Network boot operating systems with gPXE
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Contents
Introduction
gPXE is a new version of the well know Etherboot project. The project created network booting code that allows computers to load their operating system from a network.
The code can be stored in a number of places, including BIOS Flash, EPROMs, floppy, CD, HD, or other bootable media.
Required software
Software used for this howto:
- Ubuntu Linux 9.04
- gPXE 1.0.1: http://etherboot.org/wiki/download
- SysLinux 3.86: http://syslinux.zytor.com/
- Internet Systems Consortium DHCP server V3.1.1 - http://www.isc.org
- TFTP server from Linux NetKit - http://www.hcs.harvard.edu/~dholland/computers/netkit.html
NOTE: Although I used Linux in this HowTo you can use any O.S running DHCP and TFTP servers to make this work. My boot server at home runs NetBSD and works great. All you need is the compiled gPXE binary.
NOTE 2: gPXE was forked and the new project can be found at: http://ipxe.org/
Installation
Run following commands to install TFTP and DHCP servers:
# apt-get install tftpd # apt-get install dhcp3-server
Download tarball of gPXE from http://kernel.org/pub/software/utils/boot/gpxe/gpxe-1.0.1.tar.gz
Extract it and compile:
# tar zxf gpxe-1.0.1.tar.gz # cd gpxe-1.0.1/src # make
The file we need is called undionly.kpxe and you can find it in
# gpxe-1.0.1/src/bin/undionly.kpxe
Configuration
How to setup the DHCP server
Edit the config file:
/etc/dhcp3/dhcpd.conf
so it looks like this:
allow booting;
allow bootp;
ddns-update-style none;
log-facility local7;
default-lease-time -1;
max-lease-time 7200;
authoritative;
option space gpxe;
option gpxe-encap-opts code 175 = encapsulate gpxe;
option gpxe.bus-id code 177 = string;
subnet 192.168.1.0 netmask 255.255.255.0 {
use-host-decl-names on;
range 192.168.1.26 192.168.1.30;
option routers 192.168.1.1;
option broadcast-address 192.168.1.255;
option root-path "192.168.1.1:/home/tftpboot/";
next-server 192.168.1.1;
if not exists gpxe.bus-id {
filename "gpxe/undionly.kpxe";
} else {
# filename "http://192.168.1.1/boot/boot.php";
filename "gpxe/menu.gpxe";
}
server-name "lapdance";
server-identifier 192.168.1.1;
}
I will not be going into details here. This config file is using the "conventional TFTP" configuration with /home/tftpboot as it's relative root directory fetching all the files from there.
The subnet definition will hand out IPs for our clients from defined range.
PXE booting your client it will first download the gPXE binary which will "take over" from there and download it's own configuration file.
The if not exists gpxe.bus-id option is used to first hand out the undionly.kpxe file to PXE and then the menu.gpxe configuration file to gPXE.
Note: Notice the filename "http://192.168.1.1/boot/boot.php"; option. It allows you to fetch config from a HTTP server.
It can be a dymamically created config or a simple txt file as menu.gpxe but downloaded over HTTP. For more info read http://etherboot.org/wiki/appnotes/authmenus
How to setup the TFTP server
The TFTP server will run as inetd service. Therefor we have to edit /etc/inetd.conf so it looks like this:
tftp dgram udp wait nobody /usr/sbin/tcpd /usr/sbin/in.tftpd /home/tftpboot
How to setup gPXE
Create directory for our files:
/home/tftpboot/gpxe
And create there a text file called menu.gpxe looking as follows:
#!gpxe chain menu.c32 menu.cfg
This file is going to chain load menu.c32 and our menu config file. You can replace menu.c32 with vesamenu.c32 for a more fancy boot window.
As mentioned above, to be able to create a boot menu for gPXE we will need either menu.c32 or vesamenu.c32 file which are distributed with SysLinux.
