Our upcoming cyber warriors who want to come into cyber security field or have started coming into cyber security field face a lot of issues due to their concepts not being clear, so stay tuned till the end of the video and today all your doubts will be cleared. And the whole topic is going to be clear, so there are some notes for you to note down all the things, first of all you all have to watch this video completely, do not skip it at all, after that you have to sit with a notebook . You will be able to note down things point to point and lastly, for those who do not understand Hindi, there is an issue in Hindi language, I am adding subtitles, it is fine in many languages, so you people can translate with subtitles also. Welcome to NewVersionHacker Disclaimer Hello. Cyber Verse, once again I welcome all of you to my YouTube Channel NewVersionHacker, so guys, as we saw in the last video about the OSI model, so I hope you all have understood the OSI model well and if your If you have not seen the last video of OSI Model, please check it out. I will put its link in the description. Unless you watch the video of OSI Model, you will not understand this video, so here we are going to see our topic of the day. What is OSI Model vs TCP/IP Model? So about the OI Model, we have understood very deeply what is the OI Model. Similarly, today we will know about the TCP/IP Model. Okay, but before that, after reading the OSI Model. When the OI model is doing all our work, then what is the need for us to read the TCP/IP model, so let's see, first of all we start with the OSI model, so look here, something is written about the OSI model, okay The OSI Model is a Conceptual Framework that Standardizes the Function of Telecommunication and Computer System into Seven Busex Layer It also does this, but the OSI model is a complete threat model, like you people might be doing two things in school, in schools or colleges, you read a theory book and perform a practical, but when you see the theory, you don't understand the theory. That's why it is told that what is the actual process happening step by step, okay step by step, what is your process there, okay, for example, you people must have seen the cooking book, there it is written step by step that you have to add salt. Then you have to add chilli, then you have to add oil, similarly here everything is performed step by step, when will each thing be performed, when will the communication be made, when will the REQUEST packet be generated, when will your connection be established, when will the encryption be done? All the things have been explained to you in the OSI model. Okay, so OAI was a total of seven layers in OSI, which was trying to explain what would be the function of each layer. Okay, so this is the entire threat model, now TCP. The TCP/IP model is written as The TCP/IP Model is a more practical four layer conceptual framework that is widely used for the implementation of Internet. So the TCP/IP model here is the complete practical model which is actually implemented in our cyber networks. In security, it is only TCP/IP model, here O OSI is not used, only TCP/IP model is used, in TCP/IP model we have total four layers, four layers are four layers, there are five layers also, here TCP /IP is four layer and five layer models, okay, so let us see here what happens in these layers, so let's move ahead, here first of all see which layers were there in OSI and TCP/ Which layers are there in the IP model? Let's look at the four-layered one. First of all, look at the OSI model. Application Presentation Station, Transport and Network and Data Link and then the physical layer. Here there were total seven layers of OSI but TCP/IP model. What is there in TCP/IP model, there are four layers out of which look at these four layers, the first layer which is application, then transport, then internet layer and after that network interface . Well, network interface can be called as data link or physical layer. Now how, look here, the application layer, the application which is of TCP/IP model, it has the application presentation and session layer, all three are combined together, okay, so this is the application presentation and session layer here. These three are going together in which application layer means the work of these three is explained by the application layer alone or is it performing. The work of all three layers together is fine. Which application layer of TCP/IP model is fine ? Similarly, look here, which is our transport layer, it has been kept exactly as it should be, as it is in our OSI model. Here the network layer has been called Internet layer but you can call it Internet layer, there is no issue with the network layer, after that you will be able to see here that the data link layer and physical layer have been combined into a single layer. It means that it has been brought together in a single combined layer, which will look after the work of data link layer and physical layer together. Network interface layer is fine, so here these three layers are fine, which is the sole function of our OSI model. Who is providing it? The application layer is looking at it. Okay, now the application is looking at the setup layer here, the transport layer agent has been kept the same and the network layer has been kept here as the Internet layer. Both are the same, there is no difference. There is no difference in that, okay, and the data link layer, the physical layer here goes alone to the network interface layer and there it is done, that is, the work of both these layers will be handled by this network interface. Okay, so this is the four layer model of our TCP/IP. Okay. Now what will be the work of the application layer here ? So the work that these three were doing was seen in the OSI model. So before watching this video, it is important for you to see the OSI model. So it is okay to go and see it. So look here. It will do the work of all three together, that is, first HTTP HTTPS SMTP, it will generate all the things which were our protocols, then the application layer will also apply encryption, then the session management will also be done by the application layer, okay, the transport layer will also assign the port here. This is what it will do, okay, and the checkup of everything else, which was being done by the transport layer, will also be done by the transport layer here. Internet layer is okay, the internet layer will assign the IP here, okay, just like the network layer was doing it here, it will do the same work. Okay, after that, physical layer and data link layer, you know the work of these two physical layers, they decide through which medium the data will go, whether it will go wireless, wired or through light, I also explained this in the OI model. Okay, so this is the work of all the layers, so who will look after the work of data link layer and physical layer? Network layer, here the work of data link layer is that it will check all the things step by step, meaning point to point. First, it will check the point to point data link layer first on