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Ubuntu live cd

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Cesar Etxeberria edited this page Apr 12, 2020 · 12 revisions

Prepare the server

First of all we have to prepare our PXE server using one of these bootloaders

We also need to configure it as a nfs server.

Get the files from an official Ubuntu iso

If you prefer to create your own, see here.

Download a ubuntu live image from here.

wget -c http://releases.ubuntu.com/18.04.4/ubuntu-18.04.4-desktop-amd64.iso

Once downloaded, create a directory to mount the iso file and mount it. Then create a new folder inside the tftp-root and copy all the needed files there.

mkdir -p /home/tftp/livecds/ubuntu/iso
mount ubuntu-18.04.4-desktop-amd64.iso /home/tftp/livecds/ubuntu/iso
cp -r /home/tftp/livecds/ubuntu/iso/casper /home/tftp/livecds/ubuntu/

This will copy some files, filesystem.manifest filesystem.manifest-minimal-remove filesystem.manifest-remove filesystem.size filesystem.squashfs filesystem.squashfs.gpg initrd vmlinuz

We just need vmlinuz, initrd.img and filesystem.squashfs. The last one must be inside /home/tftp/livecds/ubuntu/casper folder. We will move the others.

mv /home/tftp/livecds/ubuntu/casper/vmlinuz /home/tftp/livecds/ubuntu/vmlinuz
mv /home/tftp/livecds/ubuntu/casper/initrd /home/tftp/livecds/ubuntu/initrd

Add the livecd entry to your boot menu.

Using pxelinux

nano /home/tftp/syslinux/bios/pxelinux.cfg/default

label Ubuntu live
 menu clear
 kernel /livecds/ubuntu/vmlinuz
 initrd /livecds/ubuntu/initrd
 append panic=10 ro boot=casper netboot=nfs root=/dev/nfs nfsroot=192.168.1.54:/home/tftp/livecds/ubuntu swap
 ipappend 2

Remember tha 192.168.1.54 is just an example. You must use the ip of your own nfs server. Last line (ipappend 2) is very important. When Ubuntu boots, it tries to get an ip address using dhcp, but as we are booting from pxe he already has one. With this line we are telling the system to keep it.

Using grub

nano /home/tftp/grub/grub.cfg

menuentry "Ubuntu" {
   set gfxpayload=keep
   linux /livecds/ubuntu/vmlinuz panic=10 ro boot=casper netboot=nfs root=/dev/nfs nfsroot=192.168.1.65:/home/irudiak/tftp/livecds/ubuntu ksdevice=bootif
   initrd /livecds/ubuntu/initrd.img
}

Remember tha 192.168.1.54 is just an example. You must use the ip of your own nfs server. Last part of the first command (ksdevice=bootif) is very important. When Ubuntu boots, it tries to get an ip address using dhcp, but as we are booting from pxe he already has one. With this line we are telling the system to keep it.

Using ipxe

nano /home/tftp/default.ipxe

:ubuntulive
kernel /livecds/ubuntu/vmlinuz
initrd /livecds/ubuntu/initrd.img
imgargs vmlinuz initrd=initrd.img panic=10 ro boot=casper netboot=nfs root=/dev/nfs nfsroot=192.168.1.65:/home/irudiak/tftp/livecds/ubuntu ksdevice=bootif
boot ||
goto MENU

Remember tha 192.168.1.54 is just an example. You must use the ip of your own nfs server. Last part of the first command (ksdevice=bootif) is very important. When Ubuntu boots, it tries to get an ip address using dhcp, but as we are booting from pxe he already has one. With this line we are telling the system to keep it.

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