2.4. File permissions on exported file systems

File permissions on exported file systems determine access rights to files and directories for clients accessing them over NFS.

Once the NFS file system is mounted by a remote host, the only protection each shared file has is its file system permissions. If two users that share the same User ID (UID) value mount the same NFS file system on different client systems, they can modify each other’s files.

NFS treats the root user on the client as equivalent to the root user on the server. However, by default, the NFS server maps root to the nobody account when accessing an NFS share. The root_squash option controls this behavior.

For more information about this option, see the exports(5) man page on your system.