
DNS1_IP="8.8.8.8" 

usb_networking_enable () {
    echo 1 > /sys/class/usb_composite/rndis/enable
    ifconfig usb0 up
}

usb_networking_configure () {
    ifconfig $USB_IFACE $USB_IFACE_IP
    route add default gw $GATEWAY_IP dev $USB_IFACE
    setprop net.dns1 $DNS1_IP

    # setprop net.dns1 $( cat /system/etc/resolv.conf | sed -e "s|.*#.*||" -e "s|^.*nameserver \(.*\)$|\1|g" | grep -v "^$" | head -n 1 )
}

usb_networking_disable () {
    echo 0 > /sys/class/usb_composite/rndis/enable
    ifconfig usb0 down
}

case $1 in
    "start")
        echo "Starting Replicant USB Networking" 
        usb_networking_enable
        usb_networking_configure
    ;;
    "stop")
        echo "Stopping Replicant USB Networking" 
        usb_networking_disable
    ;;
    *)
        echo "Usage: sh $0 {start|stop}" 
    ;;
esac

Now you need to copy it to your phone. Start adb server as root: # adb start-server and copy the file (as regular user): adb push run_dev.sh /data/ Get a shell on your device (adb shell) and set this file executable: # chmod a+x /data/run_dev.sh

Using the scripts¶

Now both scripts are in place. You should now:
Start "run_dev.sh" on the device: adb shell "sh /data/run_dev.sh start"
Start "run_pc.sh" as root on the host pc (you must be in the directory where you created the script): # ./run_pc.sh start

Note that if you use NetworkManager, it could notice a new network interface and try to configure it: you should disconnect this interface on NetworkManager before you run the second script.

Now everything is in place. If no error is shown, it should now be working. You can try to ping some website on the device.
If It doesn't work, try to run again each script, running the configuration one more time can't do any worse.

Getting back to normal¶

If you want to disable Replicant USB Networking, you have to:

Customizing the scripts¶

The variables at the beginning of each script can be customized for your usage:

run_pc.sh¶

run_dev.sh¶