[issue43000] All SSL requests fail with WRONG_VERSION_NUMBER when a packet sniffer is open

[Darren Skidmore]

New submission from Darren Skidmore <darrenrs0515 at gmail.com>:

As of Python 3.9.1, when attempting to perform any SSL requests when a packet sniffer tool (e.g. Telerik Fiddler) is intercepting SSL traffic, the program will hang for about a minute and then crash with a WRONG_VERSION_NUMBER error. This has been tested to occur with urllib2 and requests modules. Alternatives such as verify=False and adding the Fiddler Root Certificate to Python's cacert.pem file do not rectify this error.

This traceback was generated when attempting to access https://example.com:443 while Fiddler 5.0.20204.45441 was open:

Traceback (most recent call last):
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connectionpool.py", line 696, in urlopen
    self._prepare_proxy(conn)
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connectionpool.py", line 964, in _prepare_proxy
    conn.connect()
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connection.py", line 359, in connect
    conn = self._connect_tls_proxy(hostname, conn)
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connection.py", line 496, in _connect_tls_proxy
    return ssl_wrap_socket(
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\util\ssl_.py", line 432, in ssl_wrap_socket
    ssl_sock = _ssl_wrap_socket_impl(sock, context, tls_in_tls)
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\util\ssl_.py", line 474, in _ssl_wrap_socket_impl
    return ssl_context.wrap_socket(sock)
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\ssl.py", line 500, in wrap_socket
    return self.sslsocket_class._create(
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\ssl.py", line 1040, in _create
    self.do_handshake()
  File "C:\Users\Darren\AppData\Local\Programs\Python\Python39\lib\ssl.py", line 1309, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: WRONG_VERSION_NUMBER] wrong version number (_ssl.c:1123)

This exact question has recently been asked on StackOverflow: https://stackoverflow.com/questions/65516325/ssl-wrong-version-number-on-python-request

----------
assignee: christian.heimes
components: SSL
messages: 385476
nosy: christian.heimes, darrenrs
priority: normal
severity: normal
status: open
title: All SSL requests fail with WRONG_VERSION_NUMBER when a packet sniffer is open
type: crash
versions: Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43000>
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