Chapter 6. Preparing a UEFI HTTP installation source

As an administrator of a server on a local network, you can configure an HTTP server to enable HTTP boot and network installation for other systems on your network.

6.1. Network install overview

A network installation allows you to install Red Hat Enterprise Linux to a system that has access to an installation server. At a minimum, two systems are required for a network installation:

Server: A system running a DHCP server, an HTTP, HTTPS, FTP, or NFS server, and in the PXE boot case, a TFTP server. Although each server can run on a different physical system, the procedures in this section assume a single system is running all servers.
Client: The system to which you are installing Red Hat Enterprise Linux. Once installation starts, the client queries the DHCP server, receives the boot files from the HTTP or TFTP server, and downloads the installation image from the HTTP, HTTPS, FTP or NFS server. Unlike other installation methods, the client does not require any physical boot media for the installation to start.

To boot a client from the network, enable network boot in the firmware or in a quick boot menu on the client. On some hardware, the option to boot from a network might be disabled, or not available.

The workflow steps to prepare to install Red Hat Enterprise Linux from a network using HTTP or PXE are as follows:

Procedure

Export the installation ISO image or the installation tree to an NFS, HTTPS, HTTP, or FTP server.
Configure the HTTP or TFTP server and DHCP server, and start the HTTP or TFTP service on the server.
Boot the client and start the installation.

You can choose between the following network boot protocols:

HTTP: Red Hat recommends using HTTP boot if your client UEFI supports it. HTTP boot is usually more reliable.
PXE (TFTP): PXE boot is more widely supported by client systems, but sending the boot files over this protocol might be slow and result in timeout failures.

Additional resources

6.2. Configuring the DHCPv4 server for network boot

Enable the DHCP version 4 (DHCPv4) service on your server, so that it can provide network boot functionality.

Prerequisites

You are preparing network installation over the IPv4 protocol.
For IPv6, see Configuring the DHCPv6 server for network boot instead.
Find the network addresses of the server.
In the following examples, the server has a network card with this configuration:
IPv4 address
192.168.124.2/24
IPv4 gateway
192.168.124.1

Procedure

Install the DHCP server:
```
yum install dhcp-server
```

Set up a DHCPv4 server. Enter the following configuration in the /etc/dhcp/dhcpd.conf file. Replace the addresses to match your network card.

option architecture-type code 93 = unsigned integer 16;

subnet 192.168.124.0 netmask 255.255.255.0 {
  option routers 192.168.124.1;
  option domain-name-servers 192.168.124.1;
  range 192.168.124.100 192.168.124.200;
  class "pxeclients" {
    match if substring (option vendor-class-identifier, 0, 9) = "PXEClient";
    next-server 192.168.124.2;
          if option architecture-type = 00:07 {
            filename "redhat/EFI/BOOT/BOOTX64.EFI";
          }
          else {
            filename "pxelinux/pxelinux.0";
          }
  }
  class "httpclients" {
    match if substring (option vendor-class-identifier, 0, 10) = "HTTPClient";
    option vendor-class-identifier "HTTPClient";
    filename "http://192.168.124.2/redhat/EFI/BOOT/BOOTX64.EFI";
  }
}

Start the DHCPv4 service:
```
# systemctl enable --now dhcpd
```

6.3. Configuring the DHCPv6 server for network boot

Enable the DHCP version 6 (DHCPv4) service on your server, so that it can provide network boot functionality.

Prerequisites

You are preparing network installation over the IPv6 protocol.
For IPv4, see Configuring the DHCPv4 server for network boot instead.
Find the network addresses of the server.
In the following examples, the server has a network card with this configuration:
IPv6 address
fd33:eb1b:9b36::2/64
IPv6 gateway
fd33:eb1b:9b36::1

Procedure

Install the DHCP server:
```
yum install dhcp-server
```

Set up a DHCPv6 server. Enter the following configuration in the /etc/dhcp/dhcpd6.conf file. Replace the addresses to match your network card.

option dhcp6.bootfile-url code 59 = string;
option dhcp6.vendor-class code 16 = {integer 32, integer 16, string};

subnet6 fd33:eb1b:9b36::/64 {
        range6 fd33:eb1b:9b36::64 fd33:eb1b:9b36::c8;

        class "PXEClient" {
                match substring (option dhcp6.vendor-class, 6, 9);
        }

        subclass "PXEClient" "PXEClient" {
                option dhcp6.bootfile-url "tftp://[fd33:eb1b:9b36::2]/redhat/EFI/BOOT/BOOTX64.EFI";
        }

        class "HTTPClient" {
                match substring (option dhcp6.vendor-class, 6, 10);
        }

        subclass "HTTPClient" "HTTPClient" {
                option dhcp6.bootfile-url "http://[fd33:eb1b:9b36::2]/redhat/EFI/BOOT/BOOTX64.EFI";
                option dhcp6.vendor-class 0 10 "HTTPClient";
        }
}

Start the DHCPv6 service:
```
# systemctl enable --now dhcpd6
```
If DHCPv6 packets are dropped by the RP filter in the firewall, check its log. If the log contains the rpfilter_DROP entry, disable the filter using the following configuration in the /etc/firewalld/firewalld.conf file:
```
IPv6_rpfilter=no
```

6.4. Configuring the HTTP server for HTTP boot

You must install and enable the httpd service on your server so that the server can provide HTTP boot resources on your network.

