Set login Time out for all users. Do this by editing /etc/profile
TMOUT=7200
export TMOUT

Edit the profile file (vi /etc/profile) and change the line:
HISTSIZE=1000
To read:
HISTSIZE=10
Which means, the .bash_history file in each users home directory can store 10 old
commands and no more. Now, if a cracker tries to see the ~/.bash_history file of users on
your server to find some password typed by mistake in plain text, he or she has less chance to find one.
HISTFILESIZE=0
#each time a user logs out, its .bash_history file will be deleted so crackers will not be able to use .bash_history file of users who are not presently logged into the system.