I am not so familiar with LDAP servers. How can I add more users and groups to the Demo LDAP server?
If you use Ambari go Ambari > Knox > Config > Advanced users-ldif.
There are already some users preconfigured, but if you want to add a new one, add something similar like the following into the window
dn: uid=sample,ou=people,dc=hadoop,dc=apache,dc=org objectclass:top objectclass:person objectclass:organizationalPerson objectclass:inetOrgPerson cn: Sample sn: User uid: sample userPassword:sample-password
Have a look at the excellent Workshop: Apache Knox for Perimeter Security.
If you don't have Ambari you will find the users.ldif in the /etc/knox/conf/ directory.