By default, the ago control web gui does not have security. While this may be fine for local control, you definitely do not want to leave your web gui open to random remote access. A simple username/password system can easily be installed by doing:
/opt/agocontrol/bin/rpc-htpasswd /opt/agocontrol/html/.htpasswd mydomain.com your_username_here your_password_here
You can add additional users using the same command while using different username and password values. You can also update a user's password using the same command you used to set it initially.
NOTE: You must use 'mydomain.com' for the domain name. This may change in the future.