How can I identify a computer?

Hi All

Does anyone know of a way to identify a computer with php?

I have setup up some code that grabs the IP address of someone and puts it in my database so when they return we can pass some info back to them.

The issue I have come across is that if there is more than one person on that IP address everyone gets the last saved info.

Therefore I need to identify each computer.

Any idea?

Thanks for any help.


Using cookies is the only real way to attempt to track a user but that isn’t fool proof as the user can reject cookies.

You might be interested in researching the Etag however, I read an article about this recently that some company had been using them to track visitors which had blocked cookies and there was basically nothing they could do to prevent the use of ETags. I’m unsure of how it works myself but that may be the way forward for you.


Thanks for that. I have had a look into that but don’t think that will quite work.

I was thinking along the lines of grabbing their HDD ID or something but not too sure if that can be done from the research I have done so far.

All I need to do is identify if that computer has been to the website before and then give them information specific to that computer.

I don’t want to muck around with cookies if I don’t have to.

Any other ideas?


What you want to do can not be done with PHP, or any server side language for that matter. The closes you would come is Java applets.

Though, a computers “hardware id” is normally only used to tie a computer to a set license. Not for keeping track if a computer has visited a website.

As mentioned, your best shot and not least easiest (both for you and your visitors) is to use cookies.

Thanks. I thought that might be the case so cookies it is by the looks of it.