LinuxPlanet: Controlling Access to Your Services with xinetd

“Whenever you learn about controlling access to a Linux box, one
‘creature’ you usually encounter is the ‘superdaemon.’ A
superdaemon is a daemon that controls other daemons–and daemons
are typically network service control programs that run long-term
behind the scenes, waiting for when they need to step into
action.

“In the Linux realm, ‘the superdaemon’ has typically referred
inetd, which handles requests for a number of daemons that either
aren’t used often enough to justify running in the background all
of the time, or have such a simple job that a standalone daemon
simply isn’t needed. The problem with inetd is that this
superdaemon makes little attempt to be secure. It allows you to
disable various services if you don’t want to use them, but there
is no fine control available.

“Enter xinetd. This program is a ‘secure’ replacement for inetd,
meaning in this case that it offers many features that allow you to
control who accesses which services, and from where. I always keep
the Titanic in mind when I talk about security or safety, meaning
that nothing is fully secure, but any level of native access
control in the superdaemon certainly helps us to protect our
systems…”

Complete
Story