To set anonymous access permissions on exported filesystems:
From the Export menu,
select NFS, then select Add Export
Configuration.
Click on Anonymous Users.
Select Allowed or Not Allowed in the
Control Anonymous Access to Exported Filesystem menu.
If a request comes from an unknown user, the
uid will be used as the effective user ID if
the
anon=uid option is enabled.
NOTE:root users (UID 0) are always
considered unknown by the NFS server, unless
they are included in the root option below. The
default value for this option is -2. Setting
anon to -1 disables anonymous access.
By default, NFS will accept insecure requests as
anonymous, and those wishing for extra security can disable
this feature by setting anon to -1.