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Wake on LAN is an Ethernet computer networking standard that allows a shut-down computer to be booted remotely.
History
[edit]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
[edit]System requirements
[edit]
Wake on LAN 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. Wake on LAN must also 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
[edit]The general process of waking a computer up remotely in a LAN can be explained as such:
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
[edit]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
[edit]There are a number of programs available that make use of Wake-on-LAN. Below is a partial list.
- Wakeonlan – a Perl script that sends magic packets.
- Wake-on-LAN Tutorial, with PHP script
- Wake-on-LAN PHP script
- DSLReports.com - Wake Me Up - A free online Java program that sends a magic packet to wake up your PC. No downloads or installation required. You must have UDP port 9 forwarded in your firewall.
- Depicus – Free WOL tools to send a WOL packet from different programming environments, including WOL command line, WOL for Windows, WOL for ASP, WOL over the Internet, WOL Com (VB/PHP), WOL for Windows 3.1, WOL Pocket PC 2002/3, WOL for Apple Mac, WOL Monitor/Sniffer, Mac Address Arp Viewer
- java WOL – OS independent Java WOL utility which can be launched from browser.
- WakeOnLanOverMobilephone – Java application for mobile phones.
- enterprise Wake-On-LAN – Wake on application for your organisation. Collects MAC and IP addresses, so you can wake ANY computer in your organisation.
- HyperWRT - Firmware for Linksys wireless routers with WOL GUI.
- WOL - Magic Packet Sender – A free Windows application to store MAC addresses and send Magic Packets. Requires .NET runtime
- AMD PCnet Magic Packet Utility - magic_pkt.exe, 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.
- Apple Remote Desktop - Multifunction tool with WOL capabilities
- WakeUp for Mac OS X
- Wake550 - OS X adaptation of Wakeonlan script
Additional resources
[edit]- Troubleshooting Remote Wake-up Issues - Useful WOL troubleshooting information from Intel
- AMD's Magic Packet Technology white paper Publication# 20213
- Wake-on-LAN white paper by Philip Lieberman describes the IBM / Intel alliance that created Wake-on-LAN