Connection to an NFS server may fail in certain configurations, with a server log message that looks like this one:
Aug 4 05:44:43 leeloo kernel: nfsd: request from insecure port (11685b22:50528)!
This can happen with any version of Mac OS X. Here's why:
Mac OS X tries to make NFS connections from port numbers outside the traditional range expected by some NFS servers. Configuring your NFS server to accept connections on "insecure" ports above 1024 should resolve the issue. Please consult your server's documentation for configuration information.