the router, then on the ISP's router, then it will check the point to point data link layer. Okay, it has more work which has been explained very well on the OI model, so it is okay to go and check it out. Let us move towards our next layer which is also the fifth layer. Once we compare it, look here, this is all the layers of the OSI model. Okay, and after that, here comes the TCP/IPIP layer and all its layers. End of four layer TCP/IP and after that this is the five layer model of TCP/IP. Okay, now this is the updated model of TCP/IP. Okay, this is the updated TCP/IP. It has five layers. Now look here, it is the exact same. The work is the same here too. Now look here, this layer is handling all the three tasks alone. This is exactly the same. Okay, now here the transport layer is the same among all three. Okay, the transport layer is exact among all three. Network layer. Internet Layer and Internet Layer, these three are same, okay there is no difference in it but what is the biggest change here, both of them were together in the first four layer but in the updated one they were separated again. It means like OI model is fine then the only difference here is that they have separated these two, maybe there is some problem in communication or maybe they are facing some issue in handling the data, so they These three layers have been separated i.e. which is the updated model? If this five layer model of TCPIP is correct then this four layer model, this OAI model, this is our theory. Both of these are practically implemented, meaning they are doing the same work in real life. It is fine everywhere on our internet, so I hope Cyber Warriors, all of you must have understood the TCP/IP model and OSI model. You may have understood anything, you may not have understood the TCP/IP model, but you will understand later. We are about to go, but you must have definitely understood the OSI model because you have watched the last video. Okay, so now let us move a little further, let us move forward in our journey. Now let us move step by step towards understanding all the concepts in actual. How is networking working? How is networking working? You must have seen it, but with this example, your concept is going to be so clear that you are never going to forget how this networking and TCPI model works. Okay, so let's see here. Have you skipped the video till now? No problem, but do not skip the video from here because the concepts that are going to come next are going to clear all your concepts. Okay, your concepts will be clear in the next slides only. Okay, so don't skip. Stay last . Okay, now look here, if I want to access a website from my PC, this is my PC, if I want to access any website from this PC, then what should be the first thing to access the website? For example, take this website newversionhacker.com, okay. Now I have to access it, so what will happen here? First of all, my PC will generate the request packet. After generating the request packet, where will it send it? First of all, it will send the request packet. It will search inside its PC. You must have heard local host 127.0. .0.1 Isn't it, I told you that I will put its link in the description and I will also put the link of OSI model in the description, please check. 127. 0.0.1 Did you see that this is our local host, okay so it is PC. Before generating a request, it checks within itself, meaning when we request anything, the PC first checks within itself and then checks on its local host whether it is available with it or not. If it is not with him then he sends it to the router. Okay, now the router will check whether the thing is lying with him or not. Now the router will also check if it is not with him, then it can forward it further. Will give what happens next, next is the ISP's router, okay ISP's router means you have understood about ISP, I had told you about that too, when I told you how a router works, I had explained to you about ISP, okay so. Go and check out that video, only when we understand about ISP here, you will understand and from the previous video itself, you will understand what is ISP, so when that packet went to the ISP's router, the ISP's router Have you seen whether I have this website or not? Then it will forward it further. Now where will it be forwarded, how will it happen, we see all those things now, so after the packet reaches the Warriors ISP's router, this packet will be forwarded. Now we are watching where it will go, okay, so look here, first of all, when my PC generated the request here, okay, after generating the request, this message will be written to it, what will be the message that IP address for new version hacker, now one thing. Tell me, whenever I want to access this PC or me, then what will it do in the domain, it will write that I need to access the new version hacker, that is the new version hacker.com, there is a website which I have to access, okay. So what will it do? It will write the domain of new version hacker.com in the request packet. Okay, then it will generate a message that I have to access the new version hacker.com. Okay, after that when it will go further, okay, that is, this is our application. This is our application layer, DNS STTP is fine here, when the data comes to the application layer, it will check that the domain is written on it, but it does not have its IP, it does not have an IP, so what will happen here? Now whatever fight will happen here, whatever will happen will happen, it is okay for IP, that is, step by step, how the IP is taken, how the domain comes, that will be known either here when the packet is generated and comes to the application layer or the application itself. When the layer itself generates the packet and sends it, then to whom will it send it first? He sends it first. When does HTTP work and where does HTTP work? Does HTTP work on the website? And when will it work? When does it work? If you have the IP address of the website then it is okay then here when the application layer sent that packet to HTTP then what did the HTTP layer do? It checked whether it has an IP address or not. Okay then it looked at the IP address. If it did not have it then what did it do? DNS What did DNS do when it forwarded to DNS? Obviously, what is DNS used for? Here, translation of domain to IP is called end fee, IP to domain is fine, that is why DNS is used. What happens here is that it is also called the Address Book of the Internet. Well, it is also the Address Book of the Internet, which means it has all the IP addresses of all the domains. Well, it means it knows the IP addresses of all the websites. The records are here, with the DNS, okay, so here, when it will send this packet, okay, when HTTP sent the packet to the DNS, then see what happened, so guys, here, when our PC will generate this packet, let's see here. People understand here that when this PC generates a packet here, what will happen first, then when it generates a packet, the first thing that will happen is the application layer. It is obvious that only the application layer will generate the