Modify the ownCloud list of trusted domains
If you only have one domain configured to access your ownCloud installation, you can configure it using the bnconfig tool
$ /opt/bitnami/apps/owncloud/bnconfig --machine_hostname DOMAIN
If you have one or more domains to access your ownCloud installation, you can add them manually in the /opt/bitnami/apps/owncloud/htdocs/config/config.php file:
'trusted_domains' =>
array (
0 => "FIRST_DOMAIN",
1 => "SECOND_DOMAIN",
2 => "THIRD_DOMAIN",
),