Difference between revisions of "Wake-on-LAN"

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[[Category:Networking]]
 
[[Category:Networking]]
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.
+
[[ja:Wake-on-LAN]]
 +
[[Wikipedia:Wake-on-LAN|Wake-on-LAN]] (WoL) is a feature to switch on a computer via the network.
  
It is important to note that Wake-on-LAN applies to the computers being physically connected (ie, not wireless).
+
== Hardware settings ==
  
==Does my motherboard support Wake-on-LAN?==
+
The target computer's motherboard and [[wikipedia:Network interface controller|Network Interface Controller]] have to support Wake-on-LAN. The target computer has to be physically connected (with a cable) to a router or to the source computer, wireless cards do not support WoL.
  
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.
+
The Wake-on-LAN feature also has to be enabled in the computer's BIOS. Different motherboard manufacturers use slightly different language for this feature. Look for terminology such as "PCI Power up", "Allow PCI wake up event" or "Boot from PCI/PCI-E".
  
==Ensure that Wake-on-LAN is enabled and survives a reboot==
+
It is known that some motherboards are affected by a bug that can cause immediate or random wake-up after a ''shutdown'' whenever the BIOS WoL feature is enabled (as discussed in [https://bbs.archlinux.org/viewtopic.php?id=173648 this thread] for example). The following actions in the BIOS preferences can solve this issue with some motherboards:
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:
+
# Disable all references to ''xHCI'' in the USB settings (note this will also disable USB 3.0 at boot time)
# pacman -S ethtool
+
# Disable ''EuP 2013'' if it is explicitly an option
 +
# Optionally enable wake-up on keyboard actions
 +
{{Note|There are mixed opinions as to the value of #3 above and it may be motherboard dependent.}}
  
First query the driver to see if it's defaulted to 'on' by using ethtool:
+
== Software configuration ==
  
<pre> # ethtool eth0 | grep Wake-on
+
=== Enable WoL on the network adapter ===
        Supports Wake-on: pg
 
Wake-on: d</pre>
 
  
{{Note|We need a 'Wake-on' value of 'g' for WOL to work.}}
+
Depending on the hardware, the network driver may have WoL switched off by default.
  
To enable the wol feature in the driver, simply run the following
+
To query this status or to change the settings, install {{Pkg|ethtool}} and query the network device via this command:
# ethtool -s eth0 wol g
+
{{hc|<nowiki># ethtool net0 | grep Wake-on</nowiki>|
 +
Supports Wake-on: pumbag
 +
Wake-on: d}}
 +
The ''Wake-on'' values define what activity triggers wake up: {{ic|d}} (disabled), {{ic|p}} (PHY activity), {{ic|u}} (unicast activity), {{ic|m}} (multicast activity), {{ic|b}} (broadcast activity), {{ic|a}} (ARP activity), and {{ic|g}} (magic packet activity). The value {{ic|g}} is required for WoL to work, if not, the following command enables the WoL feature in the driver:
  
This command does not last beyond the '''next''' reboot. If using netcfg, one can make this setting persistent by adding the following to {{hc|/etc/network.d/PROFILE|2=
+
# ethtool -s net0 wol g
POST_UP='/usr/sbin/ethtool -s eth0 wol g'
+
 
 +
This command might not last beyond the next reboot and in this case must be repeated via some mechanism. Common solutions are listed in the following subsections.
 +
 
 +
=== Make it persistent ===
 +
 
 +
==== netctl ====
 +
 
 +
If using netctl, one can make this setting persistent by adding the following the netctl profile:
 +
 
 +
{{hc|/etc/netctl/''profile''|2=
 +
ExecUpPost='/usr/bin/ethtool -s net0 wol g'
 
}}
 
}}
  
*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
+
==== systemd.link ====
*For some network cards, you may also need the following command:
+
 
 +
Link-level configuration is possible through systemd. The actual setup is performed by the {{ic|net_setup_link}} udev builtin. Add the {{ic|WakeOnLan}} option to the network link file:
  
# echo enabled > /sys/class/net/eth0/device/power/wakeup
+
{{hc|/etc/systemd/network/50-wired.link|2=
 +
[Link]
 +
WakeOnLan=magic
 +
...
 +
}}
  
===With systemd===
+
{{Note|This configuration applies only to the link-level, and is independent of network-level daemons such as [[NetworkManager]] or [[systemd-networkd]].}}
  
Create a new service unit file /etc/systemd/system/wol@.service:
+
See [[systemd-networkd#link files]] and {{man|5|systemd.link}} for more information.
  
