[CentOS] Supervisory

Dear All
I have a centos server with super user password access. There are a
number of users on the same net accessing it via telnet with their
dedicated id/pwd . For the supervision purposes, I need to know which
user is issuing what command on the server . In other words ,
monitoring their activities . Can you please let me know how it can be
done on the centos?
Thank you in advance