PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

402 Chapter 17 Implementing Authentication with PHP and MySQL
In this case, the user will see an interface somewhat different from the previous listings.This
script does not provide an HTML form for login information.The user’s
browser presents her with a dialog box. Some people see this as an improvement; others
would prefer to have complete control over the visual aspects of the interface. A sample
dialog box, in this instance provided from Firefox, is shown in Figure 17.4.
Because the authentication is being assisted by features built into the browser, the
browser chooses to exercise some discretion in how failed authorization attempts are
handled. Internet Explorer lets the user try to authenticate three times before displaying
the rejection page. Firefox lets the user try an unlimited number of times, popping up a
dialog box to ask,“Authorization failed. Retry?” between attempts. Firefox displays the
rejection page only if the user clicks Cancel.
As with the code given in Listings 17.1 and 17.2, you could include this code in
pages you wanted to protect or automatically prepend it to every file in a directory.
Figure 17.4
The user’s browser is responsible for the appearance of the dialog
box when using HTTP authentication.
Using Basic Authentication with Apache’s
.htaccess Files
You can achieve similar results to the script in Listing 17.4 without writing a PHP
script.
The Apache web server contains a number of different authentication modules that
can be used to decide the validity of data entered by a user.The easiest to use is
mod_auth, which compares name-password pairs to lines in a text file on the server.