title: Unable to find the source of current linux Kernel
body: <p>While trying to install guest additions on a Debian guest I get the error:
  Unable to find the source of your current linux Kernel. Specify KERN_DIR= and run Make again. </p>
  
  <p>Some said that this is because linux headers are missing. But when I try to run</p>
  
  <pre><code>sudo apt-get install linux-headers-3.16.0-4amd64 
  </code></pre>
  
  <p>I get the error could not resolve ftp.debian.org.uk</p>