knotfreeiot

README

knotfree.net

What

This is the source code to a publish/subscribe (pubsub) service running at knotfree.net.

Services include:

• Mqtt 3.1 and Mqtt 5.0 on port 1883
• Mqtt 3.1 and Mqtt 5.0 in port 80 via websockets.
• A text based service on port 7465[^1]
• A binary pubsub service of the knotfreeiot format on port 8384[^2].
• A http forwarding service where http GET messages to http://anychannel.knotfree.net will be published to 'anychannel'
• Service is very cheap. Cheaper than giving out your email address. JWT tokens are used for access and you can get one at knotfree.net.

[^1]: See example below.

[^2]: See example in monitor_pod/main.go and definition in packets/packets.go

Why

The iot architecture that is being presented involves every message sent having a return address to accommodate a reply. Mqtt5 now has this feature. To complete the iot architecture demos, and to provide the hobbyist with an service that is undemanding required that one be written.

How

How to access the unix time server via the web.

Simply visit http://get-unix-time.knotfree.net/get/time and the return will be the unix time in seconds.

get-unix-time is an address that is being watched by a simple piece of code. There are more examples written for Arduino over at mqtt5nano. Note that the command get time is written as /get/time for the web version. Visit http://get-unix-time.knotfree.net/help to see the other commands served by get-unix-time.

How to connect using text mode and netcat.

We will create a tcp connection to the text based service at port 7465 using netcat. No drivers required.

In a terminal window enter:

nc knotfree.net 7465

Then, we will send a connect command with an access token.

C token "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2OTc2MTQ5MjMsImlzcyI6Il85c2giLCJqdGkiOiJJc2dLamd1RmdfVjNzaVVIYWQ3MFNyVlMiLCJpbiI6MTAyNCwib3V0IjoxMDI0LCJzdSI6MjAsImNvIjoyMCwidXJsIjoia25vdGZyZWUubmV0In0.9N6kW6QK4ZUk9129uzJDnU1jSrX6XTcHthsQZiAFL7nwfzRNNEqOWeZgjKlL7ekcHMF-H0VTHKizXZoR1J1_BA"

If the token here is stale or overloaded and you need your own you can get that from http://knotfree.net/. Then we will make up a random, and hopefully unique, address for ourselves for this session. We will 'subscribe' to it.

S myaddresstopicchannelthing82754459

Then we can send the command "get time" to the address "get-unix-time". Note that we send our address as the return address.

P get-unix-time myaddresstopicchannelthing82754459 "get time"

The reply is a P (for publish) in an array of strings and the destination address and the source address have been changed into a hashed format. It looks like this:

[P,=AAFKYuRRQIKzSiS2MzHbg65zVm05snxI,=xOZPbNiNsA_lM_6xJEwM1C7YmVMGlDpA,1666078249]

Where 1666078249 is the current unix time in seconds. The address get-unix-time will respond to several commands. Sent it a help command to see the possibilities.

We can do all of this at the same time by pasting this into a terminal:

nc knotfree.net 7465
C token "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2OTc2MTQ5MjMsImlzcyI6Il85c2giLCJqdGkiOiJJc2dLamd1RmdfVjNzaVVIYWQ3MFNyVlMiLCJpbiI6MTAyNCwib3V0IjoxMDI0LCJzdSI6MjAsImNvIjoyMCwidXJsIjoia25vdGZyZWUubmV0In0.9N6kW6QK4ZUk9129uzJDnU1jSrX6XTcHthsQZiAFL7nwfzRNNEqOWeZgjKlL7ekcHMF-H0VTHKizXZoR1J1_BA"
S myaddresstopicchannelthing82754459
P get-unix-time myaddresstopicchannelthing82754459 "help"

One may also subscribe to the 'testtopic' and get periodic messages. Note that this is not our proper request/response format.

nc knotfree.net 7465
C token "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2OTc2MTQ5MjMsImlzcyI6Il85c2giLCJqdGkiOiJJc2dLamd1RmdfVjNzaVVIYWQ3MFNyVlMiLCJpbiI6MTAyNCwib3V0IjoxMDI0LCJzdSI6MjAsImNvIjoyMCwidXJsIjoia25vdGZyZWUubmV0In0.9N6kW6QK4ZUk9129uzJDnU1jSrX6XTcHthsQZiAFL7nwfzRNNEqOWeZgjKlL7ekcHMF-H0VTHKizXZoR1J1_BA"
S testtopic

and then wait for tens of seconds.

Where

The server code is here at https://github.com/awootton/knotfreeiot The C++ version is Arduino clients that are to be found here: https://github.com/awootton/mqtt5nano

When

2019 to 2022.

Who

Copyright 2022 Alan Tracey Wootton. See LICENSE.

#knotfree #iot #mqtt #mqtt5 #go #mqtt5nano