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September 26, 2013

A DIY Dynamic DNS service using Cloudflare

by Jurgens du Toit

DynDNS was always the dynamic IP service of choice, but I could never get it to work properly, and I was always stuck with their lame domain names as I’m too cheap to pay for their serivces.

Luckily services of all kinds, including DNS Providers, have caught on to the fact that people want API’s. If there’s an API to do DNS updates, I can script a solution.

Some of my domains run off of Cloudflare which needs to overwrite your DNS. And, hey presto, they have an API. So here it is:

  #!/bin/bash
  curl https://www.cloudflare.com/api_json.html \
      -d 'a=rec_edit' \
      -d 'tkn=1234512345qweqwe1234512345' \
      -d 'id=12345' \
      -d 'email=jrgns@jrgns.net' \
      -d 'z=jrgns.net' \
      -d 'type=A' \
      -d 'name=home' \
      -d "content=$1" \
      -d 'service_mode=0' \
      -d 'ttl=3600'

Quick and dirty. This updates a domain (home.jrgns.net) with id 12345 with the IP address that’s passed as the first argument to the script. There’s a bunch of ways to get your external IP, my favourite is curl http://api.externalip.net/ip, but I just run this script as the postscript of my ddclient (which updates another service)

  # /etc/ddclient.conf
  
  protocol=dyndns2
  use=web, web=myip.dnsomatic.com
  ssl=yes
  server=updates.someservice.com
  login=mylogin@gmail.com
  password='123456'
  daemon=3600
  postscript=/home/jrgns/bin/cloudflare_dynamic_dns.sh

I’m sure the same can be done with outer services such as Route 53? Has anyone tried something like this?

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