[CentOS] force a PXE boot

Steve Huff
2006-07-26T15:56:49Z

On Jul 26, 2006, at 11:35 AM, Tom Brown wrote:

> I could be going mad but it there a way to force a PXE boot on next
> reboot? ie tell the box that next time it reboots try a PXE boot
> first?

that depends on the BIOS of your system; it's not an issue that
CentOS can (easily) deal with.  some Dell servers have a utility that
you can use to change BIOS settings from within the OS, but i can't
speak to how well it works.

here's how i solved a related problem when setting up a lab of
machines that would be PXE-booting to reinstall themselves without an
admin at the console:

1) in the BIOS, set the boot order to PXE,HD (you can put CD/floppy/
USB before HD if you want, but PXE must be first)
2) set up your TFTP server such that the default boot target boots
from the system's hard drive (use the "LOCALBOOT" option as
described
here: http://syslinux.zytor.com/faq.php)
3) created another PXELINUX configuration that performs a network
boot and give it a name that corresponds to either the machine's MAC
address or the machine's IP address (as described here: http://
syslinux.zytor.com/pxe.php#config)
4) if you're using the PXE boot to kickstart the machine, add a line
to the %post section of your ks.cfg that will ssh to the TFTP server
and move aside the PXELINUX config file with the machine's MAC/IP
address (you can make this process as simple or complicated as you need)

if you follow these steps, then the machine will PXE-boot when the
special config file is in place, kickstart itself, and then move the
special config file aside; when it next boots, the TFTP server won't
find the special config file, so it'll use the default config file,
which tells the machine to boot from the local hard drive.

does this make sense?

-steve

p.s. there are other ways of having the machine "phone home" to the
tftp server besides using ssh; one of my colleagues did it with a
little php script.  alternately, you could have a script running on
the TFTP server that watches the logfile for evidence of successful
PXE boots and uses that information to move aside the special config
file.


---
If this were played upon a stage now, I could condemn it as an
improbable fiction. - Fabian, Twelfth Night, III,v