Prerequisites

Find the network addresses of the server.
In the following examples, the server has a network card with the 192.168.124.2 IPv4 address.

Procedure

Install the HTTP server:
```
# yum install httpd
```
Create the /var/www/html/redhat/ directory:
```
# mkdir -p /var/www/html/redhat/
```
Download the RHEL DVD ISO file. See All Red Hat Enterprise Linux Downloads.
Create a mount point for the ISO file:
```
# mkdir -p /var/www/html/redhat/iso/
```

Mount the ISO file:

# mount -o loop,ro -t iso9660 path-to-RHEL-DVD.iso /var/www/html/redhat/iso

Copy the boot loader, kernel, and initramfs from the mounted ISO file into your HTML directory:

# cp -r /var/www/html/redhat/iso/images /var/www/html/redhat/
# cp -r /var/www/html/redhat/iso/EFI /var/www/html/redhat/

Make the boot loader configuration editable:

# chmod 644 /var/www/html/redhat/EFI/BOOT/grub.cfg

Edit the /var/www/html/redhat/EFI/BOOT/grub.cfg file and replace its content with the following:

set default="1"

function load_video {
  insmod efi_gop
  insmod efi_uga
  insmod video_bochs
  insmod video_cirrus
  insmod all_video
}

load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2

set timeout=60
# END /etc/grub.d/00_header #

search --no-floppy --set=root -l 'RHEL-9-3-0-BaseOS-x86_64'

# BEGIN /etc/grub.d/10_linux #
menuentry 'Install Red Hat Enterprise Linux 9.3' --class fedora --class gnu-linux --class gnu --class os {
    linuxefi ../../images/pxeboot/vmlinuz inst.repo=http://192.168.124.2/redhat/iso quiet
    initrdefi ../../images/pxeboot/initrd.img
}
menuentry 'Test this media & install Red Hat Enterprise Linux 9.3' --class fedora --class gnu-linux --class gnu --class os {
    linuxefi ../../images/pxeboot/vmlinuz inst.repo=http://192.168.124.2/redhat/iso quiet
    initrdefi ../../images/pxeboot/initrd.img
}
submenu 'Troubleshooting -->' {
    menuentry 'Install Red Hat Enterprise Linux 9.3 in text mode' --class fedora --class gnu-linux --class gnu --class os {
   	 linuxefi ../../images/pxeboot/vmlinuz inst.repo=http://192.168.124.2/redhat/iso inst.text quiet
   	 initrdefi ../../images/pxeboot/initrd.img
    }
    menuentry 'Rescue a Red Hat Enterprise Linux system' --class fedora --class gnu-linux --class gnu --class os {
   	 linuxefi ../../images/pxeboot/vmlinuz inst.repo=http://192.168.124.2/redhat/iso inst.rescue quiet
   	 initrdefi ../../images/pxeboot/initrd.img
    }
}

In this file, replace the following strings:

RHEL-9-3-0-BaseOS-x86_64 and Red Hat Enterprise Linux 9.3: Edit the version number to match the version of RHEL that you downloaded.
192.168.124.2: Replace with the IP address to your server.

Make the EFI boot file executable:

# chmod 755 /var/www/html/redhat/EFI/BOOT/BOOTX64.EFI

Open ports in the firewall to allow HTTP (80), DHCP (67, 68) and DHCPv6 (546, 547) traffic:
```
# firewall-cmd --zone public \
               --add-port={80/tcp,67/udp,68/udp,546/udp,547/udp}
```
This command enables temporary access until the next server reboot.
Optional: To enable permanent access, add the --permanent option to the command.
Reload firewall rules:
```
# firewall-cmd --reload
```
Start the HTTP server:
```
# systemctl enable --now httpd
```
Make the html directory and its content readable and executable:
```
# chmod -cR u=rwX,g=rX,o=rX /var/www/html
```
Restore the SELinux context of the html directory:
```
# restorecon -FvvR /var/www/html
```

Chapter 6. Preparing a UEFI HTTP installation source

6.1. Network install overview

6.2. Configuring the DHCPv4 server for network boot

6.3. Configuring the DHCPv6 server for network boot

6.4. Configuring the HTTP server for HTTP boot

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