A very clean approach to NFS authentication is using it in combination with wireguard. With NFS you can limit access to certain IPs or IP ranges. With wireguard

A very clean approach to NFS authentication is using it in combination with wireguard. With NFS you can limit access to certain IPs or IP ranges. With wireguard you add authentication that these IPs are really the users/group of users. Also it adds encryption to the actual file transfer.