This is about a classifieds website, where anyone may post classifieds. I have a security database which I intend to fill with information about the user who posts the classifieds.

I intend to record information such as IP, name, tel, email, classified_text, classified_title etc etc.

The reason for all this is that sometimes people become victims of fraud (fake classifieds etc).

So I wonder, what information is possible to get from the poster which may help in tracking him/her down?

IP is a given, but what else could be useful? And I would much like examples of how it would be useful also, as well as the code for it please, like $_SERVER['REMOTE_ADDR'].

And btw, I use PHP and have Sql as a database.

Thanks