SSH Login Email Alerts
The examples below send an email when someone logs into your server. For this to work, your server must be able to send mail using the mail command.
CentOS
Open the file ~/.bash_profile in a text editor.
Append the following lines:
IP="$(echo $SSH_CONNECTION | cut -d " " -f 1)"
HOSTNAME=$(hostname)
NOW=$(date +"%e %b %Y, %a %r")
echo 'Someone from '$IP' logged into '$HOSTNAME' on '$NOW'.' | mail -s 'SSH Login Notification' YOUR_EMAIL_ADDRESS