Let's say you're responsible for a network of 100 computers shared by students. What do you do if one of those computers starts acting funny? If you're like me, you'll just do a clean install of the operating system. But that's a lot of work, especially if you have to do it several times a week. Fortunately, most PCs sold since 2001 follow the guidelines from Intel and Microsoft, which among other things says that new computers with Ethernet interfaces must implement two useful features: wake-on-LAN and network boot.
Wake-on-LAN
If your BIOS is set to enable Wake-On-LAN, and is off, it will turn itself on when it receives a packet containing 6 bytes of FFh followed by 16 copies of its Ethernet address. (See for more details.) This can be used to help force reinstalls of the operating system in the middle of the night, when nobody's there.
Network Boot
There are several ways computers can boot over a network, but the one mandated by PC99 is called PXE. PXE is a kind of DHCP extension, so all you need is an up-to-date DHCP server and a TFTP server.
Back when PC99 and PXE were new, the normal DHCP server hadn't yet been updated to handle PXE, so Red Hat created a package called 'pxe', and has shipped it with all versions of their Linux since 6.2. You probably don't want to use it, though, now that the normal ISC DHCP software shipped with Linux can handle PXE.
Together, a DHCP server and a TFTP server can be set up to handle PXE boot requests. It's up to you what to give the PCs when they boot; several possibilities include
- Another bootloader, for instance:
- The network install boot image from a Linux distribution,
- or whatever evil program you desire.
Security
It should be mentioned that
booting from a bad server is a big potential security hole, so one should avoid booting over network connections or from servers that are not physically secure.
Examples / Recipes / Articles
Distributions of Linux designed to run as thin clients or diskless workstations
- - includes server setup tools, too
- - supports connecting to Windows Terminal Servers, too
- - a demo CD-ROM edition of Linux. Can boot remotely via PXE from a server already running KNOPPIX. Useful for clients that have a network card but no CD-rom drive.
Tools for Remote Booting and Installing
- - System Imager is a great generic network disk reimaging tool (like a Free Software version of Ghost)
- and friends. A network bootloader with a programmable user interface. (Like a Free Software version of BpBatch)
- Non-free but zero-cost network bootloader with a programmable user interface. Used to be open source.
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- - cluster management tools
Using PXE to install Linux
- , by Alf Wachsmann, alfw@SLAC.Stanford.EDU
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Using PXE to boot diskless Linux
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- , by Simon Horman, February 2002
Using PXE to boot thin client Linux
Related whitepapers and magazine articles
- , by Richard Ferri. Linux Journal, January 2002
- Network Booting of a diskless Linux device with PXE and PXELINUX, by Matt Butcher. Linux Devices, January 2002
- Network Booting a Linux STB with PXE HOWTO, by Matt Butcher. Linux Devices, January 2002
- , by Ewen McNeill, Naos Limited. Presented at NetForum 2000, October 2000.
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- , by Linux User Group Bolzano-Bozen-Bulsan. German. Good links.
- , by Ron Anderson. Network Computing, October 29, 2001. Covers commercial remote installation tools for that other operating system. (I list it here for comparison only.)
- , by Dell, 2001
- , by HP. A HOWTO for owners of their blade servers.
Schools Using Network Booting for Administration
Old Recipes
Here are a few somewhat out-of-date recipes/howtos that might still be of some interest.
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