PXEBOOT

What is PXEBOOT. The Preboot Execution Environment (PXE) is a service, Establish client/server communication and it will install the OS to the remote computer which is not loaded by any of Operating system NOTE: remote machine - enabled first boot device as NIC-PXE enabled.

PXEBOOT Important Component.

PXE BOOT STAGES 1)PXE-enabled NIC of the client(PXE client) Brodcast DHCPDISCOVER packet to UDP port 67 2)DHCP server send DHCPOFFER that contain IP address to UDP port 68 3)Now, client will be able to set their own IP address and Netmask.then PXE client send DHCPREQUEST to the DHCP server for TFTP server & Boot file name(NBP).

4)Boot server send DHCPACK packet that contain NBP filename name. 5)The NBP downloaded form TFTP server and boot it.

IN SHORT 1)Get the IP (DHCPDISCOVER & DHCPOFFER) 2)Get tftpserver IP & NBP pxelinux.0 (DHCPREQUEST & DHCPACK)

Important Port DHCP 67 - DHCP Server. DHCP 68 - DHCP Client. TFTP 69 - Trival file transfer Protocol. NBP - Network Bootstrap Program (pxelinux.o)

LAP Section 1) DHCP CONFIGURATION. 2)TFTP CONFIGURATION. 3) Setup Initial Booting Files(initrd & Vmlinuz). 4) NFS – OS IMAGE CONFIGURATION 5) BOOT MENU CONFIGURATION. 6)KICKSTART CONFIGURATION.

1)DHCP CONFIGURATION. ddns-update-style none; allow booting; allow bootp; subnet NETWORK_ID netmask SUBNET_MAST { range STARTING_IP ENDING_IP; filename "pxelinux.0"; next-server TFTPBOOT_SERVCER_IP; } NOTE : copy pxelinux.0 into TFTP- Document_root_directory.

TFTP Configuration service tftp { socket_type = dgram protocol = udp wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /var/lib/tftpboot disable = Yes – INTO NO. per_source = 11 cps = flags = IPv4 } /etc/xinetd.d/tftp - Port in 69

3)Setup Initial Booting Files(initrd & Vmlinux). 1)Mount OS IMAGE Mount -o loop OS_IMAGE.iso /mnt 2)Create OS_NAME under /var/lib/tftpboot #Mkdir -p /var/lib/tftpboot/OS_NAME 3)Copy Initial Booting files. #cp /mnt/isolinux/initrd /var/lib/tftpboot/OS_NAME #cp /mnt/isolinux/vmlinuz /var/lib/tftpboot/OS_NAME

4) NFS OS IMAGE CONFIGURATION. 1)create /export/OS_NAME 2)Copy mount_OS_IMAGE into /export/OS_NAME 3)vim /etc/exports Add the OS_IMAGE PATH.

5)Boot Message Configuration. 1)Create Directory pxelinux.cfg under /var/lib/tftpboot 2)Copy /usr/share/syslinux/menu.c32 into tftpboot- document root directory 3)For Reference see template of mboot.txt and create default fileunder /var/lib/tftpboot/pxelinux.cfg. Like UI menu.c32 Label 1 Kernel OS_IMAGE/vmlinuz append initrd=OS_IMAGE/initrd.img method=nfs:IP:/export/OS_NAME ip=dhcp

6) Kick Start Configuration. 1)System-config-kickstart – Generate kickstart file. 2) Edit boot message Configuration and add kickstart file. label 1 Kernel OS_IMAGE/vmlinuz append initrd=OS_IMAGE/initrd.img ks=nfs:IP:/export/OS_NAME/ks.cfg ip=dhcp

TEST LAP EXCERCISE 1) Remove pxelinux.o – How it will respond. 2) Change the tftpserver IP -How it will respond 3) remove pxelinux.cfg – How it will respond.