Enom Dynamic DNS Update Script

I spent an entire day Googling for simple solutions to get my 'Nix box to update my Enom Dynamic DNS. Enom does offer free Dynamic DNS for your Enom registered domain name. But the Enom Dynamic DNS documentation provided to help you actually use the service is woefully inadequate.

There are a few scripts listed for Windows (none of which I've tried since I don't personally use Windows), none at all for Mac (really?), and two for Unix. Of those, I wasn't able to get either one working and was generally irritated with how much effort and time the whole process was taking. I mean, how hard could it be? We need a simple script to check your current IP address and send some http get variables to Enom, right? So I cobbled together a quick Python script to do that and in my experience so far, it seems to work perfectly.

Disclaimer: Use at your own risk! This script may delete all your data, kill your houseplants, and set fire to your grandmother. I take no responsibity and make no guarantees.

How To Use update_enom.py

Set your values at the top (there are only four of 'em), add an entry for the script to your crontab and that's it. The first time the script runs, it will check your current ip address, update your dynamic DNS host record at Enom, and then save your IP address to a text file. Each subsequent time it runs (recommended every 5 minutes), it will compare your current IP to the one last saved in the text file. This way, we only update your Enom record in the event that the IP address has actually changed.

To get started, simply copy the script below into a text file on your 'nix box (by the way, this works on Mac OS X too), set your config settings at the top, and add a cron entry. Happy dynamic DNS updating!

The Script

#!/usr/local/bin/python

##############################################
# update_enom.py by: Sean Schertell, DataFly.Net
# ------------------------
# A simple python script to update your dynamic DNS IP for domains registered with Enom.
# 
# Requirements:
# - You have a domain registered with Enom, nameservers are set to Enom's, and you've set a domain password
# - Your client machine runs python
# - You know how to configure a cron job to periodically run this script (every 5 mins recommended)
#
# Cron example to run every 5 minutes:
# */5 * * * * /usr/local/bin/update_enom.py

##############################################
# Configure
##############################################

ip_check_url = 'http://datafly.net/ip/text-only.php' # URL which returns current IP as text only
ip_text_file = '/usr/local/etc/update_enom.txt'      # Text file to store recent ip file
domain       = 'example.com'                         # Enom registered domain to be altered
password     = 'secret'                              # Domain password

##############################################

import urllib2, os

def read_url(url):
    return urllib2.urlopen(url).read()

def read_file(path):
    return open(path, 'r').read()

def parse_enom_response(enom_response):
    enom_response_dict = {}
    for param in  enom_response.split('\n'):
        if '=' in param:
            try:
                key, val = param.split('=')
                enom_response_dict[key] = val.strip()
            except: pass
    return enom_response_dict

def save_new_ip(current_ip):
    return open(ip_text_file, 'w').write(current_ip)

def update_enom():    
    # First, ensure that the ip_text_file exists
    if not os.path.exists(ip_text_file):
        open(ip_text_file, 'w').close() 

    # Compare our recently saved IP to our current real IP
    recent_ip = read_file(ip_text_file)
    current_ip = read_url(ip_check_url)

    # Do they match?
    if recent_ip == current_ip:
        return # IP address has not changed since last update

    # No match, so let's try to update Enom
    settings = {'domain': domain, 'password': password, 'current_ip': current_ip}
    enom_update_url = 'https://dynamic.name-services.com/interface.asp?command=setdnshost&zone=%(domain)s&domainpassword=%(password)s&address=%(current_ip)s' % settings
    enom_response = read_url(enom_update_url)

    # Any errors?
    response_vals = parse_enom_response(enom_response)

    if not response_vals['ErrCount'] == '0':    
        raise Exception('*** FAILED TO UPDATE! Here is the response from Enom:\n' + enom_response)

    # Okay then, lets save the new ip
    save_new_ip(current_ip)
    return    
##############################################

update_enom()