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Depending on the choices you've made during installation, your Ubuntu Server 
likely has the OpenSSH server installed already. If you don't remember whether 
or not you opted to have this included during our initial installation, you can run 
the 
which sshd
 command at your shell prompt and you should see the output of 
/usr/bin/sshd
. You can also execute 
systemctl status sshd
 as well, and if the 
server component is present and running, then your server is ready to accept SSH 
connections:
Figure 10.6: Verifying that the OpenSSH service is running on a server
In the case that you don't have the OpenSSH server component installed on your 
server, you can install it with the following command:
sudo apt install openssh-server 
With great power comes great responsibility, though. As great as OpenSSH is, any 
service that listens for connections has the potential of being abused. An outside 
intruder finding a weakness or exploit that allows them to take control over your 
server is a really bad situation. Therefore, like any service that runs on your server, 
you should only have it running if you need to use it. Since OpenSSH is incredibly 
helpful (and it's the standard method of remote management) it's very hard to 
not
 
use it.
There are many methods you can utilize to secure such a service and help protect it. 
One method is covered in the next section, and we'll talk about security pertaining to 
OpenSSH again before the book comes to a close. Specifically, in 
Chapter 21
, 
Securing 
Your Server
, I will walk you through various configuration changes you can make to 
help minimize the threat of miscreants breaking into your server from the outside 
and wreaking havoc. 

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Chapter 10