I have been playing around with using ESP8266’s as endpoints around the house for collecting temperature, turning the sprinkler pump on, texting me when the doorbell is pressed, etc. One of the challenges when doing setup/testing is getting the IP address of them when they first come online.
I am running dnsmasq on a raspberry pi, which provides both local DNS and DHCP services. This is in no way novel, as it is a pretty vanilla configuration. What I wanted to share is a small script that monitors for updates to the dnsmasq log, watches for new client releases/renewals and then posts those to the MQTT service. There are lots of things you can do with it from there, but I usually just subscribe to the topic via terminal or mqtttool on my iPhone.
#!/usr/bin/python from pygtail import Pygtail import sys import re import time import paho.mqtt.client as mqtt client = mqtt.Client() client.username_pw_set("xxxxxx","xxxxxx") while (1): for line in Pygtail("/var/log/dnsmasq.log"): isItACK = re.search(r'DHCPACK',line) #see if its an ACK if isItACK: newInput = re.sub(r'^.*DHCPACK\(eth0\).', "", line) #strip everything before mac address newInput = newInput.rstrip() #strip newlines client.connect("xxxxxx.widgetninja.net",1883) #connect to mqtt client.publish("/network/DHCP",newInput) #publish to mqtt client.disconnect #hang up #sys.stdout.write(newInput) #debugging time.sleep(10)
Hope this helps save you some time trying to find the ip address of that new device, be it something you made or otherwise just added to your network.