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NFS, the Network File System, is the protocol of choice
when it comes to file-sharing between machines running Linux or other variants
of Unix (BSD, Mac OS X, Solaris etc). The nice thing about NFS is that the
clients do not need to have support for the underlying file system of the
server, you can use for example Mac Os X as a server for Linux clients et
vice versa. However, if your network also contains non-Unix machines, you
are advised to use a different mechanism, SMB for
example.
 Setting Up The Server
To install the necessary software, type
urpmi nfs-utils
This will install the packages portmap, nfs-utils-clients
and nfs-utils. Next, start the portmapper (as root):
service portmap start
Notice that all the installed services will be automatically
started on next boot, so you don't have to worry about that. For the current
session however, you will have to do it by hand.
Before starting the NFS server, you have to define at
least one directory to be exported. You define these directories in '/etc/exports'.
I just created a new directory '/usr/export' and my '/etc/exports' file looks
like this:
/usr/export 192.168.1.0/255.255.255.0(rw)
The first entry is the directory to be exported. The
second marks the machine(s) which are allowed to access it, and the third
lists NFS options. In this case the exported directory is /usr/export, open
for all machines on the 192.168.1.* subnet, and they are allowed to read
and write to the directory (default is read-only).
You'll need a new line for every directory you want to export. NFS does not
work across mounts, that is a subdirectory of an exported directory will
not be exported if it is on different partition or device. You will have
to export it explicitly.You can specify different machines with different
NFS options for the same directory:
/usr/export 192.168.1.75(ro) 192.168.1.76(rw)etc.
and you can specify them either by IP address or by
DNS hostname. To export a directory to all clients, regardless of
their IP, just omit the IPs:
/usr/export (ro)
As for NFS options, there are only two which are of
interest: (rw) which enables the clients to write on the exported volume
and (no_root_sqash) which allows a root user on a client to exercise root
privileges on the exported volume (by default, all NFS clients are using
the volume as user 'nobody').
If you change /etc/exports later on, issue
exportfs -ra
every time to make the changes known to the system.
Now start NFS with
service nfs start
Check with
rpcinfo -p
If everything is running correctly you should get something
like this:
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100011 1 udp 838 rquotad
100011 2 udp 838 rquotad
100005 1 udp 1031 mountd
100005 1 tcp 1040 mountd
100005 2 udp 1031 mountd
100005 2 tcp 1040 mountd
100005 3 udp 1031 mountd
100005 3 tcp 1040 mountd
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100021 1 udp 1032 nlockmgr
100021 3 udp 1032 nlockmgr
100021 4 udp 1032 nlockmgr
 section index  top
While it is in theory possible to mount the NFS share
on the client right away, I would recommend that you install portmap on it
first. Otherwise trying to mount the share may have some strange side effects
(I'm not sure if this is a bug or intended). So:
urpmi portmap && service portmap start
Assuming the NFS server is on 192.168.1.75:
mount 192.168.1.75:/usr/export /mnt/disk
mounts /usr/export read-only from the server on /mnt/disk
on the client. Do a
mount -v | grep nfs
and you should get
192.168.1.75:/usr/export on /mnt/disk type nfs
(ro,addr=192.168.1.75)
Assuming the client's IP is 192.168.1.76, doing a
showmount 192.168.1.75
on the server should return
Hosts on 192.168.1.75: 192.168.1.76
Congratulations, your NFS setup is ready :-).
Mac OS X users can use NFS, too, since
Mac OS X is a Unix in its own right.
There's a small but very important difference, however: By default, the
Linux implementation uses a privileged port (i.e. a port lower than 1024)
for NFS and denies - for security reasons - cooperation with NFS clients
using a non-privileged port. But this is what Mac OS X NFS does. So you have
to tell the Mac OS X NFS client to use a privileged port when trying to mount
an NFS share from a Linux server. This is done with the "-P" option:
mount -o "-P" 192.168.1.75:/usr/export /mnt/share
will mount the Linux NFS share to the directory '/mnt/share'
on the Mac OS X client.
section index top
 Customizing and securing NFS,
Pitfalls
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