Hi, and welcome back to Section two Network Fundamentals.
In this video, we are going to see the network O s I model.
The O Ss I model, which is composed of seven layers,
was originally published in 19 83 83 by International's
organization for Standardization,
o s I and is an industry recommended.
Standard protocols are separated according to their functions based on the O S I
model reference model.
The protocols at each layer work together to ensure data
is properly handled by the protocols at layers directly above and
below data flow through the O S I model.
So each model is in the O S I model is capable of communication only
when the layer directly above and belong it in data
encapsulation, that's mean.
Each layer in this stack is responsible for adding a header and
footer P D U Protocol Data Unit.
It includes the data being sent and all header of footer
information added to it.
The P D U change and grows in this seven layer
in each layer, the information it treats in different names, uh,
because they're in different information over there.
So in the application layer, the layer number seven,
the data is called data,
the layer six presentation. The data, the,
the packet of data is called data.
The section five session, uh,
the data is treated as data itself.
In the layer four transport,
this all information is treated with a different name. That's means segment.
If you are talking about the information in the layer four,
the name of this is segment in the Layer three network.
The disinformation is called packets.
In the layer two data link, the, the information,
this collection of of information is called frames. And finally,
in the first layer, the layer one physical,
this information is called bits.
At layer seven application layer,
it's provides a means for users to access network resources.
It's the only layer seen by the user,
and it provides the interface that is the base of all of their
network activities. At layer six,
presentation layer is transported data.
It receives into a format that can be read by the application layer.
It handles several forms of encryption and end decryption.
Use it to secure data At layers five session layer,
it's manage the session between two computers. It establish, manage,
and determines this connection Among all communication devices,
it's best responsible to establish if the connection is
duplex, two way or half duplex,
one which one way it responsible for graceful closing
a connection between hosts at layer four,
transport is responsible of providing reliable data transport
services to lower layers. It's define it flow control.
Segmentation D the segmentation error control.
IT utilize both connection oriented and CONNECTIONLESS protocols.
Certain firewalls and proxy servers operate at this layer.
At layer three network layer.
It's responsible for routing data between physical networks.
It seems to the low logical addressing of network hosts.
It also handle splitting data streams into smaller
fragments. And in some cases,
error detection routers operate at this layer.
At layer two datalink layer.
It provides addressing schema that can be used to identify
physical devices. That's been MAC addresses breaches and,
and switches are physical devices that operate at the datalink
layer. Layer one physical layer.
It defines the physical and electrical nature of all hardware usage.
It establishes,
and that means connections provides a mean of sharing communication
resources and converts signal.
From digital to analog and visor,
we are able to see a typical protocols and technology use it at each layer.
At layer seven application,
we're gonna see HT P SS M T P F T P internet
protocols. That's layer six presentation.
It's common to see s eg and jpeg.
Its layer five section net.
SS A P S D P N W V link.
At layer four transport the protocols, T C P,
uud P, and px. At layer three network,
we see protocols, IP and IP X.
At layer two data link,
we're gonna see the technology like internet token ring and F D D I.
And finally at the layer one physical, we see technologies,
wire technologies, and wireless technology.
Here you can see the type of attack According to each O
S I layer. At layer seven application, we have exploit attacks.
At layer six presentation, we have phishing attacks.
At layer five session, we have hijacking attack.
At layer four transport, we have reconnaissance and d o s attack.
At layer three network, we have men in the middle attack.
At layer two datalink, we have spoofing attack. And finally,
at layer one physical, we have sniffing attacks.
So now let's take a look of data calculation using Wireshark.
Each layer in this stack is responsible for adding a header and a
foot and a footer. So we're gonna see,
we're gonna use wire shark here with my, uh,
KA Linux distribution environment to identify this.
So we will start Wireshark. I have two options. I have,
I can search or I can type
wire wireshark.
And let me start a live caption of the information that are
drafting in my wifi, uh,
with the connection in the, my laptop that I'm using here.
So here in the packet list, we have three,
three interface here, packet list, packet details,
and packet bytes. And in the packet list,
we are seeing the, all the package flowing in my,
in my connection can start a web browser on to
have some a TT P protocols.
Okay, good.
In here.
Looked at for every package here in the packet list,
in the interface packet details. Here we gonna see, uh,
the layers for each package. Okay?
So for example,
C C P is present in the layer four transport.
And we have the frame here for the layer
1, 2, 3, and four. So we have the physical here,
the data link here, the network here,
and the transport here for T C P.
With the next video, we are gonna see more information about, uh,
the delay of four and the layer three.
But at this moment, I'm gonna see that for the layer, uh,
four transport, we have some information here for,
for this protocol. If I change of protocol here,
for example, for the d n s,
we have others layers, for example, is used.
Another protocol for layer, for, for transport layer is U D P. Okay,
we're gonna see this, but we have another information here.
So the, the packet detail here,
we see, uh, the layers present in each
protocol that I select here.
So I C M P for example, is present only.
This protocol,
we can have the stack of protocols here
because each layer add header for respective layer.
Okay?
A very interesting information here with wire shark is that I can change my
layout presentation. So for example, for, for the,
the full profile is that the full profile here and the vision here
I can see three interfaces, three frames.
For example, the packet list, the packet details,
and the packet package by,
but I can change here and edit preference, layout.
And I, we can change the layout
for example here, and we can change to
what tip of information for each panel. For example, for the pantry,
I would change for package diagram. So for example,
this is very interesting because for example,
let me stop here for this package here,
for this protocol here I have the package detail
here.
And I have changed this to have a graphical information for this
package, for this protocol, for example,
this is the, the structure of each, uh,
information from each layer present here. So for example,
for D C P, I have a short, uh,
description about the structure of this protocol.
So we have information for source port,
destination port coming information for Jackson
handle this, handle the error. For the lower layer,
they use IP protocol.
So we have here a graphical representation of this protocol.
For the lower layer, we have the ethernet.
So we have the ethernet structure here.
So this is very interesting because, uh,
we have more information from each protocol present for in each layer.
If I sell like frozen example, a, we have another configuration here,
another stack and auto graph information.
So for
each information that I select here, for example, the graphical panel,
uh,
we have a detail here and this is very interesting to turn
and to analyze each package.
In this video, we saw an introduction to the network. O s I model.
The next video, we'll take a look at the transport and network layers protocols.
I hope to see you there.