[plt-scheme] Wake on Lan in Scheme

From: Geoffrey S. Knauth (geoff at knauth.org)
Date: Tue May 1 16:35:12 EDT 2007

On May 1, 2007, at 16:11, geb a wrote:
> Since the machine is not on , it doesn't yet have an
> ip-address so what do I send the msg to - a machine address?

Send it to the broadcast address for the subnet you're on.

Suppose you're on an Internet Protocol (IP) subnet  
[1].  Then your subnet mask would be, and your  
broadcast IP address would be  You would send your  
packet to, and every machine on your IP subnet would  
see it, but only the machine with the matching MAC address ("ethernet  
address") in the packet's payload would react.

MAC addresses are hardwired into network cards.  IP addresses are  

[1] http://en.wikipedia.org/wiki/Subnetwork

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