Master Bare Metal Provisioning with PXE and iPXE for Network Booting

Introduction

“Mastering PXE, iPXE, and network booting is essential for efficient bare metal provisioning. These technologies enable automated operating system deployments, streamlining the setup of physical servers without the need for physical media like USB drives or CDs. PXE and iPXE each play a vital role, with iPXE offering enhanced capabilities such as support for additional protocols, advanced scripting, and stronger security features. In this article, we’ll dive deep into how PXE and iPXE work, compare their features, and provide step-by-step guidance on setting them up for seamless, secure bare metal provisioning.”

What is Network Booting

Imagine a world where you don’t have to plug in a USB drive or mess with a CD just to start up your machine. That’s where network booting comes in. Also known as PXE (Preboot Execution Environment), it’s like the modern, easy way for your computer to boot up. Instead of depending on local storage—like hard drives or SSDs—it gets the operating system and important files straight from the network.

Here’s how it works: Your computer’s network interface card (NIC) starts the process by reaching out to a server over the network. That server has all the files needed to boot up your system. It’s like your computer calling home to pick up its keys before heading out on its morning drive.

Why is this such a big deal? Well, for companies that manage a lot of servers, especially in data centers, it’s a total game-changer. Imagine you’ve got a whole fleet of bare metal servers (the raw, physical machines that need an OS to do anything). Instead of manually installing the OS with USB drives or CDs on each machine, network booting lets IT teams deploy the OS to all of them in one go. It’s like having a giant remote to control all your machines.

This setup is about more than just saving time and being convenient—it’s about security, too. With network booting, you can make sure that the latest operating systems and patches are deployed consistently across all your servers. No more worrying that one machine might be out of date or insecure while the others are up to date. Everything is synced and running the latest version, all because of the network.

And here’s the best part: network booting gives you flexibility and scalability. If you need to update or reconfigure a bunch of servers, you can do it all remotely. No more physically touching each machine or messing with endless USB drives. By centralizing everything, you reduce downtime, avoid mistakes, and make deployments run much smoother—especially for big enterprise or cloud-based systems that need to stay agile.

So, whether it’s for a huge cloud environment or just managing lots of bare metal machines, network booting, especially with PXE and iPXE, is the unsung hero that keeps everything running like a well-oiled machine.

What is PXE?

What is PXE

Let’s imagine you’re in charge of setting up dozens—or maybe hundreds—of computers. You might think, “I’ll need a mountain of USB drives, CD-ROMs, and hours of manual work, right?” Well, here’s the thing: you don’t. Enter PXE, which stands for Preboot eXecution Environment. It’s like a secret weapon for managing and setting up systems without needing any physical media, like those time-consuming USB drives or CDs. Instead, PXE lets you load the operating system and all the necessary files directly over the network, skipping over the old-school local storage devices like hard drives or USB sticks.

Here’s how it works: imagine each computer in your network has a network interface card (NIC) that kicks off the boot process. Instead of the machine reaching out to a local hard drive for the operating system, it sends a request over the network to a PXE server. This server then sends over the necessary boot files. It’s like the computer is borrowing the software it needs, right from the network server, instead of lugging around a disk.

PXE was first introduced by Intel in 1998, and, over time, it’s become the go-to solution for deploying systems, especially in massive enterprise environments. Think of it as the magic sauce that data centers and large-scale server setups use to keep everything running smoothly. For IT teams managing hundreds of machines, PXE is a game-changer. Without it, they’d spend endless hours booting up servers one by one with physical media. Instead, with PXE, operating systems can be automatically deployed over the network, saving time and reducing human error.

Now, if you’re working with bare metal provisioning, PXE is a lifesaver. These are those “bare-bones” servers that need an operating system installed from scratch. PXE removes the need to physically configure each server with USBs or CDs, and instead, it lets IT teams remotely install or reconfigure operating systems. This means systems are deployed faster, and it ensures that every server gets the same configuration and updates, making the whole process less error-prone.

And when it comes to updates or maintenance? PXE makes it super simple. Instead of having to go into each server individually to install the latest patches or OS versions, you can just push the updates out over the network. This makes managing large infrastructures—especially in data centers or environments with bare metal servers—quicker, easier, and more secure. PXE centralizes the boot process, meaning IT teams no longer need to rely on USB drives or CDs. In short, it speeds up deployment and maintenance, leaving less room for mistakes and ensuring your machines are always up to date.

Intel PXE Overview

What is iPXE

Imagine you’re managing a massive network of servers—hundreds, maybe even thousands—spread out across a data center. Keeping everything in sync, installing new OS versions, or recovering from failures can feel like running a marathon, especially if you have to deal with each machine one at a time. But what if I told you there’s a way to make all that easier? That’s where iPXE comes in.

Now, iPXE isn’t just any network booting tool. It’s an open-source solution that takes the basic concept of PXE (Preboot Execution Environment) and makes it way more powerful. PXE, when it first came out, allowed computers to boot up over a network, but it was a bit limited. Then came iPXE, built on top of gPXE (which itself came from a project called Etherboot), turning it into something much more flexible and capable. iPXE supports more protocols, gives you better control, and overall makes traditional PXE seem like a beginner’s tool.

One of the coolest things about iPXE is how customizable it is. Developers can take it and tweak it into different formats, depending on their needs. Want to run it as an EFI application? Easy. Need it as a regular PXE image? No problem. This means you can use iPXE in pretty much any environment, no matter what hardware you’re working with. It can even be embedded directly into the network interface card (NIC) ROM—the little chip on the network card that handles the card’s operations. And here’s where it gets really interesting: it lets iPXE run directly from the network card itself, cutting out the need for external boot media like USB drives or CDs.

Now, you might be asking, why is the NIC ROM such a big deal? Well, think of it like the gatekeeper at the front door during the system boot-up. When you start a machine, it’s the NIC ROM that gets things going, allowing your computer to connect to the network before the operating system even loads. This is especially important when you’re setting up servers from scratch (bare metal provisioning) or recovering systems. iPXE’s ability to work directly in the NIC ROM means you can fully automate the boot process, with no need for physical boot devices. In large server environments, where automation and efficiency are key, this is a huge win.

But iPXE doesn’t stop there. It expands on PXE’s abilities by supporting modern protocols like HTTP, iSCSI, and FCoE. This means IT admins can take things even further, automating tasks like boot menus or dynamically fetching configuration files based on specific conditions. In today’s fast-paced IT world, where speed, security, and scalability matter most, iPXE makes sure that your network booting operations can keep up. Whether you’re deploying operating systems across hundreds of bare metal servers or recovering systems after a failure, iPXE makes it all possible—and a whole lot more efficient.

Core Components of PXE/iPXE Boot

Let me walk you through the world of PXE and iPXE, where network booting works behind the scenes, making life easier for administrators who manage fleets of servers. Both PXE and iPXE depend on a few key components to get everything up and running. These unsung heroes are what make network booting smooth, fast, and scalable. So, let’s dive into what makes it all tick.

First, we have Dynamic Host Configuration Protocol (DHCP), which acts as the network’s friendly traffic cop. When a device—like a server—wakes up and wants to boot, it needs an address and some directions. The DHCP server gives out IP addresses to these devices and tells them where to find the boot files. Without this, your server wouldn’t know where to go to grab what it needs to start up. In a PXE/iPXE setup, the DHCP server tells the client which boot server to reach out to. This keeps everything running smoothly and ensures the process goes in the right direction.

Next up, the Boot Loader takes center stage. You can think of it as the bouncer at the club, allowing the next part of the boot process to go ahead. For PXE systems, this might be

pxelinux.0

ipxe.lkrn

undionly.kpxe

But it’s not just about loading files. Boot Configuration Files are like the script for a play—they tell the system exactly what to do next. These files specify which operating system components to load, like the kernel and the initial RAM disk (

initramfs

Then, there are the OS Images / Installation Media, the building blocks of your new operating system. These files contain everything the OS needs to install itself onto bare metal hardware. For a Linux system, for example, this would include the kernel and

initrd.img

The PXE Server is the central hub of the operation, the server that holds all the important files—like configuration files and OS images—and makes them available to the clients. It works closely with the DHCP server to make sure the clients get the right boot loader and configuration details, guiding them towards system installation or recovery.

To get those files from the PXE server to the client, we rely on Trivial File Transfer Protocol (TFTP). It’s lightweight, simple, and efficient, making it perfect for transferring boot files during the network booting process. With TFTP in action, the boot loader and configuration files are downloaded smoothly to the client, keeping things quick and efficient.

