NFS privilege problem

I am using NFS in my “white” My Book with the following /etc/exports options:

/nfs/Public *(rw,root_squash,sync)

I mount it from my client Linux with the following options in /etc/fstab: /Kovacs nfs defaults 0 0

Everything is fine, but the users have too much privilige on modifying the files. Here comes an example.

su - user1

cd /Kovacs; mkdir user1dir; cd user1dir; touch user1file

su - user2

cd /Kovacs; cd user1dir; mv user1file renamed

Unfortunately, the last command is also allowed, however the file has the owner user1 and it has -rw-r–r-- rights.

I guess there must be a bug in the NFS implementation. Does anybody know how I can fix this?

Thank you in advance.

It was not a NFS problem, but a “feature” of the “trustees” kernel module. At last, I disabled it: