--- /dev/null
+The internet is not short of tutorials about how to boot your Linux
+computer through the network, you will find links to some of these in
+the following. This is my own howto about that, with a focus on
+lightweight tools; the case for a diskless workstation will not be
+covered.
+
+You will be interested in this
+method for installing on a set of servers, as it doesn't involve
+moving a CD reader or USB stick around. The network method is useful
+also for a laptop or notebook, which may not have a CD reader.
+
+The network boot method is also fine for recovery, in case your boot
+sector is messed up and you can't use a CD reader.
+
+What about booting with USB, which is today present everywhere? See
+next section.
+
+# Booting using USB: maybe not so universal
+
+Probably the easiest for an individual installation... when it works!
+Three different ways to organize a USB key for booting seem to exist,
+and not all are always recognized by your BIOS. See for instance these
+references:
+
+1. [General information about bootable USB sticks](http://www.rm.com/Support/TechnicalArticle.asp?cref=TEC818956)
+1. ["Universal" USB key builder](http://advancemame.sourceforge.net/boot-readme.html)
+1. [About USB-ZIP](http://lime-technology.com/forum/index.php?topic=2407.0)
+1. [Debian USB install from hybrid iso](http://kitenet.net/~joey/blog/entry/Debian_USB_install_from_hybrid_iso/)
+1. [Boot Debian from an USB device](http://www.debian-administration.org/article/Boot_Debian_from_an_USB_device)
+
+Despite the above information, I was never able to boot using USB with
+one of my motherboard. This was actually one of the reason I wrote this: it's
+expensive to change a motherboard which doesn't cooperate, but cheap
+to get an ethernet card accepting network boot.
+
+# Network booting in a few simple steps
+
+## Configuring your BIOS
+
+You have to setup your BIOS to boot first through the network. The
+option label for this can be quite different between BIOSes, your
+motherboard manual can be handy here.
+
+If your motherboard doesn't have the option, you are screwed, but it's
+unlikely if it is from the [present millenium](http://www.kegel.com/linux/pxe.html).
+
+If can happen that even if the motherboard has the option, your
+network card doesn't have the ROM for network boot in the right
+specification (which is
+[PXE](http://en.wikipedia.org/wiki/Preboot_Execution_Environment)). Trying
+a more recent network card will help here.
+
+Reboot after BIOS change. You will get a message like "Intel UNDI,
+PXE...", and a few lines below the MAC address of your network
+card. Write it down somewhere, it will be useful later. These messages
+are sent by a program running on the network card ROM, which the BIOS
+has called because you selected "network boot".
+
+After a few seconds, an error message will appear, as no host on your
+LAN has replied to the bootp protocol requests that the ROM program
+has sent. Next step is then to setup such a host.
+
+## Setting up a bootp and tftp server
+
+The bootp server will be configured to send back after receiving a
+bootp request from a booting host:
+
+1. an IP address for the booting host
+1. the IP address of a tftp server
+1. pathname on that tftp server of a first stage bootloader
+
+After the bootp transaction finishes, the booting host will start
+downloading the first stage bootloader from the tfpt server, and pass
+control to it. In the simplest scenario, the first stage bootloader
+will in turn load kernel image and initrd from the tftp server. In a
+more complex scenario, an OS installer will be downloaded from the
+tftp server; it is how Debian does network installations. More details
+about all that later.
+
+For simplicity, I will give the configuration where bootp and tftp
+servers are the same. In the case you want separate servers, notice
+that the bootp server must be on the same ethernet link as the booting
+machine; the tftp server can be any IP reachable host.
+
+You have several options for a bootp and tftp servers, I use udhcpd
+(from [BusyBox](http://busybox.net/)) and
+[tftpd-hpa](ftp://ftp.kernel.org/pub/software/network/tftp/), which
+are lightweight compared to the competition. On Debian, this is a
+minimal /etc/udhcpd.conf configuration file:
+
+ start 192.168.0.22
+ end 192.168.0.22
+ interface eth0
+ max_leases 1
+ siaddr 192.168.0.99
+ boot_file pxelinux.0
+ option subnet 255.255.255.0
+ option lease 600
+ option router 192.168.0.254
+ option dns 8.8.8.8
+
+start and end bound the
+range of the addresses allocated by the server. Here there is only one
+possible address, as this example is for a recovery setup. Notice that
+the range must not be already allocated on your LAN, and the address
+allocated to the booting host can be limited to the time of the kernel
+download; after that you can change it. This allows for that
+configuration to be universal for network booting on your LAN.