packet. So, when the application layer generates the packet, then the first thing will happen. First it will send to SCTP but when does HTTP work? When it has an IP address, HTTP is used. Where is Hypertext Transfer Protocol used in websites? And when it has the IP address of the domain, then it works there. He goes and takes the data, he looked inside the packet, there was no IP address, only the domain was written, which was the new version hacker.com, okay, so what did he do, he sent the packet to DNS, okay, so Here what happened when our PC generated the request packet? Here the PC generated the request packet and first sent it to HTTP. What is HTTP ? What is HTTP, it first checked the packet, which was the request packet, after generating it, when it was generated, it saw that there is an IP address inside it, that means the domain that is there has an IP address. When does HTTP work when it has an IP address? It is obvious that when the data has an address, it will be forwarded only then it will move forward . Any parcel will move forward only when the address is written there. How will a parcel without an address move forward? So, whatever HTTP is, understand that it would move forward with the parcel. Is it yours? Here is the IP address. The request packet that was generated did not have an IP address. That's fine. So what did HTTP do? It forwarded it to DNS because it was the job of DNS to fetch the IP address of the domain. What is its work ? We call it Domain Name System. And what is its work? Its work is to convert DOMAIN into IP. Converting DOMAIN to IP or providing IP of domain. Is it okay? If our DNS is working, then it has sent this packet to the DNS, okay. Now when the packet has reached the DNS, what the DNS will do is add its headers to it and send it to the next layer which is the transport layer, okay. Now what will the transport layer do? The transport layer will add the port number here. Okay, how will the port number be added to both SOURCE and DESTINATION? Which one, first look in the source, add this port 54847 and in the destination, add port number 53, this will add the source. What is the end destination, I had also explained it to you all, it is okay, still I will tell you from where the packet is going, take it as an example, this is my PC, this one is sending the packet from here to the server, so it is okay. From here, if the packet is going, it will be source and where it is going, it will be destination, but when the reply comes, it will be source, and it will be destination. Okay, so this is the concept of source and destination, meaning where you want to go. Destination is and from where we have to go, that is the source. Okay, now look here, what ports have been added here, look carefully at the port, then look here, what is the source port, what has been added , what are the ports in the source port? We had read about ports. Everyone will remember that well known ports are registered ports and dynamic ports. Which range of ports are these? So, as far as you can see, these ports are dynamic ports. But The port number of DNS that has been added, the port number of destination that has been added is Will Known Port, Well Known Port. Okay, now here you have seen the range, what is the meaning of dynamic port, it ranges from 49152 to 49152 to 65535. It's okay, you may not be able to understand the writing, still I am telling you in words, our dynamic ports are from 4915 to 65535, similarly there are well known ports, okay, well known ports are from zero to 1023, isn't it 1024? Our registered ports are from 1 to 151. I have given good details of these ports. I have also made a detailed video in this. Go and check it out once. I will also put the link in the description. Ok, you do not need to search, ok. So here, when it added the port, which layer did the transport layer, after the transport application, did it come to the transport layer? Where and how was the request packet generated at the application layer? Whether the packet will go, it is found out whether it is ok or it is decided, after that it is decided whether the packet will go through DNS, then D DNS sent it here to transport layer, transport layer added port there, source and destination port and still the same message is generated . It must be happening that why is this message being generated? Why is this packet being generated ? It is being generated. New version hacker.com means it is fine for the IP address of this website. Now here when the ports have been added. The source and destination ports have been added to our packets, which means the path has been decided, the path has been decided as to where these packets will go, in which direction they will go, that direction has been decided, now it is the turn of the next layer. As soon as it decides the port here, it will send the packet here, where will it send the packet? Now to the next layer which is the network layer or the internet layer. Okay, so when the packet comes at the network layer, then what will the network take? If you look, then the network layer will first of all assign the IP address here, neither is it to everyone, nor will it assign the IP address to whom, then whose will be the source IP? It is obvious that the packet is going from us, so here the source IP will be ours and what will be the destination? If yes, then the destination will be where the packet has to go, where it has to go, why it has to go to the DNS server, then to find out our IP address, the new version of this domain has to be found by finding out the IP address of the domain of hacker.com, okay now. You guys, don't get confused about the domain because I have also explained about the domain. What is a domain? Okay, a simple domain is the name of a website. Okay, so you guys don't have to get confused in it. Now see the source here. After the end destination port, here the IP address will be decided, source IP address and destination IP address, here whose IP address will be in the source, this is a matter of mine, isn't it, which I have told you once, and the destination is the server. Whose server's DNS is the server's, so here it will go, where is the IP address of the DNS server? Why in the destination IP address, because we need the IP address of this website which is with the DNS server itself. Okay, so here in the destination. The IP address of the DNS server has been mentioned, now where did the IP address of the DNS server come from and where did these ports assigned come from? Okay, this question mark did not come in your mind that this is the port which is Source Port: Come on, the source port is our system, it can be given by anyone, dynamic port can be given by anyone, but when the destination port is assigned to it, where does it come from, then all the details of the DNS server are already fed. Who provides all the details of DNS in our PCs? Who provides all the details of DNS? So it is our router which provides all the details. Okay, this is our router which provides all the details of DNS because a lot of work is done through our DNS. Okay, so