title: R - makeCluster hangs on localhost in Linux
body: <p>As the title says, <code>makeCluster</code> and <code>makeSOCKcluster</code> from the <code>snow</code> package hang when running on a linux machine..</p>
  
  <pre><code>cl &lt;- makeCluster(4, type="SOCK)
  cl &lt;- makeSOCKcluster(c("localhost","localhost","localhost","localhost"))
  </code></pre>
  
  <p>Both hang and never create the workers.. This code works on my Windows 8.1 Machine (64-bit) with the same R/RStudio versions. This leads me to believe it's a configuration error. Maybe firewall? Are localhost workers affected by firewall? I've tried disabling it via <code>sudo ufw disable</code>, but the code still hangs..</p>
  
  <p>Any ideas?</p>
  
  <p>Thanks.</p>
  
  <p>Ubuntu Linux 13.04, Raring Ringtail<br>
  RStudio Version 0.98.490<br>
  R version 3.02 (2013-09-25)<br>
  Platform: x86_64-pc-linux-gnu (64-bit)<br>
  snow_0.3-13</p>