How to secure a samba server on a domain

[abefroman111]

We have a server for backups that runs Samba. Anyone on the domain can access it by going to \\backups. Is there a way I can restrict access through Active Directory? Or is there a way to restrict access through Samba?

If I try to set security how I normally would by going to a share in \\backups I go to Properties > Security > 'Everyone' has read access, root (Unix User\root) has Full Control. If I try to change these or add a new user with Full Control permissions it says "An object with the following name cannot be found."

Windows Server 2008 r2, all updates, one forest, one tree, one site, one domain, two domain controllers, workstations use Win7 with a couple of XP or Vista machines.

[ktech11]

This would be managed in the smb.conf file. You will need to set up users in the linux box and add them to the smbpasswd file.
Use this walkthrough CentOS 6.2 Samba Standalone Server With tdbsam Backend | HowtoForge - Linux Howtos and Tutorials

You can also integrate the server with AD if you want, but there are several more steps involved in that.