Wake-on-LAN

[Roberto Ragusa]

Timothy Murphy wrote:
> Has anyone experience with WOL under Fedora?
> If so, how exactly do you put the machine to sleep,
> and how exactly do you wake it up remotely?
> 
> I recently acquired an HP ML110 server (G5 Xeon 3065).
> This is said to have Wake-on-LAN capability,
> but when I suspend it to RAM I do not seem able
> to wake it remotely.
> 
> Should one (or can one) suspend to disk for this purpose?

Wake On LAN should actually be able to wake a system up
from power off state, so it should reasonably work
for suspended systems too.

As a first thing, the NIC LED (or the LED on the ethernet switch)
should be on; it will be on even when the system is switched off,
if WOL is active.

Then WOL has to be enabled. You can trust the BIOS
or, better, run

  ethtool eth0

and you will get something like

  Supports Wake-on: pumbag
  Wake-on: g

which (according to the man page) means WOL on my machine will
respond only on a specific kind of packet.

Last step is sending a proper WOL packet to the machine you want
to wake up (use wol or wakelan). Be sure to use the correct
interface on the waking machine and also try to write the MAC
address with reversed bytes (that is try 11:22:33:44:55:66
and 66:55:44:33:22:11); don't ask me why, but I have two
machines where only the inverted MAC works.

Best regards.
-- 
   Roberto Ragusa    mail at robertoragusa.it