Perfect Computer ID

[adni18]

Is there a way to get a number that is consistent with only one computer? I don't have to identify the computer or anything, just a number that no other computer has. An alternative would be to store a file other than a cookie on the user's computer. Is there a way to do either of these?

[freeflight2]

you might use the computers hardware ethernet (MAC) address... but then there some PCs without any network cards or the cards might change etc.

[adni18]

Maybe a way to store a file on the computer then?

[ddent]

Without knowing more about what you are trying to do it is hard to say... there are so many ways to approach a question that open ended.