How to communicate to a Arduino behind firewall or router from a website

Hi Gowtham,

The simple answer is, why do this? Better to run your Arduino as a client, not a server. That way you have nothing to configure on router/firewall. Simpler and safer.

It means your remote site acts as the server.

The subject line you have is different to the content of your message.

Your subject line is about NAT, port forwarding & firewall ALLOW rules.

That's how you solve the problem of communicating with an arduino behind a firewall.

The content of your message is about building an application in python to control the arduino.

Google should be able to provide more than enough reference material on this. The above also

links to an Instructable article showing you how.

Normally you would use a web framework like Flask to help create the application.

Python lives under/integrates with Flask.

This is my suggestion.

You could have saved yourself some money by using Google's Firebase service instead of paying for web hosting, as there is a free tier option. You can also use something like Cloudflare to handle the routing between Firebase and your domain name AND provides you with https options. All this is also free to use when using free tier option. Then there is an Arduino Firebase library on github (just search for it). Then use this library to control your Arduino. With this option there is no need to hassle with all the firewall issues (i.e. NAT, port forwarding etc.) and developing an unsecure Arduino web-server.

Then, if you still want to use your web hosting and php (or python), there are php libraries (similarly for python) that can link to Firebase. With this configuration, Firebase is acting as your secure bridge between your website and your Arduino.

There are a couple of alternatives to Firebase, which would be:

Pubnub.

and Nabto.

All these options offer 2 way communication.

hi shabaz, thank you for your reply. I know if we configure arduino as client we dont need port forwarding and no nat issues but how to send a data from a PHP website to to arduino. I mean how does the basic web server(PHP or Python) know that the arduino has connected to it and send message appropriately.

To put it simple consider System A is a windows application behind NAT router firewall which has a TCP client located at say location A. System B is a Arduino device which needs to be connected through TCP and it is also behind another NAT router firewall located at sat location B. I have a basic cPanel website server(I dono if this is sufficient enough). I want to communicate between system A and System B without configuring any router firewall to port forward the requests. I know we need to make System A a client and System B also as a client and use the server to be a bridge between them. But my question is how to do that in my server.

Thanks,

Hi Robert, Thank you for your reply. Your link sure would help me. But i am a bit new to python. I will definitely give it a try. I know about NAT , port forwarding and Firewall options in router but unfortunately i wont have access to router in some places. So I want to develop a server hosted in internet which acts as a bridge between application in system and Arduinio. so that both system and arduino connects to the server as a client and communicate between each other. I have seen the same happening when i use Amazon Echo to turn on a emulated device in Arduino. I can see the TCP connection coming inside the network and turning on the device on command. I hope your link help me develop a server application which can be hosted in a normal internet web server.

Thanks.

You can be sneaky about the way you manage it.

You build the intelligence into your arduino app to handle it.

The web interface contains the state of your arduino.

The arduino then just reads the information on the web interface/service and replicates the state it reads.

The web server never actually has to send commands to the arduino. This also eases the constraints on firewall and rules.

For example. if I toggle a value on the web interface. The web interface updates its state.

The arduino then calls in say every 10 seconds (or some other predetermined time) to see if the state on the website still matches its state.

If it doesn't then it updates itself.

If your app isn't real time critical/sensitive this is an easy way to handle it.

The Firebase architecture is a pretty good option for this sort of star configuration. You can have websites, mobile apps and arduinos all talking to Firebase, via its database and it will handle the updates and authentication for you.

Considering that you are looking to learn how to develop something similar using php on cpanel web hosting, I would suggest you spend that time learning Firebase as, in my opinion, I found that easier to grasp than Pubnub and have not played with Nabto enough, and is much quicker to get up and running than doing everything from scratch.

BigG

thanks for the reference and links to firebase I've started to take a look at it and I think it has some interesting potential, not only for IOT, but for a lot of other applications as well.

Thank you BigG for your response, I registered on Firebase and am trying it out. But I am also tryin gto find how a application like team viewer works to get an overview.

Usually if you have set up a gmail (test) account then next step is to open up the firebase console: https://console.firebase.google.com/

From here you create a new project. Once you click to create a new project, you are then presented with the getting started screen. In my opinion, depending on what you need to do with the app, the getting started screen is rather misleading as need to set things up first before clicking on IOS, Android or Web app icons.

Under the "Discover Firebase" section the key components are:

1. The Database - this is the central area which controls the data coming to and from Arduino/Apps/Webpages

2. The Hosting - this is where you can host web pages if you want to create a web site (then as suggested you can use cloudflare to handle routing domain name to these pages)

3. The Authentication - this is where you handle user authentication

4. The Storage - if you want to store documents such as images etc.

5. Cloud Functions - this is really powerful back end scripting engine (similar to what you use php for on web hosting)

And there loads more options too but the above covers most applications.

In your case I would suggest you start with the Database. Look out for your unique URL on the database home page as you need that for the Arduino library.

Next, to make things really simple and to help you get testing quickly go to the rules page and remove authentication by changing the following (THIS IS TEMPORARY SO DONT FORGET TO CHANGE BACK):

{ "rules": { ".read": true, ".write": true } }