NFS mount from linux to OpenIndiana ( running as KVM guest on Fedora ) failed

OpenIndiana is running as KVM guest in Fedora 17. the network uses a
DHCP local network which is translated by NAT on the KVM host.

But after creating the config file for the automounter , changing into
a NSF-mount caused a "Permission denied". 

Looking into the /var/log/messages on the NFS Server ( linux ) showed the following entry:

mountd[3493]: refused mount request from XX.XX.XX.XX for /install (/install): illegal port 1488

The problem is, that the requests from the KVM guest are translated to
ports > 1024, which Linux evaluates to insecure.
To get the directories mounted by the automounter, you have to add the
option insecure to the /etc/exports file and reexport everyhting. After this
the automount works.