The mount daemon checks the export table each time a client makes a request to
mount an exported file system. Users with the proper authority can update the
/etc/exports file to export file systems at will by adding, deleting, or changing
entries. Then the user can use the export command to update the export table.
Most system administrators configure their NFS server so that, as it starts up, it
checks for the existence of /etc/exports, which it immediately processes.
Administrators can accomplish this by specifying *ALL on the STRNFSSVR (Start
Network File System Server) command. Once the server finds /etc/exports in this
way, it uses the export command to create the export table.This makes the file
systems immediately available for client use.
Why Should I Export?
Exporting gives a system administrator the opportunity to easily make any file
system accessible to clients. The administrator can perform an export at will to fulfill
the needs of any particular user or group of users, specifying to whom the file
system is available and how.
With an efficient system of exporting, a group of client systems needs only one set
of configuration and startup files, one set of archives, and one set of applications.
The export command can make all of these types of data accessible to the clients
at any time.
Although there are many insecure ways to export file systems, using the options on
the export command allow administrators to export file systems safely. Exported file
systems can be limited to a group of systems in a trusted community of a network
namespace.
Using the ability to export allows for a simpler and more effective administration of a
namespace, from setting up clients to determining what authority is needed to
access a sensitive data set. Aproperly used /etc/exports file can make your
namespace safe and secure while providing for the needs of all your users.
TULAB Scenario
In TULAB, a group of engineering undergraduate students are working with a group
of engineering graduate students. Both sets of students have access to their remote
home directories and applications on the server through NFS. Their research
involves the controversial history of local bridge architecture. The students will be
working in different rooms of the same campus building. Chris Admin needs a way
to make data available to both groups of computers and students without making all
the data available to everyone.
Figure 18. Dynamically exporting file systems with the
″
-I
″
option
26 OS/400 Network File System Support V4R4