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The 
ss
 command allows us to view a list of processes running on our server that are 
listening for connections. It will also display which port a process is listening on. 
We'll explore this command in more detail in 
Chapter 21
, 
Securing Your Server
. But for 
now, this command should produce an output similar to the following:
Figure 10.7: Checking if the required port for SSH is listening
If, for some reason, your server doesn't show that it has an SSH server listening, 
double-check that you've started the daemon. By default, the SSH server listens for 
connections on port 
22
. This can be changed by modifying the port declaration in 
the 
/etc/ssh/sshd_config
 file, but that's a story for a later chapter. While I won't 
be going over the 
editing of this file just yet, just take note that it's the default 
configuration file for the daemon. OpenSSH reads this file for configuration values 
each time it's started or restarted.
To connect to a server using SSH, simply execute the 
ssh
 command followed by the 
name or IP address of the server you'd like to connect to:
ssh 192.168.1.120 
By default, the 
ssh
 command will use the username you're currently logged in with 
for the connection. If you'd like to use a different username, specify it with the 
ssh
 
command by including your username followed by the 
@
 symbol just before the IP 
address or hostname:
ssh fmulder@ 192.168.1.120
Unless you tell it otherwise, the 
ssh
 command assumes that your target is listening 
on port 
22
. If it isn't, you can give the command a different port with the 
-p
 option 
followed by a port number:
ssh -p 2242 fmulder@ 192.168.1.120
Once you're connected to the target machine, you'll be able to run shell commands 
and administer the system as if you were right in front of it. You'll have all the same 
permissions as the user you've logged in with, and you'll also be able to use 
sudo
 to 
run administrative commands if you normally have access to do so on that server.

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Chapter 10