how a server identifies a process requesting a GET

is User-Agent the only way?

[zredbaron]

I was playing with ethereal yesterday, and noticed that when I called up a web page, there were various fields such as User-Agent, Accept, Accept-Encoding, and a couple others that my browser used to identify itself and its html-reading capabilities.

Outside of those Strings sent from the Hyper Text Tranfer Protocol, is there any other way for the server of the web page I requested to know anything about my PC or the software requesting the GET?

If the User-Agent was changed to "None of your business" would they still be able to tell I was using firefox vs ie or some other program that wasn't necessarily a browser?

[Mareq]

HTTP protocol communication is based on Request->Response. Server has no chance to identify which requests came from you and you alone. Only way to identify you is header fields in your request, you mentioned, or cookies. Therefore, server can not gather information not listed in your request. For more information see RFC 2616 ( [faqs.org...] ), esspecially chapter 5.

[encyclo]

If you are using Firefox, right-click this page and select Page Info and then the Headers tab. There you can see the Request and Response headers sent for this page. As Mareq says, you can't get anything more out of the HTTP headers.

That's not to say that you can't make a reasonable guess based on different criteria than that of the User Agent string. For example, you can use the user agent switcher extension in Firefox to say that your browser is IE6, but this does not change the HTTP Accept header which differs considerably from the IE6 Accept string.