Install Linux Without a USB Drive: PXE Network Boot for Production Deployments

Picture a rack of servers in a data center—half have no video output, let alone USB ports. Repurposing lab desktops or automating VMs at scale? Reaching for USB sticks quickly becomes obsolete. PXE (Preboot Execution Environment) network boot offers a robust, repeatable, and zero-touch installation path for Linux, minimizing physical intervention and maximizing flexibility.

Context: Why PXE Instead of USB?

Physical restrictions: Bare-metal cages, blade servers, thin clients.
Scale: 20+ machines? Manual imaging does not scale.
Automated fleet management: Standardizing installations with configuration management (Kickstart, Preseed, or cloud-init).

PXE leverages DHCP and TFTP to deliver bootloaders and OS kernels over the wire. It’s not new—but in 2024, it’s still faster than hunting for a trustworthy flash drive (and avoids the “/dev/sdb was missing” headache).

Minimum Requirements

DHCP server (can be an existing router but granular control preferred)
TFTP server (often tftpd-hpa or dnsmasq)
Linux ISO image (verify integrity first: sha256sum ubuntu-22.04.4-live-server-amd64.iso)
PXELINUX (from syslinux package)
Target machines with PXE/network boot enabled in BIOS/UEFI
Optional: NFS/HTTP server if network-based install media is needed

PXE Boot Sequence (High-level)

      ┌───────────────┐              ┌──────────────┐
      │   PXE Client │──────────────▶│ DHCP Server  │
      └──────┬───────┘  DHCPDISCOVER └──────┬──────┘
             │       ◀───────────────       │
             │       DHCPOFFER (PXE opts)   │
      ┌──────▼───────┐              ┌──────▼──────┐
      │   PXE Client │──────────────▶│ TFTP Server │
      └──────┬───────┘  TFTP GET     └─────────────┘
             │
     [Loads pxelinux.0 → kernel/initrd → installer]

Step 1: Install and Configure TFTP

Debian/Ubuntu 22.04+:

sudo apt update
sudo apt install tftpd-hpa

Edit /etc/default/tftpd-hpa:

TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/srv/tftp"
TFTP_ADDRESS="0.0.0.0:69"
TFTP_OPTIONS="--secure"

sudo mkdir -p /srv/tftp
sudo chown -R tftp:tftp /srv/tftp
sudo systemctl enable tftpd-hpa --now

Note: SELinux/AppArmor can silently block file access on some distros—check logs if transfers fail.

Step 2: Extract PXE Boot Components from ISO

Mount ISO and copy required files:

sudo mkdir -p /mnt/iso
sudo mount -o loop ubuntu-22.04.4-live-server-amd64.iso /mnt/iso
sudo cp /mnt/iso/casper/vmlinuz /srv/tftp/
sudo cp /mnt/iso/casper/initrd /srv/tftp/

PXELINUX Loader:

sudo apt install syslinux-common
sudo cp /usr/lib/PXELINUX/pxelinux.0 /srv/tftp/
sudo mkdir -p /srv/tftp/pxelinux.cfg

Step 3: Configure DHCP for PXE

For a dedicated ISC DHCP server:

# /etc/dhcp/dhcpd.conf example
subnet 10.0.0.0 netmask 255.255.255.0 {
    range 10.0.0.100 10.0.0.200;
    option routers 10.0.0.1;
    filename "pxelinux.0";
    next-server 10.0.0.2; # TFTP server IP
}

Restart DHCP service. Known issue: Some routers truncate filename strings; enterprise networks often block TFTP.

Step 4: Configure PXELINUX

Create /srv/tftp/pxelinux.cfg/default:

DEFAULT linux
LABEL linux
    KERNEL vmlinuz
    APPEND initrd=initrd ip=dhcp --- quiet

Tip: Add auto=true priority=critical url=http://10.0.0.2/preseed.cfg for automated installs with Preseed. For UEFI-based systems, supplement with grubnetx64.efi and adjust DHCP accordingly.

Step 5: Serve Installation Media (NFS/HTTP/FTP)

If using NFS (common for large ISOs):

sudo apt install nfs-kernel-server
sudo mkdir -p /srv/install/ubuntu
sudo rsync -a /mnt/iso/ /srv/install/ubuntu/
echo "/srv/install/ubuntu *(ro,sync,no_subtree_check,no_root_squash)" | sudo tee -a /etc/exports
sudo exportfs -ra
sudo systemctl restart nfs-kernel-server

Firewall adjustment required: NFS uses 2049/tcp (and sometimes rpcbind/111).

Step 6: Network Boot Target Machines

Set boot order: “Network (PXE)” before local disk. Common vendor quirks: some BIOS/UEFI firmware disables IPv4 PXE by default.

Expected client output if successful:

Trying to load: pxelinux.0
Loading vmlinuz...........
Loading initrd............

Troubleshooting:

TFTP errors usually mean misconfigured firewall, owner, or SELinux label.
PXE client drops to shell? Check kernel/initrd filenames for typos.

Non-obvious Details & Tips

DHCP/TFTP on same host simplifies things; DNSMasq can serve both.
Automated installation: Serve Preseed/Kickstart configs over HTTP for true unattended installs.
For UEFI-only hardware: Legacy PXELINUX does not support Secure Boot; use GRUB2 EFI network boot binaries.
VMware/VirtualBox PXE requires “Bridged” mode to reach external PXE services.

Example: Ubuntu 22.04 Automated PXE Install

Minimal pxelinux.cfg/default:

DEFAULT auto
LABEL auto
    KERNEL vmlinuz
    APPEND initrd=initrd auto=true priority=critical url=http://10.0.0.2/preseed/ubuntu.cfg netcfg/choose_interface=auto ---

/srv/www/preseed/ubuntu.cfg (served via Apache/nginx):

d-i passwd/root-password password secret
d-i passwd/root-password-again password secret
d-i clock-setup/utc boolean true
d-i partman-auto/method string regular
d-i partman-partitioning/choose_recipe select atomic

This auto-partitions and installs without manual input.

Bottom Line

PXE boot makes Linux deployments repeatable, hands-off, and fast—no USB media, just reliable network delivery. For infra at scale, or even a home lab, the initial investment in setup is quickly offset by saved hours later.

Trade-offs? Network dependencies and minor security risk if PXE is left exposed. For full automation, combine with Preseed or Kickstart—manual intervention is optional.

Practical tip: Document your PXE environment. When it breaks (it will, eventually), logs and config history are your only friends.

For distro-specific tweaks (e.g., RHEL, Debian, custom kernel args), review vendor documentation. Edge cases—multicast boot, large-scale cloud PXE—require deeper engineering.

Questions or unusual edge cases? Drop them below for practical debugging advice.

How To Install Linux Without Usb