Cloudflare DDNS Script

ddns.sh

#!/bin/bash

# --- Configuration Variables (Please modify these) ---
auth_token="YOUR_API_TOKEN"        # Your Cloudflare API Token
zone_identifier="YOUR_ZONE_ID"      # Your Cloudflare Zone ID
record_name="your_record_name.example.com" # The full DNS record name you want to update (e.g., ddns.example.com)

# --- Script Core Logic ---
echo "Checking for IP update..."

# Get current public IPv4 address
current_ip=$(curl -s4 https://icanhazip.com/)

if [[ -z "$current_ip" ]]; then
  echo "Error: Could not retrieve external IP address." >&2
  exit 1
fi

echo "Current external IP: $current_ip"

# Set authorization header for API requests
auth_header=(-H "Authorization: Bearer $auth_token")

# Get existing DNS record
record_info=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?name=$record_name&type=A" \
  "${auth_header[@]}" -H "Content-Type: application/json")

# Check if the record exists
if [[ -z "$record_info" ]] || [[ "$record_info" == *'"count":0'* ]]; then
  echo "DNS record does not exist, creating a new record..."
  # Create a new DNS record
  create_response=$(curl -s -X POST "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records" \
    "${auth_header[@]}" -H "Content-Type: application/json" \
    --data "{\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$current_ip\",\"ttl\":120,\"proxied\":false}") # Example: TTL 120s, not proxied

  # You might want to add error checking for create_response here
  if echo "$create_response" | jq -e '.success' > /dev/null; then
    echo "Successfully created DNS record."
  else
    echo "Failed to create DNS record. Response: $create_response" >&2
    exit 1
  fi
else
  # Extract old IP and record ID from existing record
  old_ip=$(echo "$record_info" | jq -r '.result[0].content')
  record_id=$(echo "$record_info" | jq -r '.result[0].id')
  echo "Existing DNS record IP: $old_ip"

  # Compare IPs
  if [ "$current_ip" == "$old_ip" ]; then
    echo "IP address has not changed, no update needed."
  else
    echo "IP address has changed, updating DNS record..."
    # Update the DNS record
    update_response=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_id" \
      "${auth_header[@]}" -H "Content-Type: application/json" \
      --data "{\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$current_ip\",\"ttl\":120,\"proxied\":false}") # Example: TTL 120s, not proxied

    # You might want to add error checking for update_response here
    if echo "$update_response" | jq -e '.success' > /dev/null; then
      echo "Successfully updated DNS record."
    else
      echo "Failed to update DNS record. Response: $update_response" >&2
      exit 1
    fi
  fi
fi

echo "DDNS update script finished."