When trying to connect to a server which only supports TLS version 1.1 or 1.2, the following error is raised: ssl.SSLError: [SSL: WRONG_VERSION_NUMBER] wrong version number (_ssl.c:598) For some reason, the SSL version is set to ssl.PROTOCOL_TLSv1 before initialisation and an SSL context is created in __init__, making any subsequent change to ssl_version useless. The only way to establish a successful connection is to pass a custom SSL context to the constructor. I think ssl_version should be settable at construction time before the context is created. I'm not sure exposing ssl_version is useful either, the documentation mentions it but it has no use after initialisation. The following lines should also be changed: if self.ssl_version == ssl.PROTOCOL_TLSv1: resp = self.voidcmd('AUTH TLS')
ssl_version is a class attribute so you can simply set that before instantiating FTP_TLS class: >>> import ftplib >>> ftplib.FTP_TLS.ssl_version = ... >>> client = ftplib.FTP_TLS(...) >>> ...
I know that, but it seems pretty unusual. And I would never had guessed from the documentation, I had to read the source. My point is that it should be easier to just connect to a TLSv1.2 server: the documentation should mention the fact that ssl_version is a class attribute or it should be set to something more compatible like ssl.PROTOCOL_SSLv23. I'm not sure about the implications of the latter. I'm not saying that this is a serious bug, but I'm used to Python providing us with something that works (more or less) out of the box.
