What does the -P option do to mount?

Question

I'm migrating from an archaic version of Red Hat to Ubuntu 9. When going through my old nfs mount script, I found that it contained the -P option.

So my script looks like:

sudo mount -t nfs -o -P ...

It looks like the -P is one of the -o options. My question is: what does the -P option do? I've searched every man page I can find, with no luck. Could it have to do with privileged ports?

Answer 1

This is what the FreeBSD man page for mount_nfs says:

-P
Use a reserved socket port number. This flag is obsolete, and only retained for compatibility reasons. (For the rare case where the client has a trusted root account but untrustworthy users and the network cables are in secure areas this does help, but for normal desktop clients this does not apply.)