How to access a local protective site from a live site?

Is it possible to do the following...

I have two identical sites, one locally and one live. Both are using the same Security Assist files and the same database. After users login, they are sent to the control panel page where they can choose, by clicking on the links, where they want to go. What I would like to do is when a link is clicked on the live site, the user is brought back to my local site and access the protected page without entering their user name and password again.

A user wouldn't be able to visit your local site at all would they? What you are talking about is a single sign-on for multiple sites. It can be done using a variety of methods by passing data in the url or through a form post.

One way to do it is to use the Server Behaviors in eCart in the "eCart->General" section. "Pass Session to Site" and "Retrieve Passed Session". It uses a form post and a back and forth verification for security to pass an entire session from one site to another. That is probably the most elegant and secure solution.