NFS: re-exporting partition - double NFS (Fedora 2)

I've successfully mounted a partition from a Windows server on my
Linux server, using:

mount -t smbfs -o ro,username="...",password=... //WinSRV/monkey
/mntpoint

Now I must mount from another Linux server "/mntpoint" but the
Permission is Denied. Trying to mount another partition is ok, so the
problem is just the "remounting" of a dir already mounted via NFS.

I searched on the net about remounting and I found "mountd" having the
option "--re-export" but I don't to know how to use it. In fact
"mountd" is invoked by "/etc/init.d/nfs" as "rpc.mountd", but it seems
to be another "rpc.mountd".
Using "man mountd", it referes to "/usr/etc/rpc.mountd" but my
"/usr/etc" is empty". Instead, "/etc/init.d/nfs" launches
"/usr/sbin/rpc.mountd", and in the man pages THIS rpc.mountd doesn't
have any "--re-export" option.

Now, I don't know how rpc+mountd work, but I wish simply to know the
way to re-export a NFS partition already NFS mounted.

Thank you,
Bracchetto

Bracchetto <(E-Mail Removed)> wrote:
> Now I must mount from another Linux server "/mntpoint" but the
> Permission is Denied. Trying to mount another partition is ok, so the
> problem is just the "remounting" of a dir already mounted via NFS.

> I searched on the net about remounting and I found "mountd" having the
> option "--re-export"

That is correct. Except you mean "rpc.mountd", not "mountd".

> but I don't to know how to use it.

That is incorrect. You know prfectly well how to use it - just like the
man page says to use it, which is by typing it out (there are no
tricks, -r is a synonym).

> In fact
> "mountd" is invoked by "/etc/init.d/nfs" as "rpc.mountd"

I don't know what you mean by this statement. Rpc.mountd should be the
name of the executable. Clarify please. How do you "invoke X as Y"?

> but it seems
> to be another "rpc.mountd".

Another than what? There is only one.

> Using "man mountd", it referes to "/usr/etc/rpc.mountd"

Nonsense. Why don't you look at the man page of your executable?

> but my
> "/usr/etc" is empty". Instead, "/etc/init.d/nfs" launches
> "/usr/sbin/rpc.mountd",

That is correct.

> and in the man pages THIS rpc.mountd doesn't

WHAT rpc.mountd! There is only one. How are you inferring that there
are different manpages for "different rpc.mountd"s, and how are you
getting hold of them?

> have any "--re-export" option.

Good. Then you can't use one on it. So be happy.

> Now, I don't know how rpc+mountd work,

Why should you? Just launch the executable you want with the options
you want.

> but I wish simply to know the
> way to re-export a NFS partition already NFS mounted.

You already know. Launch the nfsd or mountd with the reexport flag, and
make sure it's a daemon that supports that flag.

What the heck kind of crazy questions are these? They sound amazingly
petulant.

Peter

Bracchetto wrote:
> I've successfully mounted a partition from a Windows server on my
> Linux server, using:
>
> mount -t smbfs -o ro,username="...",password=... //WinSRV/monkey
> /mntpoint
>
> Now I must mount from another Linux server "/mntpoint" but the
> Permission is Denied. Trying to mount another partition is ok, so the
> problem is just the "remounting" of a dir already mounted via NFS.
>

It purposedly prohibited with NFS. The idea is to keep
the access rights at the computer where the real file
system is.

If you allowed B to mount a directory from A, and also
B to re-export it, there is no way for A to control
which other hosts are using it. The proper way is to
mount it from the original source (after permitting
it in the source exports).

HTH

Tauno Voipio
tauno voipio (at) iki fi

Tauno Voipio <(E-Mail Removed)> wrote:
> Bracchetto wrote:
> > I've successfully mounted a partition from a Windows server on my
> > Linux server, using:
> >
> > mount -t smbfs -o ro,username="...",password=... //WinSRV/monkey
> > /mntpoint
> >
> > Now I must mount from another Linux server "/mntpoint" but the
> > Permission is Denied. Trying to mount another partition is ok, so the
> > problem is just the "remounting" of a dir already mounted via NFS.

> It purposedly prohibited with NFS. The idea is to keep

Discouraged by default, not "prohibited". You can use the -r flag on
the daemon (rpc.NFSD !!!!!!).

NFSD(8) NFSD(8)


NAME
nfsd - NFS service daemon

SYNOPSIS
/usr/sbin/rpc.nfsd [ -f exports-file ] [ -d facility ] [
-P port ] [ -R dirname ] [ -Fhlnprstv ] [ --debug
facility ] [ --exports-file=file ] [ --foreground ] [
--help ] [ --allow-non-root ] [ --re-export ] ...
^^^^^^^^^^^^^^^

> the access rights at the computer where the real file
> system is.

You can give your rights of decision away, if you want to. Nothing says
you oughtn't to be able to. And the daemon allows it.

