And that look, files and command, there are many network files and commands that needs to be used
in order to configure your machine and bring it online and bring it to the network so it could communicate
from one machine to another.
It should have an interface and interface detection.
Assigning an IP address to the system is very important when you bring up a system and you need to have
it on the network, the interface configuration files are the first one is ETSI and Switch Dukkha file.
This file is located in every Linux distribution.
In fact, all these files that I'm going to talk about, all of them are and will be in your Linux system.
So for the first one is NSW Cop, which tells the system where is where it should resolve its hostname
to IP address.
So let's look at our Linux machine and then we will find out how how to read these files.
OK, the first file that we're going to look at, it's N.S.A., which suggests Dukat on Etsy and a switch
to compile, you will see it starting with host.
Let's let's do more on it instead of just cat.
So this is the read the file page by page.
OK, so all this stuff, anything that started Paon it means is just a comment.
Anything that you want to have it in effect, just remove the comment.
So let's go through it.
Let's go to the point where we don't see the comment.
So it's starting from this page on.
It says a password file.
So the first thing is telling you that look for the password file in the files, don't go anywhere.
There's no active trickery.
There's no other and IRS service that's running that's going to give you the password.
So look at C passwords.
Shadow is also Etsi Shadow, that's local group is also at group.
And when you come down to Hosta right here, it's going to tell you the and the host information off
your system is located in the files and that is ATC host.
And then it's going to say, if you can't find it, then go to DNS.
DNS is another service that is installed on a Linux machine or it could be installed in our Windows
machine, will cover that later on.
But for now, this is the NSA file looks like.
And if you want your horse to be resolved with DNS first, you switch DNS here to here and file comes
the second.
So this is the NSA switch.
While you're going to be seeing this configuration of this file many times while you're doing system
administration, next one are going to look at is at C host C Horsfall is where you define your system,
IP address and system hostname.
So if my system IP address is if config it's one two one six year, one down 14, I could go into that
ATSE file web becoming root.
V.I. The File and Ikuko at the bottom, and I could put one eye to 168, one to 14 and hostname of my
machine is a God, let me save it.
And they my first Linux OS.
So let's do it again.
My it doesn't matter, uppercase, lowercase, but my first Linux OS,
my first Linux OS.
So now if you paying my first Linux OS, it's going to Pengo IP address.
You see right here, the one that you specified in the FC file.
So that's what ETSI file does.
It's a small, a very tiny version of DNS that's sitting in your machine.
The next one we have at the CIS config network file this file.
Sorry, this it's network I believe and I know if I'm right.
So this is the file where you specify your hostname as well.
Right now it's empty because we have hardcoded the hostname, but if you want to change it, you could
modify it here and certain other parameters can be set to.
Of course, you are more than welcome to look it up.
More on the network file.
The next file that we're going to be covering is actually the file, that's where you specify your IP
address on all the network, all the subnet mask and Gateway.
And when you are in the directory, ATSE says config network scripts, I want you to do X minus TR and
the last file you're going to see is IFG.
In ENP zero three and what is this, the last one?
It's actually your interface if you go if config and you will see right here, this is the name of your
interface.
So remember, every time all those interfaces, files, all of this started, I if CFC dash and the
interface name.
So when you v.i. that file
here you will see the boot.
Proteau is defined as DCPI.
You could change that at a static and then you could define the IP address, you could define subnet
mask gateway and this way your IP address becomes permanent in your machine and does not change.
So these are a few few of the files that I really want you to understand and memorize it, because if
you are going to go into Linux jobs and you're going to be applying for it, oftentimes you're going
to get questions on these where these files are, what the files do, where they're located and so on.
So let's exit out of this file.
The last fall I have is at zero resolved outcome.
Atsu resolved.
Horcoff specifies your DNS server.
DNS server is a game once again.
It's actually resolved hostname to IP, IP to hostname and hostname to hostname.
So if you define it here every time you go to Google dot com and enter it knows Google.
I have to go into this is my gateway.
I have to go to my gateway, which is right now acting as a DNA, where I'm going to go to my DNS over
and ask where is Google and how to translate Google to IP?
And it has translated.
And this is.
The IP address of Google.
Let's go back to our lesson, the next one we had, the network commands, the network commands.
We have learned pengo already.
If you wanted to ping a server, let's say paying Hotmail dot com, that's a server outside that command
that you will run as ping if config tells you what you have.
Interfaces are in the system.
We have right now three interfaces.
The local one does not count as an interface and other one you could ignore.
The only one that I have is just one.
And this is right there.
It's telling me my IPS configured this.
Then you have if if don't if you want to bring down this interface, if you don't want to network,
you could type F up.
So if down or if you want to bring it back up, you type F up, then the next one we have nextag nets
that you can run with different options.
Irun is usually R and B, this one tells you your gateway, how your traffic is flowing from which interfaces
is flowing from in.
The last one we're going to cover is TCP dump, TCP dump.
It actually traces every single transactions that are leaving your machine and coming into your machine
to the command to run is simply TCP dump.
You have to specify the the interface interface you are sniffing, it's basically sniffing tool and
then you run it and you'll see every listening coming in, coming, going out.
It's actually listed here.
So that's how you actually run this TCAP command, that's how you run all these commands and please
memorize it, please run and man command on each and every one of them and familiarize yourself how
these network commands and files work.