FreeNAS is a dedicated operating system for Network-Attached Storage (NAS) services. Based on the m0n0wall firewall, it lets users convert a PC to a NAS server by providing disk management and software RAID. FreeNAS is intended to let people re-use old hardware.
FreeNAS supports CIFS/SMB (samba), FTP, SNMP, NFS, SSH, AFP, Unison, UPnP, AFP, RSYNC, S.M.A.R.T., iSCSI protocols, local and MS Domain authentication, server name configuration, software RAID (JBOD,0,1,5), and disk encryption (GELI), with a full web configuration interface.
FreeNAS takes less than 32MB once installed on compact flash, hard drive, or USB key. The minimal FreeBSD distribution, web interface, PHP scripts and documentation are based on m0n0wall.