Net.tuts+ has published several great tutorials on user login systems. Most tutorials only deal with authenticating the user, which allows for two levels of security: logged in and not logged in. For many sites, a finer degree of control is needed to control where users can go and what they can do. Creating an access control list (ACL) system will give you the flexibility for granular permissions.

They walk you through the database creation (user information), coding the ACL and user authentication classes, how to check a user's permissions and how to create a user admin screen to allow for easy maintenance. You can find the complete source of the tutorial here.

So, here's what I'm going to do: authenticate an user against a database table using Zend Framework's Zend_Auth component. It's really a piece of cake. You can see a working example here: http://robertbasic.com/dev/login/.

He sets up a registry instance, a database table for the logins and the sample controller with both login and logout functionality. Complete code (and links to Zend Framework documentation are included).

In this article we will continue to discuss the application-wide scripts that we started to talk about in the last article. These special scripts are used by all the scripts and pages of the application. We will continue to look at the func.inc script that has several useful functions defined in it.

Their func.inc script contains the helper functions the rest of the application can use (like isAdmin, isAuthd, genpass and checkEamil). They explain each of the the functions and include an example of them in action. The also include the other half of the pair - the logout script.

• Zend Framework Login: Creating Switching for Front Page
• Zend Framework Login: Creating Logout
• Zend Framework Login: Protected Page
• Zend Framework Login: Fatal error Cannot use object of type stdClass as array
• Zend Framework Login: Creating Authentication
• Zend Framework Login: Creating Form Login
• Zend Framework Login: Preparing Database

Check out their site (or grab their feed) for more PHP-related articles and tutorials.

The main function of the logout class is to log out a user and then redirect the user to the login page. On a programmatic level, the logout class terminates and destroys the session variables that the login class created for the user and also logs the exit time to the database. This article will show you how to create a logout class. It is part of a series on application framework components.

They build out the simple part of the class first, handling the variables and all and then move on to handling the logout and updating the database to reflect the user's status. They finish the tutorial off by giving both the database structure for the component and an example of it in action.

In this three-part tutorial we are going to be creating an open blogging system. We are also going to provide scripts that will make it possible to switch to a closed blogging system. This article, which is the first part, will cover the creation of the login scripts for a closed system.

They start with a definition, the difference between an open blogging system and a closed one (if users have to register or not). They start with the creation of the database to store the users in followed by the PHP code for the simple login page. It uses sessions to keep track of which user is logged in. Of course, where there's a log in, there needs to be a log out and they give the simple code for that. Finally, they include a "forgot your password" script to help users when they can't remember the info they'd signed up with.