user and group ids scrambled when using NFS

Question

I'm using nfs to mount the folder /mirror from a server onto a node.

This works, except on the node the user and group are displayed as "4294967294".

On the server: ls -al ./ displays

-rw-r--r--  1 cu cu    0 2011-07-11 15:08 test1
-rw-r--r--  1 cu cu    0 2011-07-11 15:08 test2

whereas on the node

-rw-r--r--  1 4294967294 4294967294    0 2011-07-11 15:08 test1
-rw-r--r--  1 4294967294 4294967294    0 2011-07-11 15:08 test2

I have usermod and groupmod the username cu to have the same numbers on the node.

On the server: id displays

uid=1021(cu) gid=1007(cu) groups=1007(cu),109(admin)

on the node

uid=1021(cu) gid=1007(cu) groups=1007(cu)

I'm stumpeed as to what the problem could be.

I should perhaps add that the home directory is /mirror/cu (so that the users share the same account when mounted). Not sure if thats relevent though...

My /etc/exports file (on the server) looks like this

/mirror *(rw,sync) 

and I do the mount (on the node) with

sudo mount server:/mirror /mirror

Answer 1

As @PriceChild notes, this question is a duplicate.

However, no answers were accepted to that question. I tried this answer first, namely adding

-o vers=3 

to the mount command, and that worked for me.

The rationale for this (using version 3 of NFS rather than version 4) is that

NFSv4 doesn't use UID/GIDs anymore. There are quite a few significant differences between NFSv3 and v4; security is one of them.

Note: I was satisfied with this fix and I didn't get to the root of the problem. If you want to take if further, the aforementioned links should help.