Play audio streams on OpenWrt (Internet Radio)

I own some old ADSL modems that are no longer suitable for modern networks. OpenWrt can be installed on them, but they are limited by hardware to 100 Mbps LAN and 54 Mbps WiFi. Therefore, using these devices as routers, network attached storage or anything else that requires high transfer speeds is no longer wanted. Fortunately, OpenWrt comes with many software packages available to install using its included package manager.

One of the tasks that are suitable for most low-speed OpenWrt routers is audio playing. However, there are some hardware requirements. You need a router on which you can install OpenWrt firmware. It must have at least 8 MB flash storage memory and, the most important: at least one USB port. I haven’t heard of routers with audio output, yet there are plenty with USB ports (for GSM modem or USB storage). With an USB sound card and proper software, you will be able to play audio from any OpenWrt router. In this post I will talk about internet radio streams. However, if you have an extra USB port or you plan to use a hub, you may also play music files from USB drive.

USB audio card plugged in the USB port of the router

Configure Mosquitto™ broker with TLS certificate

Following my previous post, you should have now a running Mosquitto based MQTT broker on your OpenWrt router that listens on port 1883 for unsecured clients and on port 8884 for TLS PSK clients. But that's not all. I want to have the broker listen to 8883 port for TLS certificate secured clients. I will use this port for remote clients over the internet.

Of course, the port can be used for local clients that support TLS. This is the highest level of transport encryption available. It's the same encryption used by HTTPS. When you (your browser) send a HTTPS request to a server (website), the server responds with its certificate and public key. The browser has a database of trusted certificate authorities and if the authority that issued the received certificate is in that database, browser will trust the server and will respond with data encrypted with the public key. Server decrypts data with its private key. Client and server will negotiate a one time key that will be used throughout the session.

Install and configure Mosquitto™ on OpenWrt

The previous post was about MQTT security layers, the advantages of running a local MQTT server and how may a network of things be structured. The OpenWrt router should be ready to install and set up the server (broker) software. The software repositories contain two variants of the Eclipse Mosquitto software. One of them is built without SSL support. If you install that one, you won't be able to accept secure clients. The SSL enabled variant requires a bit more internal storage space and that's the main reason they provide both builds.

I'm using a router with Broadcom SoC and 16 MB of internal storage. There's still 86 percent free space after installing Mosquitto, the SSL enabled build. In this post I'll show you how to configure Mosquitto broker to listen to multiple ports and to accept clients with different security settings. This is because not all microcontrollers with network connectivity have enough processing power for TLS/SSL. And, as I said in the previous post, the devices in your local network are behind (at least one) firewall, and as long as no one else has physical access to the network, transport encryption between MQTT clients and server is not really needed. However, TLS/SSL is required for remote clients, over internet.

Run a local MQTT broker on OpenWrt router

Nowadays, microcontrollers with internet connectivity are cheap and popular. Actually, not quite internet connectivity, but network interface (mostly wireless). Also, to those MCUs that do not feature this, you can connect various network or WiFi modules (known as shields). It's now easy to connect almost anything to the big network starting from a simple LED or relay.

There are plenty of projects on this topic. Most of them make use of development boards based on Espressif platform, because they are cheap and have built-in wireless LAN connectivity. An you can run basic web servers on these that offer a web interface where you can display or change parameters from any device with web browser. But that's not what everybody needs. Sometimes, the development board is just a member in a network that includes other things too.

A common protocol was needed to allow communication between devices in the network of things. Actually, one has been around a while, way before these development boards became so cheap and available. It's the Message Queuing Telemetry Transport protocol (or MQTT), which is now an ISO standard. Used wherever small amounts of data needs to be transferred, it works on top of TCP/IP.

Add and configure WAN port on OpenWrt

OpenWrt is a Linux based, embedded operating system for networking devices. Besides being open source, it is highly configurable and versatile. This post will show how to configure one of the LAN ports as WAN input (for xDSL routers, which have the WAN internally connected to the modem). There are no opensource drivers for ADSL op OpenWrt and this feature is therefore unavailable. It doesn't matter anyway, since DSL limited in bandwidth and is losing its popularity.

Many DSL routers are in fact more powerful platforms, with improved hardware, than ordinary routers. If you want to connect the router to wired LAN internet this is what you should do. I've done this on a router with a development snapshot installed (the difference is that development versions do not come with web interface preinstalled). If you have a regular release, you can skip LuCI installation, as you already have access to the web interface of the router.

Install OpenWrt on P.RG AV4202N router

AV4202N is an xDSL modem and WiFi router based on the BCM6368 SoC manufactured by Broadcom. The CPU has 2 cores running at 400 MHz, with 64 MB RAM and 16 MB flash memory. It also has 2 USB 2.0 ports and 2 WiFi internal antennas.

Currently, although the BCM63xx platform is supported by OpenWrt, there are no releases for this device. Neither LEDE Project has released a stable build for this device, but they are offering a development snapshot [3]. The problem with LEDE snapshots is that they don't work out of the box without additional software packages (you don’t get any web interface).

But, LEDE can’t be installed on the device due to the locked bootloader. This article will show you how to use JTAG to install a different bootloader that can be used to flash OpenWRT/LEDE firmware. Part 2 details LEDE configuration and internet connection.

Note! If the mentioned device was offered to you by an ISP for xDSL internet access, doing what is described next will void the warranty of the device and make it unusable. You should not attempt to change firmware in this situation. Third party firmware does not support xDSL!