Offering external services, rlogins, smtp etc: how does it work?

[Mark Phillips <mark@ist.flinders.edu.au>]

Hi, 

I am a little confused about how the external services thing works.

Suppose for example you want to allow exteral rlogins to your
computer.  I presume you modify the inetd.conf file to include the line:

login stream tcp nowait root /usr/sbin/tcpd /usr/sbin/in.rlogind

Now when is this file read?  Is it only when you do something like
"/etc/init.d/inetd restart", or is it whenever an external machine
asks to connect to one of your ports?

Now am I right in thinking that there is not an rlogin daemon running
all the time, listening for rlogin connections?  I think what happens
is that inetd listens for connections, and then if it receives one for
rlogin, it executes in.rlogind --- one for each incomming connection
--- is that right?

Now the above is all correct, I'm still a little confused, because
what about smtp?  Currently I have the following line in inetd.conf

#disabled#smtp stream tcp nowait mail /usr/sbin/exim exim -bs

So it is disabled, yet mail still works on my system!  Is this because
it is handled through a different mechanism?  I notice that I have the
following process:

mail 286 0.0 0.3 2324 204 ?  S Jun24 0:00 /usr/sbin/exim -bd -q30m

Which I am guessing does the job instead of inetd?  If so, why do it
this way instead of through inetd?

Any clarifications of my understanding of these things would be much
appreciated.

Thanks,

Mark.

P.S. Please cc replies directly to me, as I read this list via the
archives and there is a few day delay.

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        "They told me I was gullible ... and I believed them!"