Hi all, On 27.10.19 17:27, Drew Parsons wrote: > On 2019-10-27 23:13, Daniele Tricoli wrote: >> On Sun, Oct 13, 2019 at 10:31:31PM +0800, Drew Parsons wrote: >>> It conditionally works. Using curl, I found that TLSv1_0 or TLSv1_1 will >>> support a successful connection, but only if the maximum SSL_VERSION is >>> constrained to TLSv1_0 or TLSv1_1 (e.g. curl -v --tlsv1.1 --tls-max 1.1 >>> https://pub.orcid.org). Without the max, the connection fails: >>> $ curl --tlsv1.1 https://pub.orcid.org >>> curl: (35) error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake >>> failure >>> >>> The urllib3 failure was similar, but I do not know how to set tls-max with >>> urllib3. I could only find the option with curl. I could set up a custom >>> HTTPAdapter as suggested at >>> https://requests.readthedocs.io/en/master/user/advanced/#example-specific-ssl-version >>> to set ssl_version=ssl.PROTOCOL_TLSv1_1 but the ssl module doesn't have the >>> SSLVERSION_MAX_TLSv1_1 value that curl has. I could solve it with pycurl >>> using c.setopt(pycurl.SSLVERSION, pycurl.SSLVERSION_TLSv1_1 | >>> pycurl.SSLVERSION_MAX_TLSv1_1) >> >> For sure I'm missing something, but why not just set TLS version? >> I tried the following on both Python2 and Python3: >> >> >>> import ssl >> >>> from urllib3.poolmanager import PoolManager >> >>> http = PoolManager(ssl_version=ssl.PROTOCOL_TLSv1) >> >>> r = http.request('GET', 'https://pub.orcid.org') >> >>> r.status >> 200 > > > That's a good tip, I missed that permutation. I was originally trying to > access using the requests module, so didn't think to do it directly with > urllib.PoolManager > > >> >>> Evidently the orcid server only supports TLSv1.0 and TLSv1.1 and no higher >>> (why haven't they activated TLSv1.3 yet?!), while curl and urllib3 without >>> tls-max first test TLSv1.3 and then quit without cascading downwards once >>> they receive the TLSv1.3 handshake failure. Which is rather odd behaviour >>> when I think about it. The whole point of supporting multiple protocol >>> versions is to try the next available version if the first one doesn't work. >> >> Not an expert here, but I think fallback is not done on purpose due downgrade >> attacks: https://en.wikipedia.org/wiki/Downgrade_attack > > > I see. Still an odd kind of protection though. The attacker can just > downgrade themselves.
No. A sensible server will not talk to you if your requested SSL version is too low. pub.orcid.org seems to use absolutely outdated and insecure software versions. Bye Michael
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