Original: FreeNAS is a free network-attached storage server, supporting: CIFS (Samba), FTP, NFS, rsync, AFP protocols, iSCSI, S.M.A.R.T.,  local user authentication, and software RAID (0,1,5), with a web-based configuration interface.
Simplified: FreeNAS is a free network-attached storage server. It supports CIFS (Samba), FTP, NFS, rsync, AFP protocols, iSCSI, S.M.A.R.T., local user authentication, and software RAID (0,1,5).