Porteus Kiosk is a lightweight Gentoo-based Linux operating system which has been downscaled and confined to allow the use of one application only - the Firefox web browser. The browser has been locked down to prevent users from tampering with settings or downloading and installing software. When the kiosk boots, it automatically opens Firefox to the user's preferred home page. The browsing history is not kept, no passwords are saved, and many menu items have been disabled for increased security. When Firefox is restarted all caches are cleared and the browser reopens with a clean session.