Group based permissions

Is there a way to have security group based permissions? For example:

Security Groups:
Contoso - A group for all connections for Contoso, a client.
Rustco - A group for all connections for Rustco, a different client.
Users:
Johnny - Johnny is a technical lead for Rustco, and needs add / edit permissions for Rustco connections. Johnny is a developer on the Contoso project and only should have view permissions for Contoso connections.

Is this possible with an Enterprise site license without RDM Server? Is the only way to acheive this with either different databases per project or different logins per group?