ESP8266 with DHT22 temperature and humidity readings, connected to the local wifi, readings sent to the local mqtt server which is discovered with Multicast DNS.
Realted: https://github.com/esp8266/Arduino/blob/master/libraries/ESP8266WiFi/examples/WiFiClient/WiFiClient.ino https://github.com/knolleary/pubsubclient https://sgsmarthomeblog.blogspot.de/2017/01/auto-discover-mqtt-server-using-arduino.html?showComment=1492546691374#c3187617439741375862