{{bc|1=
+
==== systemd service ====
 +
 
 +
This is an equivalent of previous {{ic|systemd.link}} option, but uses a standalone systemd service.
 +
 
 +
{{hc|/etc/systemd/system/wol@.service|2=
 
[Unit]
 
[Unit]
 
Description=Wake-on-LAN for %i
 
Description=Wake-on-LAN for %i
Line 43: Line 66:
  
 
[Service]
 
[Service]
ExecStart=/usr/sbin/ethtool -s %i wol g
+
ExecStart=/usr/bin/ethtool -s %i wol g
 
Type=oneshot
 
Type=oneshot
  
Line 50: Line 73:
 
}}
 
}}
  
Then activate this new service for your network adapter:
+
Alternatively install the {{AUR|wol-systemd}} package.
 +
 
 +
Then activate this new service by [[starting]] {{ic|wol@''interface''.service}}.
 +
 
 +
==== udev ====
  
# systemctl enable wol@eth0
+
[[udev]] is capable of running any command as soon as a device is visible. The following rule will turn on WOL on all [[network interface]]s whose name matches {{ic|enp*}}:
  
and start it right now
+
{{hc|/etc/udev/rules.d/99-wol.rules|<nowiki>
 +
ACTION=="add", SUBSYSTEM=="net", NAME=="enp*", RUN+="/usr/bin/ethtool -s $name wol g"
 +
</nowiki>}}
  
# systemctl start wol@eth0
+
The {{ic|$name}} placeholder will be replaced by the value of the {{ic|NAME}} variable for the matched device.
  
==Wake-on-LAN in different situations==
+
{{Note|The name of the configuration file is important. Due to the introduction of [[Network configuration#Device_names|persistent device names]] in systemd v197, it is important that the rules matching a specific network interface are named lexicographically after {{ic|80-net-name-slot.rules}}, so that they are applied after the devices gain the persistent names.}}
  
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.
+
{{Warning|[[udev]] will match the device as soon it becomes available, be this in the [[initramfs]] (before the switch_root) or the main system. The order is not deterministic; there is no guarantee. Be sure that your initramfs includes the necessary udev rules (from {{ic|/etc/udev/rules.d}}) and supporting binaries ({{ic|/usr/bin/ethtool}}).}}
  
There are four essential things needed in order to use Wake-on-LAN on a target PC:
+
==== cron ====
  
#Some kind of Wake-on-LAN software on the host (your) PC
+
A command can be run each time the computer is (re)booted using "@reboot" in a crontab. First, make sure [[Cron#Installation|cron]] is enabled, and then [[Cron#Basic_commands|edit a crontab]] for the root user that contains the following line:
#A connection to the internet or intranet of the target PC
 
#The MAC address of the target PC
 
#The internal or external IP of the target PC
 
  
*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.
+
@reboot /usr/bin/ethtool -s [net-device] wol g
  
*'''It is recommended that you read the documentation of wol'''
+
==== NetworkManager ====
  
man wol
+
In version 1.0.6 NetworkManager [https://www.phoronix.com/scan.php?page=news_item&px=NetworkManager-WoL-Control adds Wake-on-LAN controls]. One way to enable Wake-on-LAN by magic packet is through nmcli.
wol --help
 
  
*wol requires several parameters, the most basic needed:
+
First, search for the name of the wired connection:
  
  wol MACADDRESS
+
{{hc|# nmcli con show|2=
 +
NAME    UUID                                  TYPE            DEVICE
 +
wired1 612e300a-c047-4adb-91e2-12ea7bfe214e  802-3-ethernet  enp0s25
 +
}}
 +
 
