[Interest] Unique - Hardware bound - ID

[Konrad Rosenbaum]

Just in case, two things I forgot: 

Many (if not most) computers have several MAC addresses. The laptop I'm 
writing this on has six network interfaces, four with a hardware address and 
of those three with an actual MAC:

* Ethernet device (built in, fixed MAC, which I did not bother to change)
* WLAN device (also built in, no bother at the moment, but I did change it a 
few months ago to be able to use a misconfigured WLAN)
* virtual Localhost adapter (no HW addr)
* virtual Teredo adapter (something longish made of zeroes that claims to be a 
HW addr)
* virtual ethernet device (with a random MAC that changes every boot)
* depending on loaded kernel drivers: a Firewire network adapter with a 
longish non-MAC HW addr

The same is true of most other hardware, many computers have more than one 
hard disk, more than one CPU core, etc.

Even more devastating: hardware tends to change. I've been known to connect 
two additional real ethernet cards to my laptop and then add a couple more 
vitual adapters - just for experimentation.

Unfortunately you can't tell which ones are built in, which ones are plugged 
in and which ones are purely virtual.

So:

* store all of them and insist that one or two remain
* never assume the computer will look the same after a reboot even if it is 
the same computer
* maybe: offer the user to bind to one specific instance
* plan ahead for users who lose some piece of hardware (HD crashes, burnt out 
ethernet cards, change of PC/laptop, etc.)

Soft piece of advice: don't assume that you can solve this problem 100%. 
Others have tried before and all of them failed one way or another. Keep 
yourself flexible enough to handle unexpected situations outside the software.



	Konrad

On Wednesday 15 May 2013 13:07:05 you wrote:
> I believe the mac address will suffice. In addition I will probably some
> other hardware related data and create a hash from it. I emagined there
> would be a solution for this problem but it semes its not that easy.

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