Gandi Dynamic DNS

If you have a dynamically assigned IP address from your ISP you can run this script on a cron timer to automatically update a Gandi DNS A record to your current public IP address.

This is useful if you run a service such as a webserver or VPN on your home network and want to remotely access it using a domain name.

The script uses Gandi's LiveDNS API v5. It also uses https://ifconfig.co to determine the current public IP address, but you can change this in the script to something else if you prefer.

Note: currently only supports A records and IPv4 addresses

Requirements

The following packages must be installed:

• curl
• jq

curl is used to interact with the Gandi API.

jq is used to read the JSON response from the API.

Install these with:

# Ubuntu/Debian
sudo apt install curl jq

Setup

You will need to get a Gandi API key.

• Visit https://account.gandi.net/
• Go to Security and look at the Production API Key
• Securely record the API Key, you only get to see it once otherwise you will have to regenerate another key.

Now enter the API Key into api_key.secret.sample file here, then rename the file to api_key.secret

File Permissions

Set the permission on the api_key.secret file so only you can read/write it:

chmod 600 api_key.secret

Set the permission on the gandi-dynamic-dns.sh script so only you can read/write/execute it:

chmod 700 gandi-dynamic-dns.sh

If you are running the script as root (such as through cron or systemd timer) change ownership of the files to root:

sudo chown root:root api_key.secret gandi-dynamic-dns.sh

Usage

You can manually run the script with the fully qualified domain name to update, e.g.

./gandi-dynamic-dns.sh www.example.com

cron

To automatically run the script using cron, open the crontab for root:

sudo crontab -e

Enter this line in the file substituting in the following values:

• the path to the script's directory
• the fully qualified domain name you want to update.

# Update Gandi DNS with current public IP address
0 * * * * sh /home/bob/gandi-dynamic-dns/gandi-dynamic-dns.sh www.example.com

In the example above the script will run hourly, change this to your needs.