This post will be helpful for linux admins who frequently installs diff linux os. PXE boot is one of the best option to start linux installation & for rescue of the other failed systems. we are using CentOS as pxe boot server.

Install tftp-server

yum install -y tftp-server

Enable tftp server

vi /etc/xinetd.d/tftp
service tftp
socket_type             = dgram
protocol                = udp
wait                    = yes
user                    = root
server                  = /usr/sbin/in.tftpd
server_args             = -s -vv /tftpboot
disable                 = no
per_source              = 11
cps                     = 100 2
flags                   = IPv4

Start tftp server and mark it for system startup

service xinetd restart
chkconfig --level 35 xinetd on

We have to download the latest version of syslinux and build the rpm cause there are some bugs in the existing version that ships with centos.

cd /root
tar -zxvf syslinux-3.86.tar.gz
cp syslinux-3.86/syslinux.spec /usr/src/redhat/SPECS/
cp syslinux-3.86.tar.gz /usr/src/redhat/SOURCES

Now building the rpm

cd /usr/src/redhat/SPECS
sed -i 's/BuildPrereq: nasm >= 2.03, perl/BuildPrereq: perl/g' /usr/src/redhat/SPECS/syslinux.spec
rpmbuild -ba syslinux.spec

Installing rpm

cd /usr/src/redhat/RPMS/i386
rpm -Uvh syslinux-3.86-1.i386.rpm

Copy needed files from syslinux to the tftpboot directory

cp /usr/share/syslinux/pxelinux.0 /tftpboot
cp /usr/share/syslinux/menu.c32 /tftpboot
cp /usr/share/syslinux/memdisk /tftpboot
cp /usr/share/syslinux/mboot.c32 /tftpboot
cp /usr/share/syslinux/chain.c32 /tftpboot

Create a base directory for images. Create directories for each CentOS release you are supporting.

mkdir -p /tftpboot/images/centos/i386/5.4
cp /tmp/dvd-centos-54/images/pxeboot/vmlinuz /tftpboot/images/centos/i386/5.4/
cp /tmp/dvd-centos-54/images/pxeboot/initrd.img /tftpboot/images/centos/i386/5.4/

Configure dhcp-server.
Add this to your existing or new /etc/dhcpd.conf.
Note: is the IP address of your PXE server
For configuring dhcp server you can check my previous post

allow booting;
allow bootp;
next-server; # IP of my PXE server
filename "/pxelinux.0";
service dhcpd restart

Create the directory for your PXE menus

mkdir /tftpboot/pxelinux.cfg

My sample config file

vi /tftpboot/pxelinux.cfg/default
default menu.c32

prompt 0
timeout 50
ONTIMEOUT localboot


LABEL localboot
MENU LABEL Boot From Hard Disk

LABEL CentoS 5.4 i386 Installer
MENU LABEL CentOS 5.4 i386 Installer
KERNEL images/centos/i386/5.4/vmlinuz
append vga=normal initrd=images/centos/i386/5.4/initrd.img ramdisk_size=32768

Now start the client machine, boot it from lan, it should get a DHCP lease, and start booting successfully from the network
For troubleshooting check /var/log/messages

PXE Boot server on CentOS

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