To obtain one of the files download tarball of SysLinux: http://www.kernel.org/pub/linux/utils/boot/syslinux/3.xx/syslinux-3.86.tar.gz
Unpack it and go to the menu directory:
syslinux-3.86/com32/menu/
There you will find two files, menu.c32 and vesamenu.c32. The first one can be used to create simple CLI menus and the last one alows to create more "fancy" graphical menus.
The menu.c32 works well over serial cable and we will use it in this HowTo.
Copy syslinux-3.86/com32/menu/menu.c32 and gpxe-1.0.1/src/bin/undionly.kpx to /home/tftpboot/gpxe
You can also copy syslinux-3.86/com32/mboot/mboot.c32 to /home/tftpboot/gpxe as this file is used to netboot i.e. FreeBSD and NetBSD.
Now create a config file for our boot menu and call it menu.cfg (still in /home/tftpboot/gpxe directory).
It will look like this:
PROMPT 0
ALLOWOPTIONS 0
MENU ROWS 6
MENU TITLE PLEASE CHOSE A SYSTEM TO BOOT
LABEL -
MENU LABEL NETBOOT
MENU DISABLE
LABEL SuSe
MENU LABEL ^1 SUSE
MENU INDENT 1
KERNEL vmlinuz-suse
APPEND ro root=/dev/hda1 initrd=initrd-suse.img
MENU SEPARATOR
LABEL -
MENU LABEL DEBIAN
MENU DISABLE
LABEL DEBIAN
MENU LABEL ^1 DEBIAN
MENU INDENT 1
KERNEL vmlinuz-debian
APPEND ro root=/dev/hda1 initrd=initrd-debian.img
LABEL UBUNTU
MENU LABEL ^2 UBUNTU
MENU INDENT 1
KERNEL vmlinuz-ubuntu
APPEND ro root=/dev/hda1 initrd=initrd-ubuntu.img
The options are described here: http://syslinux.zytor.com/wiki/index.php/SYSLINUX
How to create bootable Linux images is out of scope of this HowTo.
Starting services
Now we need to start the TFTP and DHCP services
To start the inetd server:
# /etc/init.d/openbsd-inetd start
The DHCP server:
#/etc/init.d/dhcp3-server start
Testing
Boot your computer using PXE network booting.
If all went you should be able to see message about DHCP address and then gPXE will get downloaded and show a menu on your screen.
Screenshots
And some screenshots. Loading of gPXE with VirtualBox :
Initial boot with PXE/gPXE:
An example of gPXE menu:
Links
http://etherboot.org/wiki/appnotes
http://syslinux.zytor.com/wiki/index.php/Comboot/menu.c32
http://syslinux.zytor.com/wiki/index.php/SYSLINUX
<comments />
And that is quite simple. 1. Grab latest tarball from http://kernel.org/pub/software/utils/boot/gpxe/ and unpack it. 2. Go to src directory in the tarball and create a text file here (for example, netboot.gpxe) with such contents:
- !gpxe
dhcp net0 initrd http://server.org/path/to/initramfs.gz kernel http://server.org/path/to/kernel/bzImage boot bzImage (Of course, replace the address paths of the initrd and kernel to the valid ones) 3. Compile the gPXE USB image using the command: make EMBEDDED_IMAGE=netboot.gpxe bin/gpxe.usb 4. You have the bootable harddisk image in bin/gpxe.usb file now, so write the image to the USB stick via dd or other tool, or create a bootloader entry to it, or just boot a virtual machine from this harddisk image to check if the boot is working. 5. Now, if you have a working wired Internet connection and your provider uses DHCP to give you IP address (and you're using no other mechanisms for Internet access such as PPTP, L2TP or PPPoE), you will be able to boot the specified kernel and initramfs via HTTP successfully.
For the current gPXE version (1.0.1) the resulting gpxe.usb image is just 336 kilobytes. I think this is the ultimate tool for truly cloud computing.[newline]dhcp net0 [newline]initrd http://server.org/path/to/initramfs.gz [newline]kernel http://server.org/path/to/kernel/bzImage [newline]boot bzImage
In our setup, I need to install OSes rather than boot the OSes thru gPXE.
Can you pls tel me what I need to change for OS installs?