Finally, we have the Network Boot Program (NBP), which is the client-side software that picks up where the DHCP server left off. After receiving the boot information, the NBP takes over and continues the boot process, making sure the right files are downloaded and everything goes as planned. It’s like the assistant that keeps things running smoothly, ensuring the operating system or installer loads without a hitch.

Put all these components together, and you’ve got a recipe for successful network booting with PXE and iPXE. Especially in environments where bare metal provisioning is needed, these technologies make the process faster, easier, and more efficient. Forget about inserting USB drives or CDs—by automating the boot process over the network, IT administrators can deploy and manage servers quickly, consistently, and securely. It’s the backbone of modern server management, especially in data centers and large-scale cloud environments where efficiency is everything.

What is PXE Boot?

How PXE Works

Imagine you’ve just powered up a server in a massive data center. It doesn’t have a local hard drive or USB to boot from, and you don’t have time to manually load operating systems onto each machine. This is where PXE (Preboot Execution Environment) steps in, acting like a behind-the-scenes pro, making sure everything runs smoothly without needing physical media like USB drives or CDs. Let’s walk through the process that makes network booting happen.

• Client PXE Request: Picture this: your machine is like an excited participant at a networking party, reaching out to the network. When the network-boot-configured server powers on, its Network Interface Card (NIC) firmware takes over, sending out a DHCP DISCOVER broadcast message. It’s like the server saying, “Hey, I’m here! I’m ready to boot, and I’m doing it over the network.” The NIC tells the network that it’s ready to begin the PXE boot process, asking for a little help with the directions to get started.
• DHCP Offer + PXE Information: The network’s DHCP server (or a proxy DHCP service) is like a friendly guide at the party. When the PXE request comes in, the DHCP server replies with a DHCP OFFER message. This is an important reply—it gives the client an IP address and points it to the PXE boot server , which holds the necessary boot files. The message also tells the client exactly which file it needs to continue. For example, it might say, “Here’s your IP address: 11.1.1.5, and here’s the boot file: pxelinux.0 from server 11.1.1.1.” This is like a map, telling the server exactly where to find its boot files.
• Client Downloads NBP via TFTP: Now, the client knows where to go. It uses the Trivial File Transfer Protocol (TFTP) to download the Network Bootstrap Program (NBP) from the PXE server. Think of TFTP as a quick and simple messenger—it does the job without any extra fluff. The NBP could be PXELINUX , an iPXE image, or even a boot file from Windows Deployment Services (WDS). This download starts the process of loading the operating system or recovery environment. Once the NBP is in place, the client is one step closer to booting up.
• Execute NBP: Now here’s where the magic happens: after the NBP is downloaded, control is passed to it. The PXE firmware hands over the baton to the NBP, and the boot process picks up speed. If PXELINUX is the NBP, it moves to the next step by fetching its configuration file over TFTP. This file might show a boot menu, or it could jump right into loading the Linux kernel using an initrd image. It’s like a conductor guiding the orchestra, making sure every piece is in place and ready to go.
• OS Load: Now, the real work begins. The NBP’s job is to load the operating system (OS) kernel into memory and get it ready for action. If needed, the NBP will also load the initial RAM disk (initrd) to support the OS kernel. Once these components are in place, the OS takes over, and the machine continues booting. It’s like opening a door to a new world—everything the server needs to get started is now ready. Once the OS kernel is loaded, the PXE boot process is complete, and the server continues booting into its full operating system environment.

This entire PXE process, from the moment the server sends that first DHCP message to when it starts running the OS, is what lets companies remotely deploy and reconfigure operating systems on machines without relying on physical media. In data centers or large-scale server farms, PXE is a game-changer. It simplifies deployment, management, and recovery, making IT teams more efficient and cutting down on human errors.

By using PXE (or iPXE), businesses can also streamline their bare metal provisioning—getting new servers up and running quickly, updating systems in bulk, and making sure every server is running the same setup. It’s a far cry from the old days of plugging USB sticks or CDs into each server. PXE’s flexibility makes it perfect for enterprises that need to manage hundreds or even thousands of servers with minimal downtime. With PXE, updating and configuring OS images across many machines is no longer a nightmare—it’s a smooth, reliable process that keeps everything running securely and efficiently.

PXE Booting Overview

How iPXE Improves on PXE

Picture this: you’ve been given the task of managing a huge network of servers—hundreds, maybe thousands—spread out across a data center. You know that keeping everything in sync, installing new OS versions, or recovering from failures can feel like running a marathon, especially when you have to deal with each machine individually. But what if I told you there’s a way to make all that easier? That’s where iPXE comes in. This hero of network booting builds on PXE (Preboot Execution Environment), taking it to the next level and offering a powerful, flexible solution that streamlines everything. Let’s break down how iPXE makes things a whole lot easier.

First off, iPXE is like PXE’s more advanced sibling. It started with gPXE, a fork of Etherboot, and added tons of cool features that make PXE look a bit, well, basic. With iPXE, you get much more flexibility and control, exactly what you need when managing large-scale environments. Here’s how iPXE steps in and enhances the process:

• Native iPXE Configuration: Imagine this: You completely swap out the firmware or ROM of your network interface card (NIC) with iPXE. This means the server doesn’t even bother with the old-school PXE setup. It boots straight from iPXE, skipping the typical PXE steps entirely. This is a simple, no-nonsense approach that cuts out a lot of unnecessary complexity.
• Chain-Loading iPXE: But let’s say you’re not quite ready to go full iPXE just yet. You can still use iPXE by “chain-loading” it. In this setup, the server first does the PXE thing, but instead of stopping there, it loads iPXE as a secondary stage. It’s like passing the torch from one runner to the next in a relay race—PXE starts the process, and iPXE takes over, offering all those extra features.

Once iPXE takes control, it unlocks a treasure chest of features that PXE simply can’t match. Here’s where it really shines:

• Expanded Protocol Support: While PXE is a bit limited, iPXE supports a whole bunch of protocols: HTTP, FTP, iSCSI, FCoE, and more. This is huge. Why? Because it means iPXE can pull boot files from multiple sources, using faster, more efficient transfer methods than the old TFTP protocol. Imagine trying to send a big package through a slow delivery service, then switching to a faster, more reliable one. That’s what iPXE does.
• Advanced Scripting: Now, here’s where things get really fun. iPXE has its own scripting engine, which means you can write custom boot scripts. These scripts allow you to automate and customize all sorts of tasks—whether it’s creating a boot menu, conditionally choosing what to boot, or pulling configuration files dynamically. For admins managing lots of machines, this is like having a superpower—automation makes everything run smoother, faster, and with fewer mistakes.
• Embedded Boot Scripts: Even better, iPXE lets you embed these scripts directly into the iPXE binary. No more messing around with external configuration files—just bake everything into the boot process. This makes the whole thing quicker and more reliable, especially in large environments where every second counts.
• Security and Authentication: Network booting might sound like it could open up security risks, but don’t worry—iPXE is built with security in mind. It supports HTTPS, 802.1x authentication, and cryptographic checks. This means your network booting process stays secure, with all the data being encrypted. So, you don’t have to worry about anyone hijacking your boot process.
• Direct Boot from Cloud Storage: One of the coolest features? iPXE lets you boot directly from cloud storage. Instead of relying on physical media, your servers can pull kernel and OS images from a cloud server using different communication protocols. This is a game-changer for businesses that rely on cloud infrastructure, making the boot process way more flexible and scalable.
• Enhanced Debugging and Commands: When you’re working with network booting, things can go wrong. But with iPXE’s built-in commands like chain , imgfetch , and autoboot , you’ve got all the tools you need to troubleshoot and control the process. It’s like having a toolbox full of precision tools to fix any issue that comes up during the boot process.

In short, iPXE is like upgrading from a reliable car to a high-performance sports car. It offers greater protocol support, more powerful security features, and advanced scripting capabilities—making it perfect for businesses that need to streamline network booting and bare metal provisioning. It’s especially useful for organizations with complex infrastructures, where every boot needs to be fast, secure, and flexible.

Example: Let’s say you need to boot a custom Linux environment. With iPXE, you can create a script like this:

#!ipxe
dhcp
get network config
kernel http://192.168.1.10/boot/vmlinuz initrd=initrd.img ro console=ttyS0
initrd http://192.168.1.10/boot/initrd.img
boot

In this script, iPXE first grabs a DHCP address, then downloads the kernel and initrd files via HTTP (which is faster than the old TFTP). Once everything’s ready, it boots the system. You can also add kernel command-line arguments, like console=ttyS0 , which sends the output to a serial port. This gives you more precise control over the system’s behavior.

