Download Building Embedded Linux Systems

If you need to install TFTP and don’t have a package available for your distribution,
the latest version of the daemon is available for download as part of the NetKit package
at ftp://ftp.uk.linux.org/pub/linux/Networking/netkit.
With the package installed, enable the TFTP service by modifying the appropriate Internet super-server configuration file. In brief, the super-server listens on designated
ports on behalf of the various network services. When a request for a certain service is
received, the super-server spawns the appropriate daemon and hands it the request.
Hence, only the minimal number of daemons run at any time. TFTP is one of the
daemons normally handled by the super-server.
To enable the TFTP service in a system based on the inetd super-server, edit /etc/in
etd.conf, uncomment the line for the TFTP service by removing the # character at the
beginning, and send a SIGHUP signal to the inetd process so that it rereads its configuration file.
To enable the TFTP service in a system based on the xinetd super-server, edit /etc/
xinetd.d/tftp and comment out the line containing disable = yes by adding a # character
at the beginning. As with inetd, you must send a SIGHUP to xinetd.
Finally, you must provide the TFTP server with a list of directories containing files that
should be made available to TFTP clients. In a system based on the inetd super-server,
append the list of directories to the TFTP line in /etc/inetd.conf. In a system based on
the xinetd super-server, edit the /etc/xinetd.d/tftp file and append the list of directories
to the server_args = line. The default directory for TFTP is /tftpboot. You may choose
to modify this to match your setup. Whichever directory you choose, make sure its
access permissions include read and execute permissions for “other.”
For example, here is a TFTP line in /etc/inetd.conf for a host using the inetd super-server:
tftp
dgram
udp
wait
root
/usr/sbin/tcpd in.tftpd /data/kernel/
In this case, kernel images are placed in the /data/kernel directory, which has the following permissions:
$ ls -ld /data/kernel/
drwxr-xr-x 2 jcm jcm 4096 2008-02-24 03:52 /data/kernel/
Here is a modified /etc/xinetd.d/tftp file from a Fedora-based installation providing the
same functionality for a host using the xinetd super-server:
service tftp
{
socket_type
protocol
wait
user
server
server_args
#
disable
per_source
282 | Chapter 9: Setting Up the Bootloader
=
=
=
=
=
=
dgram
udp
yes
root
/usr/sbin/in.tftpd
/data/kernel
= yes
= 11