[CentOS] 6.x - find interface with link up

Les Mikesell wrote:
> In earlier versions 'mii-tool' would iterate over interfaces and show
> which have link up.   In 6.x it wants an interface as a parameter.
> What is the appropriate way to find which of some number of of
> interfaces are connected?   Better yet, what is the least typing to
> get the mac addresses of those interfaces?

ethtool, or even lshw.

        mark