Cloudflare Dynamic DNS (Bash)

A minimal Bash script to keep A and AAAA records up-to-date on Cloudflare using their v4 API. The script loads its configuration from the file cloudflare-dns.conf in the same directory as the script.

Features:

• Update multiple domains and subdomains in a single run
• Independent IPv4/IPv6 configuration per subdomain
• Enable/disable IPv4 or IPv6 for specific subdomains
• Support for root domain updates using @

---

Quick Start

1. Clone or download this repository.

2. Copy the example config and edit it with your settings:

   cp cloudflare-dns.conf.example cloudflare-dns.conf
   vim cloudflare-dns.conf

   Set at least:

   • CF_API_TOKEN – your Cloudflare API token
   • DOMAINS – array of domains to manage (e.g. ("example.com"))
   • DOMAIN_<name>_IPV4_SUBDOMAINS – subdomains to update with IPv4
   • DOMAIN_<name>_IPV6_SUBDOMAINS – subdomains to update with IPv6

   Example configuration:

   DOMAINS=("example.com")
   DOMAIN_example_com_IPV4_SUBDOMAINS=("www" "@" "home")
   DOMAIN_example_com_IPV6_SUBDOMAINS=("www" "@")

3. Make the script executable and run it:

   chmod +x cloudflare-dns.sh
   ./cloudflare-dns.sh

   The script will:

   • Detect your current public IPv4/IPv6 addresses
   • Process each domain and subdomain in your configuration
   • Create DNS records if they don't exist
   • Update records only when the IP changes

---

Create an API Token

Create a restricted token with Zone → DNS → Edit and Zone → Zone → Read permissions:

• Cloudflare Dashboard → My Profile → API Tokens → Create Token

For extra security, choose Include → Specific Zone and select the zone you plan to update.

---

Configuration Guide

Managing Multiple Domains

Add multiple domains to the DOMAINS array:

DOMAINS=("example.com" "anotherdomain.net")

For each domain, define separate subdomain lists for IPv4 and IPv6:

# example.com configuration
DOMAIN_example_com_IPV4_SUBDOMAINS=("www" "@" "home")
DOMAIN_example_com_IPV6_SUBDOMAINS=("www" "@")

# anotherdomain.net configuration (dots become underscores)
DOMAIN_anotherdomain_net_IPV4_SUBDOMAINS=("blog" "mail")
DOMAIN_anotherdomain_net_IPV6_SUBDOMAINS=("blog")

Enabling/Disabling IPv4 or IPv6

To enable IPv4 for specific subdomains: Add them to the IPV4_SUBDOMAINS array for that domain.

To disable IPv4 for a domain entirely: Set the array to empty: DOMAIN_example_com_IPV4_SUBDOMAINS=()

To enable IPv6 for specific subdomains: Add them to the IPV6_SUBDOMAINS array for that domain.

To disable IPv6 for a domain entirely: Set the array to empty: DOMAIN_example_com_IPV6_SUBDOMAINS=()

Root Domain Updates

Use @ as the subdomain name to update the root domain:

DOMAIN_example_com_IPV4_SUBDOMAINS=("@" "www")  # Updates example.com and www.example.com

Variable Naming Convention

Domain names are converted to variable-safe format by replacing dots and hyphens with underscores:

• example.com → DOMAIN_example_com_IPV4_SUBDOMAINS
• my-site.co.uk → DOMAIN_my_site_co_uk_IPV4_SUBDOMAINS

---

Automating Updates

Run it periodically with cron, for example every 10 minutes:

*/10 * * * * /path/to/cloudflare-dns.sh >/dev/null 2>&1

Or use a systemd timer if you prefer.

---

Requirements

• bash (4.x or newer)
• curl
• jq (for JSON parsing)

---

License

This project is licensed under the GNU General Public License v3 or later (GPL-3.0-or-later).
See the LICENSE file for the full text.