This is a diagnostic CGI intended to make it easier to figure out what sort of machine your webserver really is. To use: upload it to your server in a directory that allows CGI execution. Change the permissions on diagnostic.cgi to 755 (which is rwxr-xr-x, or owner read-write-execute, group and world/other read and execute only.). Go to the diagnostic.html in your web browser and follow the link to the CGI (this will show you if, and how, your webserver passes refering pages in the environment).
It's written in perl and aimed at a unixish system. It will almost certainly break on non-unix webservers, and requires perl to run.
Note that you should delete diagnostic.cgi when you are done with it, as it will provide configuration information that could be helpful to a person trying to figure out what sort of cracking attempts will work on your webserver.
