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Wake-on-LAN

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Wake on LAN (WOL, sometimes WoL) is an Ethernet computer networking standard that allows a shut-down computer to be booted remotely.

History

In April of 1997, the IBM Advanced Manageability Alliance released the first glimpse of Wake on LAN technology. Other industry initiatives, such as Intel-based Wired for Management, soon supported the standard.

Technical details

System requirements

Wake-on-LAN cable connectors.

Wake on LAN (WOL) support is implemented in the motherboard of the computer. The motherboard 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. Most modern motherboards with an embedded Ethernet controller also support WOL.

Wake on LAN must be enabled in the Power Management section of the motherboard's BIOS. It may also be necessary to configure the computer to reserve power for the network card when the system is shut down.

How it works

The general process of waking a computer up remotely in a LAN can be explained thus:

The target computer is shut down, 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 the entire LAN. The listening computer receives this packet, checks it for the correct information, and then boots if the Magic Packet is valid.

Magic Packet

The Magic Packet is a broadcast frame, transmitted over port 7 or 9. It can be sent over a variety of connectionless protocols (UDP, IPX) but UDP is most commonly used. The data that is contained in a Magic Packet is the defined constant as represented in hexadecimal: FF FF FF FF FF FF followed by sixteen repetitions of the target computer's MAC address, possibly followed by a four or six byte password.

Wake-on-LAN programs

There are a number of programs available that make use of Wake-on-LAN. Below is a partial list.

Scripts

Cross-platform

Microsoft Windows

  • SoftPerfect Network Scanner - A free multi-threaded IP, NetBIOS and SNMP scanner with a modern interface and several advanced features including Wake-On-LAN and remote shutdown.
  • Specops Gpupdate (Special Operations Software) - A free Active Directory Add-On. Specops Gpupdate gives you wake-on-lan, restart, shutdown and gpupdate through your Active Directory Users and Computers GUI.
  • Depicus Wake-On-Lan Windows Graphical User Interface - Depicus Software Solutions are Free, simple, and effective software for your Windows Operating System. Depicus also makes a Remote Shutdown Daemon for Windows.
  • FUSION WakeUp on Lan - A free Windows application. Using FUSION WakeUp on Lan you can take advantage of turning on a remote PC through the net interface. Windows 98, ME, NT, 2000, XP or 2003.
  • WOL - Magic Packet Sender – A free Windows application to store MAC addresses and send Magic Packets. Requires .NET runtime
  • AMD PCnet Magic Packet Utility - mpusergd.pdf
  • WakeOnLan (AquilaTech) - A free Windows WakeOnLan program that is full featured. WakeUp, Shutdown, Ping, global shutdown all in one. Requires .NET runtime
  • MC-WOL - Command line wake on lan utility.
  • AMD PCnet Magic Packet Utility - This Windows application comes from AMD, the father of the Magic Packet. It a simple interface and a few nice features (like group announcements and scheduling).

Mac OS X

GNU/Linux

See also

Additional resources

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