# PXE Boot

## 1. Introduction to PXE Boot

PXE (Preboot eXecution Environment) is a protocol that allows a computer to boot from a network interface independently of available data storage devices or installed operating systems. PXE boot is widely used in enterprise environments for network-based installations, diskless workstations, and system recovery.

## 2. How PXE Boot Works

PXE boot operates through a client-server model:

- a) The client (computer being booted) initiates a network boot sequence.
- b) It broadcasts a DHCP request with PXE-specific options.
- c) A PXE-enabled DHCP server responds with IP configuration and PXE boot server information.
- d) The client downloads a Network Bootstrap Program (NBP) from the PXE server using TFTP.
- e) The NBP is executed, allowing further boot processes or OS installation.

## 3. PXE Boot Requirements

- Client: Network Interface Card (NIC) with PXE support
- Server: DHCP server with PXE options, TFTP server, and boot images
- Network: Properly configured switches and routers (if applicable)

## 4. Setting Up a PXE Boot Environment

### DHCP Server Configuration:

Configure your DHCP server to provide PXE-specific options:

- Option 66 (Boot Server Host Name): IP address of your TFTP server
- Option 67 (Bootfile Name): Name of the initial boot file (e.g., pxelinux.0)

Example DHCPd configuration:

```
allow booting;
allow bootp;
option option-128 code 128 = string;
option option-129 code 129 = text;
next-server 192.168.1.10;
filename "pxelinux.0";
```

### TFTP Server Setup:

Install and configure a TFTP server (e.g., tftpd-hpa on Linux):

```
apt-get install tftpd-hpa
```

Configure the TFTP root directory (e.g., /var/lib/tftpboot).

### Prepare Boot Files:

Download and place necessary boot files in the TFTP root:

- PXELINUX (part of SYSLINUX project)
- Linux kernel and initrd (for Linux installations)
- Windows PE files (for Windows deployments)

Example PXELINUX configuration (pxelinux.cfg/default):

```ini
DEFAULT menu.c32
PROMPT 0
MENU TITLE PXE Boot Menu

LABEL linux
    MENU LABEL Install Linux
    KERNEL vmlinuz
    APPEND initrd=initrd.img

LABEL windows
    MENU LABEL Install Windows
    KERNEL memdisk
    INITRD winpe.iso
    APPEND iso raw
```

## 5. Advanced PXE Boot Features

### iPXE:

iPXE is an open-source network boot firmware that extends PXE capabilities:

- Boot from HTTP, iSCSI, AoE, and more
- Support for wireless networks
- Scripting for complex boot scenarios

### Secure Boot:

Implement secure boot with PXE using:

- HTTPS for file transfers
- Digital signatures for boot files
- TPM (Trusted Platform Module) integration

### Multicast:

Use multicast for efficient deployment to multiple clients simultaneously:

- Reduce network load during mass deployments
- Requires multicast-enabled network infrastructure

## 6. Troubleshooting PXE Boot

Common issues and solutions:

- DHCP not providing PXE options: Check DHCP server configuration
- TFTP transfer failures: Verify TFTP server setup and firewall rules
- Boot file not found: Ensure correct file paths and permissions
- NIC compatibility: Update NIC firmware or use iPXE

## 7. Best Practices

- Regularly update boot images and configurations
- Implement monitoring for PXE services
- Use VLANs to isolate PXE traffic
- Document your PXE environment thoroughly

## 8. PXE Boot Use Cases

- OS deployment and imaging
- Diskless workstations
- System recovery and diagnostics
- Thin clients and VDI environments

## 9. Future of PXE Boot

As technology evolves, PXE boot continues to adapt:

- Integration with cloud-based deployment solutions
- Enhanced security features
- Support for newer protocols and hardware

## Conclusion:

PXE boot is a powerful tool for network-based system deployment and management. By understanding its components and implementing it correctly, IT professionals can streamline operations and improve system management efficiency in various environments.