With iPXE, your network booting process is no longer just about making things work—it’s about making them work better. It’s about giving your infrastructure the flexibility and control it needs to keep up with modern demands. Whether you’re provisioning bare metal servers, recovering systems, or just updating machines, iPXE helps you do it all with ease, speed, and security.

Intel’s iPXE Overview

PXE vs. iPXE – What’s the Difference?

Let’s dive into the world of PXE and iPXE, two technologies that share a common goal: enabling network-based booting. If you’re working in IT, you probably already know about PXE, the trusted method for getting a computer running without the need for local storage devices. But, there’s a stronger contender in the mix—iPXE. It takes everything PXE does and adds a little extra flair. So, what exactly makes iPXE stand out from PXE? Let’s break it down.

Source Firmware

Let’s start at the very beginning—firmware. PXE relies on firmware that’s often locked down and proprietary. This firmware is built into the Network Interface Card (NIC) ROM, and sadly, you can’t make changes to it. It’s like getting a tool that can only be used for one thing—PXE booting. Now, along comes iPXE. It’s open-source, which gives you much more freedom. You can completely replace the PXE firmware with iPXE, or if you’re not ready to go all-in with iPXE, you can chain-load iPXE from the existing PXE setup.

Protocols for Booting

When it comes to booting protocols, PXE is a bit limited. It sticks to DHCP and TFTP, which are reliable but can be a bit restrictive. iPXE, however, is like a full buffet of options. It can handle HTTP, HTTPS, FTP, iSCSI, NFS, and more. This means you’ve got a lot more flexibility when it comes to pulling boot files from the network. It’s like switching from a one-lane road to a multi-lane highway—you’ve got more choices and more speed.

Speed of File Transfer

Let’s talk about speed. PXE uses TFTP, which is lightweight but relies on UDP and can be a little slow, especially when transferring larger files like OS images. If you’ve ever tried downloading a big file on a slow network, you know how frustrating that can be. But with iPXE, you can use HTTP or HTTPS, both of which are TCP-based and much faster than TFTP. This is a game-changer, especially when you’re dealing with large-scale server deployments or cloud environments.

Boot Media Support

PXE is okay with where it boots from, but it’s still somewhat limited. It requires a PXE-capable NIC firmware to get things started. That’s pretty much it—simple, but not very flexible. On the other hand, iPXE is like the Swiss army knife of booting. It can boot from PXE or native NICs, but it doesn’t stop there. USB drives, CDs, ISO images—iPXE supports all these and more. It’s ready for whatever setup you’ve got.

Scripting & Logic

Now, here’s where iPXE really shines. PXE is a bit rigid—it follows a fixed procedure. There’s no room for customization. But iPXE has an advanced scripting engine that lets you write your own boot scripts. Want to create a boot menu? Need to conditionally choose what to boot? Or maybe you want to pull configuration files dynamically? iPXE lets you do all of that, which is a huge plus in environments where you need that kind of control.

Extended Features

Let’s talk about the bells and whistles. PXE handles the basics—network booting—but doesn’t offer much beyond that. No support for newer technologies, no wireless booting, and no fancy network setups. iPXE, on the other hand, supports a whole bunch of extra features: Wi-Fi booting, VLAN configurations, IPv6 support, and even 802.1x authentication for secure booting. iPXE is built for the future, while PXE is a bit stuck in the past.

UEFI Compatibility

If you’re working with modern systems, UEFI is a big deal. PXE does support UEFI PXE booting, but it requires a special EFI boot file, which can create compatibility issues with newer systems. iPXE handles this much better. It has robust UEFI support through the

ipxe.efi

Maintainers

Here’s the thing: PXE is usually maintained by hardware vendors, and while it’s based on an open specification, the actual implementation is closed-source and proprietary. iPXE, on the other hand, is a community-driven open-source project. It’s maintained by the open-source community, meaning it’s constantly being updated, and you can modify it however you need. You get more transparency, flexibility, and a system that’s designed to keep up with modern needs.

Use Cases

Now, when should you use PXE and when should you use iPXE? PXE works great for simple setups—think legacy systems or smaller environments where everything you need is already set up and you just want to get things going. On the other hand, iPXE is perfect for large-scale deployments, cloud integration, and environments that need advanced booting and customization. If you need to automate booting, select OS installers based on hardware detection, or display custom boot menus, iPXE is your tool. It’s like having a superpower for anyone who needs control, flexibility, and speed in their network booting operations.

The Bottom Line

In the end, iPXE takes what PXE does and makes it even better, offering a more powerful, feature-rich solution that’s perfect for modern network booting needs. Whether you’re managing a fleet of servers, working with bare metal provisioning, or trying to streamline your boot process, iPXE gives you the tools you need to get the job done faster, more securely, and with way more flexibility than PXE alone could ever offer.

iPXE Documentation

Interaction with Modern Hardware and UEFI

Imagine stepping into the world of modern computing, where technology isn’t just faster but also smarter and more secure. The shift from BIOS (Basic Input/Output System) to UEFI (Unified Extensible Firmware Interface) is like upgrading from a bicycle to a high-tech electric scooter. UEFI brings so much more to the table—better security, quicker boot times, and support for larger storage devices, just to name a few. It’s the backbone of modern computing, especially when dealing with high-performance setups like those in data centers or cloud infrastructures. But here’s the twist—while both PXE and iPXE can work with UEFI, there are some important differences to keep in mind.

UEFI PXE Boot

Back in the old BIOS days, booting over a network was pretty straightforward. You’d get a .pxe or .kpxe file, and that would kick off the process. But in the world of UEFI, things got a bit more sophisticated. Now, you need a specific .efi file to start the network boot process. It’s a bit like upgrading from a flip phone to a smartphone—it just works better and faster. These .efi files are made to fit UEFI’s features, providing better support for things like secure boot and even quicker startup times. The result? Your system boots in a more secure and efficient way compared to the old BIOS method.

Chainloading

Now, here’s where it gets interesting. Sometimes, you don’t need to completely switch from PXE. With chainloading, you can use UEFI PXE to start the boot process, and then hand it off to iPXE for the more complicated stuff. It’s like passing the baton in a relay race—PXE starts the process, and iPXE takes it the rest of the way. Why do this? Because iPXE adds features that UEFI PXE just can’t handle, like supporting advanced protocols, scripting, or booting from different types of storage. Think of it as giving your system the ability to do more than it normally would.

Native iPXE EFI Binaries

But wait—iPXE has a trick up its sleeve. It can also work directly in UEFI environments without needing to rely on chainloading. How? By using a special iPXE EFI binary, like ipxe.efi . This is like cutting out the middleman. With ipxe.efi , you can boot directly from iPXE in UEFI systems, skipping the step of using UEFI PXE. And here’s the cool part: with iPXE, you get access to all the advanced features, like support for HTTP booting, advanced scripting, and even better security features, like HTTPS support. It’s a more streamlined approach, making the boot process quicker and giving you more control over your network booting.

Ensuring Compatibility

Now, all of this is great, but you have to make sure your hardware is on the same page. UEFI has become the standard for most modern systems, and it’s important to make sure that your servers and client devices support UEFI PXE or iPXE booting. Think of it like making sure all your puzzle pieces fit together. Compatibility ensures smooth deployment and provisioning—a must when you’re working with a large fleet of systems.

Bare Metal Provisioning in High-Performance Environments

Speaking of large fleets, let’s talk about bare metal provisioning in environments where performance is everything. Imagine running GPU-accelerated servers in a data center or for AI (Artificial Intelligence) and ML (Machine Learning) workloads. These tasks need bare metal servers, which are servers that aren’t running a virtual machine. Instead, they’re directly connected to the hardware—giving them a performance boost when handling heavy workloads. In these environments, booting quickly and efficiently is crucial. That’s where PXE and iPXE step in, helping you deploy systems and perform recovery operations at lightning speed.

If you’re working with bare metal hardware, UEFI support is a game-changer. It unlocks faster boot times and makes sure the system’s motherboard features are optimized. So when you’re running AI and ML workloads, the hardware resources are fully utilized, and you can maximize performance without any bottlenecks. It’s a win for productivity and system efficiency.

Optimizing Boot Solutions for Bare Metal Servers

When you think about the cutting-edge technology that powers bare metal servers, the importance of UEFI and PXE/iPXE can’t be overstated. UEFI doesn’t just provide access to modern hardware features; it ensures you’re ready for the future. Whether it’s improving boot times, enhancing security, or supporting complex environments, iPXE and PXE are crucial in modern network booting operations. They let businesses deploy operating systems and provision servers with minimal downtime, ensuring that everything runs smoothly, even in high-demand environments.