all these details are ready . The router gives it to our PC, so by default it is saved in our PC. Okay, now look here, the source port has been assigned, which is the one given by our PC, we had a ready feed of DNS, after that here Look at the source IP, what is the source IP which will be ours, here you will see below, it is mentioned here, so this is our IP address of our system, so this is all, right, this is the system of our PC, this is the entire layer of our PC, okay. So when it is being generated from our PC, okay, this is our IP address which is a private IP address, you all must have heard about private IP address and read about public IP address, I have read about it. Details I have made a video, I will also put its link in the description, it is okay to check it if you have not seen it, now our IP address is here, okay, the private IP address is in the source and the IP address of the server is in the end destination, which is The joke was already with our PC, now here the source port is already assigned. Okay, now here is the same message that this packet is being generated, meaning the request packet that is being generated is the IP address of the new version Herd Co. This is being done to get the address, this is being done to assign it, not to assign it, this is being done to find out its IP address. You guys can say this, now all these details have been filled in our packet. Meaning, the port has been assigned, the route has been assigned, the address has been assigned, the IP address has been assigned, okay now all these things are added. After this, what will the network layer do? Till now the packet which was there, all these things were being added in the network layer, so now what will the network layer do? Now it will send all these things to the link layer, that is, where the MAC is written, see, it is okay. So now it will go to the link layer. Now here, after the port and IP address is assigned, when the packet will go to the data link layer, then what will the data link layer do? What is the function of the data link layer? MAC address has to be assigned here. But whose MAC address will appear in the source? It is obvious that if our packets are going through our system, then only our MAC address will be assigned. So look here, either the MAC address of my PC or this PC, which is the MAC address of the system, is assigned. It is already done, so this MAC address is assigned in the source, what about the destination, whose MAC address will be assigned in the destination, will the MAC address of DNS be assigned in the destination? No, because we do not have the MAC address of DNS. DNS is a network outside our range, which is not in our range, we have the MAC address of those who are in our range, okay, only those systems which are in our range have the MAC address, we have it, okay, so here Whose MAC address will be assigned? When the MAC address of our system is assigned here, it is fine in the source but the destination is not assigned, then when it assigns the MAC address of the source here, it tried to generate the frame but it did not check. What I did was that the destination does not have a MAC address, so here when the MAC address was assigned to the source, what did it do? It tried to convert the frame into FPS, that is, the data is transferred only on FPS, then it is okay, it can happen through any medium. But the data which is forwarded in FPS is fine, so here when the MAC address is assigned to the source, it is fine, then it tried to convert it into a frame but that packet was not converted because the MAC address of the destination was Otherwise, how can the data be converted into a frame without the MAC address of the destination? So here whose MAC address will we give first? The biggest problem was that whose MAC address will we give here? Now here we cannot give the DNS. If we are out of range, then whose MAC address will go here? Where will the MAC address of our router be? Where is the MAC address of the router from? Where is it found? Is it known through an RP or is it mentioned in the RP table? You must have heard about RP table. I have also taught about how a router works. RP means Address Resolution Protocol. Now what does Address Resolution Protocol do that all the systems are within range of each other? The task is to find out as many MAC addresses as possible by sending broadcasts beyond us. The task is to know whose IP address is RP's, like dot and dot, whose IP address is this. This is the IP address of our router. Yes, I told you that this MAC address is taken from the router, which means that after sending a request to an RP, the MAC address of the router is also written, although RP is not required for the router, okay, and after that, look at our PC. IP address 10 is ok, MAC address of 1001 will be written here, ok so 102 is written here, 101 is already here, I think they have removed it, ok, understand that 101 is here, 101 will remain written here, ok. Here, the MAC address and IP address of all such systems are written opposite to each other. Okay, so whenever the MAC address is needed, we pick up the packets from here or the router picks it up from here. Okay, let us tell our system. For or for our system communication, we use MAC address. These MAC addresses are fine, our packets are not forwarded only through IP address and port, here we also need MAC address which is very good. Role plays Okay, now when the source and destination MAC addresses have been assigned to both, the MAC address of our PC in the source and the MAC address of our router in the destination has been assigned, now the packet is ready to be converted into a frame and so on. To go here, what did the data link layer do? The data link layer sent this packet here. The physical layer has it okay. What will the physical layer do? Here the physical layer will decide on which medium the packet will go. Meaning. What is the medium through which packets will be transferred like wireless, wired or through light or optical fiber? So the physical layer will decide here, whatever your router is, it is obvious that there is wireless technology here, so the wireless packet will be forwarded here, okay, now the packet will go to which router, okay now. Here, when the packet reaches our router, what will the router do, then the router will first change the source and destination, what will it change? Here, first of all, the source MAC address will change, so the router has two MAC addresses. Which two MAC addresses are there? One is local router, which is used inside the local router, that means one MAC address is for private area network and one is MAC address which is good for wide area network. If we use it in one, then till now the communication that was happening inside us, like with our PCs, was using it there, its private MAC address which is used for inside and there is a separate MAC address for the one. Whatever is the source, the router will add its own MAC address, I am the one which is used in wide area network and whose one will be added by the ISP in the