Restrict ticket submission or logon by user type

My organization closes ticket submission during certain times of the year. Unfortunately, users don't read the Announcement pop-up and submit a ticket anyway. The same goes for submission during outages. For example if a server or platform fails, we need to be able to restrict ticket submission until the issue is resolved. Otherwise, we end up spending time closing tickets that didn't need to be submitted in the first place.

It would be nice to either

A: Restrict logon to service desk by user type (such as allow technicians and cab members to login but not general requesters)

or

B: Allow login but not allow new ticket/request submission.

This should be a quick function to accomplish. Allow SDAdmins to configure options for restriction and then put a link to enable/disable in the Quick Actions menu or on their dashboard.

Thank you

Kevin