Getting info about my users

I'd like to do a little data mining, to see if any of my customers are giving out their username/password.

Q: What info can I get about the PC that the person is on?

• Their IP address (presuming it's fairly static)
• Their Browser (presuming they're not ha开发者_开发百科cking the cgi scope)
• Their screen resolution
• Their cookie scope (presuming they have cookies turned on)

What else?

I want to see: "Hey! This person is logging in from three different machines!"

See here (plus comments):

http://www.coldfusionjedi.com/index.cfm/2010/11/5/Ask-a-Jedi-Preventing-logins-from-other-machines

Most of that is in the CGI scope:

<cfdump var="#CGI#">

Exactly what will be in there is determined by which Web server you're using (e.g. IIS, Apache, etc), and will vary from server to server.

Example: CGI.REMOTE_ADDR is one of the variables that might contain a usable IP address of the client.

CGI.HTTP_COOKIE may contain all of the cookies from the browser, URL-encoded. You can also dump the Cookie scope:

<cfdump var="#Cookie#">

To get screen resolution I think you'd need to use a JavaScript or Flash solution - maybe even CSS; I recall something about being able to serve different CSS files based on screen size for mobile devices. Maybe in Modernizr? http://www.modernizr.com/