destination. So the ISP also has two MAC addresses. Okay, so here Hash one means one to receive, one to forward, there are two MAC addresses, okay, so here, as if there is a hash one here, then here the MAC address is used first, okay, and the MAC address is okay, first MAC. Address: One of the two MAC addresses is fine. When will the second one be used? When will it forward? Is it fine? And what has changed? Look here, the source IP address has changed, and the source port has changed. Now, which IP address has changed? This is the IP address. The address has changed, our public IP address is fine, and which port has changed, the port has changed here, the port has changed here, it means one port number, one hash has not been used, beyond that, it is ok, so look here, now understand, take an example. Then understand one thing that the reply to the packet has come, it is fine, it has reached our router, then how will this router recognize that this packet has been given by the same PC, that PC has sent this reply since 10 days, how will it send it or what reply will it send? It has come, it has to be sent to 101 PC only, is it okay or how will it be known to which PC it has to be sent, for this it uses the net table here, so what is the net table, is the network address translation fine, so it is based on this table. OK, now what will be done here, a table is created here in which the packet has come from, OK, that means the packet from the local network, the address from which this packet has come, like it has come from this IP address. It has come from this port, okay, it is noted here and the public address is written here and which port it is using is added here to send it publicly, okay, so what here? It does this by adding all the details of the local area network, the details of the local area from which the packet has come and the details with which the packet is being sent, in the end wide area, it adds the details here, so what happens with this? Look here, the sign of Equals Two is also there, so what happens with this is that it easily recognizes that as if this port has been assigned one for this, okay, so this IP address here, the IP address does not change, that public one. So it will always be the same, each one is going to be the same for each PC, so what it does here is it assigns the port , like here one is fine, so it has assigned port one for this packet, the other PC will come. For that, if port to third port is going through simultaneously, then up to six or seven ports will be used, right, up to 10, 10, 25, 25 ports will be used, right? Then, through the port, it will be able to recognize it like a reply will come, what will it do? Check here. It will see for which IP address I have used this port number one, then it will see there that 101 was used and 5 was used for 4847 and it will forward using this, okay then this would be the work of net translation. At the same time, it also uses the MAC address, which means here which MAC address is associated with this IP address, that is, you must have seen A RP table. A also uses the RP table, that is fine, so identify it by mixing both. It is known that this system had sent me to get a reply or the packet had come from this PC. Ok, by using both of these, he finds out. Ok, he will change the source of the details that came there. Now here. Pay attention to this, our source IP address will change once, it will not change anywhere after that, okay, so what will the router do here, it will change the source IP address, meaning now. Till now our IP was being used from PC to the router, which IP was that IP, it was our private IP address, okay, now when the packet goes from here, okay, where from the router, then there, now which IP has the router used here? The address has been switched, here the router has switched the public IP address, so now when any packet goes out of the router, what will happen, it will be our public IP address is ok, so what will the router do here, it will put the public IP address ok and then Later, the port will also change, okay, now here it is only once, meaning till now we were working in private, that is, we were working on local area network, now when the packet goes on wide area network, then it is obvious that the IP will change to private. If the IP cannot be used then what will the router do here ? Will it put all the things publicly? Okay, so see what has changed here. Our source IP has changed. Okay, the destination will never change. It does not change till the last, right? End The source port has changed and the destination port and destination IP will remain the same till the end. Now from here, when our public IP has been changed once, it will never change further. Our public IP address is fine, public IP is only one here. The bar changes, now after that look here the destination MAC address and source MAC address. Now the MAC address will change everywhere. Okay, here the change that happens everywhere is only the MAC address, so look at the source, till now in the source. What was the MAC address of our PC? Then what will happen in the source here? Local router has one MAC address, that is, the router also has two MAC addresses, one for using in one local area network, fine for using it. So here the MAC address of the local router will be used. Okay, so the router here will switch its MAC address. Okay, what will come in the end destination? Still, we do not have the MAC address of DNS. Here in the destination ISP i.e. our service provider's internet service provider's router, yes, he also has a router, he also receives packets from the router, our ISP, so here the MAC address of the ISP will be entered, ok ISP. The MAC address of will be put here through which the packet will be transferred here. Okay, so now after changing all the things from our router, this packet will go to the ISP's router. Okay, now when the packet reaches the IP's router. So what will the ISP's packet do? Now look at the routers, they also work in the same way as our system, they will also have TCPIP model, they will also have three or four layers, right? There are four or five layers in our ITCP IP model. If we work in the same way then what will happen here, first of all the packet will go here, to whom will it go from the physical layer to the net data link layer, to whom will it go from the data link layer to our network layer, then as soon as our packet reaches the network layer So what the network layer will do is check what is the destination here. Now see, whatever things it adds, like our network layer adds the IP address, it can only check the IP address there . Whoever can add anything does it or whatever layer adds the thing, only that can check there. If the network layer adds the IP, then only that can check the IP address. Okay, so the network layer here. Okay, he checked what the destination was, so what was written in the destination was DNA server. Okay, DNS server, so what will it do here? It will send the packet back to the data link layer. When it passes the data link layer. When he sends that packet, what