A bash script to update a Cloudflare DNS A record with the external IP of the source machine

cloudflare-ddns-update.sh

#!/bin/bash

# A bash script to update a Cloudflare DNS A record with the external IP of the source machine
# Used to provide DDNS service for my home
# Needs the DNS record pre-creating on Cloudflare

# Proxy - uncomment and provide details if using a proxy
#export https_proxy=http://<proxyuser>:<proxypassword>@<proxyip>:<proxyport>

# Cloudflare zone is the zone which holds the record
zone=example.com
# dnsrecord is the A record which will be updated
dnsrecord=www.example.com

## Cloudflare authentication details
## keep these private
cloudflare_auth_email=me@cloudflare.com
cloudflare_auth_key=1234567890abcdef1234567890abcdef


# Get the current external IP address
ip=$(curl -s -X GET https://checkip.amazonaws.com)

echo "Current IP is $ip"

if host $dnsrecord 1.1.1.1 | grep "has address" | grep "$ip"; then
  echo "$dnsrecord is currently set to $ip; no changes needed"
  exit
fi

# if here, the dns record needs updating

# get the zone id for the requested zone
zoneid=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=$zone&status=active" \
  -H "X-Auth-Email: $cloudflare_auth_email" \
  -H "X-Auth-Key: $cloudflare_auth_key" \
  -H "Content-Type: application/json" | jq -r '{"result"}[] | .[0] | .id')

echo "Zoneid for $zone is $zoneid"

# get the dns record id
dnsrecordid=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zoneid/dns_records?type=A&name=$dnsrecord" \
  -H "X-Auth-Email: $cloudflare_auth_email" \
  -H "X-Auth-Key: $cloudflare_auth_key" \
  -H "Content-Type: application/json" | jq -r '{"result"}[] | .[0] | .id')

echo "DNSrecordid for $dnsrecord is $dnsrecordid"

# update the record
curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zoneid/dns_records/$dnsrecordid" \
  -H "X-Auth-Email: $cloudflare_auth_email" \
  -H "X-Auth-Key: $cloudflare_auth_key" \
  -H "Content-Type: application/json" \
  --data "{\"type\":\"A\",\"name\":\"$dnsrecord\",\"content\":\"$ip\",\"ttl\":1,\"proxied\":false}" | jq

The warning Could not get your IPv6. Check if you have it; e.g. on https://ifconfig.co says that you do not have any IPv6. It should work :) check your Cloudflare.

But I will add some lines to give messages that the settings is done.

Thank you very much, I had put something wrong in the text. The script works now even though I don't have an IPv6.

I have just updated the code; thanks to @jstokholm that could be found here.

#!/bin/bash
# based on https://gist.github.com/Tras2/cba88201b17d765ec065ccbedfb16d9a
# initial data; they need to be filled by the user
## API token; e.g. FErsdfklw3er59dUlDce44-3D43dsfs3sddsFoD3
api_token=<YOUR_API_TOKEN>
## the email address associated with the Cloudflare account; e.g. email@gmail.com
email=<YOUR_EMAIL>
## the zone (domain) should be modified; e.g. example.com
zone_name=<YOUR_DOMAIN>
## the dns record (sub-domain) should be modified; e.g. sub.example.com
dns_record=<YOUR_SUB_DOMAIN>

# get the basic data
ipv4=$(curl -s -X GET -4 https://ifconfig.co)
ipv6=$(curl -s -X GET -6 https://ifconfig.co)
user_id=$(curl -s -X GET "https://api.cloudflare.com/client/v4/user/tokens/verify" \
               -H "Authorization: Bearer $api_token" \
               -H "Content-Type:application/json" \
          | jq -r '{"result"}[] | .id'
         )

# write down IPv4 and/or IPv6
if [ $ipv4 ]; then echo -e "\033[0;32m [+] Your public IPv4 address: $ipv4"; else echo -e "\033[0;33m [!] Unable to get any public IPv4 address."; fi
if [ $ipv6 ]; then echo -e "\033[0;32m [+] Your public IPv6 address: $ipv6"; else echo -e "\033[0;33m [!] Unable to get any public IPv6 address."; fi

# check if the user API is valid and the email is correct
if [ $user_id ]
then
    zone_id=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=$zone_name&status=active" \
                   -H "Content-Type: application/json" \
                   -H "X-Auth-Email: $email" \
                   -H "Authorization: Bearer $api_token" \
              | jq -r '{"result"}[] | .[0] | .id'
             )
    # check if the zone ID is avilable
    if [ $zone_id ]
    then
        # check if there is any IP version 4
        if [ $ipv4 ]
        then
            dns_record_a_id=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records?type=A&name=$dns_record"  \
                                   -H "Content-Type: application/json" \
                                   -H "X-Auth-Email: $email" \
                                   -H "Authorization: Bearer $api_token"
                             )
            # if the IPv4 exist
            dns_record_a_ip=$(echo $dns_record_a_id |  jq -r '{"result"}[] | .[0] | .content')
            if [ $dns_record_a_ip != $ipv4 ]
            then
                # change the A record
                curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records/$(echo $dns_record_a_id | jq -r '{"result"}[] | .[0] | .id')" \
                     -H "Content-Type: application/json" \
                     -H "X-Auth-Email: $email" \
                     -H "Authorization: Bearer $api_token" \
                     --data "{\"type\":\"A\",\"name\":\"$dns_record\",\"content\":\"$ipv4\",\"ttl\":1,\"proxied\":false}" \
                | jq -r '.errors'
                # write the result
                echo -e "\033[0;32m [+] The IPv4 is successfully set on Cloudflare as the A Record with the value of:    $dns_record_a_ip"
            else
                echo -e "\033[0;37m [~] The current IPv4 and  the existing on on Cloudflare are the same; there is no need to apply it."
            fi
        fi
            
