Tuesday, January 22, 2008

PXE, DHCP, and no DHCP

I just read about Installing Linux with no CD and a comment asks about PXE without DHCP.

From other comments I've read, and my own personal experience, there just isn't a way to do PXE without DHCP. PXE is built into the network card's interface. It's pretty much as hard coded as the MAC Address (at least, until you boot your OS). At the risk of oversimplification... OK, I'm risking it... the basic operation of PXE goes like this:

  1. Boot
  2. Boot order...Network
  3. PXE ... seek out BOOTP/DHCP broadcast offers
  4. get an IP address
  5. find out who handles tftp (perhaps from the DHCP server itself)
  6. boot from the tftp server

No, seriously, read the link above.

In any case, one might cringe and say, "I can't have another DHCP server on my network!" Well, if you're actually attempting what is described in the above link, the thought in my head is simply that you probably don't need to worry about that.

In essence, there are only a few barriers, most can be summed up by creating a DHCP server in your zone.

The barriers (as I understand them):

  • You have a router that doesn't pass DHCP
  • You have an administrator who doesn't want another DHCP server on his LAN
  • You feel that DHCP has its own administrative nightmare

It's ok. If you're already trying to install LINUX, chances are you probably are game enough to run your own DHCP server. But you don't have to do a big range. Just set it up with some settings like this:

host apxecomputer {
hardware ethernet 00:15:FF:FF:FF:FF;

The point *is* PXE install of Linux, isn't it?

OK, if not, an alternate bet in this day and age is to boot locally with a Live USB Distro. What? You can't afford $10 for a 2GB USB flash drive?

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