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LUA Code: How to send emails notifications from Barionet 200-400-1000-1100

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In this knowledge base article we'll go through the process of configuring your new generation Barionet device to work as an SMTP mail sender, so that it could send emails in any condition where it is programmed to do so.

New Generation Barionet devices are based on Linux OpenWRT, a Linux distribution typically found on networking embedded devices. OpenWRT offers several modules that can be used to handle emails, we will use one of the simplest ones to manage and to configure: SSMTP. Later in the article we'll show also how to create a lua function that can be used in scripts so that i.e. you can send an email when a digital input on the device is closed, while also triggering the playback of a file on IP Audio Client. 

Install SSMTP

The first thing to do is to install ssmtp in the Barionet, as it is not present by default on the image. To install this package (or any other) it is necessary to SSH as root in the device.

From any terminal or command prompt launch: 

CODE 
ssh root@<Barionet_IP>

The Barionet will ask you to input the password. If the password was never changed it is the default one, printed on the bottom of the device (PW). If the password was changed, enter your new password for the root user

NOTE: in any Linux terminal application, for security reasons, when a password is entered, it is never displayed to the user. Just type it all the way through and push RETURN on your keyboard when done.


The screen will look like this: 


First update the package system repositories with 

CODE 
opkg update

Then install SSMTP as follow: 

CODE 
opkg install ssmtp

The installation will begin, wait until the process is over. 

Configure SSMTP

Once installed SSMTP places 2 files that must be configured in order for the application to run correctly. The files are located in /etc/ssmtp/ and are: 

  1. ssmtp.conf
  2. revaliases

To edit the files use VIM text editor, already present in the Barionet. 

ssmtp.conf

To open this file with vim: 

CODE 
vim /etc/ssmtp/ssmtp.conf

For VIM beginners: To start type in VIM press "i" (input) on your keyboard. Now you can type and modify the file. Use the arrows to move between the lines. 

This is the main configuration file of the mail sender app.

Here is where we connect the application with our SMTP service provider (i.e. GMAIL or any other). The file is quite easy and straightforward to configure, below is an example (note that text after – is a comment). In the below example is how to setup the conf file in a way that a username and password are provided to the SMTP server to send emails through it. It's also possible to use TLS Certificates with the right PKI management

ssmtp.conf

CODE 
root=postmaster						# example: myname@gmail.com
mailhub=smtp.provider.net:465		# example: smtp.gmail.com:587
rewriteDomain=provider.net			# example: gmail.com
hostname=mein.server.com			# example: <your_router_hostname>
FromLineOverride=YES				# allows to use an email address in the "from line" of the envelope					--
UseTLS=YES							# Use TLS encryption to send emails
UseSTARTTLS=YES						# 
AuthUser=youremail@provider.net		# example: myemail@gmail.com
AuthPass=your_password				# example: the password provided by your provider. How to create an app specific password in GMAIL: https://support.google.com/mail/answer/185833?hl=en-GB  
AuthMethod=LOGIN					# The login method to be used

Once the file is configured according to your requirements press "esc" on your keyboard, this will tell VIM to exit the input mode. Now press ":x!" and then RETURN to Save and close VIM text editor. 

revaliases

To open this file with vim: 

CODE 
vim /etc/ssmtp/revaliases

For VIM beginners: To start type in VIM press "i" (input) on your keyboard. Now you can type and modify the file. Use the arrows to move between the lines. 

revaliases

CODE 
# Format: local_account:outgoing_address:mailhub
# example: root:your_login@your.domain:mailhub.your.domain[:port]


root:myemail@gmail.com:smtp.gmail.com:587

Once the file is configured according to your requirements press "esc" on your keyboard, this will tell VIM to exit the input mode. Now press ":x!" and then RETURN to Save and close VIM text editor. 

Send a test email

There are multiple ways to use ssmtp command to send emails.

Case 1: Send Mail Directly From The Command Line

For this, copy-paste the below command, and you're ready to send email from your command line:

CODE 
echo "Test message from Linux server using ssmtp" | ssmtp -vvv receivers-email@gmail.com

-vvv: is the verbosity of the output after sending the command, it prints a log on the screen, useful to make sure there are no errors.

receivers-email@gmail.com: add here the receivers (i.e. receiver1@gmail.com)

Case 2: Send Mail from a Lua script

The below code block can be used as an "email function" to be added in your lua scripts. 

