Can't login to Tomcat 6 getting 401 Unauthorized error.

Issue

• We're installing Tomcat 6 on Redhat 6. We ran the yum install tomcat6-webapps tomcat6-admin-webapps, and then configured the user admin in tomcat-users.xml. So while accessing the url : http://ip:8080, we get the Tomcat 6 portal.Clicking on Status or Tomcat Manager it ask for login prompt. But after entering the username and password correctly, it result into 401 Unauthorized.