• 🪜 1. Install prerequisites
• 🧩 2. Find your PXE server IP and interface
• 🏗️ 3. Download and expose the Ubuntu Desktop ISO
• ⚙️ 4. Prepare TFTP root and signed EFI bootloaders
• 🧱 5. (Optional) Copy kernel & initrd from the ISO
• 📄 6. Configure GRUB menu
• 📡 7. Configure dnsmasq DHCP/TFTP
• 🚀 8. Boot the client PC
• 🌐 9. Fix networking after PXE boot
  • A) If PXE server is on Wi-Fi (and client has Wi-Fi)
  • B) If client is Ethernet-only
• 🧹 10. Cleanup PXE server when done
• ⚙️ 11. Disable Cloud-Init inside PXE-booted Ubuntu Desktop
• 🕒 Boot Performance (reference)
• ✅ Working Setup Summary
• 🧠 Notes & Troubleshooting
• 🏁 Example Successful Boot Sequence

This guide explains how to set up a minimal PXE environment to boot Ubuntu Desktop Live ISOs (24.04–25.10) entirely over HTTP, without NFS or IP forwarding.
It works using only dnsmasq (for DHCP+TFTP) and apache2 (for HTTP), and supports both Ethernet and Wi-Fi PXE servers.

✅ Tested on:

• Ubuntu 24.04, 25.04 and 25.10 Desktop & Server

• Both Wi-Fi (wlp0s20f3) and USB-C Ethernet (enx0…) as PXE servers;
  NOTE: You must use Ethernet as PXE client!

• Clients booting via UEFI Secure Boot

• NVIDIA RTX 4090 and other GPUs

§🪜 1. Install prerequisites

sudo apt update
sudo apt install dnsmasq apache2

§🧩 2. Find your PXE server IP and interface

List your active connections:

nmcli connection show
ip -4 a

Pick your serving interface:

• Wi-Fi → usually wlp0s20f3

• Wired → enx0… or eno1

Find its IP (e.g. 192.168.8.117) — this will be PXE_SERVER_IP in the config below.

§🏗️ 3. Download and expose the Ubuntu Desktop ISO

sudo mkdir -p /srv/http/ubuntu
cd /srv/http/ubuntu
wget https://releases.ubuntu.com/25.10/ubuntu-25.10-desktop-amd64.iso

Link for Apache (no restart required):

sudo ln -sv /srv/http/ubuntu /var/www/html/ubuntu

Confirm:

curl -I http://192.168.8.117/ubuntu/ubuntu-25.10-desktop-amd64.iso

§⚙️ 4. Prepare TFTP root and signed EFI bootloaders

sudo mkdir -p /srv/tftp/amd64/grub
cd ~/signed-efi
apt download shim-signed grub-efi-amd64-signed
dpkg-deb --fsys-tarfile shim-signed_*_amd64.deb | tar -x ./usr/lib/shim/shimx64.efi.signed.latest
dpkg-deb --fsys-tarfile grub-efi-amd64-signed_*_amd64.deb | tar -x ./usr/lib/grub/x86_64-efi-signed/grubnetx64.efi.signed

sudo cp usr/lib/shim/shimx64.efi.signed.latest /srv/tftp/amd64/shimx64.efi
sudo cp usr/lib/grub/x86_64-efi-signed/grubnetx64.efi.signed /srv/tftp/amd64/grubx64.efi

§🧱 5. (Optional) Copy kernel & initrd from the ISO

This makes booting faster since the kernel/initrd don’t need to be downloaded each time.

sudo mkdir -p /srv/tftp/amd64/desktop /mnt/iso
sudo mount -o loop /srv/http/ubuntu/ubuntu-25.10-desktop-amd64.iso /mnt/iso
sudo cp /mnt/iso/casper/{vmlinuz,initrd} /srv/tftp/amd64/desktop/
sudo umount /mnt/iso
sudo chmod 644 /srv/tftp/amd64/desktop/{vmlinuz,initrd}

§📄 6. Configure GRUB menu

/srv/tftp/amd64/grub/grub.cfg

set default=0
set timeout=5

# Use the Desktop ISO's kernel+initrd you copied to /srv/tftp/amd64/desktop/
# Pure-HTTP boot like 24.04 guides (no NFS)

menuentry "Ubuntu 25.10 Desktop (HTTP ISO, casper)" {
    linux /desktop/vmlinuz boot=casper rd.neednet=1 ip=dhcp url=http://192.168.8.117/ubuntu/ubuntu-25.10-desktop-amd64.iso live-media-path=/casper rootfs_name=minimal.squashfs maybe-ubiquity ---
    initrd /desktop/initrd
}

