Recently I've been wrestling with WOL for one of my linux servers. I
found a WOL client called etherwake, which installs just fine in
OpenDebianSlug using the command apt-get install etherwake.
However, I found that I was having problems on the other end. I
noticed that if I switch off the computer using the front power switch
at the GRUB boot menu, I could wake the machine using etherwake,
whereas if I use shutdown -h now from within linux, nothing happens.
The tell-tale sign is that the port light on my 3Com router/switch is
lit in the first instance, and dark in the second.
A bit of googling around suggested that this is a common problem. The
explanation was something along the lines of "linux shuts down your
network card on OS shutdown". (For the pedantic, this should be
rephrased as "most linux distributions shutdown the network card on
shutdown"). The Gentoo Wiki's page on WOL suggested removing the
-i option from halt.
Starting from this, I managed to get my machine to shutdown and be WOL'able!
My machine is running Fedora Core 4, though these change would likely
work for other versions of Fedora and Redhat/CentOS. I changed the
script /etc/init.d/halt so that the last few lines were changed from
HALTARGS="-i -d"
[ -f /poweroff -o ! -f /halt ] && HALTARGS="$HALTARGS -p"
exec $command $HALTARGS
to
HALTARGS="-d"
[ -f /poweroff -o ! -f /halt ] && HALTARGS="$HALTARGS -p"
/usr/sbin/ethtool -s eth0 wol g
sleep 5 # this pause seems to be important!
exec $command $HALTARGS
Note the removal of -i from HALTARGS and the extra ethtool
invocation before the last exec command.
This is the easy part. I created a file called /etc/ethers to map
names to my MAC addresses:
00:20:ED:5A:00:2B fried
00:11:09:24:1C:8B white
Now to wake up fried, all I need to do is type the following
command:
sudo etherwake fried
and fried.rice wakes up!