How to check login activities on the server?

Login activities/attempts are logged in files which are as follows:

• utmp will give you complete picture of users logins at which terminals, logouts, system events and current status of the system, system boot time (used by uptime) etc. It can be read as:

last -f /var/run/utmp

• wtmp gives historical data of utmp. It can be converted inti human readable form as:

last -f /var/log/wtmp

or

last

• btmp records only failed login attempts,

last -f /var/log/btmp

Current logged-in users, load averages etc can also be seen by:

w