Difference between revisions of "Wake-on-LAN"

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[[Category:Network]]
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[[Category:Networking]]
 
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This article deals with Wake-on-LAN (wol, wake on lan), what it is, how it can be used from an Arch Linux computer, and its general uses. Basically put, Wake-on-LAN, otherwise known as 'wol' is the ability to switch on a computer that is connected to a network (be it the internet or intranet). This can be a very useful ability.
This article deals with Wake-on-LAN (wol, wake on lan), what it is, how it can be used from an Arch Linux computer, and its general uses.
+
 
+
=What is Wake-on-LAN?=
+
 
+
Basically put, Wake-on-LAN, otherwise known as 'wol' is the ability to switch a computer that is connected to a network (be it the internet or intranet) on. This can be a very useful ability.
+
  
 
It is important to note that Wake-on-LAN applies to the computers being physically connected (ie, not wireless).
 
It is important to note that Wake-on-LAN applies to the computers being physically connected (ie, not wireless).
Line 12: Line 7:
  
 
For Wake-on-LAN to work, the target computer motherboard must support this feature. Generally speaking, the Wake-on-LAN (non)ability of the target motherboard will be specified by the hardware manufacturer. Sometimes, this ability is evident by browsing through said motherboard's BIOS and looking for something like 'PCI Power  up'. Most modern motherboards should support Wake-on-LAN.
 
For Wake-on-LAN to work, the target computer motherboard must support this feature. Generally speaking, the Wake-on-LAN (non)ability of the target motherboard will be specified by the hardware manufacturer. Sometimes, this ability is evident by browsing through said motherboard's BIOS and looking for something like 'PCI Power  up'. Most modern motherboards should support Wake-on-LAN.
 +
 +
==Ensure that Wake-on-LAN is enabled and survives a reboot==
 +
{{accuracy|reason=Should use a udev rule, not rc.local.}}
 +
 +
A common problem with the Wake-on-LAN in computers running Linux is that the network drivers have Wake-on-LAN switched off by default.  To manually switch on the Wake-on-LAN feature on your driver, you'll need ethtool:
 +
# pacman -S ethtool
 +
 +
First query the driver to see if it's defaulted to 'on' by using ethtool:
 +
 +
<pre> # ethtool eth0 | grep Wake-on
 +
        Supports Wake-on: pg
 +
Wake-on: d</pre>
 +
 +
{{Note|We need a 'Wake-on' value of 'g' for WOL to work.}}
 +
 +
To enable the wol feature in the driver, simply run the following
 +
# ethtool -s eth0 wol g
 +
 +
This command does not last beyond the '''next''' reboot. To make this setting persistent, even in the event of a power failure or crash, add the command using an absolute path to {{ic|/etc/rc.local}} using your fav text editor. 
 +
 +
. /etc/rc.conf
 +
. /etc/rc.d/functions
 +
# Setup WOL for next boot
 +
stat_busy "Setting WOL to Active"
 +
/usr/sbin/ethtool -s eth0 wol g
 +
stat_done
 +
 +
*If for some reason, you find that after using the command to switch your network drivers Wake-on-LAN feature on, the computer shuts down normally but then starts again, experiment with combinations of [u/b/m]g
 +
*For some network cards, you may also need the following command:
 +
 +
# echo enabled > /sys/class/net/eth0/device/power/wakeup
 +
 +
*For Realtek card (RTL8111/8168B) you may want to use r8168 driver instead of the defaulted loaded one r8169. Package r8168 is in community repo. If after successful setup WOL stop working randomly after some reboots, see here http://lists.debian.org/debian-user/2012/01/msg00241.html
 +
I grabbed the pci-config binary from nictools-pci debian package, as I can't find the source, and put the lasts commands in {{ic|/etc/rc.local.shutdown}}.
 +
 +
===With systemd===
 +
 +
Create a new service unit file /etc/systemd/system/wol@.service:
 +
 +
<pre>
 +
[Unit]
 +
Description=Wake-on-LAN for %i
 +
 +
[Service]
 +
Requires=network.target
 +
After=network.target
 +
ExecStart=/usr/sbin/ethtool -s %i wol g
 +
Type=oneshot
 +
 +
[Install]
 +
WantedBy=multi-user.target
 +
</pre>
 +
 +
Then activate this new service for your network adapter:
 +
 +
systemctl enable wol@eth0
 +
 +
and start it right now
 +
 +
systemctl start wol@eth0
  
