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 set up 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.
One free software DHCP server is ISC dhcpd.
For Ubuntu, the isc-dhcp-server
package is
recommended. Here is a sample configuration file for it (see
/etc/dhcp/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.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/isc-dhcp-server restart
.
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 isc-dhcp-server
packages respectively.
To use CMU bootpd, you must first uncomment (or
add) the relevant line in /etc/inetd.conf
. On
Debian 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 Section 4.4.4, “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 Section 4.4.1, “Setting up a DHCP server”. Otherwise 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 in
/etc/dhcp/dhcpd.conf
, and restart
dhcpd with /etc/init.d/isc-dhcp-server
restart
.
To get the TFTP server ready to go, you should first make sure that tftpd is enabled.
In the case of tftpd-hpa
there are two ways the
service can be run. It can be started on demand by the system's
inetd
daemon, or it can be set up to run as an
independent daemon. Which of these methods is used is selected when the
package is installed and can be changed by reconfiguring the package.
Note | |
---|---|
Historically, TFTP servers used |
All in.tftpd alternatives available in Ubuntu should
log TFTP requests to the system logs by default. Some of them support a
-v
argument to increase verbosity.
It is recommended to check these log messages in case of boot problems
as they are a good starting point for diagnosing the cause of errors.
Next, place the TFTP boot image you need, as found in Section 4.2.1, “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.