Simple Dynamic DNS Bash Script

Dynamic DNS

#!/bin/bash  

# This simple bash script will auto-update a CloudFlare DNS entry if a computer's public IP address changes.
# Simply place it in a folder called /etc/ddns and add a cron job to call it every minute or so.
# The five configuration options below are specific to your account and must be set.
DOMAIN_NAME="domain.name.tld"
AUTH_EMAIL="name@email.tld"
AUTH_KEY="__cloudflare_auth_key__"
ZONE_ID="__cloudflare_zone_identifier__"
RECORD_ID="__cloudflare_record_identifier__"

# Our current IP address and path to our IP cache file
IP_ADDRESS=`dig +short myip.opendns.com @resolver1.opendns.com`
CACHE_PATH="/etc/ddns/cache.txt"

# Fetch last value of IP address sent to server or create cache file
if [ ! -f $CACHE_PATH ]; then touch $CACHE_PATH; fi
CURRENT=$(<$CACHE_PATH)

# If IP address hasn't changed, exit, otherwise save the new IP
if [ "$IP_ADDRESS" == "$CURRENT" ]; then exit 0; fi
echo $IP_ADDRESS > $CACHE_PATH

# Update CloudFlare
curl -X PUT "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/dns_records/$RECORD_ID" -H "X-Auth-Email: $AUTH_EMAIL" -H "X-Auth-Key: $AUTH_KEY" -H "Content-Type: application/json" --data '{"type": "A", "name": "'$DOMAIN_NAME'", "content": "'$IP_ADDRESS'"}'