 
==Wake-on-LAN in different situations==
 
==Wake-on-LAN in different situations==
  
 
The computer that you want to use Wake-on-LAN on may be directly linked to your computer through a network cable, connected to the same router that you are using, or remotely, across the internet.
 
The computer that you want to use Wake-on-LAN on may be directly linked to your computer through a network cable, connected to the same router that you are using, or remotely, across the internet.
 
===In all situations===
 
  
 
There are four essential things needed in order to use Wake-on-LAN on a target PC:
 
There are four essential things needed in order to use Wake-on-LAN on a target PC:
Line 26: Line 79:
 
#The internal or external IP of the target PC
 
#The internal or external IP of the target PC
  
*Firstly, install the Wake-on-LAN software from the AUR. In this article, [http://ahh.sourceforge.net/wol/ wol] will be used.
+
*Firstly, install a Wake-on-LAN software. In this article, [http://ahh.sourceforge.net/wol/ wol] will be used. It can be installed from the [[AUR_User_Guidelines#.5Bcommunity.5D|[community]]] repository.
 
+
*To install [http://aur.archlinux.org/packages.php?do_Details=1&ID=3778&O=0&L=&C=&K=wol&SB=&SO=&PP=&do_MyPackages=&do_Orphans=&SeB= wol from the AUR], please refer to the [[AUR_User_Guidelines#How_to_use_the_AUR| AUR User Guidelines]]
+
  
 
*'''It is recommended that you read the documentation of wol'''
 
*'''It is recommended that you read the documentation of wol'''
Line 41: Line 92:
 
*But it is good practice to include the IP address or hostname, therefore this syntax should be the minimal used:
 
*But it is good practice to include the IP address or hostname, therefore this syntax should be the minimal used:
  
  wol -i HOSTNAME_OR_IP MACADDRESS
+
  # wol -i HOSTNAME_OR_IP MACADDRESS
  
 
*The documentation of wol states that:
 
*The documentation of wol states that:
Line 49: Line 100:
 
*To obtain the MACADDRESS of the target computer:
 
*To obtain the MACADDRESS of the target computer:
  
  ifconfig | grep HWaddr
+
  $ ip link
  
 
The port, IP or hostname of the target PC will be addressed in the relevant following sections.
 
The port, IP or hostname of the target PC will be addressed in the relevant following sections.
Line 85: Line 136:
  
 
===Across the internet===
 
===Across the internet===
 
+
{{Expansion|Request for OpenWRT instructions.}}
 
The syntax needed in this case:
 
The syntax needed in this case:
  
Line 91: Line 142:
  
 
*Assuming that you know the external IP of the target machine, and that the [[Wake-on-LAN#Across_your_intranet.2Fnetwork_.28router.29|router ports]] on both sides have been forwarding correctly, then this should be exactly as the syntax states.
 
*Assuming that you know the external IP of the target machine, and that the [[Wake-on-LAN#Across_your_intranet.2Fnetwork_.28router.29|router ports]] on both sides have been forwarding correctly, then this should be exactly as the syntax states.
 +
 +
 +
Usually it is necessary to forward your wol port (typically UDP 9) to the broadcast address on your network, not to a particular IP. Most routers do not allow you to forward to broadcast, however if you can get shell access to your router (through telnet, ssh, serial cable, etc) you can implement this workaround:
 +
ip neighbor add 192.168.1.254 lladdr FF:FF:FF:FF:FF:FF dev eth0
 +
 +
(The above command assumes your network is 192.168.1.0/24 and use eth0 as network interface). Now, forward UDP port 9 to 192.168.1.254. This has worked for me on a Linksys WRT54G running Tomato, and on the Verizon FIOS ActionTec router.
 +
 +
For notes on how to do it on DD-WRT routers, see [http://www.dd-wrt.com/wiki/index.php/WOL#Remote_Wake_On_LAN_via_Port_Forwarding this tutorial].
 +
 +
==Battery draining problem==
 +
Some laptops have battery draining problem after shutdown [http://ubuntuforums.org/archive/index.php/t-1729782.html]. This might be caused by enabled Wake-on-LAN. To solve this problem, we can disable it by using ethtool as mentioned above.
 +
 +
# ethtool -s eth0 wol d
 +
 +
We can also add this to the '''/etc/rc.local''' or '''/etc/rc.local.shutdown'''.
  
