/vultr-ddns-updater

Simple shell based ddns server/client for Vultr

Primary LanguageShell

Vultr ddns updater

Simple shell based ddns server/client for Vultr.

  • No dependency on an external services such as No-IP
  • No Python. Not even HTTP. Just curl, netcat, gpg and jq.
  • Allows you to restrict the use of the Vultr API key to a single host

Setup

We're going to set up

  • A ddns server on a machine with a stable public facing IP address, such as a Vultr instance
  • A ddns client on the machine with the dynamic IP that we want to have a DNS record for

Prep work on the Vultr side

Enable the API

  • Log in to Vultr
  • Go to account page > API
  • Enable API
  • Copy the API key
  • Under Access Control, add the IP of your ddns server, followed by / 32

Create a DNS 'A' record for the ddns client.

  • Go to Products > DNS
  • Select the domain under which you would like to put the dynamic record
  • Add an A record with a name that matches the hostname of the machine with the dynamic IP address
  • Example: A frohike 123.123.123.123 3600

(Use a dummy IP for now, so we can test that the setup works in the end.)

Setup of server

We'll be picking up the public IP of the dynamic IP host from the incoming connection, so the server needs to run on a host with a public IP address (i.e. not NAT'ed). For example a Vultr instance.

SSH to the server and do

$ git clone https://github.com/aioobe/vultr-ddns-updater.git
$ cd vultr-ddns-updater
$ sudo apt install jq
$ nano -w ddns-server.sh
<configure API_KEY, DOMAIN and PASSPHRASE>

Run $HOME/vultr-ddns-updater/ddns-server.sh in for example crontab @reboot, or in a tmux session.

Setup of client (the machine with dynamic IP)

SSH to the client and do

$ git clone https://github.com/aioobe/vultr-ddns-updater.git
$ cd vultr-ddns-updater
$ nano -w ddns-client.sh
<coonfigure DDNS_SERVER and PASSPHRASE>

Use the name or IP of the server you setup in the previous section, and the same passphrase as before.

Test the setup with

./ddns-client.sh

Check the Vultr DNS page and make sure the corresponding A record has been updated.

Add this (or something similar) to your crontab:

@reboot $HOME/vultr-ddns-updater/ddns-client.sh
*/30 * * * * $HOME/vultr-ddns-updater/ddns-client.sh

Troubleshooting

  • Make sure the DNS record has the same name as the output of hostname on the client (or update ddns-client.sh as you see fit)

If you've run into any other issue, please open a PR to update this section.