        # check if there is any IP version 6
        if [ $ipv6 ]
        then
            dns_record_aaaa_id=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records?type=AAAA&name=$dns_record"  \
                                      -H "Content-Type: application/json" \
                                      -H "X-Auth-Email: $email" \
                                      -H "Authorization: Bearer $api_token"
                                )
            # if the IPv6 exist
            dns_record_aaaa_ip=$(echo $dns_record_aaaa_id | jq -r '{"result"}[] | .[0] | .content')
            if [ $dns_record_aaaa_ip != $ipv6 ]
            then
                # change the AAAA record
                curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records/$(echo $dns_record_aaaa_id | jq -r '{"result"}[] | .[0] | .id')" \
                     -H "Content-Type: application/json" \
                     -H "X-Auth-Email: $email" \
                     -H "Authorization: Bearer $api_token" \
                     --data "{\"type\":\"AAAA\",\"name\":\"$dns_record\",\"content\":\"$ipv6\",\"ttl\":1,\"proxied\":false}" \
                | jq -r '.errors'
                # write the result
                echo -e "\033[0;32m [+] The IPv6 is successfully set on Cloudflare as the AAAA Record with the value of: $dns_record_aaaa_ip"
            else
                echo -e "\033[0;37m [~] The current IPv6 address and the existing on on Cloudflare are the same; there is no need to apply it."
            fi
        fi  
    else
        echo -e "\033[0;31m [-] There is a problem with getting the Zone ID (subdomain) or the email address (username). Check them and try again."
    fi
else
    echo -e "\033[0;31m [-] There is a problem with either the API token. Check it and try again."
fi

Im just going to leave my take on this script here. It only supports ipv4 but allows to use the https_proxy funcionality of cloudflare.

Hello guys, can someone tell me how to i find the zone?

@kd0034

I would basically your domain(s) that is defined for the API key.

@namnamir Thank you for the updated script, it works like a charm. I needed to update multiple hostnames and some of those had proxy set to true. I made changes to your script to accommodate. Also, for some reason, the script was timing out on the first section where it grabs the ip from ifconfig so I increased the wait time. It is available here.

Thanks, this was all I needed! ddclient was just overly complicated!

Picking up on the above, have made a few changes to fit my requirements.

• Checks for changes
• Logs each check
• Verifies if new "IP" is of correct format (to eliminate errors)
• Updates multiple entries (proxied and not)
• Logs each change

Now running a cronjob to check and update my DNS records (proxied and not) when there is an IP change, see this repo if looking for similar.
Full article can be found here.

Stripped down IPv4 version based on previous scripts. You'll need jq and curl.

#!/usr/bin/env bash
api_token=<CF token>
email=<CF account email>
zone_name=<DNS zone>
dns_record=<A record FQDN>

set -e

user_id=$(curl -s \
	-X GET "https://api.cloudflare.com/client/v4/user/tokens/verify" \
	-H "Authorization: Bearer $api_token" \
	-H "Content-Type:application/json" \
	| jq -r '{"result"}[] | .id')

zone_id=$(curl -s \
	-X GET "https://api.cloudflare.com/client/v4/zones?name=$zone_name&status=active" \
	-H "Content-Type: application/json" \
	-H "X-Auth-Email: $email" \
	-H "Authorization: Bearer $api_token" \
	| jq -r '{"result"}[] | .[0] | .id')

record_data=$(curl -s \
	-X GET "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records?type=A&name=$dns_record"  \
	-H "Content-Type: application/json" \
	-H "X-Auth-Email: $email" \
	-H "Authorization: Bearer $api_token")

record_id=$(jq -r '{"result"}[] | .[0] | .id' <<< $record_data)
cf_ip=$(jq -r '{"result"}[] | .[0] | .content' <<< $record_data)
ext_ip=$(curl -s -X GET -4 https://ifconfig.co)

if [[ $cf_ip != $ext_ip ]]; then
	result=$(curl -s \
		-X PUT "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records/$record_id" \
		-H "Content-Type: application/json" \
		-H "X-Auth-Email: $email" \
		-H "Authorization: Bearer $api_token" \
		--data "{\"type\":\"A\",\"name\":\"$dns_record\",\"content\":\"$ext_ip\",\"ttl\":1,\"proxied\":false}" \
		| jq .success)
	if [[ $result == "true" ]]; then
		echo "$dns_record updated to: $ext_ip"
		exit 0
	else
		echo "$dns_record update failed"
		exit 1
	fi
else
	echo "$dns_record already up do date"
	exit 0
fi

Liked your stripped down version. Added IPV6, config in separate file, logging and many subdomains.

https://github.com/pilang/cloudflare_ddns/

@pilang I chose your script above the others from this gist! :-)

My fork of pilang repo contains two major new enhancements:

• When logfile is set to a non-empty value, some basic sanity checks are done; an attempt at creating the given directory path and then the final file path is done at the top of the script. Failure results in the script halting with an error message.

• ipv4_command and ipv6_command can now optionally be an array. This is for the sake of redundancy -- in case one of the given URLs is offline or such. Additionally, upon the first error seen in the array looping, the script halts with an error message.

Shortly after checking out your script, I was scratching my head, wondering why the script exited without any output, nor error. Even after I had the correct user, token and so forth, it was still exiting w/o output. It turns out that I had given curl an address that it could not find the right certificate for. This is why I began improving the script with the latter feature mention (command arrays). With my improvements, it should gracefully handle this and other error conditions.

Cheers,
Jeff