 +
By following, one can view current status of Wake-on-LAN settings:
 +
 
 +
{{hc|# nmcli c show "wired1" <nowiki>|</nowiki> grep 802-3-ethernet.wake-on-lan|2=
 +
802-3-ethernet.wake-on-lan:            default
 +
802-3-ethernet.wake-on-lan-password:    --
 +
}}
  
*But it is good practice to include the IP address or hostname, therefore this syntax should be the minimal used:
+
Enable Wake-on-LAN by magic packet on that connection:
  
  # wol -i HOSTNAME_OR_IP MACADDRESS
+
  # nmcli c modify "wired1" 802-3-ethernet.wake-on-lan magic
  
*The documentation of wol states that:
+
Then reboot, possibly two times.
  
::''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).''
+
From version 1.2.0 Wake-on-LAN settings can be changed graphically using {{Pkg|nm-connection-editor}}.
  
*To obtain the MACADDRESS of the target computer:
+
=== Enable WoL in TLP ===
  
$ ip link
+
When using [[TLP]] for suspend/hibernate, the {{ic|WOL_DISABLE}} setting should be set to {{ic|N}} in {{ic|/etc/default/tlp}} to allow resuming the computer with WoL.
  
The port, IP or hostname of the target PC will be addressed in the relevant following sections.
+
== Trigger a wake up ==
  
===Across your intranet/network (no router)===
+
To trigger WoL on a target machine, its MAC address and external or internal IP should be known.
  
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.
+
To obtain the internal IP address and MAC address of the target computer, execute the following command:
  
====For two computers connected to each other====
+
{{hc|$ ip addr|
 +
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
 +
  link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
 +
  inet 127.0.0.1/8 scope host lo
 +
      valid_lft forever preferred_lft forever
 +
  inet6 ::1/128 scope host
 +
      valid_lft forever preferred_lft forever
 +
2: enp1s0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UP group default qlen 1000
 +
    link/ether '''48:05:ca:09:0e:6a''' brd ff:ff:ff:ff:ff:ff
 +
    inet '''192.168.1.20/24''' brd 192.168.1.255 scope global br0
 +
      valid_lft forever preferred_lft forever
 +
    inet6 fe80::6a05:caff:fe09:e6a/64 scope link
 +
      valid_lft forever preferred_lft forever
 +
}}
  
wol MACADDRESS_OF_TARGET_PC
+
Here the internal IP address is {{ic|192.168.1.20}} and the MAC address is {{ic|48:05:ca:09:0e:6a}}.
  
====For computers connected to a non-firewalled router====
+
One program able to send magic packets for WoL is {{Pkg|wol}}.
  
wol -i INTERNAL_IP_OF_TARGET_PC MACADDRESS_OF_TARGET_PC
+
=== On the same LAN ===
  
*To find the internal IP:
+
If you are connected directly to another computer through a network cable, or the traffic within a LAN is not firewalled, then using Wake-on-LAN should be very easy since there is no need to worry about port redirects.
{{bc|<nowiki>ip addr | grep 'inet '</nowiki>}}
 
  
*Since you are not firewalled, then there is no need to worry about port redirects.
+
In the simplest case the default broadcast address {{ic|255.255.255.255}} is used:
*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)===
+
$ wol ''target_MAC_address''
  
The syntax used in this situation:
+
To broadcast the magic packet only to a specific subnet or host, use the {{ic|-i}} switch:
  
  wol -p PORT_FORWARDED_TO_INTERNAL_IP -i INTERNAL_IP MACADDRESS_OF_TARGET_PC
+
  $ wol -i ''target_IP'' ''target_MAC_address''
  
*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.
+
{{Tip|If you intend to continue using Wake-on-LAN, it is recommended to assign a static IP address to the target computer.}}
  
*It is recommended that for multiple computers connected to one computer, to assign a different port forward to each internal IP
+
=== Across the internet ===
  
*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)
+
When the source and target computers are separated by a router, Wake-on-LAN can be achieved via [[wikipedia:Port forwarding|port forwarding]]. The router needs to be configured using one of these two options:
  
