Wake-on-LAN (WOL) is an ethernet computer networking standard that allows a computer to be turned on or woken up by a network message.
The message is usually sent by a program executed on another computer on the same local area network. It is also possible to initiate the message from another network by using subnet directed broadcasts or a WOL gateway service. Equivalent terms include wake on WAN, remote wake-up, power on by LAN, power up by LAN, resume by LAN, resume on LAN and wake up on LAN. In case the computer being woken is communicating via Wi-Fi, a supplementary standard called Wake on Wireless LAN (WoWLAN) must be employed.
The WOL and WoWLAN standards are often supplemented by vendors to provide protocol-transparent on-demand services, for example in the Apple Bonjour wake-on-demand (Sleep Proxy) feature.
- 1 History
- 2 Principle of operation
- 3 Security considerations
- 4 Hardware requirements
- 5 Software requirements
- 6 Other machine states and LAN wakeup signals
- 7 Wake on Internet
- 8 See also
- 9 References
- 10 External links
- Troubleshooting Remote Wake-up Issues Useful WOL troubleshooting information from Intel
- AMD's Magic Packet Technology white paper Publication# 20213
- Wake-on-LAN History and How-To Guide
- Wake-on-LAN Security Best Practices (Microsoft, 2008)
- Wake On Local Area Network (LAN) WOL guide for Microsoft Windows from Energy Star (EPA)
Wake on LAN (WoL) support is implemented in the motherboard of the computer. Most modern motherboards with an embedded Ethernet controller support WoL without the need for an external cable. Older motherboards must have a WAKEUP-LINK header onboard and connected to the network card via a special 3-pin cable; however, systems supporting the PCI 2.2 standard coupled with a PCI 2.2 compliant network adapter typically do not require a WoL cable as the required standby power is relayed through the PCI bus.
Wake On LAN (WOL) "How to"
OverviewWake-on-LAN (WOL) allows a computer to be powered on or awakened from standby, hibernate or shutdown from another device on a network. The process of WOL is the following:
- The target computer is in standby, hibernate or shutdown, with power reserved for the network card.
- The network card listens for a specific packet, called the "Magic Packet."
- The Magic Packet is broadcast on the broadcast address for that particular subnet (or an entire LAN, though this requires special hardware and/or configuration).
- The listening computer receives this packet, checks it for the correct information, and then boots if the Magic Packet is valid and if contains the network card's MAC address.
Enabling WOL on ComputersWOL must be enabled in the both the basic input/output system (BIOS) and the network card. In order to enable WOL in the BIOs quickly and easily, some manufacturers provide methods for managing BIOS settings remotely or through scripts. For example, BIOS settings can be configured remotely on Dell computers using Dell Open Manage and on HP/Compaq computers using Insight Manager. To see if this is available for you computer, please contact your manufacturer. In order to enable on the network card, please take the following steps:
- Click on "Network Connection" (in Control Panel) and then click on "Properties."
- Click on "Configure" next to the network card the connection is using.
- Click on the "Advanced" tab. (The settings in this example are specific to the Marvell Yucon card but should be similar for other network cards.)
- Enable "Wake From Shutdown" (may be different depending on the model of network card) by setting the Value to "On".
- Enable "Wake Up Capabilities" (may be different depending on the model of network card) by setting the Value to "Magic Packet".
- Click on "Power Management" tab. (The settings in this example are specific to the Marvell Yucon card but should be similar for other network cards.)
- Enable "Allow this device to bring the computer out of standby" by checking the box.
- Enable "Only allow management stations to bring the computer out of standby" by checking the box. This will require a Magic Packet to wake up your computer. Not selecting this will allow any traffic directed to your computer to wake it up.
Waking Up a ComputerOnce WOL is enabled, the computer can be awakened by sending a Magic Packet. A Magic Packet is a broadcast sent on port 0, 7, or 9 that contains the destination computer's MAC address. All computers on the subnet get the packet. If the MAC Address matches the network card, the computer will wake up.
