Wordpress module to redirect logged out users in protected pages

I need a simple Wordpress module, my website only allows one login at the same time per account so when another computer logs in using an account that is already logged in the previous user is disconnected. Although the previous user is now logged out he can still read the content on the page he is currently viewing. I want a plugin that if the user is on a protected page there is a check every X seconds to see if the user is logged in, if his session is logged out then redirect him to another page The plugin has to have 2 configurable global variables, the seconds to wait between checks and the redirect page if the user is not logged in When you create page in WordPress there is a new menu from this plugin where you can set if the page is protected or not (to run the check script or not) This can be done using AJAX and php