Create your .lua file: 

  1. On the Barionet directly using VIM (use the following path to make sure you create the file in the persistent directory that cannot be erased by resets to factory defaults: "/mnt/data/custom_app")
  2. Prepare your file using your favorite text editor and then upload the file in the Barionet using the dedicated "Custom App" area on the Barionet UI (NOTE: this area and feature has been added in FW release 2.17) 

The function looks like this: 


sendmail.lua

CODE 
function email(receiver)
        local sendto = receiver
        local sendfrom = "yoursendingemail@gmail.com"
        local subject = "Fire Alarm"
        local body ="Text of the E-Mail:\nAttention, a Fire Alarm has been triggered on Input 1 of Barionet400"
        local header ="Subject: "..subject .."\nFrom: "..sendfrom.."\nTo: "..sendto .."\n"

        os.execute("echo -e \""..header .."\n"..body.."\" |ssmtp ".. sendto)
end


email("receiver-email@provider.net")

When this function is being called an email is sent to the configured receiver address (the argument of the function). 

A complete example of a use case involves the possibility to send an email when a digital input (i.e. Input1) on the Barionet is closed, while sending the email it is also possible to trigger the playback of a file on an IP Audio Client (Exstreamer M400, ExstreamerMPA400, IP Former) so that a sound alarm is also played locally.  A real life scenario is: 

Barionet connected to the Fire Panel, input is closed when the panel detects fire, alarm is played and notifications is sent via email to a monitoring center. 

Below is the complete script that does that, of course it has to be modified according to your network configuration. 

fireAlarm.lua

CODE 
local socket = require "socket"											--dependencies
local udp = socket.udp()

-- The UDP Sender function is used to send the UDP command to a specific IP and Port - Insert the right IP and Port to the corresponding variables - Add the command to be sent via UDP to the udp_command variable
function UDP_sender_file1()
	local socket = require "socket"
	local udp = socket.udp()

    ipspkr_ip = "XXX.XXX.XXX.XXX" 												-- Define Destination IP
    ipspkr_udp_port = XXXX      												-- Define destionation Port 

    udp_command = "FILEPLAY=fileName.xxx\n"   									-- Define the string to be sent, the actual command

    udp:setoption('reuseaddr',true)
    udp:setsockname('*', 0)
    udp:setpeername(ipspkr_ip, ipspkr_udp_port)
    udp:send(udp_command)
end
                                                                                                                                                     
-- Send email function 
function email(receivers)
	local sendto = receivers
	local sendfrom = "youremail@gmail.com"
	local subject = "Subject"
	local body ="Text of the E-Mail\nAttention, a Fire Alarm has been triggered on Input 1 of Barionet400 located, please check immediately"
	local header ="Subject: "..subject .."\nFrom: "..sendfrom.."\nTo: "..sendto .."\n"

	os.execute("echo -e \""..header .."\n"..body.."\" |ssmtp ".. sendto)
end
                                                           
-- Sleep function to temporize the iteratrion in the app function (see below)
function sleep(sec)
    socket.sleep(sec)
end

-- my main application: a loop that keeps the digital input 1 of barionet is monitored and if value is 1 it calls the UDP sender function
-- This function can be re used to read changes in specific files of the system, just use the correct path

function mainApp()
	while true do
	local file = io.open('/dev/gpio/in1/value','r') 						-- Change the path according to where the change must be read. In this example the gpio value of Digital Input 1 is monitored. 
	local in1 = file:read('*n')
		if in1 == 1 then
			UDP_sender_file1();
			email("receiver-email@provider.com")							-- Separate email receivers with comma in between " ". Example: "email1@mail.com,email2@email.com,email3@mail.com"
			sleep(5) 														--wait 5 seconds
		end
	sleep(1) 
	end
end

-- Call the app function to run the application
mainApp()

Once loaded on the Barionet, launch the script as follow:

sendmail.lua

CODE 
lua /mnt/data/custom_app/fireAlarm/firAlarm.lua 				#Assuming the script is saved in the folder "fireAlarm" inside "/mnt/data/custom_app/"

If the device doesn't behave as described above despite following all the steps described, please contact support@barix.com 

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