UNIX for Dummies Questions & Answers

Hello mates..
i need help with these things
*Users should be allowed to login only once, i.e Multiple logins from single user should be restricted and should issue an alert if any user tries .
*statistics of everyday log in time ,duration of login,and the commands executed by the user
*Alert if the user is initiating more than 5 process in interval of 5minutes and also alert if any process of the user runs for more than 5mins.

This is a tough one. Also, number 3 is totally unrealistic - normal operations on a unix box can do 10 processes in 10 seconds.

You need to define what you mean by processes. A harmless command like this:

Code:

find . -name foo | grep -v '[:digit:]' | sort | cut -c 1-3 > newfile

uses four processes in a few seconds. If users are locked into a menuing system then you can "count" each menu selection as a process. Almost every command you enter into UNIX creates at least one new process.

You can get most of what you ask by using the script command in the user's login

Code:

.profile

with something to detect multiple logins

Code:

trap 2 3
count=$(who | grep -cF " $USER ")
if [ $cnt -gt 1 ] ; then
    echo "Warning, you are already logged in.  Duplicate logins not allowed"
    echo "$USER attempted and extra login `date`" | mailx -s 'user login warning' \
           somebody@someplace.com
    exit
fi
   filename=/path/to/user/logs/${USER}.$(date +%Y%m%m-%H%M%S).log
   script $filename
   echo 'logout at $(date +%Y%m%m-%H%M%S)" >> $filename
exit

The file is your audit. These files will need maintenance or the disk will fill up over time

The other alternative is to turn on auditing. To help you with that we need to know the exact type of UNIX you have.

Sir I'm using ubuntu 12.10. please help me in understanding how exactly i should report multiple logins to a script..

Have you tried google? because my search for "ubuntu auditing" returned this:
How to keep a detailed audit trail of what’s being done on your Linux systems

Users should be allowed to login only once

Why do you want to restrict that? Is it users setting off a whole bunch of processes in different windows?

You can use w command in a script to see how many logins, something like logins=`w | grep username | wc -l`

Okay multiple log and all I'm done. Now all I need is to report if a particular user starts more than 5 processes in 5mins.
And if a user runs one particular process for more than 5 mins..

First of all, who and users do less than w, so for only counting the user's logins I propose

Code:

logins=`users | grep -wc "${LOGNAME:-$USER}"`

(2nd attempt with $USER in case $LOGNAME is not set.)
--
For your processes requirement, check if you can use the information from

Code:

LC_ALL=C ps -u "${LOGNAME:-$USER}" -o pid,stime,etime,time

Hint: stime is neither well parse-able nor portable; etime is often better.