Limiting remote access by user to Horizon view

I am just wondering what others are doing in this circumstance:

We have a customer that is transitioning from Citrix XenApp to VMWare Horizon View.  In their Citrix environment, they are used to restricting the remote access via AD groups.

The new Horizon View environment has a View security server and two connection servers.  The customer is not currently using two factor authentication.  Has anyone found a way to limit who can access the virtual machines via the security server without using an extra set of connection servers?

Thanks,

Warren