will the data link layer do? Will it generate a new frame there? Will it generate a new packet? Why, because here also the details will have to be changed, neither the MAC will change here, only the MAC will change, as I told, MAC is everywhere. Only the change will happen. Once we come on the public network , nothing changes, only the MAC changes every time, every time in the packet. Okay, now look here, whose MAC address will appear in the source, then in the source like our router. It had two MAC addresses, one for private and one for public. Similarly, ISP's router also has two MAC addresses. Well, receiving and sending have different meanings. It will send in the same MAC address in which it will receive. Will also work, okay, so the first ISP's MAC address which we had added to our router was the second MAC address. Okay, look here, MAC and IP MAC address are written. Okay, now the MAC address of the ISP that we have added here will be the hash. It will be two because it has to be forwarded If DNS is fine, then what will be the destination MAC address here? DNS server, because ISP has the details of DNS server, hence DNS server has MAC address, so it can add it, but our router did not have it, so it is fine. If he cannot add, then here the MAC address of DNS will be written in the destination. Okay, now two things have changed here, the source which is the MAC address here and the destination which is the MAC address, after both these changes have been made here. Where will the packet go to the DNS server? Okay, when the packet reaches the DNS server, then see what happens. Now see, the packet has reached the DNS server. Now what will the DNS server do? Its physical layer will receive that packet and convert it. Back as if it is received in the frame in which it is received, then it will be brought in its regional form. The MAC address will go above it, here it will come near the MAC address, meaning the data link layer where MAC is written is our data link layer, okay. If it is received at the physical layer, then look here, it is received at the physical layer, it converts it, it will be received at the MAC address, that is, if it is received at the data link layer, then what will the data link layer do? Here, the data link layer should note down the MAC address written in the packet. Will do it and keep it, okay now when we go to the next layer, in which the network layer will also check our network layer and there the IP from which that packet has come, see from which IP it has come, the source IP is 6569, okay, this is our public IP address. Okay, so the source MAC has come from yes, and the source IP address, both of these will be written here. Also, when the packet goes up to the transport layer, it will also see the port number, which port it has come from, that is, on which port the message has come . Now, why is it noting all these things here, so it is noting because when it will reply, neither in our destination, when the destination will be signed in the packet, nor in the destination, this IP and MAC will be added by which the packet will be sent. It is okay, so that's why I am adding it here, okay and keeping it noted. Okay, now when I went above the network layer to the transport layer, I saw on the transport layer that the packet that has arrived has arrived on port number 53. Which is the one on which DNS is listening. Okay, here DNS is listening, so the port number will be visible here, if the message has come in port number 53, then it will understand that it has come in port number 53, meaning it is the IP address of the domain. It has come for the address, it is okay because the DNS server listens on port number 53 only, okay, now here, when it came to know the port number, now it has gone up, okay, on the application layer, then it must have read this message, okay. And he must have seen that what is being sought here, that is, the thing that is being sought is the address for new version r.com, that is, the IP address is being sought for this domain. Okay, so what now? It will check that IP address whether it has it or not. Obviously, DNS is there and this website is registered, so if it has that IP address, it will add it to the IP address packet. Now let's see what is the further process. Now that it has For the new version, the hacker has seen the IP address and found out what he will do here: Will he generate a new packet or not? Now see what will be written in that packet. Now there will be many chances of DNS in the source. MAC address will come i.e. it is fine in MAC. MAC address of DNS will come in source MAC address. What will come in destination MAC address? The MAC address from which he was noting down, as I said, here he was noting down to whom the MAC replied. It has come okay, that is, leave aside the matter of reply, from whom has the message come? Here, from whom has the message come, from which MAC address, the request packet has come, the person who had noted it here will see it, then add the same back here in the destination, okay. Yes, now it will add the IP address in the source. Yes, now it will add its own IP address in the source. Okay, and in the destination, the IP address that was noted here is the one from which the packet came. Okay, so whose IP address is ours in the destination? The IP address is there, but whose MAC will be that of the router, which will be the port in the end source, 53, through which the DNS replies, okay, the end destination port will be the same from which the packet came, it will not change, okay here. So, in this entire journey, you must have seen that as far as the packet has come till now, only the MAC address is changing, nothing else is changing, isn't it? MAC address is changing everywhere. What happens in our networking is that only the MAC address changes everywhere. After the public IP address, nothing changes here. Once our router goes public, our network goes public, our packet goes public, then from then onwards the MAC address changes . Addresses change everywhere, okay, so here you can see that it has generated such a packet, now see there is some mistake here, there is a typing mistake here, the IP address is also mentioned here, okay, which I will tell you in the next slide. I am going to show, so here I will put a complete IP address in this packet, like look here, it is okay like this, this complete packet was generated like this, okay, here there is only IP address, okay, in this packet, here is the IP address. It had arrived 130 27.4 5.69 So you guys add this IP address here, it's okay, there is a miss printing here, so it's okay to add this IP address here, so he also mentioned the IP address here. This packet has been completely generated, okay, it has been generated, so now where will this packet be sent, where will it be sent to the ISP's router, so now look here, all the things have been done, now on the ISP's router when it Send it, okay, who has changed the DNS server? What will the router of ASP do? Will it change the MAC again because here only the MAC is being changed and nothing