python - 确定 SSL 包使用的默认协议(protocol)版本？

Question

在 python 中，如何确定 SSL 包或请求默认使用哪个 SSL 或 TLS 协议(protocol)。

比如 TLSv1 与 SSLv3。

Answer 1

SSL socket creation Python 文档的部分包含有关 SSL 包的信息:

The parameter ssl_version specifies which version of the SSL protocol to use. Typically, the server chooses a particular protocol version, and the client must adapt to the server’s choice. Most of the versions are not interoperable with the other versions. If not specified, the default is PROTOCOL_SSLv23 it provides the most compatibility with other versions.

Here’s a table showing which versions in a client (down the side) can connect to which versions in a server (along the top):

| client / server | SSLv2 | SSLv3 | SSLv23 | TLSv1 | TLSv1.1 | TLSv1.2 |
|-----------------|-------|-------|--------|-------|---------|---------|
| SSLv2           | yes   | no    | yes    | no    | no      | no      |
| SSLv3           | no    | yes   | yes    | no    | no      | no      |
| SSLv23          | no    | yes   | yes    | yes   | yes     | yes     |
| TLSv1           | no    | no    | yes    | yes   | no      | no      |
| TLSv1.1         | no    | no    | yes    | no    | yes     | no      |
| TLSv1.2         | no    | no    | yes    | no    | no      | yes     |

Note:

Which connections succeed will vary depending on the version of OpenSSL. For example, before OpenSSL 1.0.0, an SSLv23 client would always attempt SSLv2 connections.