Cloudflare DDNS Update POSIX Script

A POSIX shell script that updates cloudflare A and AAA records for a DNS Zone whenever your external IP changes.

Useful for home servers when you do not own a static IP address.

Requirements

Although the scripts run on a POSIX shell it requires the following programs:

./update_dns.sh --zone <zone-name> --domains <comma separated records to update> --account <cloudflare-account-id> --token <cloudflare-token>

Example:

./update_dns.sh --zone domain.com --domains domain.com,about.domain.com --account 0f000000000000000 --token 0f0000000000000000

The above command will update the A and AAA records for domain.com AND about.domain.com in the domain.com zone.

To generate an access token in Cloudflare you need to go to:

My Profile -> API Tokens -> Create Token -> Edit zone DNS (Template)

The script first obtains your current IPv4 and IPv6 using curl and ifconfig.co.
It then stores the address in /tmp as a file if not yet present
It compares the current IP address you have with the previously stored
If the IPs are different it will proceed with updating the records in the zone

All program arguments can be provided as environment variables:

Example:

zone_name=<zone name> account=<account id> domains=<records to update> token=<access token> ./update_dns.sh

Note: You can use the --yes option to skip confirmation message.