OSX Server File Sharing allowing more access than configured

Question

I am working on a computer used as a server running 10.10.5.

I created a folder on the server as follows.

Folder List
Shared-Folder1
Shared-Folder2
Shared-Folder3
Shared-Folder4

User List
UserA
UserB
UserC

Permissions List (Read/write)
Shared-Folder1: UserA, UserB
Shared-Folder2: UserB, UserC
Shared-Folder3: UserA, UserC

When I login to the server using UserA's credentials using my Windows 10 computer over the network, I see Shared-Folder1, Shared-Folder2, Shared-Folder3.

I made sure that every folder's pre-defined groups in the permissions section is set to "No Access" and all permissions are assigned by username and not by groups.

When I make changes to Shared-Folder2, UserA also sees the changes.

The problem is that UserA should NOT be able to see Shared-Folder2 at all but they clearly have access to it.

Is this a bug in OSX 10.10.5?

Does anybody know how to fix this?

Thanks in advance.

---

ls -lae "Shared-Folder2" output:

Mini-Server:Raid Storage Admin-User$ ls -lae "Shared-Folder2"       total 16
drwx------+  3 Admin-User         staff   102 Oct 10 16:03 .
 0: user:_spotlight inherited allow list,search,file_inherit,directory_inherit
 1: group:com.apple.sharepoint.group.3 allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
 2: user:UserA allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
 3: user:Shared-Folder2 allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
drwxrwxr-x  18 Admin-User         staff   680 Oct 10 16:04 ..
-rw-r--r--@  1 Shared-Folder2  staff  6148 Oct 10 16:03 .DS_Store
 0: user:_spotlight inherited allow read,execute,readextattr
 1: group:com.apple.sharepoint.group.3 inherited allow read,write,execute,append,readattr,writeattr,readextattr,writeextattr,readsecurity
 2: user:UserA inherited allow read,write,execute,append,readattr,writeattr,readextattr,writeextattr,readsecurity
 3: user:Shared-Folder2 inherited allow read,write,execute,append,readattr,writeattr,readextattr,writeextattr,readsecurity
Mini-Server:Raid Storage Admin-User$

Answer 1

You probably made a mistake and got the permutations wrong.

After creating a new share use the defaults and set the standard POSIX permissions for the group and everyone to "No Access". Then add the two users (here UserA and UserB) with the +-button.

Example: Shared-Folder1

In the Terminal it looks like this for all three folders:

host:~ admin$ sudo ls -lae /Volumes/Data/Shared-Folder1/
total 0
drwx------+  2 admin     staff  -  68 Oct 12 01:07 .
 0: user:_spotlight inherited allow list,search,file_inherit,directory_inherit
 1: user:usera allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
 2: user:userb allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
drwxrwxr-x  11 admin  staff  - 442 Oct 12 01:11 ..

host:~ admin$ sudo ls -lae /Volumes/Data/Shared-Folder2/
total 0
drwx------+  2 admin     staff  -  68 Oct 12 01:07 .
 0: user:_spotlight inherited allow list,search,file_inherit,directory_inherit
 1: user:userb allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
 2: user:userc allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
drwxrwxr-x  11 admin  staff  - 442 Oct 12 01:11 ..

host:~ admin$ sudo ls -lae /Volumes/Data/Shared-Folder3/
total 0
drwx------+  2 admin     staff  -  68 Oct 12 01:07 .
 0: user:_spotlight inherited allow list,search,file_inherit,directory_inherit
 1: user:usera allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
 2: user:userc allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
drwxrwxr-x  11 admin  staff  - 442 Oct 12 01:11 ..

If you try to access the share from a remote host as UserA it will look like this on a Mac:

and a Windows 10 host: