[racket] Using Racket 6.0 through a Web proxy

Hi everyone,

I just installed Racket 6.0 on a new machine (MacOS 10.9), without any
problems. However, I didn't yet succeed in installing any packages
from the package catalog. I suspect that this is due to the Web proxy
that I have to use in my office.

My first attempt was to use raco:

   raco pkg install sxml

This already fails when resolving the package name:

   Resolving "sxml" via http://download.racket-lang.org/releases/6.0/catalog/
   tcp-connect: connection failed
     address: download.racket-lang.org
     port number: 80
     step: 6
     system error: Operation timed out; errno=60

I didn't find any information for configuring raco to use a proxy.
I have the usual environment variables set (http_proxy etc.), which makes
most Unix command-line tools happy, but it seems that raco doesn't
look at them.

Next I tried DrRacket, which has a proxy configuration in the "Browser"
tab of its preferences. With that configuration done, I can update the
package list from the catalog and see everything I need. However, installation
still fails:

    Resolving "sxml" via http://download.racket-lang.org/releases/6.0/catalog/
    Resolving "sxml" via http://pkgs.racket-lang.org
    Downloading https://github.com/jbclements/sxml/tarball/648a97f4881a8ea2f0959cf26e80bfdfec93d181
    tcp-connect: connection failed
      address: github.com
      port number: 443
      step: 6
      system error: Operation timed out; errno=60

Any suggestions?

Thanks in advance,
  Konrad.