To secure your machine, there are hundred different things you can do, but the most important thing is to know what's happening on your Machine. In that getting the alerts as soon as someone login is one of very important and must thing to do.
So, to do the same thing, you can go with two approaches:
The Basic working of the screen is already explained in my previous article and if you are not really looking for advanced screen features, you should look at my previous screen article. The link for the same is: Basics of GNU Screen
But there are a lot of advanced features which screen provides which might come handy in a lot of scenarios. I will be explaining them under.
I know most of you have already heard about screen, but for those who haven't, it is one of the best thing you could know and work with, being in this field. Everyone of you must have run through the scenarios where you are running a time consuming task on a remote server and your internet connection drops in between, you might have to run something and check the logs on the console later on, you want to give a small training to a remote person but can't show them how to do things. These are just few problems where screen will come to the rescue.
SSH is the most trusted protocol used in today's world for remote logins and secure file transfers from one machine to another. There are three different ways of authetication when trying to login with SSH protocol:
As soon as you connect to the internet to do any of your daily tasks or connect your server to provide some service, it means that you are exposing your system to lots of threat and to people who are ready to play with your system just for fun or some personal interest.