Restricting users to one login session

[Kevin Moore_2]

Hi,

I was wondering if anyone could help me. I want to restrict certain users to one login session each. Any idea of how I would do that?

Thanks,
Kevin

[Sarah Mokwana · Accepted solution]

Hi Kevin

You'll need to vi .profile of that user. DO
this:
#limit number of of logins allowed
Time_allowed = 1
Time_in = "who | grep $LOGNAME | wc -1"
if [$Time_in -gt "$Time_allowed"]
then
echo "$LOGNAME is already logged in $Time_allowed times"
exit
exec /bin/login
fi

Then you'll have to chmod 444 and chown root .profile.

Hope this will help.

[Alexander M. Ermes]

Hi there.
Add these lines to the .profile :

no_of_users=`ps -ef|grep $LOGNAME|grep -v grep |wc -l`


export no_of_users
#
if test "$no_of_users" -gt 3
then
tput clear
echo "You are already logged in more than once......"
echo "Number of: $LOGNAME user logged in: $no_of_users"
echo "exiting......"
sleep 2
exit 1
else
exec .....
fi



Rgds
Alexander M. Ermes

[Brendan Newport]

You could give this a try;

last -R | grep -v grep |grep $USER | grep "still logged in"
if [ $? = 0 ]
then
exit
fi

The routine would go in individual users login scripts, or in /etc/profile with a case routine to identify users you don't want to have multiple logins (or you could perform it on a particular group by checking the $USER(s) GID in /etc/passwd ;

[Stefan Farrelly]

Heres a couple of ways of preventing multiple logins;

SOLUTION 1:
Heres a script to test for multiple logins, just call it from /etc/profile

nologin()
{
#nologin - test for user name already logged in
num=1
u=$LOGNAME
if [ "$u" = "" -o "$u" = "root" ]
then
num=1
else
num=`who| cut -d" " -f1|grep "^$LOGNAME"$|wc -l`
fi

if [ $num -gt 1 ]
then
echo yours would be login number $num of name $LOGNAME
echo this is a big no-no!
echo please assign password to your login
echo if somebody else used your name, notify D.P. department
echo it is vital to the system\'s well being to know who the users are
echo it is with a heavy processor, that i have to deny you access.
echo have a nice day nevertheless - HAL very junior
exit
#else
# echo you are the one and only $LOGNAME - enjoy!

fi
}

SOLUTION 2:
"We use idled which works very well for both session limitations, multiple user viloations and idle limitations. You can obtain the source from ftp.cs.hope.edu in /pub/idled . This compiles just fine, and installs. This solution has idle limitations, or multiple user and session limitations, depending on which you want to use.

[Stephen Tatrai]

We use

if (( $( who | grep -c $LOGNAME ) > 1 ) then
print "You [$LOGNAME] are currently logged into another session. You cannot log in to more than one session at a time. Please log out of the other session before you start another. "
exit 1
fi

[Don Bentz]

Caution: Try it for yourself to be sure, but the "last -R | grep still..." solution will show you users who MAY or MAY NOT actually be logged in.

[Greg Conn]

# Check for multiple logins

if [ -x "/usr/bin/whoami" ]
then
WHOAMI=`whoami`

if [ "$WHOAMI" = "root" -o "$WHOAMI" = "bogie" -o "$WHOAMI" = "haninged" -o "$WHOAMI" = "opc_op" -o "$WHOAMI" = "opc_ncc" -o "$WHOAMI" = "osborna" -o "$WHOAMI" = "greyson" ]
then
:
else

# if [ `who | grep ^$WHOAMI | wc -l` -gt 1 ]
if [ `who | grep -c "^$WHOAMI"` -gt 1 ]
then
echo "\n\n W A R N I N G !"
echo "\nYou can't log in now because someone is logged"
echo "in with this user ID. If you think that"
echo "someone is using your account, please contact"
echo "the Shift Manager immediately....\n\n"
sleep 20
exit 1
fi
fi
fi

[Thierry Poels_1]

Hi,
something to think about:
putting restrictions in the users .profile is not fullproof (/foolproof:). The user can allways change his .profile when he has write privileges in his home directory, even if file privileges are limited or the owner has been changed.
The way to go is through /etc/profile, but mind not to put restrictions for root or other system logins.
BTW I was allways able to surround limitations set up by sysadmins years ago when I was a programmer; so now as a sysadmin I now the tricks of the trade ;-).
regards,
Thierry