title: Centrally secure all tomcat webapps using BASIC authentication
body: <p>I have a Tomcat 6 server containing three webapps: a custom one as ROOT, Jenkins and Nexus.</p>
  
  <p>I would like to secure all three centrally (server.xml?) using BASIC authentication.</p>
  
  <p>How can I achieve this <strong>without</strong> modifying or configuring the webapps themselves?</p>