There are several options depending on your needs:

Windows active directory
  1. authenticationserver in /emshare/_site.xconf
    <property name="authenticationserver">server.corp.com</property>
  2. Optionally set the authenticationdomain property in /emshare/_site.xconf
     <property name="authenticationdomain">ABC</property>
  3. When a user authenticates against the server it will create a new user on the fly if needed. By default this user will be in the Guest group and in the Guest role.
CAS
  1. You will need to setup Tomcat in a way that will filter web requests
  2. Edit this file: /_site.xconf or /emshare/_site.xconf and add
     <property name="oe.usernameinheader">true</property>
  3. You will need to make sure there is a Group called "guest" or add a new default group for users:
     <property name="autologingroup">users</property>
  4. When a user authenticates against the server it will create a new user on the fly if needed. By default this user will be in the Guest group and in the Guest role.
  5. Once a user is created you can give additional groups or roles using the user manager
  6. You may want to use Admin.autoLoginFromRequest instead of Admin.autoLogin