[R] Question about proxy setting of R

[qwertyui_period at yahoo.co.jp]

Hello,

I use R 3.0.2 on Win 7 through proxy server using ".Rprofile" in home
directory that includes "Sys.setenv(http_proxy=proxy_server:port)".
There has been no problem to access the internet for some years.
In this situation, I installed R 3.3.1 and then entered "update.packages
()", however, "Proxy Authentification" window didn't show up and
failed to access the internet. Error messages are as below.

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> update.packages(ask='graphics',checkBuilt=TRUE)
--- Please select a CRAN mirror for use in this session ---
Warning: failed to download mirrors file (cannot open URL
'https://cran.r-project.org/CRAN_mirrors.csv'); using local file
'C:/PROGRA~1/R/R-33~1.2/doc/CRAN_mirrors.csv'
Warning: unable to access index for repository
https://cran.ism.ac.jp/src/contrib: 
  cannot open URL 'https://cran.ism.ac.jp/src/contrib/PACKAGES' 
Warning: unable to access index for repository
http://www.stats.ox.ac.uk/pub/RWin/src/contrib: 
  cannot open URL 'http://www.stats.ox.ac.uk/pub/RWin/src/contrib/PACKAGES' 
Warning message:
In download.file(url, destfile = f, quiet = TRUE) :
  cannot open URL 'https://cran.r-project.org/CRAN_mirrors.csv': HTTP
status was '407 Proxy Authentication Required'

----------------------------------------------------------------------------------------------------------------------------

Strange to say, R 3.0.2 is able to access to the internet, and R 3.3.1
shows collect proxy setting in ".Rprofile"  by "Sys.getenv("http_proxy")"
From internet information, I added "http_proxy_user=ask" to ".Rprofile", or
" --internet2" to the desktop icon of R 3.3.1, ending up in the same
result.

Please show me the way of proxy setting of R 3.3.1.