pip install protobuf失败

• 解决方法:将Python升级到2.7.9及以上
  

  报错信息

• The server requires SNI (server name indication) and will cause a TLS alert if the SNI extension is not used. SNI is available with python 3 and with python 2.7.9+. For older versions of python see using requests with TLS doesn't give SNI support.
  服务器需要SNI（服务器名称指示），并且如果没有使用SNI扩展会引起TLS警告。python2.7.9以上的版本支持SNI。

D:\Develop Kit\Protobuf>pip install protobuf
Collecting protobuf
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:339: SNIMissingWarning: An HTTPS request has been made, but the SNI (Subject Name Indication) extension to TLS is not available on this platform. This may cause the server to present an incorrect TLS certificate, which can cause validation failures. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  SNIMissingWarning
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)': /simple/protobuf/
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)': /simple/protobuf/
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)': /simple/protobuf/
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)': /simple/protobuf/
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)': /simple/protobuf/
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Could not fetch URL https://pypi.org/simple/protobuf/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/protobuf/ (Caused by SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)) - skipping
  Could not find a version that satisfies the requirement protobuf (from versions: )
No matching distribution found for protobuf
C:\Python27\lib\site-packages\pip-10.0.1-py2.7.egg\pip\_vendor\urllib3\util\ssl_.py:137: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError(SSLError(1, '_ssl.c:504: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)) - skipping