By embracing UEFI, PXE, and iPXE, you’re setting yourself up for success in the world of modern IT. These tools ensure that your systems are always ready to go, from the moment the power button is pressed, all the way through to loading your operating system—quickly, securely, and reliably. It’s all about keeping things running smoothly, and these technologies help make that happen.

Intel UEFI and EFI Overview

Setting Up PXE and iPXE for Bare Metal Servers

Alright, let’s dive into setting up PXE and iPXE for bare metal provisioning. It’s all about getting those operating systems onto your servers without needing a USB or CD. Imagine this: no more fumbling around with bootable media. Instead, your servers are ready to go with just the power of the network. Pretty cool, right?

Prerequisites to Set Up PXE/iPXE Environment

Before we jump into the setup, you’ll want to make sure your network infrastructure is ready for action. All the servers should be on the same LAN, or if they’re across different subnets, you’ll need a DHCP relay to ensure they can communicate. Adding VLANs (Virtual Local Area Networks) can boost security by isolating the network traffic used for provisioning.

Next, check that your bare metal servers have PXE boot functionality enabled in their BIOS or UEFI settings. This allows the servers to boot via the network instead of using local storage devices. You’ll also need a DHCP server to assign IP addresses to the servers and point them to the correct boot files. On top of that, a TFTP server will handle transferring those boot files.

For iPXE integration, you’ll need an HTTP server to serve iPXE boot scripts and operating system images over the network. Gather your boot files, like pxelinux.0 , bootx64.efi , and ipxe.efi , along with your OS installation images. It’s also a good idea to dedicate a PXE server with a static IP address to host all of these services (DHCP, TFTP, HTTP).

Best Practice: Document Your Network Environment

One thing I can’t stress enough: document everything. Make a note of your IP ranges, server IPs, and any other important details. It’ll save you headaches later when you need to troubleshoot or scale up. Also, testing this setup on a test machine before pushing it live to production servers is always a good idea. This way, you can fix any issues before they affect your actual systems.

Setting Up a PXE Server

Now, let’s talk about getting the PXE server up and running. This is where it all starts. There are two key components you need to configure: DHCP and TFTP. They’ll provide the network details and transfer the boot files to the client, respectively.

1. Install and Configure DHCP with PXE Options

If you don’t have a DHCP server set up for PXE, here’s how you get started. On Debian or Ubuntu Linux servers, you can install the ISC DHCP server with:

sudo apt update && sudo apt install isc-dhcp-server

On Red Hat-based systems, you can install the DHCP service using dnf or yum. Once installed, make sure the service is enabled and starts on boot.

Basic DHCP Configuration

Next, you’ll need to configure the DHCP server by editing the configuration file, typically found at /etc/DHCP/dhcpd.conf . This file defines things like the network’s subnet, IP range, and DNS settings. You also need to add support for PXE booting by including these lines:

allow booting;
allow bootp;

Your configuration might look something like this:

subnet 192.168.1.0 netmask 255.255.255.0 {
    range 192.168.1.50 192.168.1.100;
    option routers 192.168.1.1;
    option domain-name-servers 192.168.1.1;
    …
}

Configure PXE-Specific Options

Now, you need to specify the PXE boot file and the TFTP server’s address in your DHCP configuration. You’ll use Option 66 to define the TFTP server’s address and Option 67 for the boot file. For instance, if you have PXELINUX (for BIOS systems), it will be pxelinux.0 . For UEFI clients, you might use bootx64.efi .

Here’s an example of how to do it for both BIOS and UEFI clients:

if option arch = 00:07 {
    filename “bootx64.efi”;  # UEFI x86-64
} else {
    filename “pxelinux.0”;  # BIOS
}

Start the DHCP Service

Once you’ve saved your configuration, start the DHCP service:

sudo systemctl start isc-dhcp-server

Check your logs (like /var/log/syslog ) to ensure everything is working smoothly.

2. Install and Configure the TFTP Server

Next, let’s install the TFTP server on your PXE server. On Ubuntu or Debian:

sudo apt install tftpd-hpa

For Red Hat-based systems:

sudo dnf install tftp-server

Make sure the TFTP service is enabled and open up UDP port 69 in the firewall to allow TFTP traffic.

TFTP Root Directory

Once the TFTP service is installed, you’ll need to configure the TFTP root directory. This is where all your boot files will live. The default directory is usually /var/lib/tftpboot or /tftpboot . If it’s missing, create it like this:

sudo mkdir -p /var/lib/tftpboot

Then, set the proper permissions so that the TFTP clients can read the files:

sudo chmod -R 755 /var/lib/tftpboot

Obtain PXE Boot Files

Now it’s time to get the required bootloader files into your TFTP root directory. If you’re using PXELINUX (from the Syslinux project), these files will be essential:

• pxelinux.0 (Primary PXE bootloader for BIOS clients)
• ldlinux.c32 , libcom32.c32 , libutil.c32 , menu.c32 (Menu modules for a boot menu)

For UEFI clients, you’ll need syslinux.efi or an iPXE.efi binary.

Set Up PXELINUX Configuration

Create a pxelinux.cfg directory under your TFTP root:

mkdir -p /var/lib/tftpboot/pxelinux.cfg

Then, add a default configuration file:

/var/lib/tftpboot/pxelinux.cfg/default

In this file, you can define your PXE boot menu options, like installing Linux, running a memory test, or booting from the local disk. Here’s a simple example:

DEFAULT menu.c32
PROMPT 0
TIMEOUT 600
MENU TITLE PXE Boot Menu
LABEL linux
    MENU LABEL Install Linux OS
    KERNEL images/linux/vmlinuz
    APPEND initrd=images/linux/initrd.img ip=dhcp inst.repo=http://192.168.1.10/os_repo/
LABEL memtest
    MENU LABEL Run Memtest86+
    KERNEL images/memtest86+-5.31.bin
LABEL local
    MENU LABEL Boot from local disk
    LOCALBOOT 0

NFS or HTTP Setup for OS Files

If your OS installer needs a repository (like a distro tree or an ISO), you can serve it over NFS or HTTP. For example, mount an ISO and share it over HTTP, allowing the installer to access and retrieve the necessary files.

Start/Restart TFTP Service

After everything’s in place, restart the TFTP service to ensure it recognizes the new files:

sudo systemctl restart tftpd-hpa

Final Steps

With everything set up, your PXE server should now be ready to go. When a client boots up, the DHCP server will assign an IP address and direct the client to the correct boot file, like pxelinux.0 . The client will download the file from the TFTP server, load the PXELINUX bootloader, and proceed with the OS installation based on the menu you defined.

This whole setup process automates the installation of operating systems on bare metal servers, cutting down on manual effort and making the deployment of new machines smooth and efficient. No more USBs or CDs—just fast, network-based provisioning. Enjoy the freedom of streamlined server management!

Prerequisites to Set Up PXE/iPXE Environment

Let’s break down what you need to do to get your PXE and iPXE environment up and running smoothly. Think of this as preparing your network infrastructure for a major upgrade, where all the elements need to be in place before you can deploy operating systems to your bare metal servers without ever touching a USB stick or CD.

Network Infrastructure

First things first, you need a solid network. The backbone of PXE/iPXE booting is the network infrastructure, and it needs to be able to handle the load. The best setup is when all your servers are on the same LAN. It’s like having all your team members in the same room – communication is faster, and there’s less chance for confusion. But, if your servers are spread across different subnets, don’t worry. You can set up a DHCP relay, which acts like a traffic manager, routing PXE boot requests between different subnets. It ensures that no one gets left behind.

To enhance security, consider using VLANs (Virtual Local Area Networks). Think of VLANs as giving each team their own separate work area to keep things secure and organized. By isolating the PXE network traffic from other parts of your infrastructure, you’re preventing any unwanted cross-talk between systems, which enhances both security and manageability.

BIOS/UEFI Settings

Now, let’s talk about your bare metal servers. These servers need to be set up properly in the BIOS or UEFI settings to support PXE booting. Essentially, you need to tell the server, “Hey, when you power on, forget about booting from a USB drive. You’re booting from the network.” In the BIOS/UEFI settings, you’ll find options to enable network booting. This is a key step – without it, the server won’t even attempt to connect to the network for booting. If you skip this, well, your server will be pretty stubborn and keep trying to boot from the old, slow media.

DHCP Server Configuration

At this point, you’re going to need a DHCP server to assign IP addresses to the servers when they try to boot via the network. Think of DHCP like a helpful receptionist who tells each server, “Here’s your desk, and here’s where you need to go to get your boot files.” The DHCP server will point your servers to the boot file location, making sure they get the necessary files to start their boot process. Remember that the TFTP (Trivial File Transfer Protocol) server’s address also needs to be included in the DHCP configuration. This way, the client knows exactly where to go to download the files it needs.

