Media Systems: Incorporating the TV and the HiFi - Smart Home Automation with Linux and Raspberry Pi - page 99

Creating a Server
The bootup procedure of the MediaMVP is twofold. First, it sends a DHCP request asking for an IP address of its own
and the address of a TFTP server. Second, it uses this TFTP server to download the firmware, which is what ultimately
runs on the MediaMVP to become a media device.
You begin by adding the configuration to /etc/dhcpd.conf :
group {
next-server 192.168.1.2; # IP address of your TFTP server
host mvp {
hardware ethernet 00:0d:fe:00:15:8D; # of the MediaMVP
fixed-address 192.168.1.98;
filename "dongle.bin";
}
}
The address need not be fixed; however, I've adopted a convention on my network indicating that any machine
on my subnet with an address under 100 is a “house device,” such as a server or embedded hardware, and is not liable
to change or move and therefore is always available. Everything 100 or greater is a computer that might be removed
from the network or switched off at any time.
From here, control is passed to the TFTP server, so that the MediaMVP can request the firmware, given by the
filename dongle.bin .
TFTP stands for Trivial File Transfer Protocol, which is a very much simplified version of the usual FTP often used
to copy files between machines. It's installed as normal:
apt-get install atftpd
This will add the appropriate lines to /etc/inetd.conf and /etc/default/atftp , indicating the directory for file
transfers (usually /var/lib/tftpboot ). The primary distinction with TFTP from my point of view is that no username
and passwords can be employed with TFTP. Although this might have made the programmer's original job very much
simpler, it was at the expense of security, meaning that you should not open the TFTP port (UDP 69) to the world.
You can then copy the dongle.bin file to the /tftpboot folder and switch on the MediaMVP. From here, it is a
simple matter to replace dongle.bin with one of the other firmwares available to the MediaMVP, such as MVPMC,
to provide improved functionality, such as real-time video transcoding or connecting with MythTV.
MediaMVP Media Center
This is probably the most fully featured alternate firmware currently available; it's downloadable from
http://www.mvpmc.org . It comprises a replacement dongle.bin and a configuration file. Because MediaMVP itself is
running a small version of Linux, this configuration file is, conveniently, simply a script containing shell commands,
which makes it very simple to make amendments to the firmware image without rebuilding it. At a bare minimum,
it should contain commands to mount directories into the filesystem and invoke the main mvpmc program:
mkdir /media
mount.cifs "//192.168.1.110/media" /media -o user=mvp,pass=mvppass,rsize=34000;
mvpmc &
You can then add arguments to this command according to the extra functionality you want to introduce. I'll now
cover some of them.