Python pip-无法获取URLhttps://pypi.python.org/simple/package

当我尝试使用pip 1.5.4在virtualenv中安装软件包时，会出现以下错误（例如，当我想安装六个软件包时）：

当我尝试easy_安装时，我遇到了SSL错误（我用pip解决了这个问题，但我解决了它）。包显然是存在的。。。我不使用代理-这台电脑是通过以太网直接连接到路由器与静态IP。在其他PC上进行相同的配置（也包括静态IP、同一路由器）。我的连接工作正常-我可以更新我的系统，ping google等

多谢各位

Downloading/unpacking six
  Could not fetch URL https://pypi.python.org/simple/six/: connection error: [Errno 2] No such file or directory
  Will skip URL https://pypi.python.org/simple/six/ when looking for download links for six
  Could not fetch URL https://pypi.python.org/simple/: connection error: [Errno 2] No such file or directory
  Will skip URL https://pypi.python.org/simple/ when looking for download links for six
  Cannot fetch index base URL https://pypi.python.org/simple/
  Could not fetch URL https://pypi.python.org/simple/six/: connection error: [Errno 2] No such file or directory
  Will skip URL https://pypi.python.org/simple/six/ when looking for download links for six
  Could not find any downloads that satisfy the requirement six
Cleaning up...
  Removing temporary dir /var/www/sova/venv/build...
No distributions at all found for six
Exception information:
Traceback (most recent call last):
  File "/var/www/sova/venv/lib/python3.3/site-packages/pip/basecommand.py", line 122, in main
    status = self.run(options, args)
  File "/var/www/sova/venv/lib/python3.3/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 "/var/www/sova/venv/lib/python3.3/site-packages/pip/req.py", line 1177, in prepare_files
    url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
  File "/var/www/sova/venv/lib/python3.3/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 six

Storing debug log for failure in /root/.pip/pip.log