 
==Additional Notes==
 
==Additional Notes==
  
A common problem with the Wake-on-LAN in computers running linux is that the network drivers have Wake-on-LAN switched off by default.
+
*A common problem is that some forget to switch on the Wake-on-LAN feature in their BIOS.
  
*To manually switch on the Wake-on-LAN feature on your driver:
+
*In some systems the BIOS option "Boot from PCI/PCI-E" needs to be Enabled.
  
pacman -Sy wol
+
==Example WOL script==
  ethtool -s ethX wol ubmg
+
Here is a script you can use to automate wol to several different machine. Modify as you see fit:
  
*This command does not last beyond the next reboot. To execute the command everytime you start up your computer, add the command into /etc/rc.local
+
<pre>#!/bin/bash
  
*For more information on this, please read the [http://ahh.sourceforge.net/wol/faq.html wol FAQ] (not available at the moment)
+
# definition of MAC addresses
 +
monster=01:12:46:82:ab:4f
 +
chronic=00:3a:53:21:bc:30
 +
powerless=1a:32:41:02:29:92
 +
ghost=01:1a:d2:56:6b:e6
  
*If for some reason, you find that after using the command to switch your network drivers Wake-on-LAN feature on, the computer shuts down normally but then starts again, experiment with combinations of [u/b/m]g
+
while [ "$input1" != quit ]; do
 +
echo "Which PC to wake?"
 +
echo "p) powerless"
 +
echo "m) monster"
 +
echo "c) chronic"
 +
echo "g) ghost"
 +
echo "b) wake monster, wait 40sec, then wake chronic"
 +
echo "q) quit and take no action"
 +
read input1
 +
  if [ $input1 == p ]; then
 +
  /usr/bin/wol $powerless
 +
  exit 1
 +
fi
 +
 
 +
if [ $input1 == m ]; then
 +
  /usr/bin/wol $monster
 +
  exit 1
 +
fi
 +
 
 +
if [ $input1 == c ]; then
 +
  /usr/bin/wol $chronic
 +
  exit 1
 +
fi
 +
 
 +
# this line requires an IP address in /etc/hosts for ghost
 +
# and should use wol over the internet provided that port 9
 +
# is forwarded to ghost on ghost's router
 +
 
 +
if [ $input1 == g ]; then
 +
  /usr/bin/wol -v -h -p 9 ghost $ghost
 +
  exit 1
 +
fi
 +
 
 +
if [ $input1 == b ]; then
 +
  /usr/bin/wol $monster
 +
  echo "monster sent, now waiting for 40sec then waking chronic"
 +
  sleep 40
 +
  /usr/bin/wol $chronic
 +
  exit 1
 +
fi
 +
 
 +
if [ $input1 == Q ] || [ $input1 == q ]; then
 +
echo "later!"
 +
exit 1
 +
fi
  
*Another problem is that a lot of people forget to switch on the Wake-on-LAN feature in their BIOS.
+
done
 +
echo  "this is the (quit) end!! c-ya!"</pre>
 +
== Resources ==
 +
[http://www.depicus.com/wake-on-lan/woli.aspx Wake-On-Lan]

Revision as of 12:39, 27 October 2012

This article deals with Wake-on-LAN (wol, wake on lan), what it is, how it can be used from an Arch Linux computer, and its general uses. Basically put, Wake-on-LAN, otherwise known as 'wol' is the ability to switch on a computer that is connected to a network (be it the internet or intranet). This can be a very useful ability.

