Ubuntu 20.04 搭建 PXE/iPXE Server

Introduction

验证网卡的PXE功能，需要搭建PXE server，PXE是网卡从服务器端启动，然后下载系统镜像，从来实现远程系统启动或者系统安装到本地。

PXE Server组件

DHCP Server
负责给PXE网卡分配网络IP地址，并通过网络提供指定的系统启动文件。
TFTP Server
PXE网卡通过TFTP协议获取启动文件，例如：pxelinux.0，vmlinuz，initrd.img, undionly.kpxe等。
FTP Server
PXE网卡通过FTP协议下载系统镜像文件，包含一个完整的系统。
Syslinux
是一个启动加载器集合，可以从硬盘、光盘或通过 PXE 的网络引导启动系统。
iPXE
iPXE is the leading open source network boot firmware. It provides a full PXE implementation enhanced with additional features such as:

• boot from a web server via HTTP
• boot from an iSCSI SAN
• boot from a Fibre Channel SAN via FCoE
• boot from an AoE SAN
• boot from a wireless network
• boot from a wide-area network
• boot from an Infiniband network
• control the boot process with a script

下面以 Ubuntu 20.04 为例来示例如何搭建一个自用的PXE Server的过程。

Configure Static IP Address

选定一个网卡作为接下来DHCP Server的外接端口，此处选定网卡 enp1s0 配置静态IP 192.168.10.10。

root@pxe-server:/home/pxe/Desktop# cat /etc/netplan/01-network-manager-all.yaml 
# Let NetworkManager manage all devices on this system
network:
 # version: 2
 # renderer: NetworkManager
  ethernets:
    enp1s0:
      dhcp4: no
      dhcp6: no
      addresses: [192.168.10.10/24]
      gateway4: 192.168.10.1
      nameservers:
        addresses: [114.114.114.114]

root@pxe-server:/home/pxe/Desktop# ifconfig
enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.10.10  netmask 255.255.255.0  broadcast 192.168.10.255
        ether xx:xx:xx:xx:xx:xx  txqueuelen 1000  (Ethernet)

也可以通过ifconfig的方法来配置临时IP，系统重启需要重新配置。有时发现重新开机后，之前配置的静态IP没有成功，那就手动配置一次，然后重新启动DHCP Server即可。

root@pxe-server:/home/pxe/Desktop# ifconfig enp1s0 192.168.10.10

Configure DHCP Service

1. 安装DHCP Server

root@pxe-server:/home/pxe/Desktop# apt install isc-dhcp-server

2. 编辑/etc/default/isc-dhcp-server
   此处选择DHCP Server要绑定的网卡 enp1s0.

root@pxe-server:/home/pxe/Desktop# cat /etc/default/isc-dhcp-server
# Defaults for isc-dhcp-server (sourced by /etc/init.d/isc-dhcp-server)

# Path to dhcpd's config file (default: /etc/dhcp/dhcpd.conf).
#DHCPDv4_CONF=/etc/dhcp/dhcpd.conf
#DHCPDv6_CONF=/etc/dhcp/dhcpd6.conf

# Path to dhcpd's PID file (default: /var/run/dhcpd.pid).
#DHCPDv4_PID=/var/run/dhcpd.pid
#DHCPDv6_PID=/var/run/dhcpd6.pid

# Additional options to start dhcpd with.
#	Don't use options -cf or -pf here; use DHCPD_CONF/ DHCPD_PID instead
#OPTIONS=""

# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
#	Separate multiple interfaces with spaces, e.g. "eth0 eth1".
#INTERFACESv4=""
#INTERFACESv6=""
INTERFACES="enp1s0" #可以用这个参数设置，避免后续报出Error/warning.

3. 编辑/etc/dhcp/dhcpd.conf
   此处配置DHCP Server的关键信息，包括IP地址段，路由，针对PXE Server，还需要包括pxe启动image, next-server.

root@pxe-server:/home/pxe/Desktop# cat /etc/dhcp/dhcpd.conf
# dhcpd.conf
#
# Sample configuration file for ISC dhcpd
#
# Attention: If /etc/ltsp/dhcpd.conf exists, that will be used as
# configuration file instead of this file.
#

# option definitions common to all supported networks...
option domain-name "example.org";
#option domain-name-servers ns1.example.org, ns2.example.org;#这行注释掉，有时导致DHCP client获取IP失败

default-lease-time 600;
max-lease-time 7200;

# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
ddns-update-style none;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;