Linux Network Administrator's Guide, Second Edition

The exports File

Now we’ll look at how we configure the NFS server. Specifically, we’ll look at how we tell the NFS server what filesystems it should make available for mounting, and the various parameters that control the access clients will have to the filesystem. The server determines the type of access that is allowed to the server’s files. The /etc/exports file lists the filesystems that the server will make available for clients to mount and use.

By default, rpc.mountd disallows all directory mounts, which is a rather sensible attitude. If you wish to permit one or more hosts to NFS-mount a directory, you must export it, that is, specify it in the exports file. A sample file may look like this:

# exports file for vlager
/home             vale(rw) vstout(rw) vlight(rw)
/usr/X11R6        vale(ro) vstout(ro) vlight(ro)
/usr/TeX          vale(ro) vstout(ro) vlight(ro)
/                 vale(rw,no_root_squash)
/home/ftp         (ro)

Each line defines a directory and the hosts that are allowed to mount it. A hostname is usually a fully qualified domain name but may additionally contain the * and ? wildcards, which act the way they do with the Bourne shell. For instance, lab*.foo.com matches lab01.foo.com as well as laboratory.foo.com. The host may also be specified using an IP address range in the form address/netmask. If no hostname is given, as with the /home/ftp directory in the previous example, any host matches and is allowed to mount the directory.

When checking a client host against the exports file, rpx.mountd looks ...