If your machine is connected to a local area network, you may be able to boot it over the network from another machine, using TFTP. If you intend to boot the installation system from another machine, the boot files will need to be placed in specific locations on that machine, and the machine configured to support booting of your specific machine.
You need to setup a TFTP server, and for many machines a DHCP server, or BOOTP server.
BOOTP is an IP protocol that informs a computer of its IP address and where on the network to obtain a boot image. The DHCP (Dynamic Host Configuration Protocol) is a more flexible, backwards-compatible extension of BOOTP. Some systems can only be configured via DHCP.
The Trivial File Transfer Protocol (TFTP) is used to serve the boot image to the client. Theoretically, any server, on any platform, which implements these protocols, may be used. In the examples in this section, we shall provide commands for SunOS 4.x, SunOS 5.x (a.k.a. Solaris), and GNU/Linux.
![[Note]](../../libs/admon/note.png)
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To use the Pre-boot Execution Environment (PXE) method of TFTP
booting, you will need a TFTP server with |
There are two BOOTP servers available for GNU/Linux. The first is CMU
bootpd. The other is actually a DHCP server: ISC
dhcpd. In Ubuntu these are contained in the
bootp and dhcp3-server
packages respectively.
To use CMU bootpd, you must first uncomment (or
add) the relevant line in /etc/inetd.conf. On
Debian GNU/Linux or Ubuntu, you can run update-inetd --enable
bootps, then /etc/init.d/inetd
reload to do so. Just in case your BOOTP server does not
run Debian or Ubuntu, the line in question should look like:
bootps dgram udp wait root /usr/sbin/bootpd bootpd -i -t 120
Now, you must create an /etc/bootptab file. This
has the same sort of familiar and cryptic format as the good old BSD
printcap, termcap, and
disktab files. See the
bootptab manual page for more information. For
CMU bootpd, you will need to know the hardware
(MAC) address of the client. Here is an example
/etc/bootptab:
client:\
hd=/tftpboot:\
bf=tftpboot.img:\
ip=192.168.1.90:\
sm=255.255.255.0:\
sa=192.168.1.1:\
ha=0123456789AB:
You will need to change at least the “ha” option, which specifies the hardware address of the client. The “bf” option specifies the file a client should retrieve via TFTP; see the section called “Move TFTP Images Into Place” for more details.
By contrast, setting up BOOTP with ISC dhcpd is
really easy, because it treats BOOTP clients as a moderately special
case of DHCP clients. Some architectures require a complex
configuration for booting clients via BOOTP. If yours is one of
those, read the section the section called “Setting up a DHCP server”. In that case, you
will probably be able to get away with simply adding the
allow bootp directive to the configuration
block for the subnet containing the client, and restart
dhcpd with /etc/init.d/dhcpd3-server
restart.
One free software DHCP server is ISC dhcpd.
For Ubuntu, the dhcp3-server package is
recommended. Here is a sample configuration file for it (see
/etc/dhcp3/dhcpd.conf):
option domain-name "example.com";
option domain-name-servers ns1.example.com;
option subnet-mask 255.255.255.0;
default-lease-time 600;
max-lease-time 7200;
server-name "servername";
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.200 192.168.1.253;
option routers 192.168.1.1;
}
host clientname {
filename "/tftpboot/tftpboot.img";
server-name "servername";
next-server servername;
hardware ethernet 01:23:45:67:89:AB;
fixed-address 192.168.1.90;
}
In this example, there is one server
servername which performs all of the work
of DHCP server, TFTP server, and network gateway. You will almost
certainly need to change the domain-name options, as well as the
server name and client hardware address. The
filename option should be the name of the
file which will be retrieved via TFTP.
After you have edited the dhcpd configuration file,
restart it with /etc/init.d/dhcpd3-server restart.
Here is another example for a dhcp.conf using the
Pre-boot Execution Environment (PXE) method of TFTP.
option domain-name "example.com";
default-lease-time 600;
max-lease-time 7200;
allow booting;
allow bootp;
# The next paragraph needs to be modified to fit your case
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.200 192.168.1.253;
option broadcast-address 192.168.1.255;
# the gateway address which can be different
# (access to the internet for instance)
option routers 192.168.1.1;
# indicate the dns you want to use
option domain-name-servers 192.168.1.3;
}
group {
next-server 192.168.1.3;
host tftpclient {
# tftp client hardware address
hardware ethernet 00:10:DC:27:6C:15;
filename "pxelinux.0";
}
}
Note that for PXE booting, the client filename pxelinux.0
is a boot loader, not a kernel image (see the section called “Move TFTP Images Into Place”
below).
To get the TFTP server ready to go, you should first make sure that
tftpd is enabled. This is usually enabled by having
something like the following line in /etc/inetd.conf:
tftp dgram udp wait nobody /usr/sbin/tcpd in.tftpd /tftpboot
Ubuntu packages will in general set this up correctly by default when they are installed.
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Historically, TFTP servers used |
Look in /etc/inetd.conf and remember the directory which
is used as the argument of in.tftpd[3]; you'll need that below.
If you've had to change /etc/inetd.conf, you'll have to
notify the running inetd process that the file has changed.
On an Ubuntu or Debian machine, run /etc/init.d/inetd reload; on
other machines, find out the process ID for inetd, and run
kill -HUP .
inetd-pid
Next, place the TFTP boot image you need, as found in the section called “Where to Find Installation Images”, in the tftpd boot image directory. You may have to make a link from that file to the file which tftpd will use for booting a particular client. Unfortunately, the file name is determined by the TFTP client, and there are no strong standards.
For PXE booting, everything you should need is set up in the
netboot/netboot.tar.gz tarball. Simply extract this
tarball into the tftpd boot image directory. Make sure
your dhcp server is configured to pass pxelinux.0
to tftpd as the filename to boot.
[3]
The -l argument enables some versions of
in.tftpd to log all requests to the system logs;
this is useful for diagnosing boot errors.
