In order to use the Ethernet bridging functionality, you'll need the
  userspace tools. These programs and documentation are available

  at http://www.linuxfoundation.org/en/Net:Bridge.  The download page is

  http://prdownloads.sourceforge.net/bridge.
  
  If you still have questions, don't hesitate to post to the mailing list 

  (more info https://lists.linux-foundation.org/mailman/listinfo/bridge).