Hey everybody welcome to the next video.
So in this video we're gonna be going over firewalls.
Now what is a firewall for all of you who have never heard of these before.
These are a software based application that prevents unauthorized access from one side to another.
So whatever whether that's the one network to another one hosts from the outside to the inside of the
host.
Think of that as the sides the firewall sits in between.
Now this can be host based or network based as we said.
Now a host based firewall you're familiar with this as on Windows side is Windows Defender windows defender
has a firewall that's already built into play when we were going through the windows server install
we had turned off the firewall tool to help us just get through the process of installing things and
making sure there wasn't any hiccups.
Now that firewall is part of the Windows Defender suite.
Now Linux has two other default options.
The main one you're going to be handling and seeing on a daily basis when you're a sysadmin of a Linux
environment it's going to be IP IP tables.
Now there's another one called firewall D.
We're not going to go over that in this particular video but or IP tables for that matter.
Take a second take a look at those get familiar with IP tables because that's going to be the most universal
one that you're going to find.
Now as far as also that's host based and sometimes can be network based is a web application firewall
or a laugh which will have a whole video on later in this course.
Now network based there's a large amount of vendors to pick from Cisco P.F. sense Dell.
There's there's a large variety.
Everybody seems to be making firewalls.
Now it's up to you to decide which one you want to use in this course we're going to be going over P.F.
since it's free.
You can get a VM for it.
It doesn't require physical hardware.
So if you can we can work with it a little bit easier and kind of get familiar with the firewall at
once.
Now the network base is normal.
It's commonly used between the networks and the Internet or between network to network.
In most organizations you're going to have a firewall in between each network.
And at the end at the exit points where your main data come in.
Now when we talked about a DMZ This is what creates the DMZ a firewall handles all the rules that create
the DMZ environment.
Now there's two types of firewall settings or modes per say it's a packet filtering and the state full.
Now these can be broken down in individual modes but we're just going to hit these two in this particular
course.
Now what I want to make you all understand is that every firewall has something called an ACL or an
access control list.
Now this ACL or this list holds all the access rules for a firewall in most cases a firewall is going
to be you're going to want to do a deny all first by default and only allow what you want some firewalls
come this way some just come everything open for sake of sanity for configuration purposes.
But in the world world environment you're going to have a block all within allow only in most enterprise
environments.
Now this ACL each entering the ACL could allow block or drop silently.
There's quite a few other options based on any number of parameters so this could be based on the source
port the destination port the IP maybe the the type of traffic that's actually going through it.
What type of protocols being used on a particular port.
So there's a large variety of options you can use here just to understand what the ACL.
Because a lot of a lot of industry professionals are going to call it an ACL not an access control list
outright.
Get used to abbreviations in this line of work it's going to happen.
So just get this has been a high level overview of firewalls we're going to dip into packet filtering
and stateless state full firewalls in the next few.