title: Could not generate persistent MAC address for vethXXXXX: No such file or directory
body: <p>I'm starting to use CoreOS (on AWS ECS). After having it launch my first container, I see this in <code>journalctl</code>:</p>
  
  <pre><code>Could not generate persistent MAC address for vethXXXX: No such file or directory
  </code></pre>
  
  <p>Here's more context. I've removed the time and instance information, but this is all within the same second. Note there are two distinct <code>veth</code> entries. I don't know if that means anything.</p>
  
  <pre><code>systemd[1]: Started docker container 1234
  systemd[1]: Starting docker container 1234
  dockerd[595]: time="2015-07-23T23:30:52Z" level=info msg="GET /v1.17/containers/1234/json"
  dockerd[595]: time="2015-07-23T23:30:52Z" level=info msg="+job container_inspect(1234)"
  systemd-timesyncd[473]: Network configuration changed, trying to establish connection.systemd-udevd[7501]: Could not generate persistent MAC address for vethYYYY: No such file or directory
  kernel: device vethXXXX entered promiscuous mode
  kernel: IPv6: ADDRCONF(NETDEV_UP): vethXXXX: link is not ready
  systemd-udevd[7508]: Could not generate persistent MAC address for vethXXXX: No such file or directory
  systemd-networkd[497]: vethXXXX: Configured
  kernel: eth0: renamed from vethYYYY
  kernel: IPv6: ADDRCONF(NETDEV_CHANGE): vethXXXX: link becomes ready
  kernel: docker0: port 2(vethXXXX) entered forwarding state
  kernel: docker0: port 2(vethXXXX) entered forwarding state
  systemd-networkd[497]: vethXXXX: Gained carrier
  </code></pre>
  
  <p><a href="https://forums.virtualbox.org/viewtopic.php?f=3&amp;t=43090">I found a discussion of this error on Ubuntu and it comes down to removing a udev rule</a>, which doesn't seem to exist on CoreOS. <a href="https://forums.openvpn.net/topic18713.html">There's a discussion about iptables with OpenVPN</a>, which again doesn't seem to apply. <a href="http://ubuntuforums.org/showthread.php?t=2275372">Here's a bridge rule for LXC on Ubuntu</a>. Again, I don't see how to apply that.</p>
  
  <p>I haven't done anything with the networkd or flannel configuration. If the problems are in that area, I need specific steps on how to fix it for use in AWS ECS.</p>