Dynamic DNS for Linode

Dynamic DNS kind of sucks at home, but setting DNS dynamically with your Linode is awesome.

Linode provides the API, so let's use it.

Installation

Step 1

Configure the settings in datastore/dd_config.json:

Linode API key
Your own personal key
Hostnames to listen on, including
a Domain ID
a Resource ID

You can find the Linode API key via your Linode Profile. Your specific subdomain IDs are a little more complicated to fetch. You can use the Domain List API call to get the list of your domain records, look for the top-level domain, then use its ID in conjuction with the Domain Resource API call. You can formulate both in a simple GET request right in the browser.

Here is an example of datastore/dd_config.json:

{
  "api_key": "c2dtWpcPKkOwifKyFV93X1w729@fwGhHSkSFfDsFgmZf1yqnMmB", 
  "token": "kOiwrXNiKdkD",
  "hosts": {
    "fennekin": {"domain_id": "7422875", "resource_id": "5404200"}
  }
}

The hostname must match the hostname of the computer that will be pinging this script on your Linode. This example assumes a computer at home (which will be pinging the server periodically) is named fennekin.

In the hosts array object, you can additionally define updatable; setting that to false will disable Linode DNS updates for that specific host, but the script will still keep a record of it.

Step 2

Copy sample.htaccess to .htaccess, and set your RewriteBase path in the .htaccess file. If you haven't set your php.ini date-timezone, you should.

Step 3

After the server script is setup (on the Linode), configure your clients.

To do so:

Copy the sample.dynamic-dns.sh to some location on your client
Replace the DOMAIN and PATH markers to mimic your server installation
Replace the TOKEN marker with your chosen personal token
Run the script to test it out; it will probably require a chmod +x to work correctly

You should notice a log file created in your home directory, likely called .dynamic-dns-result.log.

You will also want to add this script to your crontab so that it will run periodically.

Step 4

Make sure you initially created a domain or subdomain in your Linode DNS Manager.

Usage

Assuming everything works, the subdomain of your choice (determined by your Domain and Resource IDs), and you have set your cronjob to run occasionally, your subdomain should eventually point to the external IP where a host was pinging the Linode from.

You can also view some information. Browse to ~root/view-hostname where ~root is the location of your installation, and hostname is the name you would like to view. This will display a nice clickable link.