[R] Changing R network connections

[Alexandre Fabrice Letimier]

Dear all,
I have some difficulties to get R to download the various packages. 
It seems that it's a problem of the network that I'm on. I would need 
to configure R so that I can put the proxy address and the port of 
the network that I'm on. Can anyone explain to me how to change these 
in R. I've looked at the preferences but couldn't find it there. 
Thanks a lot for you help.
Regards,
Fabrice Letimier
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