Debian and Ubuntu place startup files for all deamons in /etc/init.d. Symbolic links are then placed in /etc/rc.X to control when deamons are to be started and stopped. While it would certainly be possible to manage it manually, there are a few tools that makes life easier whenever you want to control which daemons are started by default.
usage: update-rc.d [-n] [-f]
remove update-rc.d [-n] defaults|multiuser [NN | sNN kNN] update-rc.d [-n] start|stop NN runlvl [runlvl] [...] . -n: not really -f: force