dhcpcd-discuss

On 6/15/20 4:35 AM, Roy Marples wrote:
> On 15/06/2020 12:15, Stuart Henderson wrote:
> > On 2020/06/13 17:30, Bruce Ferrell wrote:
> > > I'm in the process of tracking down the MAC address of all the android
> > > devices... Like my Amazon smart plugs.  They don't to respond to pings so
> > > it's an interesting issue to track down.
> >
> > btw, for this you might like the program called "arp-scan".
>
> There is a known issue with some Pi boards where they don't respond to ARP requests either unless the interface is in promiscous mode.
> There is a recent thread on this list about it.
>
> I also have parpd, a Proxy ARP Daemon.
> https://roy.marples.name/projects/parpd/
>
> You could set this do proxy a subnet outside your real one and run it in debug foreground mode.
> It will log all incoming ARP requests along with the MAC address of the sender.
>
> Roy

That issue was in some of the very early PI boards... I think it was the PI 1 generation.  I think back then they were synthesizing MAC addresses and they changed on every boot.  
The units I'm working with right now are all fairly recent PI 3+ or PI 4+ boards.

A tool like arp-scan looks to be useful for hunting unknown devices that don't necessarily respond to ICMP... Like smartplugs.

I noticed they don't tend to print their MAC addresses on the device case.  Quite vexing when trying to chase down problems but semi-understandable.