Debian install from PXE

Our new server has PXE support to boot from scratch from the network, so
I decided to try to install Debian with it. I didn’t just do this for fun
(it wasn’t much fun): the new server had a gigabit ethernet card
that wasn’t supported by my usual Debian network boot CD.

I started with syslinux, as it
includes pxelinux and lots of helpful documentation. I choose
atftpd for my TFTP server since its author (Jean-Pierre Lefebvre) wrote
it to use with pxelinux.

I wanted to use udhcpd as the DHCP server because I liked
udhcpc, but the client machine didn’t seem to like it: it seems that PXE
might use some non-standard DHCP features. So, I used ISC dhcpd3, and it
worked. But that was another surprise: it worked even though the DHCP port was being
filtered by the local firewall! I assume this is becuase dhcpd3 uses the packet
protocol to bypass the normal protocol stack. That’s also why it requires
packet socket and socket filtering to be compiled into the kernel. I don’t like
it, but it works.