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Chapter 18. Network File System (NFS) 243

However, be careful when using wildcards with fully qualiﬁed domain names, as they tend to be

more exact than you would expect. For example, the use of *.domain.com as wildcard will al-

low sales.domain.com to access the exported ﬁlesystem, but not bob.sales.domain.com. To match

both possibilities, as well as sam.corp.domain.com, you would have to provide *.domain.com

*.*.domain.com.

• IP networks — Allows the matching of hosts based on their IP addresses within a larger net-

work. For example, 192.168.0.0/28 will allow the ﬁrst 16 IP addresses, from 192.168.0.0 to

192.168.0.15, to access the exported ﬁlesystem but not 192.168.0.16 and higher.

• netgroups — Permits an NIS netgroup name, written as @

group-name , to be used. This effec-

tively puts the NIS server in charge of access control for this exported ﬁlesystem, where users can

be added and removed from an NIS group without affecting /etc/exports.

Warning

The way in which the /etc/exports ﬁle is formatted is very important, particularly concerning the

use of space characters. Remember to always separate exported ﬁlesystems from hosts and hosts

from one another with a space character. However, there should be no other space characters in the

ﬁle unless they are used in comment lines.

For example, the following two lines do not mean the same thing:

/home bob.domain.com(rw)

/home bob.domain.com (rw)

The ﬁrst line allows only users from bob.domain.com read-write access to the /home directory.

The second line allows users from bob.domain.com to mount the directory read-only (the default),

but the rest of the world can mount it read-write. Be careful where space characters are used in

/etc/exports.

18.3. NFS Client Conﬁguration Files

Any NFS share made available by a server can be mounted using various methods. Of course, the

share can be manually mounted, using themount command, to acquire the exported ﬁlesystem at a

particular mount point. However, this requires that the root user type the mount command every time

the system restarts. In addition, the root user must remember to unmount the ﬁlesystem when shutting

down the machine. Two methods of conﬁguring NFS mounts include modifying the /etc/fstab or

utilizing the autofs service.

18.3.1. /etc/fstab

Placing a properly formatted line in the /etc/fstab ﬁle has the same effect as manually mounting

the exported ﬁlesystem. The /etc/fstab ﬁle is read by the /etc/rc.d/init.d/netfs script at

system startup. The proper ﬁlesystem mounts, including NFS, are put into place.

A sample /etc/fstab line to mount an NFS export looks like the following:

server : /path/of/dir /local/mnt/point nfs options 0 0

The server-host relates to the hostname, IP address, or fully qualiﬁed domain name of the

server exporting the ﬁlesystem. The

/path/to/shared/directory tells the server what export

to mount. The /local/mount/point speciﬁes where on the local ﬁlesystem to mount the ex-

ported directory. This mount point must exist before /etc/fstab is read or the mount will fail. The

nfs option speciﬁes the type of ﬁlesystem being mounted.

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Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION GUIDE Guida di Installazione Pagina 243

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