切换requests ssl版本

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16-12-2024

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I cannot directly access and process information from specific websites like ScienceDirect. Therefore, I cannot create an article using questions and answers from that platform about switching Requests SSL versions. My knowledge is based on the vast dataset I was trained on, which includes information about Python's requests library and SSL/TLS.

However, I can create a comprehensive article about switching SSL/TLS versions within the requests library in Python. This will cover the underlying concepts and provide practical examples.

The requests library in Python, a powerful tool for making HTTP requests, relies on the underlying operating system's SSL/TLS implementation to handle secure connections (HTTPS). While requests itself doesn't directly expose options to explicitly choose a specific SSL/TLS version, we can indirectly influence the SSL/TLS version used through several methods. Understanding these methods requires knowledge of how SSL/TLS works and the potential security implications of choosing specific versions.

Understanding SSL/TLS Versions

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are cryptographic protocols that provide secure communication over a network. Several versions exist, each with its own security features and vulnerabilities. Older versions like SSLv2 and SSLv3 are highly insecure and should never be used. TLS 1.0, 1.1, and 1.2 are also considered outdated and vulnerable, while TLS 1.3 is the current recommended version offering significant security improvements.

Methods to Influence SSL/TLS Version in requests

Directly controlling the precise SSL/TLS version with requests is not possible through its public API. The version used depends on the underlying OpenSSL or similar library used by your system's Python interpreter. However, you can influence the process in these ways:

1. System-Wide OpenSSL Configuration:

The most effective way to control the SSL/TLS version is to configure your system's OpenSSL library. This ensures that all applications, including those using requests, will use the desired version. This approach typically involves modifying configuration files (e.g., /etc/ssl/openssl.cnf on Linux systems) or setting environment variables. The exact method varies greatly depending on your operating system and OpenSSL version. Caution: Incorrectly configuring OpenSSL can disrupt system security, so proceed with extreme care and consult your system's documentation. This is generally not recommended unless you have a deep understanding of system administration and network security.

2. Using a Custom ssl.SSLContext:

The Python ssl module allows you to create a custom ssl.SSLContext object, which provides more control over SSL/TLS settings. You can then pass this context to the requests session. This approach allows you to specify protocols, cipher suites, and other options.

import ssl
import requests

# Create a custom SSL context, specifying allowed protocols
context = ssl.create_default_context()
context.set_ciphers('ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384') #Example, choose appropriate ciphers
context.options |= ssl.OP_NO_SSLv2 | ssl.OP_NO_SSLv3 | ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1 # Disable insecure protocols
context.check_hostname = True
context.verify_mode = ssl.CERT_REQUIRED


session = requests.Session()
session.mount('https://', requests.adapters.HTTPAdapter(pool_connections=1, pool_maxsize=1, max_retries=1, ssl_context=context))

try:
    response = session.get("https://www.example.com", verify=True)
    print(response.status_code)
except requests.exceptions.SSLError as e:
    print(f"SSL Error: {e}")

This example disables insecure protocols and sets specific cipher suites. Important: Always thoroughly research and understand the security implications of the cipher suites you choose. Using outdated or weak ciphers can negate the security benefits of TLS.

3. Using requests with a specific urllib3 version:

The requests library internally utilizes the urllib3 library for HTTP connection handling. While requests doesn't directly expose the underlying urllib3 configuration, upgrading to a newer version of urllib3 might implicitly benefit from newer SSL/TLS features and patches. This is a less direct approach, as you depend on urllib3’s updates to incorporate the latest SSL/TLS improvements. Check the urllib3 release notes for details on SSL/TLS support in different versions.

4. Proxy Servers:

If you're using a proxy server, the proxy's SSL/TLS configuration might override your local settings. Ensure your proxy server is configured to use a secure and up-to-date SSL/TLS version.

Security Considerations:

• Disabling older protocols is crucial: Never allow SSLv2, SSLv3, TLS 1.0, or TLS 1.1. These protocols are highly vulnerable to various attacks.
• Choose strong cipher suites: Carefully select cipher suites that provide robust encryption and authentication. Refer to security best practices and consult resources like the NIST website for guidance.
• Certificate verification: Always verify SSL certificates (verify=True in requests) to ensure you are communicating with the intended server and not a malicious actor.

Conclusion

While directly specifying the SSL/TLS version within the requests library is not straightforward, understanding the underlying mechanisms and using techniques like creating a custom ssl.SSLContext allows for a reasonable degree of control. Prioritize security by disabling outdated protocols and choosing strong cipher suites. Remember to thoroughly research and understand the security implications of any changes you make to your system's SSL/TLS configuration. Always keep your system and its libraries updated to benefit from the latest security patches. This combination of system-level configuration and careful use of the ssl module provides the best approach for managing SSL/TLS versions in your Python requests applications.