NFS uses hosts.allow and hosts.deny for IP address restriction.
Reload /etc/exports
exportfs -ra
Display available mounts
showmount -e nas
ZFS allows setting up an NFS share directly with the filesystem.
zfs set sharenfs=on zpool/zfsset
You can also set the NFS settings directly:
zfs set sharenfs=[nfs settings] zpool/zfsset
I have *not* had any success setting this up with ZFS on Linux (0.6.3). I get server access denied no matter what configuration I try. In contrast, I've tried it with NAS4Free, and it works fine.
Read-only to subnet
/var/nfs/images *(ro,no_subtree_check)