Determining a user’s NT username in JSP

My team is building an Intranet using JSP’s, Servlets & Beans (not EJB’s.) All users of the Intranet will use NT Workstation 4 as their client OS. We would like to automatically log the users in to the Intranet application based upon their login to NT. So, is there any way to determine a user’s NT username from a JSP page?