I got this problem when I was trying to install pytorch 
ConnectionError: HTTPConnectionPool(host=‘download.pytorch.org 1’, port=80): Max retries exceeded with url: /whl/cu80/torch-0.1.12.post2-cp27-none-linux_x86_64.whl (Caused by NewConnectionError(’<pip._vendor.requests.packages.urllib3.connection.HTTPConnection object at 0x7f3575aae2d0>: Failed to establish a new connection: [Errno -2] Name or service not known’,))
I used the command:
sudo pip install http://download.pytorch.org/whl/cu80/torch-0.1.12.post2-cp27-none-linux_x86_64.whl 13

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