===Across the internet===
+
* Forward a different port to each target machine. This requires any target machine to have a static IP address on its LAN.
{{Expansion|Request for OpenWRT instructions.}}
+
* Forward a single port to the [[wikipedia:Broadcast_address|broadcast address]]. This is likely not possible on your router with the stock firmware, in this case refer to [[#Forward a port to the broadcast address]] for workarounds.
The syntax needed in this case:
 
  
wol -p X -i HOSTNAME_OR_EXTERNAL_IP_OF_TARGET MACADDRESS
+
In both cases, run the following command from the source computer to trigger wake-up:
  
*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.
+
$ wol -p ''forwarded_port'' -i ''router_IP'' ''target_MAC_address''
  
 +
==== Forward a port to the broadcast address ====
  
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:
+
Most routers do not allow 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
+
  $ ip neighbor add 192.168.1.254 lladdr FF:FF:FF:FF:FF:FF dev net0
  
(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.
+
(The above command assumes your network is ''192.168.1.0/24'' and uses ''net0'' as network interface). Now, forward UDP port 9 to 192.168.1.254. This has worked for me on a Linksys WRT54G running [[Wikipedia:Tomato_(firmware)|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].
+
For notes on how to do it on a router with [[Wikipedia:DD-WRT|DD-WRT]] firmware, see [http://www.dd-wrt.com/wiki/index.php/WOL#Remote_Wake_On_LAN_via_Port_Forwarding this tutorial].
  
==Battery draining problem==
+
For notes on how to do it on a router with [[Wikipedia:OpenWrt|OpenWrt]] firmware, see [https://wiki.openwrt.org/doc/uci/wol this tutorial].
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
+
== Miscellaneous ==
  
We can also add this to the '''/etc/rc.local''' or '''/etc/rc.local.shutdown'''.
+
=== Check reception of the magic packets ===
 +
In order to make sure the WoL packets reach the target computer, one can listen to the UDP port, usually port 9, for magic packets.
  
==Additional Notes==
+
This can be performed by installing {{pkg|gnu-netcat}} from the [[official repositories]] on the target computer and using the following command:
  
*A common problem is that some forget to switch on the Wake-on-LAN feature in their BIOS.
+
# nc --udp --listen --local-port=9 --hexdump
  
*In some systems the BIOS option "Boot from PCI/PCI-E" needs to be Enabled.
+
Then wait for the incoming traffic to appear in the {{ic|nc}} terminal.
  
==Example WOL script==
+
The magic packet frame expected contains 6 bytes of FF followed by 16 repetitions of the target computer's MAC (6 bytes each) for a total of 102 bytes.
Here is a script you can use to automate wol to several different machine. Modify as you see fit:
 
  
<pre>#!/bin/bash
+
=== Example of WoL script ===
 +
Here is a script that illustrates the use of {{ic|wol}} with different machines:
 +
{{bc|<nowiki>
 +
#!/bin/bash
  
 
# definition of MAC addresses
 
# definition of MAC addresses
 
monster=01:12:46:82:ab:4f
 
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
 
ghost=01:1a:d2:56:6b:e6
  
while [ "$input1" != quit ]; do
 
 
echo "Which PC to wake?"
 
echo "Which PC to wake?"
echo "p) powerless"
 
 
echo "m) monster"
 
echo "m) monster"
echo "c) chronic"
 
 
echo "g) ghost"
 
echo "g) ghost"
echo "b) wake monster, wait 40sec, then wake chronic"
+
echo "q) quit"
echo "q) quit and take no action"
 
 
read input1
 
read input1
   if [ $input1 == p ]; then
+
case $input1 in
   /usr/bin/wol $powerless
+
   m)
   exit 1
+
    /usr/bin/wol $monster
fi
+
    ;;
 +
   g)
 +
    # uses wol over the internet provided that port 9 is forwarded to ghost on ghost's router
 +
    /usr/bin/wol --port=9 --host=ghost.mydomain.org $ghost
 +
    ;;
 +
   Q|q)
 +
    break
 +
    ;;
 +
esac</nowiki>}}
 +
 
