How to Change User and Group Permissions in OS X Lion’s File Sharing Pane
After you create a share point folder or drive in Lion Server, you can use the File Sharing pane in the Server app to change permissions for a share point, a user or a group.
A share point you create has three default entries: Owner, Primary Group, and Everyone. You can’t delete these entries. Everyone means everyone with a user account on the server. This differs from Guest, which means anyone on the network, even people without an account.
To change the permissions of the user and groups for a share point, make sure the window of the share point is open in the File Sharing pane of the Server app.
To change the access permission for a user or group in the Access list, click the arrows to the right of the permission and select a new permission from the pop-up menu.
For users and groups that you add to the Access list, you have three choices of permissions: Read and Write, Read Only, and Write Only.
For the default users and groups — Owner, Primary Group, and Everyone — you have a fourth choice, No Access. This setting is a complete ban and overrides other settings. You can use this setting to prevent access by a user who is a member of a group that has access to the shared folder.
If you see the word Custom listed as a permission for a user or group, it means that the permissions are set by ACL permissions in the server’s pane.
When you’re finished making changes to permissions, click the Done button.