Encryption for NAS box

Hi guys,

I'm looking for a solution for encrypting a NAS box connected directly to the network and managed by our Linux server. Unfortunately I'm finding it hard to find a product that can do this.  We simply use the NAS box to backup the date from the Linux server. No need for multiple users to access the NAS box simultaneously, just the Linux server.  We need to encrypt the backups on the NAS box.

Does Symantec have anything that can do this for us?

Thanks