How to create a PXEboot for tails OS?

Question

I have a PC that can only boot from DD or network. It is standard bios (not UEFI). I have managed to set-up a PXE boot infrastructure and I've been able to install different Debian based OS on the PC.

For Tails, I'm not able to make it working.

I have tried by extracting some files from the .iso to the TFTP server and adding the following in pxelinux.cfg/default:

label 3
menu label ^3) Install Tails OS
kernel tails/vmlinuz
append  initrd=tails/initrd.img

And when I boot the PC, Tails tells me that it can't initialise as it says root device is missing.

I also tried with the .img file for usbdisk and the following config:

label 4
menu label ^4) Install Tails OS img
kernel memdisk
append  initrd=tailsimg/tails.img

This time the boot is going further. I can see tails page, but then it stall and indicates that he can't find the medium with a live instance.

Answer 1

You cannot use the memdisk approach on targets that switch to protected mode during the boot process, that rules out really a lot of targets.

In order to Net boot Tails you can see what Serva does here, basically:

;-Serva v3.0 Asset Information File
;-Boot/Install:
;  Tails Linux Live
;-Tested on: 
;  tails-amd64-4.7.iso
;  tails-amd64-4.5.iso
;  tails-amd64-4.4.1.iso

[PXESERVA_MENU_ENTRY] asset    = Tails Live 4.7 platform = amd64

kernel_bios    = /NWA_PXE/$HEAD_DIR$/live/vmlinuz 
append_bios    = initrd=/NWA_PXE/$HEAD_DIR$/live/initrd.img,/NWA_PXE/$HEAD_DIR$/live/INITRD_N26.5.GZ boot=live config live-media=removable nopersistence noprompt timezone=Etc/UTC block.events_dfl_poll_msecs=1000 noautologin module=Tails slab_nomerge slub_debug=FZP mce=0 vsyscall=none page_poison=1 init_on_alloc=1 init_on_free=1 mds=full,nosmt fetch=http://$IP_BSRV$/NWA_PXE/$HEAD_DIR$/live/filesystem.squashfs ipby=dhcp ro ipv6.disable=1   
ipappend_bios  = 2

kernel_efi64   = /NWA_PXE/$HEAD_DIR$/live/vmlinuz 
append_efi64   = initrd=/NWA_PXE/$HEAD_DIR$/live/initrd.img,/NWA_PXE/$HEAD_DIR$/live/INITRD_N26.5.GZ boot=live config live-media=removable nopersistence noprompt timezone=Etc/UTC block.events_dfl_poll_msecs=1000 noautologin module=Tails slab_nomerge slub_debug=FZP mce=0 vsyscall=none page_poison=1 init_on_alloc=1 init_on_free=1 mds=full,nosmt fetch=http://$IP_BSRV$/NWA_PXE/$HEAD_DIR$/live/filesystem.squashfs ipby=dhcp ro ipv6.disable=1 
ipappend_efi64 = 2

As you can see Serva provides an aditional initrd (INITRD_N26.5.GZ) that contains the components and scripts in order to properly PXE Tails. The info provided works on version 4.7 for newer version you have to try and see if a new version of the additional initrd is needed or not.

If you do not use Serva you can easily adapt the provided lines to your Pxelinux or Grub environment