Welcome to distributed systems and storage.
Direct-Attached Storage (DAS) and Storage Area Network (SAN) storage are "local" storage, and managed by the host. (Yes, there are extra steps involved on the host and out on the SAN storage controllers to get the storage visible to the host.)
Any storage off-host is going to have to be at least partially managed on the box that's hosting the storage. This includes dedicated Network Attached Storage (NAS) boxes, ftp and WebDAV, as well as other host operating systems (Mac OS X, Linux, OpenVMS, z/OS, whatever) that are serving up storage.
Off-host storage management requires some coordination between the remote identity and the local identity, either via mapping UID values, username and password or certificate credentials, or shared authentication via Kerberos or such.
How you establish the mapping and coordinate the identities depends on the protocols used, and the particular device or host.