Bash script that automatically updates all A records in a Cloudflare DNS zone to match your current public IPv4 address. Useful for home servers or any machine with a dynamic IP.

You need both of these installed before running the script:

• curl - for making HTTP requests
• jq - for parsing JSON responses

curl -O https://raw.githubusercontent.com/nixietab/cf-ddns/refs/heads/main/cf-ddns.sh

chmod +x cf-ddns.sh

You need two things from Cloudflare:

Zone ID

• Log in to the Cloudflare dashboard
• Select your domain
• Scroll down on the Overview tab — the Zone ID is in the right-hand sidebar

API Token

• Go to My Profile → API Tokens → Create Token
• Use the Edit zone DNS template, or create a custom token with:
  • Permissions: Zone > DNS > Edit
  • Zone Resources: Include the specific zone you want to update
• Copy the token

Run the script by passing your Zone ID and API token as arguments:

./cf-ddns.sh -z <zone_id> -t <api_token>

Example:

./cf-ddns.sh -z 1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d -t your_cloudflare_api

To run the script automatically (e.g. every 5 minutes), add it to your crontab:

crontab -e

Add a line like:

*/5 * * * * /path/to/cf-ddns.sh -z <zone_id> -t <api_token> >> /var/log/cf-ddns.log 2>&1

• Only A records (IPv4) are updated - AAAA and other record types are left untouched
• The script updates all A records in the zone, not just a specific subdomain
• TTL and proxy settings on each record are preserved