OpenWRT on ALIX with PPPoA ADSL Conexant based USB modem (cxacru)

Awesome post title… anyway,

This is how I built a powerful Wi-Fi ADSL router, using my ALIX2D3 (previously running PFsense), a spare USB ADSL modem (Trust MD-3100) and a CM9 atheros-based miniPCI card.


  • ADSL modem (Conexant based for this howto)
  • Average Linux knowledge
  • vi editor familiarity
  • USB CF card reader

Installing OpenWrt on CF card for ALIX boards

Boot your favourite Linux distribution. If you don’t have one try Ubuntu LiveCD: it loads in RAM and leave you data untouched.
Plug your CF card in your USB CF reader, and plug it in your USB connector. If your CF card isn’t formatted, your Linux may auto-mount the card’s partitions; if so, unmount them.
Type in terminal as root (may need su or sudo command):

fdisk -l

In the list of disks shown, identify your CF card and write down its name, the device size should help you (tip: assuming /dev/sda as your first sata disk, CF card should be named /dev/sdb).
Now download from here the 8.09.1 (lastest at the time of writing) version of OpenWrt x86 image.
All we need to do now, is to copy the image over the CF card.
WARNING: if you use the wrong device name for the next command, you may wipe out all your hard disk data.
Assuming your CF card device name /dev/sdX type this:

dd if=openwrt-x86-ext2.image of=/dev/sdX

Wait some time, and the command should end printing a report of written blocks. Now start GParted or your favourite partition editor, and grow the ext2 partition of your card up to fill the empty space.

Installing LuCI or X-Wrt web interface

OK, it is pretty useless for what we’re doing, but with a 1GB CF card, why not waste some space for a cool web interface??? Choose one of the following:

#1 LuCI:

opkg update
opkg install luci-admin-full

And then add all the luci-app-*** packages you want to simplify your applications management.

#2 X-Wrt:

echo "src X-Wrt" >> /etc/opkg.conf
opkg update
opkg remove -recursive luci-* //NOTE: only if you have previously installed LuCI
opkg install webif

Configuring ADSL modem

Install needed USB kernel modules:

opkg update
opkg install kmod-usb-atm-cxacru kmod-usb2 kmod-usb-uhci

Download and put the ADSL modem firmware (cxacru-fw.bin) in /lib/firmware/.
Plug in the USB modem, and type:

dmesg | tail

Keep checking the output of this command, until you’ll get the “ADSL Line: up” state:

cxacru 1-1:1.0: receive of cm 0x90 failed (-104)
cxacru 1-1:1.0: found firmware cxacru-fw.bin
ATM dev 0: ADSL state: stopped
ATM dev 0: ADSL line: down
ATM dev 0: ADSL state: running
ATM dev 0: ADSL line: initializing
ATM dev 0: ADSL line: down
ATM dev 0: ADSL line: attempting to activate
ATM dev 0: ADSL line: down
ATM dev 0: ADSL line: attempting to activate
ATM dev 0: ADSL line: training
ATM dev 0: ADSL line: attempting to activate
ATM dev 0: ADSL line: training
ATM dev 0: ADSL line: channel analysis
ATM dev 0: ADSL line: up (7584 kb/s down | 480 kb/s up)

Configuring WAN interface

Now we’ll set up the WAN using the ppp0 interface that will be created by pppd.
The following configuration works for my ISP (Telecom Italia) edit it with your ISP parametes.

uci set network.wan=interface
uci set network.wan.proto=pppoa
uci set network.wan.ifname=ppp0
uci set network.wan.encaps=vc
uci set network.wan.vpi=8
uci set network.wan.vci=35
uci set network.wan.username=aliceadsl
uci set network.wan.password=aliceadsl
uci set network.wan.peerdns=1
uci commit network
/etc/init.d/network restart

Now the ppp0 interface should come up and you’ll be able to reach internet.

ADSL sync wait script

The only problem is that on startup, before upping the WAN interface, the system must wait for the ADSL line to come up. I solved this problem with this simple script that start on boot, wait for ADSL sync and then restart the OpenWrt network. It is a modified version of the one you find in Reference #2 at the bottom of this post.
Create the file /etc/init.d/adsl and paste this script in it:

#!/bin/sh /etc/rc.common
# ADSL start script


boot() {
 until [[ -e /proc/net/atm/cxacru\:0 ]]
 if [[ $exsist = '0' ]]
 echo "InitAdsl Waiting cxacru.fw loading"
 echo "InitAdsl Firmware loaded"
 while [[ $end = '0' ]]
 if [[ $sync = '0' ]]
 echo "InitAdsl Waiting sync"
 if [[ `grep Line /proc/net/atm/cxacru\\:0 | cut -d' ' -f2` = 'up' ]]
 /etc/init.d/network restart
 echo "InitAdsl Sync done"

Save the file and type on terminal:

/etc/init.d/adsl enable

Now reboot your router. Everything should work automagically. My router in 3 minutes is connected and providing natted internet service to the dhcp clients.

Configuring wireless interface



  1. LuCI Reference
  2. Modem sync wait script from
  3. Various infos taken from Paolo Minazzi’s page
  4. PC Engines’ ALIX boars

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