This describes how to run node-red and the MQTT server on Android, using Termux.
An Android device with an internet connection. I used a Moto G2 running stock Android 6.0
Termux is an app that provides a Linux environment running on Android. Install from the Play Store. When opened it should provide a terminal interface to the Linux system.
See https://termux.com/touch-keyboard.html for how to enter Ctrl chars etc. In particular Ctrl-C is Vol Down+C and Up arrow is Vol Up+W
Allow Termux to access the device filesystem [optional]
I found it useful to allow Termux to access the Android filesystem, so that it became easy to move files between the device and the PC by plugging it into the PC USB. To do this, in Termux, run
This setups up a folder
storage in termux which is a symlink to
ls -al storage
to see what is there. For example
storage/downloads is the Download folder.
Install an editor
You will need an editor for editing configuration files and such like.
the simplest. To install it using the Termux package manager, which is a
wrapper round apt, run
pkg install nano
If you prefer another editor then install that instead.
Install ssh server [optional]
If you are like me then as soon as possible you will want to install the ssh server in Termux so that you can connect to the Linux system from your PC so you don’t have to laboriously enter terminal commands using the touch screen. Install the ssh server.
pkg install openssh
The ssh server only allows connection using keys rather than a username/password
so you need the public key from your client (the PC). This will likely be in
.ssh folder on the PC and will be called
id_rsa.pub. If you haven’t got
a public key then you can generate this on the PC using
ssh-keygen -t rsa
This needs to be copied to the Android device. This can be done by connecting it to the PC using a USB cable then using the file manager on the PC to move the file into the Download folder on the device. Alternatively it could be picked up directly from the PC using scp on the device. The key then needs to be added to the authorized_keys file on the device which can be done using
cat storage/downloads/id_rsa.pub >> .ssh/authorized_keys
Now start the ssh server on the device using
To connect to the device using ssh it needs to be accessible on the local network and you need to know its IP address. In termux run
Look for the section starting wlan0 (assuming you have connected via wifi) and in that section you should see something like
which is the IP address. I like to allocate a fixed IP address so that the device always has the same address but I am not going to cover that here.
To connect from the PC you also need an ssh client. On Linux this is likely to be ssh. On Windows you will may have to use something like PuTTY. Here I will assume that ssh is the command. So on the PC run
ssh -p 8022 <IP>
<IP> is the IP address, so for example
ssh -p 8022 192.168.1.105
and you should be connected.
Start ssh server automatically
The server can be started automatically be creating a file called
putting in there
# start ssh daemon if not already running #if ! pgrep sshd >/dev/null 2>&1; then # sshd #fi
That file will be executed when Termux is opened and will start the server provided it is not already running.
Most of the following can now be run on the PC connected to the device.
pkg install mosquitto
Create a configuration file for mosquitto
cd ~ mkdir .mosquitto nano .mosquitto/mosquitto.conf
and put in there
persistence true autosave_interval 300 persistence_location /data/data/com.termux/files/home/.mosquitto/ (note, trailing / is mandatory) log_dest file /data/data/com.termux/files/home/.mosquitto/mosquitto.log
If you don’t want to use retained topics then you don’t need the first three lines.
Mosquitto is then started using
mosquitto -c /data/data/com.termux/files/home/.mosquitto/mosquitto.conf -d
which will start it in the background, with the log going to
Running the command
tail -f .mosquitto/mosquitto.log
will show that file in the terminal, and will show new entries as they appear,
which can be useful if all is not working as expected. To get more verbose
-v to the mosquitto command line.
Start mosquitto automatically
As for the ssh server, mosquitto can be started automatically be adding to
# start mosquitto in daemon mode provided not already running if ! pgrep mosquitto >/dev/null 2>&1; then mosquitto -c /data/data/com.termux/files/home/.mosquitto/mosquitto.conf -d fi