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1. Introduction

This document does not resemble a common HOWTO, meaning referencing to general principles, but it is rather an on-hand approach to a by nature complex matter. It borrows the structure of the current Root over NFS , but differs from it in the following points:

This HOWTO expects that you have a general knowledge of what you are up to, so first read the Diskless Nodes HOW-TO.

1.1 The setting

It is a common case a University computer lab to have a lot PC's running Windows 98 or/and NT and a powerful UNIX server to satisfy the need of an alternative operating environment. This UNIX server is most of times idle or meerly accessed by telnet and running stupid tasks. On the other hand, students, especially those attending a computer science department, feel like taking full advantage of it, just for fun or for "educational purposes" (breaking in, hacking it...). The restrictive environment of telnet does not allow us to enjoy the use of a power server.There are 2 alternatives to that:

The network at the computer lab consists of the following.

The task I had to accomplish was the following: Provide a complete working solution without new expenses and without modifying anything but the necessary on the server.

1.2 The alternatives

Being the responsible for the project, I had to choose between a variety of solutions about it. I choose the following, for the reasons illustrated:

1.3 General Principles

To be able to boot a Linux system, you have to provide it with the following:

You should notice that after a clean install, the total size of these directories is not that big, ranging from 30 to 40 MB. The main load of files exists in the /usr and /opt directories. So, it is possible to create a directory for every diskless client containing the above listed directories and mount points for directories like /usr that will be exported by the server. The boot process, as assumed by this document, is the following:
  1. The user reboots the computer, and using a diskette boots the Linux kernel.
  2. The kernel takes control of the system, identifies the system devices, and uses BOOTP to obtain the IP address matching the NIC 's hardware address.
  3. The init programm is started. Before switching to a run level, it calls a script described in the /etc/inittab file. This script is responsible for building the library cache, initialise and mount a swap file, load some system specific kernel modules and set the hostname.
  4. The boot script finishes and the init programm switches to the specified runlevel. It starts to execute the scripts located into the /etc/rc.d/rcX directory where 'X' is the name of the runlevel. These scripts are responsible for starting the portmapper and mounting the NFS exported /usr, /home and /opt directories.
  5. The user is able to login.
To sum up, the system administrator has to do the following tasks:
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