TFTP and HTTP Servers

The TFTP server plays a starring role in a PXE setup. It’s responsible for transferring the boot files, like

pxelinux.0

bootx64.efi

ipxe.efi

But that’s not all! For iPXE specifically, an HTTP server will be required. Why? Well, if you’re dealing with large OS images or taking advantage of iPXE’s advanced features like scripting or booting from remote storage, HTTP will offer faster transfer speeds and more flexibility. It’s like upgrading from a bicycle to a race car – everything moves quicker!

Gather Necessary Boot Files

Before you dive into setting everything up, gather the essential boot files. For PXE, the primary bootloader file is usually

pxelinux.0

bootx64.efi

ipxe.efi

Dedicated PXE Server

To keep everything running smoothly, it’s a great idea to use a dedicated PXE server with a static IP address. Think of this as giving the server its own desk in the office. By dedicating a server to host the DHCP, TFTP, and HTTP services, you’re ensuring those services are always available when needed, without the load of other tasks slowing things down. This makes troubleshooting easier and ensures that your setup won’t break down under pressure.

Best Practice: Document Your Network Environment

Here’s a simple, but crucial, tip: Document everything. Track your IP address ranges, server IPs, and any configuration settings you make. This document is your cheat sheet, and it will come in handy when troubleshooting or expanding the setup in the future. Trust me – it saves a lot of time and frustration.

Testing the PXE Setup

Before you hit the go button on your production servers, always test the setup on a test machine first. Think of this as a dry run for a big performance. By testing in a safe environment, you’ll catch any issues that could arise—like network hiccups or boot file errors—before they impact your actual production systems. Once the test run goes smoothly, you’ll know everything is locked in and ready to go live.

By following these steps, you’ll have a fully functional PXE/iPXE environment set up, ready to automate and streamline the process of bare metal provisioning across your network. Your servers will be up and running faster, and you won’t have to worry about physical media anymore. It’s all about efficiency and making your life easier!

DHCP Protocol

Setting Up a PXE Server

Imagine you’re tasked with setting up a network that can boot systems over the network, bypassing the need for USB sticks, DVDs, or other physical media. Well, that’s where PXE comes into play, and with a little effort, you can get it running smoothly. To make it work, you’ll need to configure a few essential components that will work together perfectly. The two main players in this setup? The DHCP server and the TFTP server.

Install and Configure DHCP with PXE Options

The first step is to install a DHCP server if one isn’t already running. This server acts like the first responder in a network booting scenario, assigning IP addresses and directing clients to the correct boot file. For Debian or Ubuntu systems, setting up the ISC DHCP server is easy—just run the following command:

sudo apt update & sudo apt install isc-dhcp-server

If you’re on a Red Hat-based system, use dnf or yum instead. Once the DHCP service is installed, don’t forget to enable it to start at boot time!

Basic DHCP Configuration

Now that the DHCP server is up and running, you’ll need to configure it. This is where things get a bit more technical, but hang tight. You’ll find the configuration file at /etc/DHCP/dhcpd.conf for ISC DHCP. Inside, you’ll define your network’s subnet, IP range, gateway, DNS settings, and more. Here’s an example of what this might look like:

subnet 192.168.1.0 netmask 255.255.255.0 {  range 192.168.1.50 192.168.1.100;  option routers 192.168.1.1;  option domain-name-servers 192.168.1.1;}

Make sure you also add the necessary lines to support PXE booting and Bootstrap Protocol (BOOTP):

allow booting;allow bootp;

Configure PXE-Specific Options

Next up, tell your DHCP server about the PXE boot file and the TFTP server address. For example:

next-server 192.168.1.10; # Replace with your TFTP server’s IPfilename “pxelinux.0”; # Boot file for BIOS-based clients

For UEFI clients, you might use bootx64.efi instead. If your network supports both BIOS and UEFI, you can use conditional logic to provide the right boot file based on the client’s architecture:

if option arch = 00:07 {  filename “bootx64.efi”; # UEFI x86-64}else {  filename “pxelinux.0”; # BIOS}

Start the DHCP Service

After you’ve got your DHCP configuration just right, it’s time to start the service. Simply run:

sudo systemctl start isc-dhcp-server

Once that’s done, take a quick glance at the system logs (you’ll find them at /var/log/syslog or /var/log/messages ) to make sure everything’s running smoothly.

Install and Configure the TFTP Server

Now that the DHCP server is ready to go, let’s move on to the TFTP server. The TFTP server is essential because it’s responsible for delivering the boot files (like pxelinux.0) to the client. Here’s how you install it.

Install TFTP Service

For Ubuntu or Debian systems, just run:

sudo apt install tftpd-hpa

For Red Hat or CentOS, use:

sudo dnf install tftp-server

Make sure TFTP is enabled and that your firewall allows traffic through UDP port 69.

Configure TFTP Root Directory

Next, you’ll need to define where your TFTP server will store its boot files. The default location is usually /var/lib/tftpboot or /tftpboot . If the directory doesn’t exist, create it with:

sudo mkdir -p /var/lib/tftpboot

Once you’ve got the directory, make sure TFTP clients can access the files without requiring specific user accounts:

sudo chmod -R 755 /var/lib/tftpboot

Obtain PXE Boot Files

With the TFTP server set up, it’s time to gather the necessary boot files. For PXELINUX (from the Syslinux project), you’ll need files like pxelinux.0 , ldlinux.c32 , libcom32.c32 , and vesamenu.c32 . You can typically find them in /usr/lib/PXELINUX/ on most Linux distributions. For UEFI clients, you’ll need syslinux.efi or an iPXE.efi binary (especially if you’re using iPXE for UEFI). If you’re using Red Hat, you can extract these files directly from the Syslinux RPM.

Set Up PXELINUX Configuration

Now that the boot files are in place, you’ll need a configuration file for PXELINUX. This file specifies the boot options for the clients. First, create the pxelinux.cfg directory:

sudo mkdir -p /var/lib/tftpboot/pxelinux.cfg

Then, create a default configuration file:

sudo nano /var/lib/tftpboot/pxelinux.cfg/default

Here’s an example of what that file could look like:

DEFAULT menu.c32PROMPT 0TIMEOUT 600MENU TITLE PXE Boot MenuLABEL linuxMENU LABEL Install Linux OSKERNEL images/linux/vmlinuzAPPEND initrd=images/linux/initrd.img ip=dhcp inst.repo=http://192.168.1.10/os_repo/LABEL memtestMENU LABEL Run Memtest86+KERNEL images/memtest86+-5.31.binLABEL localMENU LABEL Boot from local diskLOCALBOOT 0

Start or Restart TFTP Service

After setting up the configuration file, restart the TFTP service to make sure it recognizes the new files:

sudo systemctl restart tftpd-hpa

Although TFTP doesn’t always need a restart for new files, it’s a good habit to double-check and confirm everything’s working.

Testing the PXE Setup

Now that the PXE server is configured, it’s time for the final test. When a client machine boots, the DHCP server will assign it an IP address and point it to the correct boot file. The client will download this file from the TFTP server, load the PXELINUX bootloader, and start the OS installation as defined in your PXE boot menu. If everything goes according to plan, your PXE setup will now be ready for bare metal provisioning across your network, automating OS installations and simplifying server management like never before!

Installing and Configuring iPXE

Picture this: You’ve got a bunch of servers sitting idle, waiting to be configured and booted, but you’re tired of relying on physical media like USB drives or CDs. That’s where iPXE comes in. By chainloading iPXE through PXE, you get the power of network booting and the added benefit of advanced features that make life a whole lot easier. In this guide, we’ll walk through the process of getting iPXE set up on your system, and how to do it in a way that’s both efficient and customizable.

Download or Compile iPXE

So, you’ve decided to use iPXE. Great choice! But now the question is: how do you get it? You’ve got two main options:

1. Precompiled Binaries: You could go the easy route and grab the pre-built iPXE ISO images. These are perfect for quickly testing things out.
2. Compile from Source: Or, you can roll up your sleeves and compile it yourself. This is the best choice if you need the latest features or want to add specific customizations like embedding scripts or enabling HTTPS support.

