Unique Device Identifier

Question

Hi! Is there a way to identify what device the user is using in accessing the website?

I am using ASP.Net/C#.Net. Aside from getting the HostName and IP_Address. I already know how to get the Host Name and IP, but the problem is there's a big possibility that the user might change it.

I came up with detecting the Hard disk ID which the user cannot really change it. But the problem is, what if the user is using other gadgets like iPhone, iPad or other devices aside from Laptops and Desktops...