https://askubuntu.com/questions/179889/how-do-i-set-up-an-email-alert-when-a-ssh-login-is-successful
Modify or create /etc/ssh/sshrc with the following contents:
ip=`echo $SSH_CONNECTION | cut -d " " -f 1`
logger -t ssh-wrapper $USER login from $ip
echo "User $USER just logged in from $ip" | sendemail -q -u "SSH Login" -f "Originator <from@address.com>" -t "Your Name <your.email@domain.com>" -s smtp.server.com &
This will effectively notify you by email anytime someone logs in through SSH, and the login will be logged in the syslog.
Note: You'll need the sendemailpackage (sudo apt-get install sendemail) for the email notification to work.
