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Wake-on-LAN frame analyze

Wake-On-Lan is the ability to switch on remote computers through special network packets. This only works with network cards and motherboards that are Wake-On-Lan (WOL) compliant. Wake-On-Lan is the generic name for the AMD "Magic Packet" technology. It's very similar to the modem "wake on ring" signal line. The basic idea is that the network adapter has a very-low-power mode to monitor the network for special packet data that will wake up the machine. This packet must contain a certain byte-sequence, but can be encapsulated in any kind of packet (IPX, IP, anything). In this article in choose to use a UDP frame to send my packet, as the NIC only listens to incoming packets, it does not reply anything...

I've analyzed the frame below send by the Intel Remote Wake-up Utility (GUI). To switch on a remote computer (in that case the NIC mac address was 00d0b72a46xx), the following packet was send by my workstation:

 

Packet analyse with a sniffer

 

This is a UDP broadcast frame send to port 2050, I guess other ports may also be used. The data send have this structure :

00 d0 b7 2a 46 xx 00 74 ff ff ff ff ff ff 00 d0 b7 2a 46 xx
00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx
00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx
00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx
00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx
00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx 00 d0 b7 2a 46 xx
40 00 90 90 40 00

Very easy, isn't it? Now you just have to do the same with the mac addresses of your PC's...

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