Here\'s a working web.xml:
You must specify a target for the Servlet Filter. Either provide a value for 'servletNames' or 'urlPatterns'.
http://docs.oracle.com/javaee/6/api/javax/servlet/annotation/WebFilter.html
e.g.
@WebFilter(filterName="mustBeSignedInFilter", urlPatterns={ "/signed/in/path/*" })
public class MustBeSignedInFilter implements Filter