Core PHP Programming: Using PHP to Build Dynamic Web Sites

HTTP Authentication

If you have any experience with the Web, you're familiar with basic HTTP authentication. You request a page, and a small dialog window appears asking for username and password. As described in Chapter 8, "I/O Functions," PHP allows you to open URLs with the fopen function. You can even specify a username and password in the URL in the same way you do in Navigator's location box. Authentication is implemented using HTTP headers, and you can protect your PHP pages using the header function.

To protect a page with basic HTTP authentication, you must send two headers. The WWW-Authenticate header tells the browser that a username and password are required. It also specifies a realm that groups pages. A username and password are ...