Script that compares the first input argument (the domain) to the current external IP. If they do not match it attempts to send a Telegram message.

dynip-alert.py

#!/usr/bin/python
# python 2.7
#_*_ coding: utf-8 _*_

"""
@file			dynip-alert.py
@author			Simon Burkhardt - simonmartin.ch
@date			2018-03-01
@version		1.1
@copyright		CC0 - https://creativecommons.org/publicdomain/zero/1.0
@brief			compare dns ip of given domain against the public ip of the host and send a telegram message
@details		none
@note			originally to compare two dns entries against each other
"""

# dynip-alert [domain] [telegram-name]

try:
	import sys
	import os
except:
	print ("error: library missing")
	exit()

# check argument length
if ( len(sys.argv) < 3 ):
	print ( "error: too few arguments" )
	exit()

domain_ns   = sys.argv[1]
#domain_dyn  = sys.argv[2]

# main code
try:
	resp_ip_ns  = os.popen("nslookup " + domain_ns  + " | grep Address").read()
        resp_ip_dyn = os.popen("curl -s checkip.dyndns.org | sed -e 's/.*Current IP Address: //' -e 's/<.*$//'").read()
#	resp_ip_dyn = os.popen("nslookup " + domain_dyn + " | grep Address").read()

#	print resp_ip_dyn

	if (resp_ip_ns.count("Address") < 2) :
		print ("error: could not find name")
		exit()
	else :
		ip_ns  =  resp_ip_ns.split("\n")[1].replace("Address: ", "")
		ip_dyn = resp_ip_dyn
		if not (ip_ns in ip_dyn):
			message = "DYN-DNS Alert\nthe resolved IP addresses do not match!\n" + domain_ns  + "\t" + ip_ns + "\nExternal IP \t" + ip_dyn
			print(message)
#			os.system("telegram-send " + sys.argv[2] + " \"" + message.replace("\"", "\\\"").replace("'", "\\\'") + "\"")
			os.system("telegram-bot -u " + sys.argv[2] + " -t \"" + message.replace("\"", "\\\"").replace("'", "\\\'") + "\"")
		else:
			print("the ip addresses match: " + ip_ns)


# enables abortion of the program by CTRL + C
except KeyboardInterrupt:
	print("")
	exit()