For use in an enterprise, WOL is usually used in conjunction with a management system that already stores this subnet and MAC address information. If using a management system such as Microsoft Systems Management Server (SMS), Altiris, or LANDesk, WOL capabilities may be built in or add-ons may be available. A few free applications available for waking up computers using WOL are provided below. (Inclusion in this list does not constitute EPA ENERGY STAR program endorsement, approval, or certification of these software packages.)
- For waking up computers on other subnets, the MAC address and subnet for each computer will be needed and must be updated if a computer is moved to another subnet.
- Since WOL uses Directed Broadcasts to send Magic Packets to the destination computer, some network configuration may be to necessary wake up computers on a different subnet. On most routers Directed Broadcasts are disabled by default due to vulnerabilities associated with them. To securely enable Directed Broadcasts, access lists should be created or modified to allow them from one or more IP address or subnets and deny them from all others. This allows Magic Packets to be sent from management computers but keeps the rest of the network secure from Directed Broadcast vulnerabilities. This access list would have to be added to all routers between the source of the WOL Magic Packet and the destination computers that will be woken up.
You can use Task Scheduler to wake the computer.
- Click Start, type Task Scheduler in the Start Search box, and then click Task Scheduler in the Programs list.
- In the Actions pane of the Task Scheduler dialog box, click Create Task.
- In the Create Task dialog box, click the Conditions tab.
- Click to select the Wake the computer to run this task check box.
- In the Create Task dialog box, configure the options on the other tabs as appropriate for your needs, and then click OK.
The computer will wake up from standby if it receives a "magic packet" from the LAN, so I've configured SSH on the router, and I just run a script that will SSH into the router and then execute the wake-on-lan script from the router interface.
I created a variation of this script: DD-WRT Useful Scripts
the power options on our ethernet controler
= "Magic Packet"
= "Wake Up Frame"
My system is a dell xps 720 (A06 Bios) running XP and i had a problem very similar to what wickpica wrote. More specifically i was trying unsuccessfuly to get Logmein on a client computer to wake up my remote host computer the dell xps 720. The client computer just could not wake up the host computer. I believe i have solved the problem and wish to share it.
On the power management tab of the 57xx gigabit controller (nic card?) settings, i had to unclick the box beside "only allow management stations to bring the computer out of standby". (the other 2 boxes above that stayed clicked on).
This solved the problem. I am now able to remotely access the dell xps 720 via "wake on lan" WOL. However, a new problem arose and luckily i figured that out also.
The new problem was that under this new setting, the computer kept coming out of standby on it own without me touching the mouse or keyboard. I made a guess that logmein was causing the computer to come out of standy (based on the packets i could see thru viewing the network activity of comodo firewall). Also I read a very good post at http://en.community.dell.com/forums/p/19301828/19601275.aspx and figured out that under the Advanced tab of the 57xx gigabit controller settings --wake on lan capabilities, i should choose --magic packet
.....where both would include "wake up frame" and "magic packet".
By choosing .--magic packet on the drop down menu, the annoying wakeup from standby problem caused by logmein was solved. (on the other dell forum above, it was suggested to disable wake on directed packets, this must be a similar function as "wake on frame" ...it seems that disabling them prevents random wakeups form standby )
The last comment is about the following quote from wickpika above:
"The worst part...
After attempting to "wake on LAN", I cannot get the PC to resume from standby, even at the console. My only option is to power down the PC by holding the power button"
i experienced this same real hassle although in my case it was a slightly different change in the behaviour of standby mode (related to the time it took to come out of standby and how deeply it went into standby). It was almost a bit of a nightmare because it was permanently doing this. I realize that the only change i had made was switching from S3 default setting to the S1 setting (in the bios) under power management (i think). I know (or i'm pretty sure) that this bios change caused the annoying change in standby - probably a registry change corruption (?). It shouldn't have caused it but that is the nature of random events. Going back to an earlier restore point (3 hours earlier) solved this problem for me.
I think I FINALLY found the answer. I'll document it in case some other poor soul has this problem and googles it.
Windows Shutdown and Wake On LAN Primer
Hard disks and other non-S1 compliant devices are powered off
|CPU powered off||RAM Powered off||Wake Devices Powered Off||PC can resume||Power can safely be removed||PC can be woken remotely|
|S2 / S3 (Standby)||Yes||Yes||No||No||Yes||No||Yes|