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A bash script to update a Cloudflare DNS A record with the external IP of the source machine
#!/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 4.ipquail.com/ip)
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\":true}" > /dev/null
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