Debian's OpenSSL now disables TLS 1.0 and 1.1, letting some of the python tests fail.  Please make them use a newer protocol version, or make the use of the older versions conditional.

failing tests:

https://ci.debian.net/data/packages/unstable/amd64/p/python3.6/latest-autopkgtest/log.gz

3.7 does no longer use PROTOCOL_TLSv1 except for test_ssl.py, see #31346

By the way Debian Sid/Buster broke support for SSL and TLS < 1.2. see #31453. There is no way to enable the protocols from Python.

Two tests are failing in 3.7 branch:

======================================================================
ERROR: test_PROTOCOL_TLS (test.test_ssl.ThreadedTests)
Connecting to an SSLv23 server with various client options
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/heimes/dev/python/cpython/Lib/test/test_ssl.py", line 2660, in test_PROTOCOL_TLS
    try_protocol_combo(ssl.PROTOCOL_TLS, ssl.PROTOCOL_TLSv1, 'TLSv1')
  File "/home/heimes/dev/python/cpython/Lib/test/test_ssl.py", line 2343, in try_protocol_combo
    chatty=False, connectionchatty=False)
  File "/home/heimes/dev/python/cpython/Lib/test/test_ssl.py", line 2268, in server_params_test
    s.connect((HOST, server.port))
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 1108, in connect
    self._real_connect(addr, False)
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 1099, in _real_connect
    self.do_handshake()
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 1076, in do_handshake
    self._sslobj.do_handshake()
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 697, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:864)

======================================================================
ERROR: test_protocol_tlsv1_1 (test.test_ssl.ThreadedTests)
Connecting to a TLSv1.1 server with various client options.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/heimes/dev/python/cpython/Lib/test/test_ssl.py", line 2734, in test_protocol_tlsv1_1
    try_protocol_combo(ssl.PROTOCOL_TLS, ssl.PROTOCOL_TLSv1_1, 'TLSv1.1')
  File "/home/heimes/dev/python/cpython/Lib/test/test_ssl.py", line 2343, in try_protocol_combo
    chatty=False, connectionchatty=False)
  File "/home/heimes/dev/python/cpython/Lib/test/test_ssl.py", line 2268, in server_params_test
    s.connect((HOST, server.port))
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 1108, in connect
    self._real_connect(addr, False)
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 1099, in _real_connect
    self.do_handshake()
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 1076, in do_handshake
    self._sslobj.do_handshake()
  File "/home/heimes/dev/python/cpython/Lib/ssl.py", line 697, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:864)

----------------------------------------------------------------------

Matthias,
is there any way to detect Debian's modifications of OpenSSL from header files or with an API call? Otherwise we have no way to reliable detect and correctly skip the test. At the moment there is no way to retrieve the minimum protocol from OpenSSL SSL_CTX. I landed an OpenSSL patch just a couple of days ago to add SSL_CTX_get_min_proto_version(), https://github.com/openssl/openssl/pull/4364

Christian, I assume you'd like to see a test which can be done at *runtime*, not *buildtime*.  Assuming you have that openssl upstream patch available in your build dependency, would that help with the detection?  If yes, I'll talk to Debian's and Ubuntu's openssl maintainers to backport it, so the _ssl module could use it depending on a configure check.

PR 3660 and PR 3661 address most of the failing tests. The two failures in msg302531 are discussed in issue #31453.

New changeset aab225840360719516eca55a7a69cfee45aee2af by Christian Heimes in branch '3.6':
bpo-31518: Change TLS protocol for Debian (#3660)
https://github.com/python/cpython/commit/aab225840360719516eca55a7a69cfee45aee2af

New changeset 8d4d17399fb82801eaaca5beeb97a19908b40222 by Christian Heimes in branch '2.7':
bpo-31518: Change TLS protocol for Debian (#3661)
https://github.com/python/cpython/commit/8d4d17399fb82801eaaca5beeb97a19908b40222