 +
== Troubleshooting ==
 +
 
 +
=== Battery draining problem ===
 +
Some laptops have a battery draining problem after shutdown [http://ubuntuforums.org/archive/index.php/t-1729782.html]. This might be caused by enabled WOL. To solve this problem, disable it by using ethtool as mentioned above.
 +
 
 +
# ethtool -s net0 wol d
 +
 
 +
=== Realtek ===
  
if [ $input1 == m ]; then
+
Users with Realtek 8168 8169 8101 8111(C) based NICs (cards / and on-board) may notice a problem where the NIC seems to be disabled on boot and has no Link light. See [[Network configuration#Realtek no link / WOL problem]].
  /usr/bin/wol $monster
 
  exit 1
 
fi
 
  
if [ $input1 == c ]; then
+
If the link light on the network switch is enabled when the computer is turned off but wake on LAN is still not working, booting the system using the {{Pkg|r8168}} kernel module at least once and then switching back to the r8169 kernel module included with the kernel seems to fix it at least in the following configurations:
  /usr/bin/wol $chronic
+
* MSI B85M-E45 motherboard, BIOS version V10.9, onboard Realtek 8111G chipset
  exit 1
 
fi
 
  
# this line requires an IP address in /etc/hosts for ghost
+
For the {{ic|r8168}} module you might need to set the {{ic|1=s5wol=1}} [[Kernel_modules#Setting_module_options|module option]] to enable the wake on LAN functionality.
# and should use wol over the internet provided that port 9
 
# is forwarded to ghost on ghost's router
 
  
if [ $input1 == g ]; then
+
===alx driver support===
  /usr/bin/wol -v -h -p 9 ghost $ghost
 
  exit 1
 
fi
 
  
if [ $input1 == b ]; then
+
For some newer Atheros-based NICs (such as Atheros AR8161 and Killer E2500), WOL support has been disabled in the mainline {{ic|alx}} module due to a bug causing unintentional wake-up (see [http://www.spinics.net/lists/netdev/msg242477.html this patch discussion]). A patch can be applied (or installed as a [[dkms]] module) which both restores WOL support and fixes the underlying bug, as outlined in [https://bugzilla.kernel.org/show_bug.cgi?id=61651 this thread].
  /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
+
== See also ==
echo "later!"
 
exit 1
 
fi
 
  
done
+
* [http://www.depicus.com/wake-on-lan/woli.aspx Wake-On-Lan]
echo  "this is the (quit) end!! c-ya!"</pre>
 
== Resources ==
 
[http://www.depicus.com/wake-on-lan/woli.aspx Wake-On-Lan]
 

Latest revision as of 12:11, 16 December 2017

Wake-on-LAN (WoL) is a feature to switch on a computer via the network.

Hardware settings

The target computer's motherboard and Network Interface Controller have to support Wake-on-LAN. The target computer has to be physically connected (with a cable) to a router or to the source computer, wireless cards do not support WoL.

The Wake-on-LAN feature also has to be enabled in the computer's BIOS. Different motherboard manufacturers use slightly different language for this feature. Look for terminology such as "PCI Power up", "Allow PCI wake up event" or "Boot from PCI/PCI-E".

It is known that some motherboards are affected by a bug that can cause immediate or random wake-up after a shutdown whenever the BIOS WoL feature is enabled (as discussed in this thread for example). The following actions in the BIOS preferences can solve this issue with some motherboards:

  1. Disable all references to xHCI in the USB settings (note this will also disable USB 3.0 at boot time)
  2. Disable EuP 2013 if it is explicitly an option
  3. Optionally enable wake-up on keyboard actions
Note: There are mixed opinions as to the value of #3 above and it may be motherboard dependent.

Software configuration

Enable WoL on the network adapter

Depending on the hardware, the network driver may have WoL switched off by default.

