pip安装失败，出现“连接错误：[SSL:CERTIFICATE\u VERIFY\u FAILED]CERTIFICATE VERIFY FAILED（\u SSL.c:598）”

Question

我对Python很陌生，并试图在Windows 7上> pip install linkchecker。一些注释：

• 无论软件包如何，pip安装都将失败。例如，> pip install scrapy也会导致SSL错误。
• Python 3.4.1的普通安装包括pip 1.5.6。我试着做的第一件事就是安装linkchecker。Python2.7已经安装，它与ArcGIS一起提供。python和pip在我安装3.4.1之前无法从命令行获得。
• > pip search linkchecker有效。也许这是因为pip search没有验证站点的SSL证书。
• 我在一个公司网络中，但我们不通过代理访问互联网。
• 每个公司的计算机（包括我的计算机）都有一个受信任的根证书颁发机构，它用于各种原因，包括启用对https://google.com的TLS流量的监视。不确定这是否与此有关。

以下是运行pip install linkchecker后mypip.log的内容：

Downloading/unpacking linkchecker
  Getting page https://pypi.python.org/simple/linkchecker/
  Could not fetch URL https://pypi.python.org/simple/linkchecker/: connection error: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:598)
  Will skip URL https://pypi.python.org/simple/linkchecker/ when looking for download links for linkchecker
  Getting page https://pypi.python.org/simple/
  Could not fetch URL https://pypi.python.org/simple/: connection error: HTTPSConnectionPool(host='pypi.python.org', port=443): Max retries exceeded with url: /simple/ (Caused by <class 'http.client.CannotSendRequest'>: Request-sent)
  Will skip URL https://pypi.python.org/simple/ when looking for download links for linkchecker
  Cannot fetch index base URL https://pypi.python.org/simple/
  URLs to search for versions for linkchecker:
  * https://pypi.python.org/simple/linkchecker/
  Getting page https://pypi.python.org/simple/linkchecker/
  Could not fetch URL https://pypi.python.org/simple/linkchecker/: connection error: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:598)
  Will skip URL https://pypi.python.org/simple/linkchecker/ when looking for download links for linkchecker
  Could not find any downloads that satisfy the requirement linkchecker
Cleaning up...
  Removing temporary dir C:\Users\jcook\AppData\Local\Temp\pip_build_jcook...
No distributions at all found for linkchecker
Exception information:
Traceback (most recent call last):
  File "C:\Python34\lib\site-packages\pip\basecommand.py", line 122, in main
    status = self.run(options, args)
  File "C:\Python34\lib\site-packages\pip\commands\install.py", line 278, in run
    requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File "C:\Python34\lib\site-packages\pip\req.py", line 1177, in prepare_files
    url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
  File "C:\Python34\lib\site-packages\pip\index.py", line 277, in find_requirement
    raise DistributionNotFound('No distributions at all found for %s' % req)
pip.exceptions.DistributionNotFound: No distributions at all found for linkchecker

Answer 1

kenorb’s answer非常有用（非常好！）。
在他的解决方案中，也许这是最简单的一个： --trusted-host

例如，在这种情况下，您可以

pip install --trusted-host pypi.python.org linkchecker

pem文件（或任何其他文件）是不必要的。