i-auth is a simple user authentication script using session variables. Originally i-auth was written to be included into an index page although this can easily be changed by simply changing the links.
To restrict access rights for any page to those who have logged in you just need to add a small section of code as shown in the readme file.
iClans is a game clan or guild management system, which uses plain text files. Only russian language version is currently available. It includes user registration with approve or deny options, several access levels, members pages (login and password protection), and members list, and much more.
J-SESSIONS is a session package designed to protect pages with a very small footprint. The bulk of the code is less than 176 lines. A live demo can be seen at: http://www.jeremybrand.com/admin.
keepSecured provides all required features to you for protecting your pages and only letting privileged users to login and access your private content. You can create unlimited member groups, security zones (pages or directories) and protect them easily. You can use your existing member database or create a new member database in keepSecured. keepSecured is fully re-brandable and you can use different screens (login, password reminding, etc.) for different private pages. Try online demo for to discover all unique features.
Lite Login System is a secure php login system that uses sessions and allows you stop people viewing webpage unless they are registered. It uses md5 encryption and so is very secure, however it also saves an unecrypted password in the database.