TFTP server manage netboot kernels

TFTP configuration

TFTP can manage different configurations, up to 1 per host!

This is how a ThinClient (= netBoot client) will retrieve its configuration:

As you can see you have 3 possibilities:

1. MAC @ filter. Configuration file name must be:

• Start with ARP type '01-'
• all in lower case hexadecimal
• dash '-' separators instead of ';'

for example a MAC @ 88:99:AA:BB:CC:DD would search for the filename 01-88-99-aa-bb-cc-dd.

2. IP @ filter. Configuration file name must be:

• host IP / network address in hexadecimal
• all in upper case

e.g. 192.0.2.91 -> C000025B

3. Default configuration

To learn more about all the available option, check out http://www.syslinux.org/wiki/index.php/PXELINUX.

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Create Boot menu and Kernel setup

The first thing to do is to setup a booting kernel. To do so we'll use the "syslinux" files.

Reminder If your client(s) will use some smart-cards driver then you MUST install these drivers on the on the NFS server + reboot the server ; before going through the following steps. See Drivers#Smart-card_drivers

Create NetBoot menu | defaults

Now, we have to specify which kernel to use and which distributions are available for NetBoot.

Create the default configuration file:

vim /tftpboot/pxelinux.cfg/default

Put the following:

# Debian 7.x
LABEL wheezy
    kernel images/wheezy/vmlinuz
    initrd images/wheezy/initrd.img

# Ubuntu 14.04
LABEL trusty
    kernel images/trusty/vmlinuz
    initrd images/trusty/initrd.img


# Prompt user for selection
PROMPT 1
# No timeout
TIMEOUT 0

• Each LABEL is a specific configuration that will displayed on the NetBoot menu.
• PROMPT 0 = enable user prompt so you can choose the configuration
• TIMEOUT 0 = timeout (in seconds) before the default option is chosen. 0 == no timeout

Note that I used a reference to "trusty/", that's a folder I need to create later on.

Init Kernel files

Create directories

Create the target kernel folders. You should create 1 folder for each distribution you'd like to provide in NetBoot.

# Debian 7.x
mkdir -p /tftpboot/images/wheezy

# Ubuntu 14.04
mkdir -p /tftpboot/images/trusty

Prepare initramfs to boot over NFS

This step must to be run on the machine that has the kernel you are going to serve to your clients.

>>> In our case it has to be run on the TFTP server

Copy initramfs settings for PXE boot

cp -r /etc/initramfs-tools /etc/initramfs-pxe

Adjust PXE boot configuration

cd /etc/initramfs-pxe/
vim /etc/initramfs-pxe/initramfs.conf

Add / adjust the following options:

BOOT=nfs
MODULE=netboot

Copy and prepare kernel

You have to copy your current kernel files to the boot folder:

# Debian 7.x
cp /boot/vmlinuz-`uname -r` /tftpboot/images/wheezy/vmlinuz
cp /boot/initrd.img-`uname -r` /tftpboot/images/wheezy/initrd.img

# Ubuntu 14.04
cp /boot/vmlinuz-`uname -r` /tftpboot/images/trusty/vmlinuz
cp /boot/initrd.img-`uname -r` /tftpboot/images/trusty/initrd.img

Enable NFS boot on target kernel:

mkinitramfs -d /etc/initramfs-pxe -o /tftpboot/images/trusty/initrd.img

Adjust rights:

chmod -R 755 /tftpboot/images/

Notes:

• Do NOT use some symlink for "vmlinuz" and "initrd.img" !! It won't work.

• If you don't want to use `uname -r` [current kernel version and architecture] then adjust the values to target kernel number + architecture

• You have to run mkinitramfs for each kernel you'll provide

• Don't forget to adjust the rights to 755 for every distribution