title: Why am I getting an RTNETLINK Operation Not Permitted when using Pipework with Docker containers?
body: <p>I'm running CoreOS stable 494.5.0 using Vagrant/VirtualBox and am running the vanilla ruby:2.1.5 Docker image. I'm trying to use Pipework to connect the Docker container to a local physical interface (as opposed to using <code>--net=host</code> when running the container) so I can sniff traffic. Pipework creates <code>eth1@if2</code> in the container and sets its IP address correctly, but the link ends up in the <code>UNKNOWN</code> state and when I try to bring the link up using <code>ip link</code> I get <code>RTNETLINK answers: Operation not permitted</code>.</p>
  
  <p>If it makes a difference, I have to use <code>ip link set dev eth1 up</code> instead of <code>ip link set dev eth1@if2 up</code> or else I get <code>Cannot find device "eth1@if2"</code>.</p>
  
  <p>Any ideas what I'm doing wrong?</p>