Cloudflare API dynamic DNS with bash

Overview:

Author: Diyaa
Published date: August 3rd, 2024
Last updated: August 3rd, 2024

This document explains how to use the DDNS-Cloudflare-bash script to dynamically update DDNS with CloudFlare using API keys. I am using a bash script from this public Github repository DDNS-Cloudflare-Bash. This article is simply the documentation of how to use the script in the DDNS-Cloudflare-Bash repository.

I am using this script to update an FQDN DNS record automagically through crontab on multiple Linux virtual private servers in different cloud regions.

Warning

I am using a TTL of 120 seconds on the FQDN record. You might see this TTL value as low. Feel free to change it when modifying the script variables.

Technical procedure:

Get an API token from Cloudflare:

Login to your Cloudflare account and navigate to the home page (websites tab):

Navigate to the DNS zone records:

Create the record you wish to modify with DDNS (the record must exist before using it with the script):

Note

You can add an invalid IP or a documentation IP in the type A record to start with. Example: 198.51.100.1 (documentation range IP). Tip: Do not try to resolve the record before it updates.

Get the zone id from cloudflare:

Navigate to your profile to create an API key for the script:

Create a new API token:

Change the name of the token to something you will recognize in the future in case you need to create more tokens:

It should look similar to this at the end:

Create the token:

Make sure to copy the API token as you won’t be able to view it again when you go to API tokens in your account:

Modify the variables in the script:

Add a user for the script (non-privileged user):

sudo adduser --disabled-password --gecos "" cloudflare-ddns

Switch to the new user:

sudo su cloudflare-ddns

Install the script in the non-privileged user directory by pasting the command below into the command line:

mkdir $HOME/cloudflare-ddns/; cd $HOME/cloudflare-ddns/; \
wget https://raw.githubusercontent.com/fire1ce/DDNS-Cloudflare-Bash/main/update-cloudflare-dns.sh; \
wget https://raw.githubusercontent.com/fire1ce/DDNS-Cloudflare-Bash/main/update-cloudflare-dns.conf; \
chown $USER:$USER -R $HOME/cloudflare-ddns; chmod 600 update-cloudflare-dns.conf; \
chmod 700 update-cloudflare-dns.sh

Edit the config file to add your parameters to it:

nano $HOME/cloudflare-ddns/update-cloudflare-dns.conf

Modify the variables in the config file:

Important

You only need to modify the following variables:

• dns_record: The fully qualified domain name of the record the script should update in your DNS zone (example: test.mydomain.com)
• zoneid: The Zone ID you copied in the previous section.
• cloudflare_zone_api_token: The API token you generated in the previous section.
• proxied: Keep set to false if you need this record to be a DNS only record without Cloudflare proxy.
• ttl: This is the Time To Live (TTL) for your DNS record. The minimum allowed by this script is 120 seconds (2 minutes).

run the script to test it:

./update-cloudflare-dns.sh ./update-cloudflare-dns.conf

If you do not get any errors proceed to adding a crontab for this script:

Important

Do not run this command with sudo. The whole point of creating a new user for the script is so that it runs as an unprivileged user.

crontab -e

Add the following line to the bottom of the user crontab:

* * * * * $HOME/cloudflare-ddns/update-cloudflare-dns.sh update-cloudflare-dns.conf

Save the crontab and exit from the user account:

exit

Related Notes:

• Link to Home-Page.

References:

Github DDNS-Cloudflare-Bash