> If you allowed B to mount a directory from A, and also
> B to re-export it, there is no way for A to control
> which other hosts are using it.

And fine - if that's what A wants, that's what A wants. And yes, there
is a way, if B chooses to cooperate. It's all about choice.

> The proper way is to
> mount it from the original source (after permitting
> it in the source exports).

Well, I would also recommend that! It used to be that -r was also
readonly.

Peter

P.T. Breuer wrote:

> Tauno Voipio <(E-Mail Removed)> wrote:

>> It purposedly prohibited with NFS. The idea is to keep
>
> Discouraged by default, not "prohibited". You can use the -r flag on
> the daemon (rpc.NFSD !!!!!!).

> NAME
> nfsd - NFS service daemon
> SYNOPSIS
> /usr/sbin/rpc.nfsd [ -f exports-file ] [ -d facility ] [
> -P port ] [ -R dirname ] [ -Fhlnprstv ] [ --debug
> facility ] [ --exports-file=file ] [ --foreground ] [
> --help ] [ --allow-non-root ] [ --re-export ] ...

My nfsd manpage (on Fedora Core 2) doesn't include that option.
....
NAME
rpc.nfsd - NFS server process
SYNOPSIS
/usr/sbin/rpc.nfsd [-p port] nproc
....


I think that option was specific to the old, deprecated/unmaintained
user-space nfs implementation.

AFAIK, the newer kernel-space nfs-utils doesn't do that.

-- Rex

Rex Dieter <(E-Mail Removed)> wrote:
> > NAME
> > nfsd - NFS service daemon
> > SYNOPSIS
> > /usr/sbin/rpc.nfsd [ -f exports-file ] [ -d facility ] [
> > -P port ] [ -R dirname ] [ -Fhlnprstv ] [ --debug
> > facility ] [ --exports-file=file ] [ --foreground ] [
> > --help ] [ --allow-non-root ] [ --re-export ] ...

> My nfsd manpage (on Fedora Core 2) doesn't include that option.

Get a different rpc.nfsd, or "Don't Do That Then".

Peter

>
> > have any "--re-export" option.
>
> Good. Then you can't use one on it. So be happy.
>

Great, Peter. Now tell me HOW, please.
Thank you.

Bracchetto.

P.T. Breuer wrote:

> Rex Dieter <(E-Mail Removed)> wrote:
>> > NAME
>> > nfsd - NFS service daemon
>> > SYNOPSIS
>> > /usr/sbin/rpc.nfsd [ -f exports-file ] [ -d facility ]
>> > [ -P port ] [ -R dirname ] [ -Fhlnprstv ] [ --debug
>> > facility ] [ --exports-file=file ] [ --foreground ] [
>> > --help ] [ --allow-non-root ] [ --re-export ] ...
>
>> My nfsd manpage (on Fedora Core 2) doesn't include that option.
>
> Get a different rpc.nfsd, or "Don't Do That Then".

That's exactly my point: *There is no different rpc.nfsd* (*)

(*) Not that's supported/maintained anyway.

-- Rex

Rex Dieter <(E-Mail Removed)> wrote:
> P.T. Breuer wrote:

> > Rex Dieter <(E-Mail Removed)> wrote:
> >> > NAME
> >> > nfsd - NFS service daemon
> >> > SYNOPSIS
> >> > /usr/sbin/rpc.nfsd [ -f exports-file ] [ -d facility ]
> >> > [ -P port ] [ -R dirname ] [ -Fhlnprstv ] [ --debug
> >> > facility ] [ --exports-file=file ] [ --foreground ] [
> >> > --help ] [ --allow-non-root ] [ --re-export ] ...
> >
> >> My nfsd manpage (on Fedora Core 2) doesn't include that option.
> >
> > Get a different rpc.nfsd, or "Don't Do That Then".

> That's exactly my point: *There is no different rpc.nfsd* (*)

That's a matter of opinion, to be exact. But since you're placing
yourself in the DDTT class, DDTT!

> (*) Not that's supported/maintained anyway.

I have 2.2beta47, and there are package updates to at least Mon, 16
Aug 2004 21:19 :00 +0200. The manpage is as above.

Peter

P.T. Breuer wrote:

> Rex Dieter <(E-Mail Removed)> wrote:

>> That's exactly my point: *There is no different rpc.nfsd* (*)
>> (*) Not that's supported/maintained anyway.

> That's a matter of opinion, to be exact. But since you're placing
> yourself in the DDTT class, DDTT!

what's DDTT?

> I have 2.2beta47, and there are package updates to at least Mon, 16
> Aug 2004 21:19 :00 +0200. The manpage is as above.

That's probably the build-time of the package.

As I said, development on the user-space nfs implementation is dead, and the
userspace nfs tarball from
ftp://linux.mathematik.tu-darmstadt....x/people/okir/
dates back to Nov 1999. It's old, unmaintained, NFS2 only, doesn't support
File locking...

If, knowing that, you're still willing to try to use it, then knock yourself
out.

-- Rex