[ale] Remote file systems and tunnels

[Alex Carver]

I'm working on setting up a pair of systems that will need to have the 
storage volumes on one (file server) mounted by the other (application 
server).  The first problem is they're both going to be on different 
subnets (no choice).

I'd like to have a secure link between the two.  I could set up NFS 
though that exposes the NFS server's ports to all machines (although I 
suppose I could also run iptables and allow only the app server 
through).  I was thinking it might be possible to tunnel NFS (or 
something similar and suitable) via SSH.  Then I only need the SSH port 
open on the server.

The problem is that any document I find for tunneling NFS seems to be 
several years old.

Thoughts?