Alt-F provides a free alternative firmware for the DLINK DNS-320/320L/321/323/325/327L.
Alt-F has Samba and NFS; supports ext2/3/4, VFAT, NTFS and ISO9660 filesystems; RAID 0, 1, 5 (with external USB disk) and JBOD; supports 2/3/4TB disks; rsync, ftp, sftp, ftps, ssh, lpd, DNS and DHCP servers, DDNS, fan and leds control, clean power up and down... and more.
Alt-F also has a set of comprehensive administering web pages, you don't need to use the command line to configure it.
Besides the built-in software, Alt-F also supports additional packages on disk, including ffp packages, that you can install, update and uninstall using the administering web pages
Alt-F is still beta and is being developed and tested on a DNS-323-rev-A1/B1, a DNS325-rev-A1, a DNS-320L-rev-A1 and on a DNS-327L-rev-A1 hardware boards. Other models and boards are said to work.
Support Forum: http://groups.google.com/group/alt-f
Can't figure out this thing at all. About as user-friendly as a sharpened stick. Can't even tell what its doing half the time or if it even properly supports my 4tb Seagates Vague error messages, endless demands to log in whenever I do anything...just a really rough bit of software. Using DNS-321 which from what I can see not that many people have..I can't even find any detailed reports from other owners. You'd need to be a Linux guru to get anywhere with this firmware, I think.