Here’s the thing: if you decide to compile from source, you’ll need some build tools. On a Debian/Ubuntu system, you can install them like this:

$ sudo apt install -y git make gcc binutils perl liblzma-dev mtools

Once that’s done, clone the iPXE repo and compile it:

$ git clone https://github.com/ipxe/ipxe.git
$ cd ipxe/src

# Build the BIOS PXE binary:

$ make bin/undionly.kpxe

# Build the UEFI PXE binary for x86_64:

$ make bin-x86_64-efi/ipxe.efi

Now, you’ve got the binaries sitting in bin/ or bin-x86_64-efi/. If you want to include a startup script, add EMBED=script.ipxe to the make command.

Configure DHCP for Chainloading iPXE

Now that you’ve got iPXE, the next step is setting up the DHCP server. The idea here is simple: when the client machine boots, it sends a request for the boot file, and the DHCP server provides the iPXE boot file. You’ll need to tell the server which file to serve based on whether the client is a BIOS or UEFI system.

For BIOS clients, you’ll configure the DHCP server to provide undionly.kpxe via TFTP. For UEFI clients, it’ll be ipxe.efi . Here’s an example of the configuration:

if option arch = 00:07 {
    filename “bootx64.efi”;  # UEFI x86-64
} else {
    filename “undionly.kpxe”;  # BIOS
}

This way, no matter what kind of system you’re dealing with, the correct boot file is always delivered.

Avoiding Boot Loops

Alright, now here’s a classic hiccup you might run into: boot loops. The issue happens because iPXE sends its own DHCP request after loading, and if the DHCP server hands back undionly.kpxe or ipxe.efi , you get stuck in a loop.

To break this cycle, iPXE uses a user-class identifier (“iPXE”) to identify itself. This way, the server knows it’s dealing with iPXE and can break the loop by sending it to an HTTP URL where the iPXE script lives. Here’s how you’d set it up:

if exists user-class and option user-class = “iPXE” {
    filename “http://192.168.1.10/”;  # Custom iPXE script location
} else {
    filename “undionly.kpxe”;  # First-stage bootloader for BIOS clients
}

With this, iPXE gets directed straight to the HTTP server (where you’ve hosted your boot scripts), avoiding the loop altogether.

Setting Up an HTTP Server for iPXE

So, now iPXE is configured to fetch boot scripts via HTTP. To make that happen, you’ll need an HTTP server. You can use Apache or Nginx, and you can install it on the PXE server or any other accessible machine. On Ubuntu, installing Apache is as simple as:

$ sudo apt install apache2

Ensure the web server is up and running, and open port 80 on the firewall so HTTP traffic can flow freely.

Create iPXE Script File

Now it’s time for the fun part—writing your iPXE script. This is the file iPXE will grab over HTTP, and it will direct the boot process. You’ll usually place it in the server’s root directory (/var/www/html/). A basic iPXE script might look something like this:

#!ipxe
kernel http://192.168.1.10/os_install/vmlinuz initrd=initrd.img nomodeset ro
initrd http://192.168.1.10/os_install/initrd.img
boot

This script tells iPXE to fetch the kernel and initramfs over HTTP and start the boot process.

Host OS Installation Files

Before iPXE can actually do its thing, you’ll need the OS installation files, like the kernel and initrd images. These should be placed in a directory that’s accessible via your HTTP server, such as /var/www/html/os_install/. You can verify that everything is set up correctly by checking the files with the curl command:

$ curl http://192.168.1.10/os_install/vmlinuz

If it returns the file without issue, you’re good to go.

Creating iPXE Boot Scripts

One of iPXE’s strongest features is its scripting capabilities. With iPXE, you can create complex boot menus, automate OS selection, and dynamically pass kernel parameters. To start an iPXE script, you always begin with the #!ipxe shebang line, and then you can add whatever commands you need.

Let’s look at an interactive boot menu script:

#!ipxe
console –x 1024 –y 768  # Optional: Set console resolution
menu iPXE Boot Menu
item –key u ubuntu  Install Ubuntu 22.04
item –key m memtest  Run Memtest86+
choose –timeout 5000 target || goto cancel:ubuntu
kernel http://192.168.1.10/boot/ubuntu/vmlinuz initrd=initrd.img autoinstall ds=nocloud-net;s=http://192.168.1.10/ubuntu-seed/
initrd http://192.168.1.10/boot/ubuntu/initrd.img
boot:memtest
kernel http://192.168.1.10/boot/memtest86+
boot:cancel
echo Boot canceled or timed out. Rebooting…
reboot

In this script, iPXE gives the user a choice: install Ubuntu, run Memtest86+, or do nothing and reboot. If the user doesn’t select anything in 5 seconds, the process is canceled and the machine reboots. The Ubuntu installation uses cloud-init to automate the process, while Memtest86+ is for testing memory.

Now you have a powerful and flexible boot menu that can adapt to different use cases! With this setup, you’re all set to automate and streamline the process of bare metal provisioning across your network using iPXE. By leveraging its advanced features, like HTTP booting, scripting, and security capabilities, you can simplify OS deployment and manage systems more efficiently, all without needing to touch a single USB stick. Pretty awesome, right?

Avoiding Loops

Imagine this: You’re all set to deploy an operating system across multiple bare metal servers using iPXE. Everything seems to be working smoothly when, suddenly, the boot process starts looping endlessly. Over and over, iPXE keeps loading itself, never quite making it to the operating system. Not exactly what you had in mind, right? This is a classic issue when working with iPXE—the dreaded boot loop. The problem starts when iPXE sends out its own DHCP request after it boots for the first time. And, of course, the DHCP server responds with the boot files, such as undionly.kpxe or ipxe.efi . The next thing you know, iPXE starts over, and you’re stuck in a never-ending cycle. But don’t worry; there’s a simple fix.

The solution? Configure the DHCP server to recognize when iPXE is already running, so it doesn’t keep sending the same boot file to the client. By default, iPXE uses a user-class identifier set to “iPXE,” which makes it easy for the server to tell when it’s dealing with an iPXE client.

Here’s how you can set it up in the ISC DHCP server configuration to prevent the loop:

if exists user-class and option user-class = “iPXE” {
    filename “http://192.168.1.10/”;          # Custom iPXE script URL
} else {
    filename “undionly.kpxe”;          # BIOS bootloader
}

What’s happening here is this: When the DHCP server sees that the client is iPXE, it skips over the usual TFTP boot file and sends the client straight to an HTTP URL where your custom iPXE script lives. No more looping. If the client is still in the initial BIOS PXE boot stage, the server will send the undionly.kpxe bootloader, allowing the machine to continue the process by loading iPXE as a second-stage bootloader.

But what if you’re dealing with UEFI clients instead of BIOS? No problem—this method still works. For UEFI clients, you just swap out undionly.kpxe for the ipxe.efi file. Then, as with BIOS, the DHCP server will send the UEFI bootloader to the client, and once iPXE takes over, it will fetch the boot script through HTTP.

Now let’s dive into a bit more detail. You want to make sure the DHCP server knows what boot file to serve depending on whether the client is BIOS or UEFI. Here’s how you can differentiate between the two:

if option arch = 00:07 {
    filename “bootx64.efi”;           # UEFI x86-64
} else {
    filename “undionly.kpxe”;           # BIOS
}

This way, the UEFI clients will receive the bootx64.efi file, while the BIOS clients get the undionly.kpxe bootloader. It’s that simple!

Steps in the Process

Now that everything’s set up, let’s walk through what happens when a BIOS client starts the PXE booting process:

1. The BIOS client kicks off the PXE boot and starts downloading undionly.kpxe from the TFTP server.
2. iPXE takes over and makes a second DHCP request.
3. The DHCP server recognizes that it’s dealing with iPXE and sends it directly to the HTTP URL where your custom iPXE script is hosted.
4. iPXE fetches the script via HTTP and moves forward with the boot process.

This method ensures that iPXE will only download what it needs, keeping it from endlessly requesting the same boot file. It’s a neat, straightforward way to streamline the boot process and avoid the loop while using iPXE for network booting.

So there you have it—by tweaking your DHCP server and configuring iPXE properly, you can avoid the frustrating boot loop and have your network-based deployments running smoothly in no time.

iPXE Network Boot Solution

Set Up an HTTP Server for iPXE

Now that you’ve got the hang of configuring iPXE to fetch a boot script and other essential files over HTTP, let’s dive into setting up the HTTP server that will actually serve those files. Think of this server as your iPXE’s supply chain, delivering the boot files needed during the network booting process.

Install the HTTP Server

To begin, you’ve got a couple of options for where to place the HTTP server: you can install it on the same PXE server or set it up on a separate machine within your network. But for the sake of simplicity, let’s install it directly on the PXE server. You’ve got your choice of web servers, but Apache and Nginx are two of the most popular options. So, let’s get Apache up and running. If you’re working with an Ubuntu server, just type in the following:

$ sudo apt install apache2

Once it’s installed, make sure the server is up and running smoothly. Test it out by checking if it’s accessible from your target network. Oh, and don’t forget to double-check your firewall settings—port 80, which is the default HTTP port, needs to be open for the server to talk to the outside world.

