PXE Boot server on CentOS

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 tftp-server -y

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
#wget http://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-3.86.tar.gz
#tar -zxvf syslinux-3.86.tar.gz
#cp syslinux-3.86/syslinux.spec /usr/src/redhat/SPECS/
#cd ..
#cp syslinux-3.86.tar.gz /usr/src/redhat/SOURCES

Now building the rpm
#cd /usr/src/redhat/SPECS
#rpmbuild -ba syslinux.spec

Installing rpm
#cd /usr/src/redhat/RPMS/i386
#rpm -ivh 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: xxx.xxx.xxx.xxx is the IP address of your PXE server
Configuring dhcp server on centos

allow booting;
allow bootp;
next-server xxx.xxx.xxx.xxx; # 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  
 
MENU TITLE PXE Menu  
   
LABEL localboot  
MENU LABEL Boot From Hard Disk  
LOCALBOOT  0  

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
Credits