Wake-on-LAN

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Revision as of 18:08, 12 October 2006 by Ikbenkwik (Talk | contribs)

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I got tired of running down the stairs to my mythbox to power it on, whenever i wanted to access it from my desktop. I figured, it would be nice to be able to powerup my mythbox using wake-on-lan (wol). Wake-on-lan works by broadcasting a 'magic packet' over the network. This packet contains a MAC address. The network card examines the packet, determines whether the MAC address matches its own and if so, starts the computer. I used an Epia M10000 with Fedora Core 4.

Setting up

If you have a network card that supports wake-on-lan, you can powerup your mythbox by sending it a 'magic packet' over the network. Here's what i did:

First, find out whether your network card supports wol:

# ethtool eth0
Settings for eth0:
       Supported ports: [ TP MII ]
       Supported link modes:   10baseT/Half 10baseT/Full
                               100baseT/Half 100baseT/Full
       Supports auto-negotiation: Yes
       Advertised link modes:  10baseT/Half 10baseT/Full
                               100baseT/Half 100baseT/Full
       Advertised auto-negotiation: Yes
       Speed: 100Mb/s
       Duplex: Full
       Port: MII
       PHYAD: 1
       Transceiver: internal
       Auto-negotiation: on
       Supports Wake-on: pumbg
       Wake-on: g
       Current message level: 0x00000001 (1)
       Link detected: yes

The 'g' in Supports Wake-on: pumbg indicates that wake-on-lan by using a 'magic packet' is indeed supported. Next, you need to make sure that wake-on-lan support is enabled in the BIOS (although, this does not seem to be necessary for my motherboard). In addition, you need to tell your network card to enable wake-on-lan:

# ethtool -s eth0 wol g

Since after rebooting Wake-on will be reset, you might what to add it to /etc/rc.local:

# echo 'ethtool -s eth0 wol g' >> /etc/rc.local

Now turn off you mythbox and send it a 'magic packet'.

Sending 'magic packet' to wake up your mythbox

You will need a wake-on-lan client to send 'magic packets' over your network. First, determine the MAC address of the machine you what to power on:

# ifconfig

Turn off you mythbox and from another computer execute the following command (replacing the MAC address with the one you just found). I used a wake-on-lan client from Sourceforge.

$ wol 00:4F:49:07:0B:5F

If all went well, your mythbox will start booting! There are other clients for Windows and Mac OS X as well.

Useful links:

  1. http://ahh.sourceforge.net/wol/ (wake-on-lan client + additinal information)
  2. http://dag.wieers.com/packages/wol/ (wol packages for RedHat and Fedora)
  3. http://www.die.net/doc/linux/man/man8/ethtool.8.html (man page for ethtool)
  4. http://www.sourceforge.net/projects/gkernel/ (gkernel package that contains ethtool)