\b(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.
  (25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.
  (25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.
  (25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\b