Build a PXE Boot Server

Author:

Dimitry Dukhovny

Installing a pre-boot execution environment (PXE) in your network takes some planning and should only exist in your DHCP sandbox, not in production.

Required packages under Centos/RHEL/Fedora

yum -y install httpd xinetd syslinux tftp-server mtools
# Do not forget SELinux
setsebool -P tftp_anon_write 1
setsebool -P tftp_home_dir 1

• httpd is the Apache web server

• xinetd is the extended inetd that will trigger the tftp server

• syslinux is a boot loader bundling ISO, PXE, and EXT Linux boots

• tftp-server is the trivial file transfer protocol server

• mtools is an MSDOS disk management suite

Stage OS disk

For this example, we will use Centos7 from the DVD ISO.

mount -o loop /mnt/images/Centos7-DVD.iso /mnt/pxe/centos7

Web server

/etc/httpd/conf.d/pxe.conf

Alias /centos7 /mnt/pxe/centos7
<Directory /mnt/pxe/centos7>
Options Indexes FollowSymLinks
Order Deny,Allow
Allow from all
<Directory>

Then, bounce Apache.

OS stage

• Copy boot loaders to TFTP server location

mkdir /var/lib/tftpboot
ln -s /usr/share/syslinux/* /var/lib/tftpboot/
mkdir /var/lib/tftpboot/centos7
ln -s /mnt/pxe/centos7/images/pxeboot/* /var/lib/tftpboot/centos7/
mkdir /var/lib/tftpboot/pxelinux.cfg
touch /var/lib/tftpboot/pxelinux.cfg/default

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

default menu.c32
prompt 0
timeout 300
ONTIMEOUT 1

menu title CentOS 7 PXE Menu

label 1
menu label ^1) Install CentOS 7
menu default
kernel centos7/vmlinuz
append initrd=centos7/initrd.img method=http://10.168.123.11/centos7 devfs=nomount

label 2
menu label ^2) Boot from local drive
localboot 0

Services

• Set “disable=yes” to be “disable=no” in xinetd.d/tftp

/etc/xinetd.d/tftp

service tftp
{
        socket_type             = dgram
        protocol                = udp
        wait                    = yes
        user                    = root
        server                  = /usr/sbin/in.tftpd
        server_args             = -s /var/lib/tftpboot
        disable                 = no
        per_source              = 11
        cps                     = 100 2
        flags                   = IPv4
}

/usr/lib/systemd/system/tftp.service

[Unit]
Description=Tftp Server

[Service]
ExecStart=/usr/sbin/in.tftpd -c -s /tftpboot
StandardInput=socket

[Install]
WantedBy=multi-user.target

systemctl restart xinetd
systemctl enable xinetd
systemctl restart httpd
systemctl enable httpd
# Open port 80 for fetching Linux bits
firewall-cmd --permanent --add-service=http
# Open port 69 for TFTP itself
firewall-cmd --permanent --add-port=69/udp
firewall-cmd --permanent --add-port=69/tcp
firewall-cmd --reload