2026 免費 DDNS 教學：GCP+Cloudflare+Draytek 零成本實作

				
					import http.server
import socketserver
from urllib.parse import urlparse, parse_qs
import sys
import requests

# ==========================================
# [設定區] 請修改以下資訊
# ==========================================
PORT = 8080                          # 伺服器監聽埠號 (請記得在 GCP 防火牆開啟此埠號)
CF_API_TOKEN = "貼上您從Cloudflare複製的API權杖"
ZONE_NAME = "domain.com"             # 您的根網域名稱

# 定義允許更新的網址與對應密碼
ROUTER_SECRETS = {
    'office.domain.com': 'SuperSecretPasswordForOffice',
    'home.domain.com': 'AnotherPasswordForHome',
}
# ==========================================

API_BASE_URL = "https://api.cloudflare.com/client/v4"
HEADERS = {
    "Authorization": f"Bearer {CF_API_TOKEN}",
    "Content-Type": "application/json"
}

class DDNSHandler(http.server.SimpleHTTPRequestHandler):
    def do_GET(self):
        # 解析請求參數
        parsed_path = urlparse(self.path)
        params = parse_qs(parsed_path.query)
        
        # 獲取參數 (使用 get 防止出錯)
        hostname = params.get('hostname', [''])[0]
        new_ip = params.get('ip', [''])[0]
        secret = params.get('secret', [''])[0]

        # 1. 安全驗證
        if ROUTER_SECRETS.get(hostname) != secret:
            self.send_error_and_log(401, f"[{hostname}] 認證失敗：密碼錯誤或網址未授權")
            return
            
        print(f"[{hostname}] 認證成功，收到 IP: {new_ip}")

        try:
            # 2. 呼叫 Cloudflare API
            url = f"{API_BASE_URL}/zones"
            response = requests.get(url, headers=HEADERS, params={'name': ZONE_NAME})
            response.raise_for_status()
            result = response.json()['result']
            if not result:
                raise Exception(f"找不到 Zone: {ZONE_NAME}")
            zone_id = result[0]['id']

            url = f"{API_BASE_URL}/zones/{zone_id}/dns_records"
            response = requests.get(url, headers=HEADERS, params={'name': hostname, 'type': 'A'})
            response.raise_for_status()
            dns_records = response.json()['result']

            current_ip = dns_records[0]['content'] if dns_records else None
            
            if new_ip == current_ip:
                print(f"[{hostname}] IP 未變更 ({new_ip})，無需更新。")
                self.send_success_response("good", new_ip)
                return

            print(f"[{hostname}] IP 已從 {current_ip} 變為 {new_ip}，準備更新...")
            
            # 強制 proxied: False (直連模式)
            dns_record_data = {'type': 'A', 'name': hostname, 'content': new_ip, 'ttl': 120, 'proxied': False}
            
            if dns_records:
                record_id = dns_records[0]['id']
                url = f"{API_BASE_URL}/zones/{zone_id}/dns_records/{record_id}"
                response = requests.put(url, headers=HEADERS, json=dns_record_data)
            else:
                url = f"{API_BASE_URL}/zones/{zone_id}/dns_records"
                response = requests.post(url, headers=HEADERS, json=dns_record_data)
            
            response.raise_for_status()
            if not response.json()['success']:
                 raise Exception(f"Cloudflare API 操作失敗: {response.json()['errors']}")
            
            print(f"***** [{hostname}] 操作成功！DDNS 更新完成！ *****")
            self.send_success_response("good", new_ip)

        except Exception as e:
            self.send_error_and_log(500, f"!!! [{hostname}] 發生嚴重錯誤: {e} !!!")

    def send_success_response(self, status, ip):
        self.send_response(200)
        self.end_headers()
        self.wfile.write(bytes(f"{status} {ip}", "utf-8"))

    def send_error_and_log(self, code, message):
        print(message, file=sys.stderr)
        self.send_response(code)
        self.send_header('Content-type', 'text/plain; charset=utf-8')
        self.end_headers()
        self.wfile.write(message.encode('utf-8'))

    def log_message(self, format, *args):
        return # 關閉預設的 HTTP Log，使用我們自定義的輸出

if __name__ == "__main__":
    with socketserver.TCPServer(("", PORT), DDNSHandler) as httpd:
        print(f"多設備 DDNS 伺服器 (v5.1) 已在通訊埠 {PORT} 啟動...")
        print("請確保 GCP 防火牆已允許此通訊埠流入。")
        httpd.serve_forever()