## Trimming Down inetd.conf
## Alex Zepeda <garbanzo@hooked.net>

inetd is essentially the internet "super server".  It will listen on 
various ports (UDP and TCP) and run small servers (well even apache
can be tweaked to use inetd).  It's very convenient, because once you
specify all the valid servers in the configuration file 
(/etc/inetd.conf) you only need to run inetd to start them all up (and
inetd is usually started up by default).  However, inetd is a bad idea
for bigger servers (ftp, web, smtp, etc.).  This is due to the way 
that connections are handled by inetd.  By default, inetd is set to
run all sorts of servers, many of which are probably not needed by the
average user (or server).  Lines in /etc/inetd.conf that start with a
# are comment lines.

Examples of unneeded servers are:

	shell   stream  tcp     nowait  root    /usr/libexec/rshd       rshd
	login   stream  tcp     nowait  root    /usr/libexec/rlogind    rlogind

rsh and rlogin are both quite similar to telnet, but a bit more 
insecure due to the fact that you can set them to not prompt for
passwords based on hostnames of the person trying to connect.  In
turn, this can be faked easily enough to cause trouble.  Using ssh is
a better alternative.

	echo   stream  tcp     nowait  root    internal
	echo   dgram   udp     wait    root    internal

These are dangerous because anything that is sent to these ports will
be sent back, creating an easy way to waste bandwidth.

	chargen stream tcp     nowait  root    internal
	chargen dgram  udp     wait    root    internal

These two are even more dangerous, because these will send data (it
iterates through the ascii values) without stopping, creating a huge
bandwidth waste (the last four were commented out by default).

Restarting inetd is somewhat of a black art, but generally, you can
check in /var/run/inetd.pid to find the process id of inetd, and then
kill <process-id>, wait a few seconds and run "inetd" again to restart
it.

Another method is if you use the sh or bash (anything sh derived)
shell.  Anything between two `'s (i.e. `foo`) will be executed, and
the output of foo substituted.

So if you type kill `cat /var/run/inetd.pid`, this will take the
contents of /var/run/inetd.pid (in this case the process id of inetd),
and use it as an argument for the kill command.

- Alex

$Id: inetd.txt,v 1.1 2000/02/16 08:07:53 jim Exp $