To query this status or to change the settings, install ethtool and query the network device via this command:

# ethtool net0 | grep Wake-on
Supports Wake-on: pumbag
Wake-on: d

The Wake-on values define what activity triggers wake up: d (disabled), p (PHY activity), u (unicast activity), m (multicast activity), b (broadcast activity), a (ARP activity), and g (magic packet activity). The value g is required for WoL to work, if not, the following command enables the WoL feature in the driver:

# ethtool -s net0 wol g

This command might not last beyond the next reboot and in this case must be repeated via some mechanism. Common solutions are listed in the following subsections.

Make it persistent

netctl

If using netctl, one can make this setting persistent by adding the following the netctl profile:

/etc/netctl/profile
ExecUpPost='/usr/bin/ethtool -s net0 wol g'

systemd.link

Link-level configuration is possible through systemd. The actual setup is performed by the net_setup_link udev builtin. Add the WakeOnLan option to the network link file:

/etc/systemd/network/50-wired.link
[Link]
WakeOnLan=magic
...
Note: This configuration applies only to the link-level, and is independent of network-level daemons such as NetworkManager or systemd-networkd.

See systemd-networkd#link files and systemd.link(5) for more information.

systemd service

This is an equivalent of previous systemd.link option, but uses a standalone systemd service.

/etc/systemd/system/wol@.service
[Unit]
Description=Wake-on-LAN for %i
Requires=network.target
After=network.target

[Service]
ExecStart=/usr/bin/ethtool -s %i wol g
Type=oneshot

[Install]
WantedBy=multi-user.target

Alternatively install the wol-systemdAUR package.

Then activate this new service by starting wol@interface.service.

udev

udev is capable of running any command as soon as a device is visible. The following rule will turn on WOL on all network interfaces whose name matches enp*:

/etc/udev/rules.d/99-wol.rules
ACTION=="add", SUBSYSTEM=="net", NAME=="enp*", RUN+="/usr/bin/ethtool -s $name wol g"

The $name placeholder will be replaced by the value of the NAME variable for the matched device.

Note: The name of the configuration file is important. Due to the introduction of persistent device names in systemd v197, it is important that the rules matching a specific network interface are named lexicographically after 80-net-name-slot.rules, so that they are applied after the devices gain the persistent names.
Warning: udev will match the device as soon it becomes available, be this in the initramfs (before the switch_root) or the main system. The order is not deterministic; there is no guarantee. Be sure that your initramfs includes the necessary udev rules (from /etc/udev/rules.d) and supporting binaries (/usr/bin/ethtool).

cron

A command can be run each time the computer is (re)booted using "@reboot" in a crontab. First, make sure cron is enabled, and then edit a crontab for the root user that contains the following line:

@reboot /usr/bin/ethtool -s [net-device] wol g

NetworkManager

In version 1.0.6 NetworkManager adds Wake-on-LAN controls. One way to enable Wake-on-LAN by magic packet is through nmcli.

First, search for the name of the wired connection:

# nmcli con show
NAME    UUID                                  TYPE            DEVICE
wired1  612e300a-c047-4adb-91e2-12ea7bfe214e  802-3-ethernet  enp0s25

By following, one can view current status of Wake-on-LAN settings:

# nmcli c show "wired1" | grep 802-3-ethernet.wake-on-lan
802-3-ethernet.wake-on-lan:             default
802-3-ethernet.wake-on-lan-password:    --

Enable Wake-on-LAN by magic packet on that connection:

# nmcli c modify "wired1" 802-3-ethernet.wake-on-lan magic

Then reboot, possibly two times.

From version 1.2.0 Wake-on-LAN settings can be changed graphically using nm-connection-editor.

Enable WoL in TLP

When using TLP for suspend/hibernate, the WOL_DISABLE setting should be set to N in /etc/default/tlp to allow resuming the computer with WoL.

Trigger a wake up

To trigger WoL on a target machine, its MAC address and external or internal IP should be known.

