Q: How to share group folders with read only permission (Authentication=Yes)?

1. Read General Notes
2. Read How to install Samba Server for files/folders sharing service?

3. sudo mkdir /home/group
   sudo chmod 777 /home/group/
   sudo cp /etc/samba/smb.conf /etc/samba/smb.conf_backup
   sudo gedit /etc/samba/smb.conf

4. Find this line

   ...
   ;   security = user
   ...

5. Replace with the following lines

      security = user
      username map = /etc/samba/smbusers

6. Append the following lines at the end of file

   [Group]
      comment = Group Folder
      path = /home/group
      public = yes
      writable = no
      valid users = system_username1 system_username2
      create mask = 0700
      directory mask = 0700
      force user = nobody
      force group = nogroup

7. Save the edited file (sample)
8. Read How to add/edit/delete network users?

9. sudo testparm
   sudo /etc/init.d/samba restart