else is changing, so here the router has changed the Max of IP, meaning its own. Earlier there were two here which were going towards the DNS server but the MAC address here will now be the first MAC address of the ISP, so here you must have seen that there are two MAC addresses, ssh and ssh two of the IP, so here The MAC address of Pay Have will be assigned to the end destination, which is the MAC address of our local router which is used in wide area. Like I said, our router has two MAC addresses near our MAC address, one in local area. For a wide area network i.e. for world wide, then in the destination, which sign will be our MAC address of the local router which is the one, okay, all the other things are exact as if the DNA server had entered and here also Also sent the IP address, that version is ok for hacker.com. Now further, when this packet reached our router, ok, when this packet reached our local router, which is our router, then what is the router here? Now when the ISP's router has sent this packet to our local router, what will happen then the packet will be received here, first of all it will come to the public IP, first of all now what will it do after coming to the public IP as we saw. It will use the net table again, the network address translation of net translation will use it here and will know for whom I have used port number one, then it will know that I had added it for 10, okay then this packet again here. But if the packet changes, then whose source IP will be put here, it will come from that router, meaning the DNS will come from the router of the DNS which was added and sent from there, okay, DNS also has a router, so it will come from the router of the DNS, okay. The packet has come from here, it will add 10 to the nation, which is the IP of our local network. Okay, and here in the source port, brother 53 will add back to the destination port the same port from which this reply had come, i.e. our dynamic port. Okay, here it will add to this packet and also this message which was received along with it that the thing for which we had accessed it or the thing for which we had sent the packet, here is that packet, okay And here's the thing, what is this new version, the IP address of hacker.com is fine, so that too will be added here and forwarded to our PC, but before that, the MAC address will also be known here because only from our IP address we will be able to access the website here. Things are not forwarded here, MAC address is also found here, so look here, when the MAC address is assigned here, it means it will be the turn of MAC address, when the MAC address is seen, what will happen, A RP table will be used, now near A RP table. So all the details are there that which MAC address is attached with which IP, so look here, this is the MAC address which is attached with this IP, right? This is the MAC address of our 10, this is the MAC address of our 10, so it is okay. Now this MAC address will also be added, right here, after adding the MAC address, this packet is ready to come to our PC. Now when the packet is ready here to come to our PC, like see now. What happened to this packet, it was received from the internet, okay, our router received it in which address? Before finding out the public IP on IP, it used the net table to find out which port I used, for whom it was used, now here it will translate all the things using the net table and will add all the things to the old public which will send that packet. Was received means the packet from which it was received and the port from which it was received, all those things will be returned here as before. Okay, when the MAC address is assigned, then to assign the MAC address, a is used here. The use of RP table was taken. Okay, how was the use of RP table taken? So here it was written that this is the IP address and this is its MAC address, both of them were added here i.e. which one will be added to the source. The router will be added ok, whose MAC address will be assigned in the destination , whose MAC address will be used in the destination, our PC's ok, so here our MAC address is assigned, ok, so after doing all this, all the things have been added here, ok Now this packet is ready to go to our PC, okay, now when the packet has been received by our PC , what will happen here, so here, where will the packet be received first, on our physical layer, on the physical layer, okay on the physical layer, Will convert then it will send it to the data link layer. What will the data link layer do? It will check the MAC address there, whether the things that have come are correct or not, then the IP IP means that here on our network layer, it will check the IP address from which it has come. Now Here it will check that the reply that has come has come from this IP which is the end port 53 of DNS which is also of DNS, so to whom will this reply go? It is obvious that this reply will go to DNS, now to DNS. When that reply goes to DNS, it will open it and then it will check that it has got the IP address. It is ok. What will DNS do after getting the IP address? After getting the IP address, DNS will send this packet back to HTTP. Will send what STTP will do Will generate its new packet Will generate HTML request Whatever request goes to the website, we call it HTML request, it is also called HTML response, okay, the reply that comes is called response, so here when HTTP The IP address has come to the new weight of Hacker Co, so what will it do there? It will generate a new request. After generating this request, it will perform the same things again i.e. it will go down. Here the IP address will be assigned. Okay, look here what will happen here. The same things will happen again , so when it has done all these things, here all the things are added on, then a new packet is generated, how did that happen, first the source MAC address will be assigned here, when the new packet will be assigned the destination MAC address. Which router's end source IP will be assigned? Which will be our own end destination IP? The IP we have got here will be the new version of the hacker and will be received, meaning it will be connected here, okay, this packet is okay. So which IP is assigned in the destination, our new version is ha.com, okay, the source port will be any, dynamic, whatever goes from here, when it goes to the router, any port gets assigned, from here to there the router decides. It decides on which port to send, now which will be the destination, port number 80 because where is the packet going, whether it is going through SCTP or HTTP, okay, whose port number is 80, it is our STTP . Okay, you must remember that we had seen in the services, now what message will be generated here, earlier the message was being generated that whose IP do we need, the new version of ha.com, now the message is being generated here, send me the HTML file at. New Version Hacker means the HTML file of New Version Hacker means whatever file is required to access that website, you have to go to its server and bring it. Okay, now this packet will