As of version 2.3.0, Beltane supports groups for hosts and users. I.e., you can assign a client to a group, such that only users pertaining to that group may view that client (and messages reported by that client). The following rules apply:
Each clients can at most be in one group.
Clients which are in no group are only visible to users that are in no group.
Clients which are members of a group are visible to users that are in that group, and to users that are in no group.
Users can be in zero or more groups (the User group(s) field in an account definition accepts a comma-separated list).
If a user is member of one or more groups, that user can only view hosts in that group.
If a user is not member of any groups, that user is unrestricted, i.e. that user can view all hosts.