Create the iPXE Script File

Now, here comes the fun part! You’re going to create an iPXE script file, which is like a blueprint for iPXE to follow when it boots up. This script will tell iPXE exactly what to do—whether it’s chainloading to another script or directly loading an OS installer.

First, make sure there’s a directory in your web server’s root folder (if it doesn’t exist already), like /var/www/html/. Inside that directory, create your iPXE script file, and this is where you’ll define the boot options. Here’s a simple example of what the script might look like:

#!ipxe
kernel http://192.168.1.10/os_install/vmlinuz initrd=initrd.img nomodeset ro
initrd http://192.168.1.10/os_install/initrd.img
boot

In this setup, iPXE is instructed to grab the Linux kernel (vmlinuz) and the initial RAM disk (initrd.img) from your HTTP server at http://192.168.1.10 , then proceed to boot the system. This is a great basic configuration for automating OS installation over the network, especially when you’re deploying across a fleet of machines.

Host OS Installation Files

Before iPXE can do its magic, you need to make sure it has access to the actual OS installation files. These are usually the kernel (vmlinuz), the initramfs (initrd.img), or, if you’re working with a complete OS installer, the entire ISO or repository of packages.

Place these files in a dedicated directory on the web server, like /var/www/html/os_install/, so that iPXE can easily grab them. For example, you would copy your Linux distribution installer files (such as vmlinuz and initrd.img) into that directory.

And here’s a little nugget of info: iPXE can even fetch large files like Windows PE images or entire Linux ISOs over HTTP. This flexibility means you can load the OS directly into memory or pass it to the bootloader for further installation.

Test HTTP Access

Before you get too excited, let’s do a quick check to ensure everything is working as expected. The last thing you want is to find out that iPXE can’t access the files when it’s too late.

Use the curl command from another machine on the same network to test your HTTP server. For example, try:

$ curl http://192.168.1.10/os_install/vmlinuz

If everything is set up correctly, you should either see the kernel file’s contents or at least receive a successful HTTP response. This test ensures iPXE will be able to retrieve the necessary files during the boot process.

Summary

So, to sum it all up, here’s what you’ve done so far:

• Installed the Apache HTTP server (or Nginx, if you prefer).
• Created your iPXE script file that defines the boot process.
• Hosted the OS installation files on the HTTP server.
• Ran a quick test to verify that the HTTP server is properly serving the files.

By setting up your HTTP server in this way, you’ve taken a giant leap toward streamlining the OS deployment process using network booting. With iPXE fetching the boot script and installation files via HTTP, you’ve automated and simplified the provisioning of bare metal servers across your network.

Setting Up Apache2 on Ubuntu

Creating iPXE Boot Scripts

One of the standout features of iPXE is its powerful scripting capability. Imagine being able to program the boot process of your machines with flexibility and precision—this is exactly what iPXE’s scripting allows you to do. The process is simple: write a text file containing a series of iPXE commands that define the behavior of the boot sequence. The script starts with the shebang line #!ipxe , followed by various commands that make the network booting process smarter and more customizable.

Basics of iPXE Scripting

To create a functional iPXE script, there are a few key commands you’ll need to work with. Think of these commands as the building blocks of your iPXE boot process:

• kernel: This command selects the kernel or bootloader that will be downloaded and executed.
• initrd: The initrd command tells iPXE where to get the initial RAM disk, a critical component for the system’s boot process.
• boot: Once the kernel and initrd are ready, the boot command launches them, kicking off the system’s boot process.
• chain: The chain command is your secret weapon for complex boot configurations. It lets you pass control from one script or bootloader to another, enabling more advanced setups.

But that’s not all! iPXE also has flow control commands, which allow for decision-making in your script. These include commands like goto, ifopen, and those related to menus like menu, item, and choose. These interactive commands make it easy to create boot menus, prompt users for input, and provide different boot options based on the user’s choices.

What’s even cooler is the fact that you can use the chain command to load another script, like boot.ipxe , from an HTTP server. This flexibility lets you layer scripts for more complex boot environments, making iPXE as customizable as you need it to be.

Example: Interactive Boot Menu Script

Let’s see iPXE scripting in action! Imagine you want to create an interactive boot menu that allows users to choose between installing an OS or running diagnostic tools. Here’s an example script that brings this idea to life:

#!ipxe
console –x 1024 –y 768  # Set console resolution (optional)
menu iPXE Boot Menu
item –key u ubuntu Install Ubuntu 22.04
item –key m memtest Run Memtest86+
choose –timeout 5000 target || goto cancel
:ubuntu
kernel http://192.168.1.10/boot/ubuntu/vmlinuz initrd=initrd.img autoinstall ds=nocloud-net;s=http://192.168.1.10/ubuntu-seed/
initrd http://192.168.1.10/boot/ubuntu/initrd.img
boot
:memtest
kernel http://192.168.1.10/boot/memtest86+
boot
:cancel
echo Boot canceled or timed out. Rebooting…
reboot

Explanation of the Script

Let’s break it down:

• console: This line sets the console resolution. While it’s optional, it helps make the output look cleaner, especially for users interacting with the system.
• menu: This creates a boot menu titled “iPXE Boot Menu,” where users will choose what they want to do.
• item: These lines define the options on the menu. In this case, you can either install Ubuntu or run Memtest86+.
• choose: This command prompts the user to choose an option. If no choice is made within 5 seconds, it jumps to the cancel label.
• kernel and initrd: These lines define which kernel and initramfs are to be loaded, whether it’s for the Ubuntu installation or Memtest.
• boot: This tells iPXE to boot the selected option.
• reboot: If no selection is made in time, the system will automatically reboot.

Key Features and Benefits of the Script

• Interactive Boot Menu: The script builds a boot menu where users can select from multiple options—Ubuntu installation or running a memory test. This adds a layer of interactivity that makes the boot process much more user-friendly.
• Ubuntu Installation: If the user selects the “u” option, the Ubuntu installer is automatically triggered. The script fetches the necessary kernel and initramfs files over HTTP, simplifying the OS deployment process.
• Run Memtest86+: The “m” option runs a memory test, perfect for diagnosing any hardware issues. It’s an essential tool for checking your system’s health without needing to touch physical hardware.
• Automatic Reboot: If the user doesn’t select anything or the process times out, the system reboots automatically, keeping things smooth and automated.

This script is a great example of iPXE’s flexibility, allowing for remote bare metal provisioning and OS installation with minimal intervention. By leveraging iPXE’s scripting capabilities, administrators can build highly customizable and automated network booting solutions. This scripting approach not only automates the OS installation but also adds advanced functionality like menu-driven choices and diagnostics. Whether you’re managing a fleet of servers or setting up a remote environment, iPXE gives you the tools to make the booting process as smooth, fast, and reliable as possible.

GNU GRUB Manual

Security Implications of Network Booting and Mitigations

Network booting is like a magic trick for IT professionals—it’s incredibly powerful and makes life easier by enabling remote provisioning and operating system deployment. But, like any tool with immense power, it can also open doors to potential threats if not properly configured. Imagine this: an attacker could impersonate a DHCP or TFTP server, sending malicious boot images or configurations to client machines, leading to unauthorized access or, worse, a full system compromise. Yikes, right? This is why it’s crucial to understand the security implications of network booting and set up the necessary safeguards. Let’s dive into some strategies to secure your PXE and iPXE booting processes.

Use Separate VLANs for Network Booting

One of the easiest and most effective ways to protect your network booting environment is by using separate VLANs (Virtual Local Area Networks). Picture this: you have two networks—your production network, where all your critical systems live, and a provisioning network where bare metal provisioning and booting occur. By keeping these two networks separated, you create a protective boundary. Even if attackers somehow manage to infiltrate your provisioning network, the damage won’t spread to your operational systems. It’s like keeping your valuables locked in a safe room while you’re working in the garage—secure but still functional.

Use iPXE with HTTPS for Secure Communication

Now, iPXE is a great tool for network booting, but if you’re using it without HTTPS, you’re leaving the door wide open for attackers to intercept or tamper with boot files. Here’s where iPXE’s ability to fetch files over HTTPS comes in handy. By configuring iPXE to pull boot files securely from HTTPS-enabled servers, all the data exchanged during the boot process is encrypted. Think of it like sending sensitive documents in a sealed envelope rather than just a postcard—nobody can read or alter what’s inside while it’s in transit. By adding this extra layer of security, you ensure that attackers can’t intercept those critical boot files or configurations.