be generated and will go like this. Now the packet will be generated and will go to the server. Who will it pass to now, the new version will go to the hacker's server, okay? Now from there, this reply will be added on and will come back. Who will we have? Okay, now when the new version hacker's server will reply to us, it is okay about the HTML request, when that Will give a response, there will be many things in that response through which we can access the website, which is okay, it contains the code of the entire website which we access, okay, so the entire packet is performed like this, which is a complete step of our TCPIP model. By step things are performed like this, in every step all these things are being performed, one by one things are being performed, okay so once we are last Let's see the overview to see how all these things performed, it will become a little more clear. Okay, so here we go back to our first slide. So here we are back to our same first slide. So here we go. In this slide it will be explained to us or we will understand how this happened in short, it is complete, so look, this is the PC which generated the packet here, first of all, it is ok at the application layer, the packet was generated at the application layer, ok in the application layer. After generating the packet, it went to HTTP, but when does HTTP work when it has an IP address? Whose domain is it? Now STTP did not have an IP address, so who could have brought the IP address? Our DNS, so what did DNS do? STTP . What did DNS do? What did DNS do? What did the transport layer do? What did the transport layer do? It added a port number to it. Source port and destination port i.e. own port means the port of DNS and where that packet goes. It means from where that packet is going, it will come to the source, we will come to our port and destination, whose port is the DNS server, then here when the packet is going from the transport layer to the network layer, then what will the network layer do? Will add the source IP address and destination IP address, after that the packet will go to the data link layer. What will the data link layer do? Here it will assign the MAC address. Source MAC address and destination MAC address. In the beginning, the source MAC address will be ours, right? And the destination MAC address will be Because we do not have the MAC address of the DNS in the beginning, after that it will reach the physical layer, the physical layer will send it, okay, now when the packet went here and got sent to the router, then the router received that packet, okay. Now here he will change all the things, he will put his own source in the source IP, he will put the public IP address in the end source MAC address, he will put his own MAC address in the end source MAC address , he will change the end port number. No, by using the net table, when the packet goes to the IP, it is okay. Now when the work of the packet router from our router is finished, the packet goes to the ISP. The packet of the ISP added its details to it and forward here. Did it pass the DNS packet or is it right with the DNS server? Like the packet came to the DNS server, checked everything in the DNS server, where did the port come from i.e. in which port did it come, in which IP address did the things come, now it got whatever was asked for. That packet contained the new version IP address of hacker.com, that IP address was checked and the entire packet was created again by adding the source destination and the IP address that we had asked for. After adding all the things to the IP address, the ISP's router will send the packet back. It will go from the ISP's router to our router, it is ok. It will go to our PC, it is ok. Now our PC will read all the packets here and will pick up the IP address from there. New version of hacker.com. New version of hacker.com. After getting the IP address, our PC will generate a new request which will be HTML request, now this HTML request will perform the same things again, first it will go to the router, from the router to the ISP, now here this packet will not go to the DNS here. From this it will be diverted to the website's router and to the website's server. Because he also uses the internet, he also has a router, so to whose router did this packet go? Now to whose router did this packet reach the server? Which server is the new version of hacker.com's server? Now the server will reply, then here we will get that packet which is the response packet, it will have all the things in it, how to access the website, all the coding will be done, after that we will give that website. If you can access then all the things are performed like this. So I hope guys, you all must have understood today's concept of TCPIP model and also OI model. You must have understood how it is working step by step. Many people may be concerned that why are we studying networking? Look, when your networking concept is clear, you can crack any level of certification or exam. Well, whether it is of Ethical EACH, it is fine of this council or OSCP or any higher exam, unless your concept of network or networking is clear, you cannot crack those exams or else If you cannot perform anything, then basically your concept of networking is very important to be clear. Okay, now I have a last request to all of you that see, there will be many such children around you in our country who are interested in ethical hacking. Or they can't afford the fees of big institutes because the certifications are a bit expensive and they can't afford it, so my concern of opening this channel was that every person, every child who wants to study can Wants to read Cyber Security Ethical Hacking? Okay, so our channel is not that famous right now, that's why our videos are not able to reach everywhere, so make this video reach everywhere. What you guys are watching is similar to what anyone around you is doing. What will happen if you share it with a child who wants to learn? This will help our channel and also help that child who needs this video or who wants to study. Now overall when every person or every child. Will be aware of the cyber security concept. Okay, if he starts understanding everything, then the cyber crime rate will automatically reduce because see, you do not know how crimes are happening. If you send a link, then how that crime is happening by sending the link. How is the money being deducted? Okay, if this concept of how the money is being deducted by giving OTP becomes clear then the crime rate will automatically reduce. You people will automatically be aware of how cyber security is and how ethical hacking works which generates links. How do we do all these things, so basically, we are securing our own country, we are securing our own country, okay, so my concern is that our cyber crime rate should be reduced, right? This is the last request to all of you so that a child can learn, it is okay to do this much. Thanks for watching this video and don't forget to like, subscribe and share, we will meet in the next video, till then good bye .
