You need to edit your OpenStack Identity configuration file (keystone.conf) and change the bind parameters:
On Havana:
bind_host = 192.168.42.103
On Icehouse, the admin_bind_host option lets you use a private network for the admin access.
public_bind_host = 192.168.42.103 admin_bind_host = 192.168.42.103
To be sure all data will be highly available, you should be sure that you store everything in the MySQL database (which is also highly available):
[catalog] driver = keystone.catalog.backends.sql.Catalog ... [identity] driver = keystone.identity.backends.sql.Identity ...