It is important to note that Wake-on-LAN applies to the computers being physically connected (ie, not wireless).

Does my motherboard support Wake-on-LAN?

For Wake-on-LAN to work, the target computer motherboard must support this feature. Generally speaking, the Wake-on-LAN (non)ability of the target motherboard will be specified by the hardware manufacturer. Sometimes, this ability is evident by browsing through said motherboard's BIOS and looking for something like 'PCI Power up'. Most modern motherboards should support Wake-on-LAN.

Ensure that Wake-on-LAN is enabled and survives a reboot

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: Should use a udev rule, not rc.local. (Discuss in Talk:Wake-on-LAN#)

A common problem with the Wake-on-LAN in computers running Linux is that the network drivers have Wake-on-LAN switched off by default. To manually switch on the Wake-on-LAN feature on your driver, you'll need ethtool:

# pacman -S ethtool

First query the driver to see if it's defaulted to 'on' by using ethtool:

 # ethtool eth0 | grep Wake-on
        Supports Wake-on: pg
	Wake-on: d
Note: We need a 'Wake-on' value of 'g' for WOL to work.

To enable the wol feature in the driver, simply run the following

# ethtool -s eth0 wol g

This command does not last beyond the next reboot. To make this setting persistent, even in the event of a power failure or crash, add the command using an absolute path to /etc/rc.local using your fav text editor.

. /etc/rc.conf
. /etc/rc.d/functions
# Setup WOL for next boot
stat_busy "Setting WOL to Active"
/usr/sbin/ethtool -s eth0 wol g
stat_done
  • If for some reason, you find that after using the command to switch your network drivers Wake-on-LAN feature on, the computer shuts down normally but then starts again, experiment with combinations of [u/b/m]g
  • For some network cards, you may also need the following command:
# echo enabled > /sys/class/net/eth0/device/power/wakeup

I grabbed the pci-config binary from nictools-pci debian package, as I can't find the source, and put the lasts commands in /etc/rc.local.shutdown.

With systemd

Create a new service unit file /etc/systemd/system/wol@.service:

[Unit]
Description=Wake-on-LAN for %i

[Service]
Requires=network.target
After=network.target
ExecStart=/usr/sbin/ethtool -s %i wol g
Type=oneshot

[Install]
WantedBy=multi-user.target

Then activate this new service for your network adapter:

systemctl enable wol@eth0

and start it right now

systemctl start wol@eth0

Wake-on-LAN in different situations

The computer that you want to use Wake-on-LAN on may be directly linked to your computer through a network cable, connected to the same router that you are using, or remotely, across the internet.

There are four essential things needed in order to use Wake-on-LAN on a target PC:

  1. Some kind of Wake-on-LAN software on the host (your) PC
  2. A connection to the internet or intranet of the target PC
  3. The MAC address of the target PC
  4. The internal or external IP of the target PC
  • Firstly, install a Wake-on-LAN software. In this article, wol will be used. It can be installed from the [community] repository.
  • It is recommended that you read the documentation of wol
man wol
wol --help
  • wol requires several parameters, the most basic needed:
wol MACADDRESS
  • But it is good practice to include the IP address or hostname, therefore this syntax should be the minimal used:
# wol -i HOSTNAME_OR_IP MACADDRESS
  • The documentation of wol states that:
Each MAC-ADDRESS is written as x:x:x:x:x:x, where x is a hexadecimal number between 0 and ff which represents one byte of the address, which is in network byte order (big endian).
  • To obtain the MACADDRESS of the target computer:
$ ip link

The port, IP or hostname of the target PC will be addressed in the relevant following sections.

Across your intranet/network (no router)

If you are connected directly to another computer through a network cable, or have disabled your router firewall (not a good idea), then using Wake-on-LAN should be very simple.

For two computers connected to each other

wol MACADDRESS_OF_TARGET_PC

For computers connected to a non-firewalled router

wol -i INTERNAL_IP_OF_TARGET_PC MACADDRESS_OF_TARGET_PC
  • To find the internal IP (it's the first grepped entry):
ifconfig | grep 'inet addr'
  • Since you are not firewalled, then there is no need to worry about port redirects.
  • If you intend to continue using Wake-on-LAN, it is recommended that you assign your computer's MACADDRESS to a specific IP on your router. Consult your router for details as to how to do this.

