PXE Boot - Boot Your Machine Over the Net

See http://syslinux.zytor.com/

At certain times of the year I might be attempting to install dozens of machines for our cluster. Inserting a CD is fine for one, not for twenty. Of more interest, though, is that I want a variety of things to boot. I want a Debian Stable ISO to boot. Most importantly, I want to boot Dell diagnostics.

This process usings something called PXE. It requires your machine's BIOS to make a request of a TFTP server for a bootable image (the equivalent of inserting a CD and booting). Most modern higher-end machines can do this - and particularly all Dell PowerEdge machines, which is what I support. I use a Debian distribution, so what follows is debianish. Whatever you have will almost certainly have something similar. You should also check out the SARA package of utilities at https://subtrac.sara.nl/oss/pxeconfig.

• Install a tftp server. I chose atftpd and did the following:

    apt-get install atftpd
  
    # Set up atftpd  (do not use inetd, since it hardly ever gets used)
    touch /var/log/atftp.log     # Enable logging
    vi /etc/default/atftpd
      USE_INETD=false
      #  verbose=7 --trace will trace every packet
      OPTIONS="--daemon --verbose --tftpd-timeout 10 --retry-timeout 5 \
        --mcast-port 1758 --mcast-addr 192.168.0.0-65535 --mcast-ttl 10 \
        --maxthread 10 --verbose=5 --logfile=/var/log/atftp.log /tftpboot"
    update-inetd --disable tftp
    /etc/init.d/atftpd restart
  

  
  
  
• Install syslinux and set up a TFTP boot server. DHCP can do this for you. Here's what I did:

    apt-get install syslinux
    mkdir -p /tftpboot/boot tftpboot/pxelinux.cfg
    chmod 777 /tftpboot
    # Copy files from syslinux distribution to /tftpboot
    cp -p /usr/lib/syslinux/pxelinux.0 /tftpboot
    cp -p /usr/lib/syslinux/menu.c32   /tftpboot
    cp -p /usr/lib/syslinux/memdisk    /tftpboot/boot
  

  
  
  
• Configure dhcp so it allows a TFTP boot to happen. I won't provide the all DHCP details, but for this step all you need do is add some lines like this to your dhcp.conf file. Yes, the pxelinux.0 file you see below is the same one from the previous step.

  allow booting;
  allow bootp;
  filename "/tftpboot/pxelinux.0";
  next-server 192.168.1.5;
  

  
  
  
• Make default menus for pxelinux. Note that executables to be run (kernel keyword) cannot have special chars. Keep these names v-e-r-y simple. The menu.c32 is a small program to generate a menu so you can select what to do. Here's what I have right now:

  cat /tftpboot/pxelinux.cfg/default
  DEFAULT menu.c32
  PROMPT 0
  MENU TITLE CSG PXE Boot Menu
  TIMEOUT 100
  
  #   First one is default unless 'DEFAULT name' specified
  LABEL delldiags
    MENU LABEL Dell Diagnostics (EW5091A1 DOS mode)
    kernel boot/memdisk
    append initrd=boot/delldiag.img
  
  LABEL installi386
    MENU LABEL Install Debian Etch I386 over Network
    kernel boot/debian/i386/linux
    append vga=normal initrd=boot/debian/i386/initrd.gz -- 
  

  
  
  
• Get memtest from http://www.memtest.org. Download the file labelled Download - Pre-Compiled package for Floppy (DOS - Win) and then do:

    cd /tmp    # or some directory for temporary files
    unzip memtest86+-1.70.floppy.zip 
    cp -p floppy/memtestp.bin  /tftpboot/boot/memtestp
    rm -rf /tmp/floppy
  

  
  
  
• Get the Debian network installer (or your favorite). The process for this is described in: http://www.debian.org/releases/stable/i386/ch04s06.html.en, http://www.debian.org/releases/stable/i386/ch04s02.html.en#where-files, and http://ftp.debian.org/debian/dists/etch/main/installer-i386/current//images/netboot/. Fetch netboot.tar.gz and extract it in a safe place:

    mkdir -p /tftpboot/boot/debian/i386
    cd where-netboot-extracted
    cp -p debian-installer/i386/linux     /tftpboot/boot/debian/i386
    cp -p debian-installer/i386/initrd.gz /tftpboot/boot/debian/i386
    # Edit /tftpboot/pxelinux.cfg/default and add an entry from pxelinux.cfg/default as necessary.
  

• Get Dell diagnostics from http://support.dell.com/.
  • Select Drivers and Downloads
  • Select product by model, service tag or whatever. PowerEdge works fine, others apparently do not
  • At page Drivers and Downloads Search Criteria, select Operating System as MS-DOS
  • Select Diagnostics
  • Download the 2MB image
  • Extract on a Windows system. What! Of course, remember it's called a MONOPOLY. Fine, visit one of your poor friends who are stuck on a Windows machine. Copy the 2MB file to the Windows machine, then execute it. This program copies files to a directory and invokes an application which will create Floppy boot images, USB boot image or a 'Bootable Image'
  • Select Bootable Image and save the *.img file
  • Copy the *.img file back to your Linux and do cp -p diags.img /tftpboot/boot/delldiag.img
  • Edit /tftpboot/pxelinux.cfg/default and add an entry for Dell diagnostics as necessary
  
  
  

You should now be able to boot a machine on your DHCP network and choose to boot from the network. On Dell machines this is F12 labelled 'PXE Boot'. If all went well, you should get a menu showing you several things defined in /tftpboot/pxelinux.cfg/default and allow you to boot from these.

I must tell you, it's a real joy to PXE boot and run diagnostics so easily. Good job, Dell.