I need authentication to use internet, say these are my variables:
You are probably on Windows, so I would advice you to check the 'R on Windows FAQ' that came with your installation, particularly Question 2.19: The Internet download functions fail. You may need to restart R with the --internet2 option (IIRC) for the proxy settings to come into effect.
I always found this very cumbersome. An alternative is to install a proxy-aware webdownloader as eg wget (as a windows binary) where you set the proxy options in a file in your home directory. This is all from memory, I think the last time I was faced with such a proxy was in 2005 so YMMV.