[lug] pxe boot and routing

Quentin Hartman qhartman at gmail.com
Wed Jan 13 10:06:22 MST 2016


Hard to say w/o more details from your DNS (bind?) config. On the private
network can you hit port 53 on server? That would at least tell you that
the DNS server is listening where you expect it to, just not responding.
Also, what distro? You might have an out-of-the-box firewall that is
busting your chops.

QH

On Wed, Jan 13, 2016 at 9:57 AM, Michael J. Hammel <
mjhammel at graphics-muse.org> wrote:

> I had to set up a PXE boot process for automated installs at work.  I
> know about Cobbler, et al but this was something much simpler.  They
> just wanted an easy way to bring up a Linux box for Windows people. And
> I'm doing this without getting corp IT involved, so I'm hiding it on a
> private network just for our development group.
>
> Anyway, I have a system setup up with DHCP and a TFTP server.  The host
> system PXE boots a minimal rootfs built with Buildroot and runs an init
> script (S99platform) that downloads a task-specific script based on the
> PXE configuration for that host.  The task-specific script (in this
> case) partitions the disk on the host, downloads a bootfs and rootfs
> and unpacks them on the appropriate partitions.
>
> The last step is to install legacy grub on the MBR.  I do this by
> chrooting into the rootfs I just installed and running grub-install.
> During testing I discovered that the rootfs.tar.gz I created didn't
> have the legacy grub to do this, so I added an apt-get install to get
> it from within the chroot.
>
> Problem is that the PXE boot is on a private network, not the corp
> network.  The host can see the TFTP server, no problem.  It can ping
> corp addresses.  It can't use DNS.  Without that, apt-get doesn't work.
>
> The TFTP server has the private network set as an IP address manually
> added to an existing interfaces, as in:
>
>    ifconfig eth0:1 <ip address> ...
>
> The TFTP server is also the DNS server.  So while I can ping from the
> host to the TFTP server (both eth0 and eth0:1) I can't get the DNS
> server to respond to requests to the host on the private network.
>
> The DNS config looks correct ("any" instead of specific IPs/networks in
> all the right places).  Any thoughts on what I can do to get DNS
> working in this scenario?  I have a work around for this particularly
> problem (put the needed tools in the source rootfs.tar.gz so I can
> avoid having to do it during install) but I'd like to know how to fix
> the routing/DNS problem.
> --
> Michael J. Hammel <mjhammel at graphics-muse.org>
>
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