需要 Python 3.4+，一个参数用来选择测试搜索服务还是 GAE 服务。测试 GAE 服务的话需要先修改开头的两个变量。从标准输入读取 IP 地址或者 IP 段（形如 192.168.0.0/16）列表，每行一个。可用 IP 输出到标准输出。实时测试结果输出到标准错误。50 线程并发。

#!/usr/bin/env python3

import sys
from ipaddress import IPv4Network
import http.client as client
from concurrent.futures import ThreadPoolExecutor
import argparse
import ssl
import socket

# 先按自己的情况修改以下几行
APP_ID = 'your_id_here'
APP_PATH = '/fetch.py'

context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
context.verify_mode = ssl.CERT_REQUIRED
context.load_verify_locations('/etc/ssl/certs/ca-certificates.crt')

class HTTPSConnection(client.HTTPSConnection):
  def __init__(self, *args, hostname=None, **kwargs):
    self._hostname = hostname
    super().__init__(*args, **kwargs)

  def connect(self):
    super(client.HTTPSConnection, self).connect()

    if self._tunnel_host:
      server_hostname = self._tunnel_host
    else:
      server_hostname = self._hostname or self.host
      sni_hostname = server_hostname if ssl.HAS_SNI else None

    self.sock = self._context.wrap_socket(self.sock,
                                          server_hostname=sni_hostname)
    if not self._context.check_hostname and self._check_hostname:
      try:
        ssl.match_hostname(self.sock.getpeercert(), server_hostname)
      except Exception:
        self.sock.shutdown(socket.SHUT_RDWR)
        self.sock.close()
        raise

def check_ip_p(ip, func):
  if func(ip):
    print(ip, flush=True)

def check_for_gae(ip):
  return _check(APP_ID + '.appspot.com', APP_PATH, ip)

def check_for_search(ip):
  return _check('www.google.com', '/', ip)

def _check(host, path, ip):
  for chance in range(1,-1,-1):
    try:
      conn = HTTPSConnection(
        ip, timeout = 5,
        context = context,
        hostname = host,
      )
      conn.request('GET', path, headers = {
        'Host': host,
      })
      response = conn.getresponse()
      if response.status < 400:
        print('GOOD:', ip, file=sys.stderr)
      else:
        raise Exception('HTTP Error %s %s' % (
          response.status, response.reason))
      return True
    except KeyboardInterrupt:
      raise
    except Exception as e:
      if isinstance(e, ssl.CertificateError):
        print('WARN: %s is not Google\'s!' % ip, file=sys.stderr)
        chance = 0
      if chance == 0:
        print('BAD :', ip, e, file=sys.stderr)
        return False
      else:
        print('RE  :', ip, e, file=sys.stderr)

def main():
  parser = argparse.ArgumentParser(description='Check Google IPs')
  parser.add_argument('service', choices=['search', 'gae'],
                      help='service to check')
  args = parser.parse_args()
  func = globals()['check_for_' + args.service]

  count = 0
  with ThreadPoolExecutor(max_workers=50) as executor:
    for l in sys.stdin:
      l = l.strip()
      if '/' in l:
        for ip in IPv4Network(l).hosts():
          executor.submit(check_ip_p, str(ip), func)
          count += 1
      else:
        executor.submit(check_ip_p, l, func)
        count += 1
  print('%d IP checked.' % count)

if __name__ == '__main__':
  main()

脚本下载地址。

2014年9月3日重要更新：由于失误，之前的脚本没有检查 SSL/TLS 证书，所以将错误的 IP 认为是可用的。现已更新。