View source for Didj Network Bridging

This page includes steps that describe how to use bridging on your host to enable your Didj to access to the wider Internet via the USB connection.

They have been tested in Ubuntu 8.04 Hardy Heron (2.6.24-26 kernel), and are based on similar instructions for other handheld devices.

'''Prerequisites'''
# You have set up USB networking as per http://elinux.org/Didj_Networking_HOWTO
# The required tools are provided by the bridge-utils package:

<code>
 sudo apt-get install bridge-utils
</code>


'''Configuring the Host'''

In this example, we assume that the host has an ethernet connectoion on ''eth0''. (your own config may be different; for example, you may be using a Wifi adapter. In theory, aside from your LAN specific configuration, the steps outlined below should still work.)

The bridge will be made up of the host's usb ethernet link to the Didj ''usb0'', combined with the ethernet connection ''eth0'' in a virtual 'bridge' interface called ''br0''. 

The bridged interface ''br0'' will be assigned the IP configuration for the PC. 

(In later steps, you will assign the Didj an IP address on the same network).

Configure the host machine's /etc/network/interfaces file as follows (adjusting IP addresses as needed):

<code>
 auto lo
 iface lo inet loopback
 auto eth0
 iface eth0 inet dhcp
 auto usb0
 iface usb0 inet static
        address 192.168.0.199
        netmask 255.255.255.0
        up echo 1 > /proc/sys/net/ipv4/ip_forward
        up iptables -P FORWARD ACCEPT
        up iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24
        down echo 0 > /proc/sys/net/ipv4/ip_forward
        down iptables -t nat -F POSTROUTING
 iface br0 inet dhcp
         pre-up   echo     "Adding ethernet bridge between Didj and LAN"
         pre-up   ifconfig eth0 0.0.0.0
         pre-up   brctl    addbr br0
         pre-up   brctl    setfd br0 0
         pre-up   brctl    stp br0 off
         pre-up   brctl    addif br0 eth0
         pre-down echo     "Removing ethernet bridge between Didj and LAN"
         post-down brctl    delif br0 eth0
         post-down brctl    delbr br0
         post-down ifdown eth0
         post-down ifup eth0
</code>

To apply these new settings:

<code> 
 sudo /etc/init.d/networking restart
</code>
(of course, rebooting the host will also work)
 
At this point, to activate your bridge, just enter: 
<code>
 sudo ifup br0
</code>

If you are using DHCP as we do in the above example,  make a note of your br0 ip address by typing ifconfig.

'''Configuring the Didj'''

If you are using a standard Didj configuration and you have not yet done so, rmmod the g_file_storage kernel module and insmod the g_ether/ko module.
(see http://elinux.org/Didj_Networking_HOWTO#Installing_g_ether.ko)

With the USB cable connected to your host, configure an IP address on the ''same'' subnet as the rest of your LAN

On the Didj:
<code>
 ifconfig usb0 192.168.0.200 netmask 255.255.255.0
</code>

Next, add a route to the host, making it the gateway, using the ip address you found for br0 via running ifconfig on the host.

On the Didj:
<code>
 route add default gw 192.168.0.116 usb0
</code>

Finally, add nameservers to your Didj's /etc/resolv.conf file (you can add the lines from this example which uses the OpenDNS servers)
<code>
 nameserver 208.67.222.222
 nameserver 208.61.220.220
</code>


At this point, assuming ''br0'' is brought up on your host, your Didj is connected to the outside world - and a ping or a wget to yahoo or google should work.


'''References'''
 
http://wiki.maemo.org/USB_networking

http://wiki.openzaurus.org/HowTos/Bridging_with_Ubuntu