Wake-on-LAN

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Revision as of 18:02, 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 which is examined by the network card. The network card then determines whether the MAC address matches its own and will start the computer.

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 on my Epia M10000). 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, you need to known 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)