See request headers tool,php $_server variables,request variables

It's free online tool for find request headers, something like php print_r($_SERVER) or phpinfo. You can read related article here - $_server php request data. PHP $_SERVER is an automatic created by server array containing information such as headers, paths, and script locations. The entries in this array are created by the web server. There is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here.
The $_SERVER global variable in PHP is perhaps the most useful of any global variable and or function that you will come across during your adventure in scripting with PHP. Now I am not going to reiterate what can be found in the documentation I am just going to clarify where the documentation is vague and show a few examples as well. Now the easiest way to mop up and clarify everything all at once is for you to create the following file on your server and run it and take a look at the output this should clarify everything for you.
I spend a good deal of time reading about PHP security over at the PHP Developer’s Network forums. In one of the many discussions I have had over there, I recall one in particular that really opened my eyes to how easy it can be to overlook a very serious security issue. As you may know, there is a predefined array of server-related variables in PHP, named $_SERVER. (information from $_SERVER,$_SERVER info, my request headers)