PXE boot with Synology NAS and UDM router

In this post, I have documented the steps I followed to install RHEL 8 by booting from a PXE server over the network with a Kickstart file using Synology NAS as TFTP, HTTP server, and UDM as DHCP.

Install & Configure TFTP
Install & Configure HTTP server
Enable network boot on UDM
PXE Boot setup

Install and Configure TFTP

Trivial File Transfer Protocol (TFTP) is a simple file transfer protocol, generally used for transferring configurations or boot files when authentication is not required.

Synology NAS comes with TFTP file services

To configure TFTP

Go to Control Panel > File Services > Advanced

Select Enable TFTP Service
In the TFTP root folder field, specify which folder on the Synology NAS can be accessed by TFTP clients

Install and Configure HTTP server

We also need a service to host our image repository, we can use FTP or HTTP, or NFS to host our image repository. Synology NAS comes with web hosting features. In Web Station, we will create a port-based virtual host to host the contents of our image repository.

Install the following packages from the Synology package center

Web Station
Apache HTTP Server 2.4

Create a virtual host

Open Web Station and go to Web Service Portal > Select Create Service Portal

Select Virtual Host

In the virtual host wizard

Select Port-based with protocol as HTTP and enter port number 8080
Select the Document root directory which is the same PXE location as TFTP
Select Apache HTTP Server as the back-end server
Click Create to save settings

We need to enable simple directory browsing on the virtual host we just create to access the contents of images and configuration files to perform PXE Boot.

In the Document root directory create a file named .htaccess with the following content

Options +Indexes

Navigate to IP:8080 and you should see a similar screen with files in the folder

PXE Boot setup

Prepare Installation Repository

Download the ISO image file of the full installation DVD
Create a directory named images/rhel/8.6 under root directory of TFTP/HTTP server
Mount the ISO image
Copy all the files from the ISO to the previously created directory on TFTP/HTTP server. You will need around 10GB of storage to copy all the files from the ISO to the local directory.

mount rhel-8.6-x86_64-dvd.iso /mnt
scp -pr /mnt/* nas-user@nas-address:/media/PXE/images/rhel/8.6

To perform UEFI PXE Boot installation, we will need the following PXE boot files

grubx64.efi provided by grub2-efi-x64 rpm
shimx64.efi provided by shim-x64 rpm
BOOTX64.EFI provided by shim-x64 rpm

cp -pr /mnt/BaseOS/Packages/grub2-efi-x64-2.02-81.el8.x86_64.rpm /tmp
cp -pr /mnt/BaseOS/Packages/shim-x64-15-11.el8.x86_64.rpm /tmp/

Extract the packages

cd /tmp
rpm2cpio shim-x64-15-11.el8.x86_64.rpm | cpio -dimv
rpm2cpio grub2-efi-x64-2.02-81.el8.x86_64.rpm | cpio -dimv

Copy the EFI boot images from the /tmp directory to the PXE root directory

scp /tmp/boot/efi/EFI/BOOT/BOOTX64.EFI nas-user@nas-address:/media/PXE
scp /tmp/boot/efi/EFI/centos/shimx64.efi nas-user@nas-address:/media/PXE
scp /tmp/boot/efi/EFI/centos/grubx64.efi nas-user@nas-address:/media/PXE

Add a configuration file named grub.cfg to the TFTP/HTTP root directory. We need initrd and vmlinuz files to load the Operating System until the hard disk and other interfaces are detected. In the grub.cfg take a note of linuxefi and initrdefi I am referring to TFTP/HTTP image directory location.

set timeout=30
menuentry 'Install RHEL 8.6 on T7910' {
    linuxefi images/rhel/8.6/images/pxeboot/vmlinuz inst.stage2=http://192.168.100.160:8080/images/rhel/8.6 quiet
    initrdefi images/rhel/8.6/images/pxeboot/initrd.img
}

Prepare kickstart file

Next, we will create our kickstart file to have an unattended automated installation. I have used the Kickstart Configuration Tool available at https://access.redhat.com/labs/kickstartconfig/ in the Red Hat Customer Portal Labs. This tool will walk you through basic configuration and allows you to download the resulting Kickstart file.

Create a new directory named ks under the root directory of TFTP/HTTP server to store the kickstart file for the UEFI PXE Boot purpose
Copy the downloaded kickstart file into the previously created location

scp kickstart.cfg nas-user@nas-address:/media/PXE/ks

Update the grub.cfg to use the kickstart file during installation. The inst.ks= boot option specifies the location of the kickstart location

The final grub.cfg will look like this:

set timeout=30
menuentry 'Install RHEL 8.6 on T7910' {
    linuxefi images/rhel/8.6/images/pxeboot/vmlinuz inst.ks=http://192.168.100.160:8080/ks/rhel8-t7910.cfg inst.stage2=http://192.168.100.160:8080/images/rhel/8.6 quiet
    initrdefi images/rhel/8.6/images/pxeboot/initrd.img
}

Perform PXE boot

We are all set up to perform UEFI PXE Boot. The shortcut button to boot over the network may vary for different hardware but in most cases we are expected to press F12 to boot from the network:

If your UEFI PXE Boot Server configuration is proper, then the TFTP files should get successfully