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Especially old computers often fail to boot from USB Sticks, but, however, can do a PXE netboot - and as a person who often wants to install stuff on old machines, or does not have a USB stick of sufficient size when needed (let alone a cd), it is a good thing to have all the necessary software installed.

Dnsmasq has everything needed: A TFTP server, a DHCP server and a DNS server. Its central configuration file (under Debian) is /etc/dnsmasq.conf.

To enable the TFTP server with a given root directory to host, the options enable-tftp and tftp-root can be used. To then actually set the pxe boot path, there is the dhcp-boot option. To activate the dhcp server, there is the dhcp-range option, that gives the IP address range that can be passed to the dhcp clients. A further important option to set is the router option, which sets the gateway IP adress. If it is not set, it defaults to your computer, and if you did not configure your computer to actually route, you will not be able to access the internet. Just set it to the appropriate gateway adress of the actual router.

A dangerous but necessary option is the autoritative option, which makes the dhcp server autoritative. Do not use this option if you are not in your own network, or know exactly what you do: It overrides your router's dhcp server, and might keep other users from connecting.

I use this setup only temporarily, to quickly install a few clients and then turn it off again. Therefore, I turn the daemon off with the appropriate option in /etc/default/dnsmasq, per default.

This setup is comparably easy (even though still complicated), and for a complicated setup like ltsp, it is not sufficient, but for the quick setup of a few computers in the network, it is nice.