Scanning machines on a network

Dar Scott dsc at swcp.com
Sun Mar 10 15:58:00 EST 2002


On Sunday, March 10, 2002, at 12:00 PM, Richard Gaskin wrote:
> A lot of software packages scan the local network to see if other 
> copies of
> the software may be running with the same serial number.
>
> I've thought of many ways to accomplish this, but all of them seem 
> slow and
> inefficient.

Here is an idea.  Invert the idea of scanning.  Each copy UDP 
Broadcasts its serial number at startup and every minute or so to a 
obscure port of your choosing, eg. 255.255.255.255:47011.  Each 
copy also listens on that port.  If a serial number comes in from a 
different computer that matches that of the listening copy, there's 
a serial number clash.  (I have no idea whether this can be done in 
Revolution; I'm new to Revolution.)  (If you need to know at the 
start of execution, add a poll code to the datagram.)

> How is this done?

Well.  I've done quite a bit of TCP/IP programming, but have never 
done this, so take this with a grain of salt.  Folks who have 
solved the problem may have tried and rejected this idea long ago.

Dar Scott






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