+
+siaddr is the address of the tftp server. In case the tftp server is
+outside your subnet, you have to give a router option and a dns option.
+
+boot_file is the pathname of the first stage bootloader. The pathname
+is relative to the root directory of the tftp server, see below.
+
+For Debian, the tftpd-hpa configuration file is called
+/etc/default/tftpd-hpa and contains arguments to the daemon called
+in.tfpd:
+
+ RUN_DAEMON="yes"
+ OPTIONS="-v -l -a 192.168.0.99 -s /var/lib/tftpboot"
+
+Option -a must be consistent with siaddr above. Argument -s is the
+root directory of the files to be downloaded. So file pxelinux.0 is
+located at /var/lib/tftpboot/pxelinux.0
+
+## Putting in place files to be downloaded by tftp: OS installation
+
+I will be a bit Debian specific here, as I don't use regularly other distros.
+
+Have a look at [the Debian network installation manual](http://www.debian.org/releases/stable/i386/ch04s05.html.en),
+which gives the project blessed method for network
+installation. You will find reference to a file netboot/netboot.tar.gz
+at the end of that page, it's what you have to untar in
+/var/lib/tftpboot/. That's all!
+
+Notice: when the Debian installer asks for a network address through
+DHCP, and you let it go ahead with udhcpd, you will need a router
+and a dns option in /etc/udhcpd.conf, so as to be able to reach the internet and
+download packages.
+
+## Putting in place files to be downloaded by tftp: recovery
+
+For recovery, you can use the pxelibux.0 from Debian package syslinux-common, part of the
+[syslinux project software](http://www.syslinux.org/wiki/index.php/The_Syslinux_Project).
+Here is how the /var/lib/tftpboot looks like:
+
+ /var/lib/tftpboot/:
+ total 7545
+ drwxr-xr-x 63 root root 2048 Jun 10 22:06 ..
+ drwxr-xr-x 2 root root 1024 Oct 4 2010 pxelinux.cfg
+ -rw-r--r-- 1 root root 6165406 Oct 4 2010 initrd.img-2.6.26-1-686
+ drwxr-xr-x 3 root root 1024 Oct 4 2010 .
+ -rw-r--r-- 1 root root 1505936 Oct 4 2010 vmlinuz-2.6.26-1-686
+ -rwxr-xr-x 1 root root 15820 Oct 4 2010 pxelinux.0
+
+ /var/lib/tftpboot/pxelinux.cfg:
+ total 3
+ drwxr-xr-x 2 root root 1024 Oct 4 2010 .
+ -rw-r--r-- 1 root root 230 Oct 4 2010 01-aa-bb-cc-dd-ee-ff
+ drwxr-xr-x 3 root root 1024 Oct 4 2010 ..
+
+Notice the 01-aa-bb-cc-dd-ee-ff file: it's a syslinux configuration
+file, whose name is a network MAC address, prefixed with 01-.
+
+This a simple authorization mechanism: pxelinux.0 will look for a
+syslinux configuration file in pxelinux.cfg/ whose name
+matches the MAC address of the host doing the tftp request: if none is
+found, booting stops. So you can use a specific kernel and initrd for
+every host you want to boot through the network.
+
+Now the content of a syslinux config file fit for the above listing:
+
+ totaltimeout 50
+ timeout 50
+ ontimeout /vmlinuz-2.6.26-1-686
+ append root=/dev/sda1 ro quiet initrd=/initrd.img-2.6.26-1-686
+ label single
+ kernel /vmlinuz-2.6.26-1-686
+ append root=/dev/sda1 ro single initrd=/initrd.img-2.6.26-1-686
+
+More info about the MAC authorization mechanism and other configuration options can be found at the
+[syslinux project](http://www.syslinux.org/wiki/index.php/The_Syslinux_Project).
+
+## Final remarks
+
+You will experience that downloading the kernel and especially the
+initrd is quite slow, due to tftp using UDP packets of 512 bytes
+only. So it is a method to recommend only in case of problems, or for
+a first installation.
+
+It can be noticed that a tftp download is sent in clear and so is not
+secure.
+
+Information in this page should remain valid for
+[EFI](http://en.wikipedia.org/wiki/Extensible_Firmware_Interface)
+motherboards and architecture derived IA-32, but I have no direct
+experience of these. However, mobile computers like smartphones and
+tablets are mostly not covered.
projects / reminder / commitdiff