title: R Package installation Issue
body: <p>I'm not able to install any packages in R. I tried in all versions of R starting from 3.2.2 till 3.2.4(revised), but I get the same error. It seems like a proxy issue to me as I'm connected to my college firewall. I was able to install the packages when I'm connected to my home network. Can you please guide me to resolve this issue.?
  Here are the error messages</p>
  
  <pre><code>&gt; chooseCRANmirror()
  Error in download.file(url, destfile = f, quiet = TRUE) : 
    cannot open URL 'https://cran.r-project.org/CRAN_mirrors.csv'
  In addition: Warning message:
  In download.file(url, destfile = f, quiet = TRUE) :
    InternetOpenUrl failed: 'The server name or address could not be resolved'
  &gt; install.packages("ggplot2")
  Installing package into ‘C:/Users/HP/Documents/R/win-library/3.2’
  (as ‘lib’ is unspecified)
  Warning: unable to access index for repository https://cran.rstudio.com/src/contrib
  Warning: unable to access index for repository 
  Warning: unable to access index for repository 
  Warning: unable to access index for repository 
  Warning message:
  package ‘ggplot2’ is not available (for R version 3.2.2)
  </code></pre>