Add mqtt post

content/post/mqtt-telegraf-influx.md

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+---
+title: "Set up and secure an MQTT broker on Ubuntu"
+date: 2021-01-01T18:18:10+02:00
+draft:  false
+image: "uploads/raspi_small2.png"
+categrories: ['English']
+tags: ['monitoring', 'english']
+---
+
+I had some IoT devices that I wanted to integrate in my monitoring. For this I set up a MQTT broker as the MQTT protocol is a simple solution to send data from IoT devices to a server. This tutorial is focusing on setting up the server, but I also introduce a Python based MQTT client to test our installation.
+
+On your server, first install mosquitto, our MQTT server/broker.
+```bash
+sudo apt-get install mosquitto
+```
+
+Allow standard mqtt port in firewall (if you have ufw installed)
+```bash
+sudo ufw allow 1883
+```
+
+Now on the client side connect to the server and publish some fake sensor values.
+First install the mqtt client
+```bash
+sudo pip install phao-mqtt
+```
+and then use the following python code on your client side to send fake values to your server. You only need to change `mqtt.example.com` to your servers IP/domain.
+```python
+import time
+import paho.mqtt.client as mqtt
+import numpy
+import numpy as np
+
+def calc_temp():
+    temp = np.sin(time.time()%(3600)*2*np.pi)*5+20
+    return temp
+
+def on_connect(client, userdata, flags, rc):
+    print("Connected with result code " + str(rc))
+
+client = mqtt.Client()
+#client.username_pw_set(username="username",password="my_super_secret_pw")
+client.on_connect = on_connect
+
+client.connect("mqtt.example.com", 1883, 60)
+
+client.loop_start()
+
+while True:
+    time.sleep(2)
+    client.publish("test/temperature", calc_temp())
+
+```
+
+You can check if the broker accepts the values by subscribing to the topic:
+```python
+#!/usr/bin/env python
+import paho.mqtt.client as mqtt
+
+def on_connect(client, userdata, flags, rc):
+    print("Connected with result code " + str(rc))
+    client.subscribe("test/#")
+
+def on_message(client, userdata, msg):
+    print(msg.topic + " " + str(msg.payload))
+
+client = mqtt.Client()
+#client.username_pw_set(username="username",password="my_super_secret_pw")
+client.on_connect = on_connect
+client.on_message = on_message
+
+client.connect("mqtt.example.com", 1883, 60)
+
+client.loop_forever()
+
+```
+
+Now secure your broker by creating a user with a password
+```bash
+sudo mosquitto_passwd -c /etc/mosquitto/passwd <username> 
+```
+
+and configure mosquitto to use it in `/etc/mosquitto/conf.d/default.conf`:
+```
+allow_anonymous false
+password_file /etc/mosquitto/passwd
+```
+
+Now restart mosquitto to enable the protection
+```bash
+sudo systemctl restart mosquitto
+```
+Test the installation by uncommenting `client.username_pw_set(username="username",password="my_super_secret_pw")` and filling in your credentials.
+The result code `0` indicates a valid connection. `5` indicates a authentication error.
+
+
+I hope this helps setting up a MQTT broker. Hopefully I will have the time to write how to connect such a broker to Grafana via Telegraf and Influx DB.