[thelist] FW: MAC Addresses/Physical Address!

Judah McAuley judah at wiredotter.com
Wed Oct 2 17:08:01 CDT 2002

Mark Anderson wrote:
> I'm trying to obtain programmatically the MAC Addresses/Physical Address for
> ADSL modems! I have tried using the code I have for mac addresses on
> ethernet cards (from Microsoft's msdn) but it looks like ADSL modems don't
> have a mac address...
> I have a client that wants to be able to uniquely identify a whole series of
> pc's they have which are spread around the country and connected to the
> internet and check a unique unalterable id against a central database so
> they can load appropriate updates etc. Basically it's to be part of a
> licensing system!
> Can anyone point me in the right direction (need to do it in VB6)

Physical Addresses aren't sent over the network.  That info is at the
wrong network level (Physical layer versus the Transport layer).  You
might be able see a physical address for a DSL modem on a local network,
but that information is not included in the information that is passed
out over the Internet.  When the packet gets to the router on the far
end of the request, the destination router looks up the MAC address on
its local network using ARP to match an IP address to a MAC address.
For more info check out: http://www.nwfusion.com/news/tech/0201tech.html

Bottom line:  you might be able to do a MAC address lookup on a local
network, but you won't be able to do one remotely.


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