将php.ini 中的 

expose_php = On

改为 

expose_php = Off

关于expose_php这个选项： 

; Decides whether PHP may expose the fact that it is installed on the server
; (e.g. by adding its signature to the Web server header).  It is no security
; threat in any way, but it makes it possible to determine whether you use PHP
; on your server or not.
; http://php.net/expose-php