Remove built-in NFS packages.
$ sudo apt-get purge nfs-common nfs-kernel-server
Build and install this legacy one.
$ ./configure --prefix=/usr --enable-multiple-servers
$ make
$ sudo checkinstall make install
Edit /etc/exports
/rootfs 10.0.0.0/255.255.0.0(rw,sync,no_root_squash)
Run NFS server
$ sudo ./S60nfs