[9fans] Authenticated mounts from non-plan9 systems

[johnny@sorosj.hd.free.fr]

Hi eveyone!
I've been a fan of plan9 for quite a while, using it whenever I had a machine that would run it.
Now I have a small network of machines at home, with one plan9 auth+cpu+fs server (yeah, I know that's not much, but I don't have any more hardware that would run it).
I'd like to be able to mount the exports on that machine to other machines (mostly linux): I've been able to get a non-authenticated mount via p9p, but I can't seem to be able to get an authenticated mount. srv says there is no authentication needed. I was wondering if this was a p9p limitation or wether my cpu+auth+fs server was missing something, or if I was doing something wrong.
Here is how I am mounting it right now:
$ srv -a sorosj.hd.free.fr
rx: exportfs: authentication not required

so there is no authentication, though I can do
$ 9 mount `namespace`/sorosj.hd.free.fr /tmp/tmp

and then I can see my root, but I can't write to it. This is regardless of wether I supply mount with authentication parameters or not (eg. -o user=$USER,....,proto=UNIX )
Any help would be greatly appreaciated.
Thanks!
Johnny