WebNFS Developer's Guide

Can I Use an NFS Proxy Server?

No, not directly. The HTTP protocol is designed for proxy use, but protocols like FTP and NFS cannot be proxied directly; that is. you cannot send an NFS request to a proxy server with instructions to forward the request to (and reply from) another NFS server. However, as with FTP, NFS can be proxied by an NFS-capable HTTP proxy server if you need to be able to browse directories graphically or transfer files.