Telnet sessions limit by user.

[Jose Cristovao]

I need to limit the number of telnet sessions opened by the same user.

[Steven E. Protter · Accepted solution]

Run a little script with cron on a regular interval:

ps -ef | grep telnetd | awk '{print $1} > /tmp/file

while read -r username
do
numsession=$(ps -ef | grep $username | grep telnetd | wc -l)
if [ numsession -gt 1 ]
then
pid=$(ps -ef | grep $username | awk '{print $2}')
kill $pid
fi
done < /tmp/file

Some code modification required for smooth operation. Depending on the application that is being used, you may need to add code to handle smooth session shutdown.

Even better: in /etc/profile

telsession=$(ps -ef | grep $LOGNAME | grep telnetd| wc -l)

if [ telsession -ge 1 ]
then
echo "already logged in, one session per customer"
sleep 15
exit
fi

Take out the sleep to avoid user breaking to the shell.

SEP

[Doug O'Leary]

Hey;

The /etc/profile mod is probably the best bet; however, it doesn't take into account other access methods such as ssh or rlogin. You could run a ps -ef | grep ${user} | grep ksh to find out if the user has an active shell. Another good modification would be to have an exclusion list. For instnace, sysadmins and dbas could be allowed to have multiple sessions while normal users are only allowed one.

If you're absolutely sure that the only access method is telnet, then the /etc/profile mod as written will do what you want.

HTH;

Doug

[Gopi Sekar]

if you want it instantaneous then put it /etc/profile

or from a cron job:

w | wc -l

minus the count by 2 to take care of the title output of w

then take the decision

Regards,
Gopi

[DCE]

You can set the max number of logins allowed per non root user in /etc/default/security. You simply set NUMBER_OF_LOGINS_ALLOWED=X, where X is the max number of telent sessions you want any user to have

Dave

[Steven E. Protter]

Didn't know about that option in the security file.

Anyone test it?

SEP
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