[Bridge] Ubuntu: network bridging between wireless and wired connection fails

[Nicolas de Pesloüan]

> 2009/4/30 richardvoigt at gmail.com <richardvoigt at gmail.com>:
>>

>> That's at the IP stack.  At the firmware level, most wireless cards will
>> refuse to transmit/receive packets with other MAC addresses, making them
>> useless for AP or bridging.  Yours is apparently not one of those since
>> bridging works in Windows (or else the Windows bridge code does transparent
>> routing w/MAC address replacement, rather like NAT or PAT but working at
>> layer 2 instead of 3).
>>
>> That's why I suggested testing for the DHCP discover on a different wireless
>> node.

Can you also explain why you are trying to use bridge ?

Are you just trying to share a common IP address between two links 
(Ethernet and wifi), in order to switch automatically to wifi when you 
unplug the Ethernet wire, without loosing any active connections ?

If this is what you are trying to do, you might try the bonding module 
instead of bridge, and have a look at the ifenslave-2.6 package from 
Debian, which should work on Ubuntu. This package enhance the ifupdown 
system and allow you to bond an Ethernet and a Wifi link, in an 
active/backup mode. An "Ethernet+wifi" example configuration is provided 
in the documentation.

You configuration should look like this :

auto bond0
iface bond0 inet dhcp
	bond-slaves eth0
	bond-mode 1
	bond-miimon 100
	bond-primary eth0

iface eth0 inet manual
# Useless, unless NetworkManager is enabled on you system.

auto eth1
iface eth1 inet manual
	bond-master bond0
	bond-give-a-chance 10
	wpa-bridge bond0
	wpa-driver wext
	wpa-ssid ##SSID##
	wpa-ap-scan 1
	wpa-proto RSN
	wpa-pariwire CCMP
	wpa-group CCMP
	wpa-key-mgmt WPA-PSK
	wpa-psk ##PSK KEY##

'hope this help.

	Nicolas.