# Fallback: same idea but with the netboot kernel/initrd from the tarball
menuentry "Ubuntu 25.10 Desktop (HTTP ISO via netboot kernel)" {
    linux /linux boot=casper rd.neednet=1 ip=dhcp url=http://192.168.8.117/ubuntu/ubuntu-25.10-desktop-amd64.iso live-media-path=/casper rootfs_name=minimal.squashfs toram ---
    initrd /initrd
}

This works too:

# cat /srv/tftp/amd64/grub/grub.cfg
set default=0
set timeout=5

menuentry "Ubuntu 25.10 Desktop (HTTP ISO, casper)" {
    linux  /linux ip=dhcp boot=casper iso-url=http://192.168.8.129/ubuntu/ubuntu-25.10-desktop-amd64.iso toram ---
    initrd /initrd
}

(Replace 192.168.8.117 with your own PXE_SERVER_IP.)

§📡 7. Configure dnsmasq DHCP/TFTP

/etc/dnsmasq.d/pxe.conf

interface=wlp0s20f3             # or your Ethernet NIC
bind-interfaces
dhcp-range=192.168.8.100,192.168.8.150,12h
dhcp-boot=shimx64.efi,,192.168.8.117  # PXE server IP (next-server)
enable-tftp
tftp-root=/srv/tftp/amd64
tftp-no-blocksize                 # fixes buggy PXE stacks (no blksize OACK)
log-dhcp
dhcp-authoritative

Restart dnsmasq:

sudo systemctl restart dnsmasq

§🚀 8. Boot the client PC

1. Enter BIOS/UEFI → enable PXE Boot (UEFI IPv4).

2. Use F12/F8 to open boot menu → select PXE IPv4.

3. You should see:

   Fetching shimx64.efi
   Fetching grubx64.efi
   

   then the GRUB menu.

Select Ubuntu 25.10 Desktop (HTTP ISO, casper).
It will:

• Load kernel/initrd over TFTP (~7 min on Wi-Fi)

• Download ISO via HTTP (~2–3 min)

• Boot to the full Ubuntu Desktop Live session

§🌐 9. Fix networking after PXE boot

§A) If PXE server is on Wi-Fi (and client has Wi-Fi)

List your connections and prioritize Wi-Fi:

nmcli connection show
nmcli connection modify "Wi-Fi connection" ipv4.route-metric 100
nmcli connection down "Wi-Fi connection"
nmcli connection up "Wi-Fi connection"

This ensures Internet uses Wi-Fi, not the PXE Ethernet.

§B) If client is Ethernet-only

The PXE server’s DHCP assigns itself as the gateway (e.g. 192.168.8.117).
Remove that route so your router takes over (e.g. 192.168.8.1):

ip route
ip route delete default via 192.168.8.117 dev eno1
ip route show default
# should now show: default via 192.168.8.1 dev eno1

Now the installer has Internet connectivity while keeping PXE active.

§🧹 10. Cleanup PXE server when done

When you no longer need PXE boot:

sudo systemctl stop dnsmasq apache2
sudo apt remove dnsmasq apache2
sudo rm -rf /root/signed-efi /srv/tftp /srv/http /var/www/html/ubuntu /etc/dnsmasq.d/pxe.conf

§⚙️ 11. Disable Cloud-Init inside PXE-booted Ubuntu Desktop

When Ubuntu Desktop is booted via PXE, cloud-init may run automatically even though this is a local live session.
This can cause:

• Slow boot or stuck splash screen

• Network reconfiguration that breaks connectivity

• Extra cloud metadata lookups

To disable and remove it cleanly:

sudo systemctl disable --now cloud-config.service cloud-final.service cloud-init-local.service cloud-init-main.service cloud-init-network.service

sudo systemctl mask cloud-init.service
sudo systemctl reset-failed

sudo apt purge -y cloud-init
sudo rm -rf /etc/cloud /var/lib/cloud

Reboot once after this if you plan to keep using the PXE-booted session long-term.

§🕒 Boot Performance (reference)

§✅ Working Setup Summary

§🧠 Notes & Troubleshooting

• tftp-no-blocksize is essential for buggy UEFI PXE stacks that choke on OACK.

• If you get a black screen on NVIDIA GPUs → it’s loading; framebuffer may take ~1–2 min.

• To show progress messages, append to the linux line:

  splash=off debug=1 ---
  

• Apache access log (/var/log/apache2/access.log) confirms ISO download progress.

• PXE Desktop tip: disable cloud-init using Section 11 to prevent unwanted background reconfiguration.

§🏁 Example Successful Boot Sequence

Fetching shimx64.efi
Fetching grubx64.efi
GRUB menu appears
Loading vmlinuz and initrd…
Downloading ubuntu-25.10-desktop-amd64.iso via HTTP…
Loopback detected capacity change
Starting casper (live session)...
Welcome to Ubuntu 25.10 Live!