To obtain the internal IP address and MAC address of the target computer, execute the following command:

$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
   inet 127.0.0.1/8 scope host lo
      valid_lft forever preferred_lft forever
   inet6 ::1/128 scope host
      valid_lft forever preferred_lft forever
2: enp1s0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UP group default qlen 1000
    link/ether 48:05:ca:09:0e:6a brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.20/24 brd 192.168.1.255 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::6a05:caff:fe09:e6a/64 scope link
       valid_lft forever preferred_lft forever

Here the internal IP address is 192.168.1.20 and the MAC address is 48:05:ca:09:0e:6a.

One program able to send magic packets for WoL is wol.

On the same LAN

If you are connected directly to another computer through a network cable, or the traffic within a LAN is not firewalled, then using Wake-on-LAN should be very easy since there is no need to worry about port redirects.

In the simplest case the default broadcast address 255.255.255.255 is used:

$ wol target_MAC_address

To broadcast the magic packet only to a specific subnet or host, use the -i switch:

$ wol -i target_IP target_MAC_address
Tip: If you intend to continue using Wake-on-LAN, it is recommended to assign a static IP address to the target computer.

Across the internet

When the source and target computers are separated by a router, Wake-on-LAN can be achieved via port forwarding. The router needs to be configured using one of these two options:

  • Forward a different port to each target machine. This requires any target machine to have a static IP address on its LAN.
  • Forward a single port to the broadcast address. This is likely not possible on your router with the stock firmware, in this case refer to #Forward a port to the broadcast address for workarounds.

In both cases, run the following command from the source computer to trigger wake-up:

$ wol -p forwarded_port -i router_IP target_MAC_address

Forward a port to the broadcast address

Most routers do not allow 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 net0

(The above command assumes your network is 192.168.1.0/24 and uses net0 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 a router with DD-WRT firmware, see this tutorial.

For notes on how to do it on a router with OpenWrt firmware, see this tutorial.

Miscellaneous

Check reception of the magic packets

In order to make sure the WoL packets reach the target computer, one can listen to the UDP port, usually port 9, for magic packets.

This can be performed by installing gnu-netcat from the official repositories on the target computer and using the following command:

# nc --udp --listen --local-port=9 --hexdump

Then wait for the incoming traffic to appear in the nc terminal.

The magic packet frame expected contains 6 bytes of FF followed by 16 repetitions of the target computer's MAC (6 bytes each) for a total of 102 bytes.

Example of WoL script

Here is a script that illustrates the use of wol with different machines:

#!/bin/bash

# definition of MAC addresses
monster=01:12:46:82:ab:4f
ghost=01:1a:d2:56:6b:e6

echo "Which PC to wake?"
echo "m) monster"
echo "g) ghost"
echo "q) quit"
read input1
case $input1 in
  m)
    /usr/bin/wol $monster
    ;;
  g)
    # uses wol over the internet provided that port 9 is forwarded to ghost on ghost's router
    /usr/bin/wol --port=9 --host=ghost.mydomain.org $ghost
    ;;
  Q|q)
    break
    ;;
esac

Troubleshooting

Battery draining problem

Some laptops have a battery draining problem after shutdown [1]. This might be caused by enabled WOL. To solve this problem, disable it by using ethtool as mentioned above.

# ethtool -s net0 wol d

Realtek

Users with Realtek 8168 8169 8101 8111(C) based NICs (cards / and on-board) may notice a problem where the NIC seems to be disabled on boot and has no Link light. See Network configuration#Realtek no link / WOL problem.

If the link light on the network switch is enabled when the computer is turned off but wake on LAN is still not working, booting the system using the r8168 kernel module at least once and then switching back to the r8169 kernel module included with the kernel seems to fix it at least in the following configurations:

  • MSI B85M-E45 motherboard, BIOS version V10.9, onboard Realtek 8111G chipset

For the r8168 module you might need to set the s5wol=1 module option to enable the wake on LAN functionality.

alx driver support

For some newer Atheros-based NICs (such as Atheros AR8161 and Killer E2500), WOL support has been disabled in the mainline alx module due to a bug causing unintentional wake-up (see this patch discussion). A patch can be applied (or installed as a dkms module) which both restores WOL support and fixes the underlying bug, as outlined in this thread.

See also