Hi Haliparotin
FreeNAS supports authentification via SMB or LDAP.
Theoretically you could use the SMB (Windows Domain) to get your SME users over to FreeNAS - only this doesn't work well. FreeNAS will display the users and groups from SME, but will not allow auth or a connection to a Windows user logged on to SME. The same goes for Openfiler. Both do work, when a real MS-Server does the auth - no matter if modern AD or even if it's an old NT4 PDC. But SME? Just haven't got that to work reliably...
FreeNAS would be nice eg. as a backup server for "Backup to Workstation" using SMB, but only if the users are defined locally.
My 2 Cents...
Andy