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Wake on LAN help sending packet?


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I am trying to setup Wake on LAN for a computer of mine. I read that you need a wireless adapter that supports it, so instead of going out and buying one, I have decided to hook two computers up with an ethernet cable. The other computer uses a wireless adapter, and stays on most of the time because its old and quiet. Now comes the hard part.

I know a decent bit about sending TCP/UDP, so I thought I will just have the other computer send the magic packet to 192.168.1.xxx, but as I run that through my head I am finding that might not work... The computer that's turned off gets its internet through the wireless adapter, so if the other computer tries to send it a packet, won't it still be trying to do it via the adapter? Is there a way to direct the packet to be sent through the ethernet cable?

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Yes, I know that is uses MAC addresses, and I was planning on writing my own script to send the magic packet. I guess I am a little confused with how UDP works then? Say the IP of the computer thats off is 192.168.1.123, would I just send a UDP message "FF FF FF FF FF FF [6-byte MAC address of ethernet cable 16 times]" to 192.168.1.123 on port 9?

Edited by clonetrooper9494
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You don't use the receving (sleeping) computer's IP address, you'll have to send

its MAC-address (16 times) inside that magic packet over using a (UDP) datagram

as a network broadcast (IP address 255.255.255.255).

In pseudo (Delphi) Pascal-code:

Type
TMACAddress = Array[0..5] Of Byte;

TWakeRecord = Packed Record
Header : Array[0..15] Of Byte; // These are all $FF's
MAC : Array[0..15] Of TMACAddress;
End;

Procedure WakeComputer(Const AMAC : TMACAddress);
Var
I : Integer;
WR : TWakeRecord;
Begin
FillChar(WR.Header, SizeOf(WR.Header), $FF);
For I := 0 To 15 Do
WR.MAC := AMAC;

SendPacket('udp', '255.255.255.255', SomePort, WR);
End;

Greetz,

Peter.

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