Enable Client Authentication for Added Protection

Imagine your network booting environment as a secure VIP club: you don’t want just anyone strolling in. This is where client authentication becomes your bouncer. iPXE allows you to require username/password validation or even certificate-based authentication before a system can begin booting. By setting this up, only systems with the proper credentials will be allowed to boot from the network and receive those sensitive boot images. It’s like ensuring that only authorized personnel can enter the server room—no unauthorized guests allowed.

Configure Secure Boot to Block Unauthorized Boot Loaders

What if you could ensure that only trusted bootloaders and operating systems get the green light to boot on your machines? Enter Secure Boot. This feature, available through UEFI (Unified Extensible Firmware Interface), ensures that only signed, trustworthy bootloaders are allowed to run. When enabled, Secure Boot blocks any unapproved bootloaders—such as those maliciously deployed through network booting—before they can even start. While it might add some extra setup challenges, particularly when using custom boot loaders or operating systems, it’s like installing a high-tech security system that only lets in the good guys.

Implement DHCP Snooping to Prevent Unauthorized Servers

One of the sneakiest attacks you could face involves a rogue DHCP server. Without the proper protection, an attacker could set up a fake DHCP server and begin issuing malicious boot files. That’s like a hacker pretending to be a trusted network administrator and sending clients on a wild goose chase. Thankfully, DHCP snooping is here to save the day. This feature, supported by network switches, acts like a bouncer at a nightclub. It monitors DHCP messages and blocks any unauthorized servers from distributing IP addresses or sending boot instructions. With DHCP snooping enabled, only trusted servers can hand out the boot files, protecting your systems from those pesky rogue servers.

Putting it All Together

Securing a network booting environment is a multifaceted effort—like assembling a defense team for your network. From setting up iPXE with HTTPS to enabling client authentication, secure boot, and DHCP snooping, each of these best practices forms an essential piece of your security puzzle. By implementing these measures, you’re ensuring that your PXE and iPXE booting processes are secure and protected from unauthorized access or malicious attacks. This proactive approach will keep your systems and data safe while allowing you to streamline the bare metal provisioning process. Just like locking your doors and windows, these security steps keep unwanted visitors at bay, ensuring only the right systems can boot and connect to your network.

Complete Guide to DHCP Snooping

Common Issues and Troubleshooting Tips

When you’re working with PXE and iPXE, things don’t always go as smoothly as planned. While network booting is an incredible tool for streamlining provisioning and OS deployments, you might run into some bumps along the way. But don’t worry! With a bit of troubleshooting, you can save yourself from a world of frustration. Let’s explore some of the most common issues you might face with PXE/iPXE and how you can troubleshoot them like a pro.

Issue: PXE Boot Not Triggering

Troubleshooting Tip: First things first—check your BIOS or UEFI settings. You want to make sure the network adapter is set up for booting, and that the network boot option is higher in the boot order than your hard drive or other local storage devices. This ensures that your system will first try to boot over the network before falling back to the usual local media. If the boot order is wrong, your system might skip the network boot and go straight to the local disk.

Issue: No DHCP Offer (PXE-E51)

Troubleshooting Tip: This one’s a classic! The most likely cause is that your DHCP server is either down or not reachable by the client machine. Make sure your DHCP server is up and running. If the client and the server are on different subnets, you’ll need to configure a DHCP relay or IP Helper on the network. This helps pass DHCP packets between the subnets, ensuring the client gets the necessary boot information.

Issue: PXE Download Fails / TFTP Timeout (PXE-E32)

Troubleshooting Tip: When you see this issue, it usually means there’s a hiccup between your TFTP server and the client machine. The TFTP server might be down, or the file paths for the boot files might be wrong. Check that your TFTP server is up and running. Also, double-check your firewall settings to make sure TFTP traffic (which uses UDP port 69) is allowed. Lastly, ensure that the TFTP root directory is correctly configured so that the files are accessible.

Issue: Infinite Boot Loop (iPXE Chainloading)

Troubleshooting Tip: Ah, the dreaded infinite loop! If iPXE keeps loading itself over and over, it’s likely that the DHCP server is responding with the same boot file repeatedly. This can happen when iPXE requests the same boot file after it’s already been loaded. To fix this, ensure your DHCP server sends a different boot filename when iPXE is detected. You can also use an embedded iPXE script to chainload to the next boot stage using an HTTP URL. This prevents the system from getting stuck in the loop.

Issue: iPXE Command Failed

Troubleshooting Tip: If you see the dreaded “iPXE Command Failed,” it’s usually a sign that the URL or filename in your iPXE script is incorrect. Double-check the script and test the HTTP links by trying them in a browser. You can also verify TFTP file retrieval with a TFTP client to ensure that the files are accessible from the client machine.

Issue: UEFI Boot Issues

Troubleshooting Tip: If you’re dealing with UEFI boot issues, you want to make sure you’re using the right binary. For x86_64 UEFI systems, the correct file is ipxe.efi . Additionally, check the Secure Boot settings in the UEFI firmware. Secure Boot might block unsigned bootloaders, so either disable Secure Boot or make sure the boot file is signed. It’s like checking your ID at a club—if you don’t pass the verification, you’re not getting in.

Issue: TFTP Access Denied

Troubleshooting Tip: TFTP access issues can often be traced back to file permissions. Ensure that the TFTP server has the correct permissions to access and serve the boot files. Make sure the boot files are in the TFTP root directory, and ensure that no firewall rules are blocking access to UDP port 69. Think of it like a locked door—make sure the server has the right keys (permissions) to open it.

Issue: Slow PXE Boot

Troubleshooting Tip: Slow PXE booting can be a pain, especially when you’re trying to deploy operating systems across multiple systems. The solution? Switch from TFTP to HTTP or HTTPS to load boot files faster. HTTP and HTTPS are generally faster than TFTP, especially when large boot files or OS installation images are involved. It’s like upgrading from a tricycle to a sports car—you’ll zoom past those slow loading times.

Issue: PXE VLAN Misconfiguration

Troubleshooting Tip: PXE booting across different VLANs can be tricky. If the PXE VLANs are not properly tagged, or if the DHCP relay is not configured correctly to pass PXE packets between VLANs, the boot process can fail. Make sure your VLANs are tagged correctly and that your relay settings are configured to allow PXE traffic to pass through. It’s all about making sure the network traffic flows smoothly, like a well-oiled machine.

Issue: Client Architecture Mismatch

Troubleshooting Tip: You may run into issues when your DHCP server sends the wrong boot file to the client, especially when dealing with both BIOS and UEFI clients. Ensure that your DHCP server correctly differentiates between BIOS and UEFI clients. BIOS clients should receive BIOS-compatible boot files (e.g., pxelinux.0 ), while UEFI clients need UEFI-compatible files (e.g., bootx64.efi ). It’s like sending the right invitation to the right party—if you send a UEFI client the wrong boot file, it won’t know what to do with it.

General Troubleshooting Tips

Sometimes, troubleshooting PXE and iPXE issues can feel like detective work. There are so many moving parts—the client machine, DHCP server, TFTP server—but don’t fret, there’s a systematic way to approach it. Here are some steps to follow:

1. Check DHCP Functionality: Did the client receive a valid IP address from the DHCP server?
2. Verify TFTP File Retrieval: Did the client successfully download the boot file from the TFTP server?
3. Ensure Boot File Execution: Did the boot file execute and start loading the operating system?

For more advanced troubleshooting, you can refer to Microsoft’s documentation on debugging PXE issues. Tools like Wireshark are also invaluable for capturing and analyzing DHCP and TFTP exchanges between the client and server, helping you pinpoint network-related issues.

With these tips, you’ll be well-equipped to handle any roadblocks you face while working with PXE or iPXE, ensuring smooth, efficient network booting every time.

Conclusion

In conclusion, PXE and iPXE are essential technologies for efficient bare metal provisioning and network booting. By leveraging these tools, businesses can automate operating system deployments, simplify server provisioning, and improve overall IT infrastructure management. While PXE offers a reliable and simple approach, iPXE enhances the process with advanced features like additional protocol support, powerful scripting capabilities, and stronger security measures. Understanding how to set up and troubleshoot these technologies is crucial for optimizing bare metal server provisioning. As network booting continues to evolve, staying updated on new developments and features in PXE and iPXE will ensure that your systems remain efficient, secure, and ready for the future.Snippet: Master bare metal provisioning with PXE and iPXE for efficient, secure network booting and automated operating system deployments.

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