Across your intranet/network (router)

The syntax used in this situation:

wol -p PORT_FORWARDED_TO_INTERNAL_IP -i INTERNAL_IP MACADDRESS_OF_TARGET_PC
  • When you send the MagicPacket signal to the target computer via a specific port, the signal passes through your router. The router must be instructed to forward any signal heading for that specific port to the internal IP of the target PC.
  • It is recommended that for multiple computers connected to one computer, to assign a different port forward to each internal IP
  • For port forwarding help, please consult http://portforward.com/ (though this website has some Windows specific content, it has a very large database of router web interfaces)

Across the internet

Tango-view-fullscreen.pngThis article or section needs expansion.Tango-view-fullscreen.png

Reason: Request for OpenWRT instructions. (Discuss in Talk:Wake-on-LAN#)

The syntax needed in this case:

wol -p X -i HOSTNAME_OR_EXTERNAL_IP_OF_TARGET MACADDRESS
  • Assuming that you know the external IP of the target machine, and that the router ports on both sides have been forwarding correctly, then this should be exactly as the syntax states.


Usually it is necessary to forward your wol port (typically UDP 9) to the broadcast address on your network, not to a particular IP. Most routers do not allow you to forward to broadcast, however if you can get shell access to your router (through telnet, ssh, serial cable, etc) you can implement this workaround:

ip neighbor add 192.168.1.254 lladdr FF:FF:FF:FF:FF:FF dev eth0

(The above command assumes your network is 192.168.1.0/24 and use eth0 as network interface). Now, forward UDP port 9 to 192.168.1.254. This has worked for me on a Linksys WRT54G running Tomato, and on the Verizon FIOS ActionTec router.

For notes on how to do it on DD-WRT routers, see this tutorial.

Battery draining problem

Some laptops have battery draining problem after shutdown [1]. This might be caused by enabled Wake-on-LAN. To solve this problem, we can disable it by using ethtool as mentioned above.

# ethtool -s eth0 wol d

We can also add this to the /etc/rc.local or /etc/rc.local.shutdown.

Additional Notes

  • A common problem is that some forget to switch on the Wake-on-LAN feature in their BIOS.
  • In some systems the BIOS option "Boot from PCI/PCI-E" needs to be Enabled.

Example WOL script

Here is a script you can use to automate wol to several different machine. Modify as you see fit:

#!/bin/bash

# definition of MAC addresses
monster=01:12:46:82:ab:4f
chronic=00:3a:53:21:bc:30
powerless=1a:32:41:02:29:92
ghost=01:1a:d2:56:6b:e6

while [ "$input1" != quit ]; do
echo "Which PC to wake?"
echo "p) powerless"
echo "m) monster"
echo "c) chronic"
echo "g) ghost"
echo "b) wake monster, wait 40sec, then wake chronic"
echo "q) quit and take no action"
read input1
  if [ $input1 == p ]; then
  /usr/bin/wol $powerless
  exit 1
fi

if [ $input1 == m ]; then
  /usr/bin/wol $monster
  exit 1
fi

if [ $input1 == c ]; then
  /usr/bin/wol $chronic
  exit 1
fi

# this line requires an IP address in /etc/hosts for ghost
# and should use wol over the internet provided that port 9
# is forwarded to ghost on ghost's router

if [ $input1 == g ]; then
  /usr/bin/wol -v -h -p 9 ghost $ghost
  exit 1
fi

if [ $input1 == b ]; then
  /usr/bin/wol $monster
  echo "monster sent, now waiting for 40sec then waking chronic"
  sleep 40
  /usr/bin/wol $chronic
  exit 1
fi

if [ $input1 == Q ] || [ $input1 == q ]; then
echo "later!"
exit 1
fi

done
echo  "this is the (quit) end!! c-ya!"

Resources

Wake-On-Lan