title: python: installing packages via pip behind corporate proxy server
body: <p>I'm trying to install numpy (but this problem is replicated with everything i tried so far, including jupyer), using:</p>
  <pre><code>pip install --proxy=https://user:pass@name:port --trusted-host pypi.org --trusted-host pypi.python.org --trusted-host files.pythonhosted.org numpy
  </code></pre>
  <p>getting this error:</p>
  <pre><code>WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', FileNotFoundError(2, 'No such file or directory'))': /simple/numpy/
  
  ERROR: Could not find a version that satisfies the requirement numpy (from versions: none)
  ERROR: No matching distribution found for numpy
  </code></pre>
  <p>Not sure what to do next. 'No such file or directory'. It's all there under <a href="https://pypi.org/simple/numpy/" rel="nofollow noreferrer">https://pypi.org/simple/numpy/</a>. Is the proxy server interfering still? What can I do about that?</p>