1. Introduction

1.1. What is this all about?

Recent linux kernels offer the possibility to boot a linux box entirely from network, by loading its kernel and root filesystem from a server. In that case, the client may use several ways to get the first instructions it has to execute when booting: home made eproms, special network cards implementing the RARP, BOOTP or DHCP protocols, cdroms, or bootloaders loaded from a boot floppy or a local hard drive.

1.2. Thanks

Logilab sponsored this HOWTO. Check their website for new versions of this document. I also thank the etherboot, netboot, plume and linux terminal server project developers and webmasters, who made it really possible to boot a Linux worstation over a network.

Very special thanks go to Ken Yap, member of the etherboot project, whose comments greatly helped to improve the quality of this document.

I also thank Jerome Warnier, main developer of the plume project, Pierre Mondié, Kyle Bateman, Peter T. Breuer, Charles Howes, and Thomas Marteau for their comments and contributions.

1.3. Diskless booting advocacy

1.3.2. Advantages of diskless computers

Diskless computers will become more and more popular in the next years. They will be very successful because of the availability of very high-speed network cards at very low prices. Today 100 Megabit per second (12.5 MB per sec transfer rate) network cards are common and in about 1 to 2 years 1000 MBit (125 MB per sec transfer rate) network cards will become very cheap and will be the standard.

In near future, monitor manufacturers will place the CPU, NIC, RAM right inside the monitor to form a diskless computer. This eliminates the diskless computer box and saves space. The monitor will have outlet for mouse, keyboard, network RJ45 and power supply.

The following are benefits of using diskless computers:

1.4. Requirements

1.4.1. Hardware requirements

The most important thing in order to boot from network is to have an equipment which enables the stations to execute a bootloader, which will get the kernel on the server and launch it. Another solution is to use a device which will load a local kernel, which will mount the root filesystem on the server. There are several solutions: home made eproms containing the first instructions to execute when booting the station, boot with BOOTP/DHCP capable network adapters, or a local floppy, a tiny hard drive, or a cdrom to load the kernel. Note that some vendors also sell network booting capable stations: for instance, some Sun stations implement the BOOTP protocol.

Other hardware requirements depend on the configuration you plan to use: on some sites, every application run by the stations is executed remotely on the server, this implies that a very high-performance server is required, but only light stations are required: depending on what they will have to do, 80486 CPUs with 16 MB of RAM may be enough. On the other side, if application programs are really executed locally on the stations, the requirements for the stations depend completely on these applications. In that case, only a small server is required. A 80486 CPU with 32 MB of RAM will be sufficient for a small number of stations, but more memory will be necessary in very large installations with hundreds or thousands of machines. Note the server's CPU does not really matter for such an installation.

1.5. Acknowledgements and related documentation

This documentation has been written for experimented system administrators, who are already aware of linux fundamentals, like the use of grep, sed, and awk, basic shell programming, the init process and the boot scripts, kernel compilation, and NFS server configuration. Experience of kernel arguments passing should also help. Information on these subjects can be found respectively in the grep, sed, awk, and bash man/info pages, in the Bootdisk-HOWTO, the From-PowerUp-To-Bash-Prompt-HOWTO, the Kernel-HOWTO, the BootPrompt-HOWTO, the bootparam man page, the rdev man page, the NFS-HOWTO, and the exports manual page.

There are many sources of information on network booting, but, and this is why I wrote this HOWTO, none describes all the existing ways of booting over a network, and much of them are specific to a way of operating. The most useful to me has been the documentation provided by the linux terminal server project, although I did not use the packages they recommend, and I have chosen to describe here how to proceed without these packages, because they configure things so that every application program is executed remotely on a server. Useful information can also be found on the etherboot project's homepage.

At last, you can also find useful but succinct information in the kernel's source tree, in /usr/src/linux/Documentation, assuming your kernel source tree resides in /usr/src/linux.

1.6. Feedback

I will highly appreciate any feedback about this document. Please feel free to mail me at if you have any comment, correction, or suggestion. You may also use .

1.7. Copyright Information

This document is copyrighted (c) 2001 and is distributed under the terms of the GNU Free Documentation License. You should have received a copy along with it. If not, it is available from http://www.fsf.org/licenses/fdl.html.

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