Linux Januar 2012/Add users

Purpose

When adding students on a Linux/UNIX box its desirable to let the students choice their own login names.

How to add student logins

Make a username and password public to the students. When the students login they are prompted for desired loginname/password

Adding the create-students account

Add user ny with password ny or whatever username/password you prefer to make public to the students. remember to change all references in the following to the username you choice.

File: /home/ny/.profile

Add the following line to the start of /home/ny/.profile

trap '' 1 2 3 15

Add the following two lines to the end of /home/ny/.profile

/home/ny/bin/nybruger
exit

File: /etc/sudoers

Add the following line to /etc/sudoers using visudo.

ny ALL = NOPASSWD: /usr/sbin/adduser --gecos [a-zA-Z0-9]* [a-zA-Z0-9]*

Remark

This line should be commented out when the students have added them selves.

File: /home/ny/bin/nybruger

Create the /home/ny/bin directory and add the file /home/ny/bin/nybruger with the following content. (Remember to change mode to executable)

#!/bin/bash
tput clear
echo -e "                        Tilføj bruger"
echo -e "                        ============="
echo -e "\n\n\nIndtast dit ønskede bruger login. Et ord indeholdene bogstaver eller/og tal."
LOOP=1
while test $LOOP -eq 1
do
  echo -en "\nBruger login: "
  read LOGIN
  if echo -n $LOGIN | grep -E "^[0-9A-Za-z]*$"  >/dev/null  2>&1
  then
    if grep $LOGIN /etc/passwd  >/dev/null  2>&1
    then
     echo -e "Det valgte bruger login er allerede i brug!!!"
    else
     LOOP=0
    fi
  else
    echo -e "login navnet skal være ET ord bestående af bogstaver a-z, A-Z eller tal 0-9"
  fi
done

sudo /usr/sbin/adduser $LOGIN
if grep $LOGIN /etc/passwd
then
  COUNT=5
  while test $COUNT -gt 0
  do
    echo -en "\r Bruger $LOGIN oprettet. Sessionen afsluttes om $COUNT sekunder"
    $((COUNT-=1)) 2> /dev/null
    sleep 1
  done
else
COUNT=5
  while test $COUNT -gt 0
  do
    echo -en "\r FEJL: Bruger $LOGIN er IKKE oprettet. Sessionen afsluttes om $COUNT sekunder"
    $((COUNT-=1)) 2> /dev/null
    sleep 1
  done
fi
exit

Security

Change all files to root ownership so the students cant change the script catching other students passwords etc.

chown root:root /home/ny
chown root:root /home/ny/.profile
chown root:root /home/ny/bin
chown root:root /home/ny/bin/nybruger