Example of TFTPd with Debian

apt-get install tftpd

The TFTP package should automatically put a proper configuration line in
/etc/inetd.conf but you might have to adapt it to your system. By default,
it will use /boot as the directory to serve TFTP files. Edit the
/etc/inetd.conf file and make sure it contains a line like this:
	tftp dgram udp wait nobody /usr/sbin/tcpd /usr/sbin/in.tftpd /home/x

chmod 777 /home/x
/etc/init.d/inetd restart

/etc/hosts.allow | /etc/hosts.deny:
	in.tftpd : FQD or IP

files cannot be written to unless they are world writable:
	touch      router-confg
	chmod 666  router-confg
	chmod a+rw router-confg

chmod:
	The format of a symbolic mode [ugoa...][[+-=][rwxXstugo...]...][,...]
	Multiple symbolic operations can be given, separated by commas.