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To: gestur@islandia.is (Gestur A. Grjetarsson)
From: gestur@islandia.is (Gestur A. Grjetarsson)
Subject: Re: prevent paralell modem connection
Cc: freebsd-hackers@freebsd.org, freebsd-questions@freebsd.org,
        admin@islandia.is
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> Hello,
> 
> I'd like to ask you,
> 
> Could users on FreeBSD system hold two or more modem connections at
> same time, parallel logged on ?

Sure.

> If so, is there a way to prevent people to be able to get connection on
> the system from two or more places at one time, like if users share their
> accounts, taking two modems and only paying for one account ?

Sure.  Stick a "cron" job in to count the number of times that a user is on
a tty line.  Think about something like:

#! /bin/sh -

PATH=/bin:/usr/bin; export PATH

who | grep " ttyd" | sort | uniq -c | (
	while read count user; do
		if [ ${count} -gt 1 ]; then
			kill -HUP `ps agxu | grep "^${user} " | awk '{print $2}'`
		fi
	done
)

This is of course very simplistic but could be effective if run out of cron,
say, every 5 minutes (excuse any errors, I have NOT tested it, you shouldn't
run it unless you understand what it is doing and can fix my bugs)...

This is simpler than the network/X11 pty case, of course..  ;-)

> My system has limited amount of modems attached, so it would be of good
> appreaciation if I could manage to prevent parallel modem connections for
> one user.

... Joe

-------------------------------------------------------------------------------
Joe Greco - Systems Administrator			      jgreco@ns.sol.net
Solaria Public Access UNIX - Milwaukee, WI			   414/342-4847


   Međ kveđju,
   Sincerely,

   -----------------------------------------------------------
   Gestur A. Grjetarsson
   kerfisstjóri islandia.is               sysadmin islandia.is

         Islandia, Grensásvegur 7, 2h.t.h., 108 Reykjavik
            sími 5884020, modem 5884120, fax 5884014

                     http://www.islandia.is
                http://www.islandia.is/english.htm

   -----------------------------------------------------------
     Programmers never die, they just GOSUB without RETURN !