What

It's a script to build a customized OpenWRT firmware image (basic familiarity with OpenWRT is assumed).

If this image is flashed on a device it will try to automatically set up extroot on any (!) storage device plugged into the USB port (/dev/sda). Keep in mind that this will erase any inserted storage device while the router is in the initial setup phase! Unfortunately there's little that can be done at that point to ask the user for confirmation.

Why

So that e.g. customers can buy a router on their own, flash our custom firmware, plug in a pendrive, and manage their SIP (telephony) node from our webapp.

How

Building

e.g. ./build.sh TLWDR4300

Results will be under build/OpenWrt-ImageBuilder-ar71xx_generic-for-linux-x86_64.

To see a list of available targets, run this in the ImageBuilder dir: make info.

Setup stagesd

Blinking leds show which phase the extroot setup scripts are in. Consult the sources for details: autoprovision-functions.sh.

Stage 1

At the first boot after flashing the firmware the autoprovision script will wait for anything (!) in /dev/sda to show up, then erase it and set up a swap, an extroot, and a datafilesystem (for the remaining space), and then reboot.

Stage 2

Once it booted into the new extroot, it will continuously attempt to install some OpenWRT packages until an internet connection is set up on the router (either by using ssh or LuCI if you could include it in the firmware).

Login

After flashing the firmware the router will have the standard 192.168.1.1 IP address, and SSH will listen (in all stages) using the keys specified in authorized_keys (this repo contains my own ssh public key as an example, either delete it or replace it with yours!).

By default the root passwd is initialized to a random string. If you want to set up a password, then edit the stage 2 script: autoprovision-stage2.sh.

Once connected, you can read the log with logread -f.

Status

This is more of a template than something standalone. You most probably want to customize this script here and there; search for CUSTOMIZE for places of interest.

Most importantly, set up your own public ssh key, or delete the default.

I've extracted this from a project where OpenWRT nodes auto-provision themselves in 3 stages, but I thought it's useful enough for making it public (stage 1: extroot setup; stage 2: install packages; stage 3: a Python script for an app-level sync feature).

At the time of writing it only supports a few ar71xx routers out of the box but it's easy to extend it.

Tested with

OpenWRT Chaos Calmer 15.05 RC1 on a TP-Link WDR4300.

Troubleshooting

• If the build doesn't yield a firmware file: if there's not enough space in the flash of the target device to install all the requested packages then the OpenWRT ImageBuilder silently skips that target. Remove some packages from the build and try again.