CloudFlare as a Dynamic DNS (DDNS)

cloudflare-ddns.sh

#!/bin/bash

# CloudFlare as a Dynamic DNS (DDNS)
# Support CloudFlare API v4
# Author: Tunghsiao Liu (t@sparanoid.com)

# Setup envrionment
export PATH=/usr/local/bin:/usr/local/sbin:$PATH

# NOTE: You need `curl` v7.19.4 or higher to support `--noproxy` flag.

# First install jq on macOS:
# brew install jq

# Add this script to cron, run it every 10 mins:
# */10 * * * * bash ~/Documents/Mac/Scripts/server-update-cloudflare.sh

# CloudFlare Global API key
TOKEN="<api_key>"

# CloudFlare account
ACCOUNT="<email>"

# Domain name
DOMAIN="example.com"

# The record you want to update
# e.g. blog, use the bare domain if you want to update root (@) record
RECORD="myhome.example.com"

# Record TTL
TTL=120

# The DNS record type you want to update, must be UPPERCASED
RECORD_TYPE="A"

# jq location
JQ=`which jq`

# Log location, no permission for `/var/log/`, so I have to store it in `/tmp/`
LOGFILE="/tmp/update-cloudflare.log"

# CloudFlare API functions
# Example: getcf "/zones?name=nio2.com" ".result[0].id"
getcf () {
  curl -sS -X GET "https://api.cloudflare.com/client/v4$1" \
    -H "X-Auth-Email: $ACCOUNT" \
    -H "X-Auth-Key: $TOKEN" \
    -H "Content-Type: application/json" | $JQ -r "$2"
}

# Example: putcf "/zones?name=nio2.com" ".result[0].id"
putcf () {
  curl -sS -X PUT "https://api.cloudflare.com/client/v4$1" \
    -H "X-Auth-Email: $ACCOUNT" \
    -H "X-Auth-Key: $TOKEN" \
    -H "Content-Type: application/json" --data $2 | $JQ
}

CF_ZONE_ID=$(getcf "/zones?name=$DOMAIN" ".result[0].id")
echo "   Retrived zone id: $CF_ZONE_ID"

IPOLD=$(getcf "/zones/$CF_ZONE_ID/dns_records" ".result[] | select(.name == \"$RECORD\") | select(.type == \"$RECORD_TYPE\") | .content")
echo "    Retrived old IP: $IPOLD"

# Get current external IP address
IP=`curl --noproxy '*' -s http://whatismyip.akamai.com/`
echo "Retrived current IP: $IP"

# Check if VPN is active
IPVPN=`ifconfig | grep -o ppp`

# Validate IP
function valid_ip() {
  local ip=$1
  local stat=1

  if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
    OIFS=$IFS
    IFS='.'
    ip=($ip)
    IFS=$OIFS
    [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
      && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
    stat=$?
  fi
  return $stat
}

# Compare IPs
if ! valid_ip $IP; then
  echo "[`date`] ERROR: Invalid IP '$IP'" >> "$LOGFILE"
  exit 1
fi

# Check if the IP has changed
if [ "$IP" == "$IPOLD" ] || [[ $IPVPN ]]; then
  echo "Same IP, nothing to change."
  echo "[`date`] SAME: $IP $IPVPN" >> "$LOGFILE"
  exit 0
else
  # Only get record ID if IP changed, this could help reduce 1 API request
  CF_RECORD_ID=$(getcf "/zones/$CF_ZONE_ID/dns_records" ".result[] | select(.name == \"$RECORD\") | select(.type == \"$RECORD_TYPE\") | .id")
  echo " Retrived record id: $CF_RECORD_ID"
  echo "        JSON output:"
  putcf "/zones/$CF_ZONE_ID/dns_records/$CF_RECORD_ID" "{\"id\":\"$CF_RECORD_ID\",\"type\":\"$RECORD_TYPE\",\"name\":\"$RECORD\",\"content\":\"$IP\",\"ttl\":$TTL,\"zone_id\":\"$CF_ZONE_ID\",\"zone_name\":\"$DOMAIN\"}"
  echo "[`date`] UPDATE: $IPOLD >>> $IP" >> "$LOGFILE"
fi