OK, so now let's talk about Farmville, you all have heard a word firewall, we know whenever you go
to buy a new PC and the person who's going to sell you the piece, you say that do not forget to install
the firewall on your network or if you are working in a company, sometimes a website or the application
says you are being blocked by a firewall.
You cannot access this website, go back and go back to the safe mode.
So what exactly is a firewall?
Yeah, let's answer this in this lecture.
So basically firewalls are your networks, the security guards.
And to be real, they're probably the most important things to implement on your network.
That's because today's networks are almost always connected 24 by seven to the Internet, a situation
that makes security very crucial.
The firewall protects your land resources from invaders that use Internet for unprotected networks while
simultaneously preventing all or some of your land's computers.
Now you can use firewalls to filter packets based on the rules that you or a network administrator create
and configure strictly to eliminate the type of packets which are not intended for your PC.
For example, let's say you configure your firewall to discard all the packets having the protocol HTP,
which is hypertext transfer protocol and it is not a secure protocol.
OK, wait, don't get confused between NHTSA, we are going to see all these protocols in upcoming lectures
for time being, just understand that HTP and ATP's are two different protocols, that extra DPS is
more secure protocol.
So now if you employ a signature or if you imply a rule that says that, please discard all the packets
that have HTP, your firewall will not allow a packet entering from the Internet having htp a protocol.
So far, all can operate on multiple layers of the user model and some firewalls can operate up to the
application layer, which have a great functionality on your PC.
A firewall can either be a standalone black box or a software implementation placed on a certain router,
either via the firewall will have at least two network connections, one to the Internet.
That is the public side from where all the data comes to a network.
And the other one is the network known as the private side.
Now, sometimes that is a second wire fall as I'm sorry, there is a second firewall, as you can see
on the screen now, this firewall is used to connect to servers and equipment that can be considered
both public and private, like Web email servers.
I'll show you.
Just give me a second and.
Yeah, so you can see this part here.
This is one firewall.
This is the first firewall.
This is the first of all, this is the second firewall in between.
There are these servers that need to be protected.
Now, these servers are directly accessible to the normal person, but there is a firewall in between.
And these servers are also a private property of a company.
So the zone between two different firewalls, OK, this zone, this zone is known as demilitarized zone.
That is the.
And the that is demilitarised zone firewalls are the first line of defense for an Internet connected
network without any place a firewall, any network that is connected to the Internet is essentially
wide open to anyone with the technical savvy who seeks to exploit all the resources.
So, for example, if you don't have this firewall in place, an attacker here, an attacker here can
directly access your servers.
And if he's able to exploit one of these servers, he can directly have access to the whole Internet.
And in this way, your whole Internet can get compromised.
And that is why firewalls are really very important.
In the next lecture, we'll have a look at the detection systems, intrusion detection systems and prevention
systems as well.
So they are also kind of firewalls which protect your network, but they function.
There are a couple of differences between firewall and the detection and prevention systems that does
exclude them in the next lecture.