Setup SSH Login Email Alert on Cent OS 7

This is similar to this post but not exactly.

First, you need to install mailx
# yum install -y mailx

Second, create /etc/ssh/ssh_alert.sh with the following:
#!/bin/sh

# Change these two lines:
sender="sender@some_email.com"
recepient="recepient@some_email.com"

if [ "$PAM_TYPE" != "close_session" ]; then
    host="`hostname`"
    subject="SSH Login: $PAM_USER from $PAM_RHOST on $host"
    # Message to send, e.g. the current environment variables.
    message="`env`"
    echo "$message" | mailx -r "$sender" -s "$subject" "$recepient"
fi

Lastly, add the following line to /etc/pam.d/sshd
session required pam_exec.so seteuid /bin/sh /etc/ssh/ssh_alert.sh

That's it!