Assess each and tell that these are the two main services that run Linux to accept connections from
outside, tell that is an old and unsecure connection between two computers and a lot of companies don't
use anymore.
The message is a newer connection, establish protocol that is completely secure.
There are two type of packages for most of the services that you see on a Linux machine.
One is a clean package and the other one is a server package.
So you have a server, it sends a connection request and SSA requests to another server.
So in this case, you are the client and the computer you are trying to connect is a server.
So let's take it the other way.
So if you are on the right hand side and the server is on the right hand side, when it tries to think
it's time to you, as in through the A.P. protocol, then it's no longer the server.
It becomes a client and then you become the server.
So let's look at our message and tell that both of these those services that we have and how they work
in our computer.
I will connect it through the putty session and I'll confirm I am route, it's clear the screen and
the service that runs the first one is Telnet.
So when you run Telnet, you see it says command phone.
Why?
Because by default now Lennix don't include telnet in the installation.
So if you have to install 10 that you would have to do Jum install telnet and it will go to the repositories
and it will find it will match the the option I have put on that.
And it found one package and it's telling me, do you want to download now.
We will not be using telnet in our environment.
But if there is, if you are troubleshooting, talent is sometimes a tool that allows you to troubleshoot
some of the issue, some of the network communication issues.
But for this lesson, we will just skip that and we don't want to download the next one.
We have the SSA.
Do we have Secich?
Yes, we do.
That's why we got this usage of Secich.
We could do Secesh to follow by the IP address of the remote computer.
But since we don't have a remote computer, we'll just say local computer, which is the same box that
we are trying we are already logged into.
When you do hit enter, yes, you're logging in as rules are put in the root password and you log into
the same machine that you were logged in before.
So you can create as many sessions as you want.
So you could exit out and you'll come back to your first session to check the service of SS H.
D will run F to see if the process is running and you'll see the process is right here.
It says User SBN, SS, SAHD.
This is the process that actually listening for all the incoming traffic, if I stop this process,
I will not be able to log into this machine anymore.
But before we do that, I wanted to check my IP and my IP address is 192 168 dot 112 and let's go ahead
and stop the SS HD service.
When you hit enter, you get the back.
It means it's not running.
You could do minus F again to grab it and you will see the SS, HD and SS HD.
This is this already established connections is telling me, but it is not showing the one we looked
for before which just use it has been SAHD, so it means it will not accept any incoming sessions anymore.
How can we confirm that?
Let's log into a new PUDI session and I will put in the IP address of this machine again one I to 168
dot one dot 12.
She says get connection refused because there is no SAHD demon that is running.
So we'll click.
OK, close this out and this time will start to S.H. D process.
It is started because we got a prompt back.
How do we verified you can run minus F again SSD and you will see right here the process is running
now.
Now it will accept the connection.
Another way to find out if their service is running is by doing system CTL status as the safety and
right here is telling you, active, active and running.
So now if you try to connect to that IP when I 216000 one that will you should be able to 192 168 to
twelve bingo.
You see how SAHD works.
So this is how you could stop the connection to your server or refine or restrict your computer.
This is a way and has way to implement security on your system.