The OSI Model - Explained by Example
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- Опубликовано: 20 июн 2024
- OSI is a model that standardized the communication in computer system, its what the internet runs on. In this video we will try to learn about the OSI model by example! Stands for Open Systems Interconnection model.
In this video we will make a HTTP GET request to a web server and explain how the data flow through the OSI model layers from the application layer, presentation layer, session layer, transport layer, network layer, data link layer and finally physical layer. we will also explain why people tell you not to connect to public WIFIs.
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0:00 Intro
2:15 public vs private ip address
4:00 Application Layer
5:30 Presentation Layer
6:20 Session Layer
7:20 Transport Layer
9:20 Network Layer
11:20 Data Link
13:00 ARP protocol
14:00 Physical Layer
19:00 Why you shouldn’t connect to public WIFI
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Hussein
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Hussein 
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Hey guys in minute 16:00 I forgot to mention this is a WIFI configuration not wired .
so all devices within range will receive the those packets since they are in radio vicinity and drop them if they are not intended for them.
if that was wired than the router (acting like a switch) will be smart enough to only forward to required device by identifying which port it is connected to.
I was really confused until i saw this comment. Thanks! However, I do have a question, in a network of only wired computers, how could someone listen for packets? If the router is only sending the packets to the intended recipients, then I don’t see how someone could sniff packets unless they had access to that router. Basically, would tcpdump or wireshark work in a completely wired network?
Yup. At 16:00 i paused the video came to comments section.
in case of wifi, doesn't the client set the destination as a router(which is a default gateway for it) at some layer and then the router directs the packages to the server? So, basically, the server receives the package twice: first time from the client and second time from the router; but first package it drops at some lower layer as it doesn't know yet that it is the destination of that packag. Or in case of wifi, the router even doesn't takes a place in client-server communication? Why I'm asking, becasue at the moment when client sets the destination at data link layer it doesn't know what media will be used to transfer the data(wifi or wired connection) so it sets as a address its gateway
that's what is was wondering shouldn't router/switch do it for you
Great video.
I feel like I want to quit my job and spend a few weeks just studying your backend topic videos. Really interesting stuff. I was even able to explain to my wife why she can't access homebanking in a starbucks.
Same way I feel!! So sad I discovered Hussien late!
I quitted my job and and I discovered this channel... I know that feeling, i think I need at least one month to watch all the videos and after that maaybe get another job 😆
@@dicksonchibuzor2792 seriously
exactly. I was also thinking to take a break from my job to deep dive into backend.
i am also doing it
Guys here are some jump codes to help you navigate, 2:15 public vs private ip address, 4:00 Application Layer, 5:30 Presentation Layer, 6:20 Session Layer, 7:20 Transport Layer, 9:20 Network Layer, 11:20 Data Link, 13:00 ARP protocol, 14:00 Physical Layer, 19:00 Why you shouldn’t connect to public WIFI
I enjoyed making this video!
I have a lot of question. Would you help me?
Thank you for this great tutoriol❤
Hi Hussein, thank you for making this video. I just want to clarify one thing. At 16:20, you say that the stream of bits that are being sent from the client will go into server 1,2,3,4..etc essentially to all servers. This is not correct. I'm a software engineer working in networking domain, and in networking the direction of packets is either "unicast" (meaning it's directed to one client only), multicast (meaning it's directed to two or more known clients), or broadcast (meaning the traffic is directed to any machine that's on that network). In your case, since the server is hosted on machine C, the data is directed to that machine and it will only go to the router first and then to that machine regardless of the medium used to transfer the packet (Ethernet or WiFi). If the stream of bytes were transferred using WiFi, you are right in that the data will be broadcasted all over the place using radio waves but only the router will be able to interpret those packets, because that's how WiFi works, and the other machines (even if they have a WiFi receiver) will not be able to decode the packet and see the bit streams. Just wanted to point this out to clear any confusion. Thanks for making these video. They're very useful and informative.
I looked in the comments specifically for this
but how does physical layer know that the server is hosted on C ? How does it decide to route to C at physical level ?
@@devarsdk the physical layers knows that this is for him, and he then checks to what local ip he needs to redirects it request and then it broadcast the wave again and that;s for C
Hi, this context helped me a lot. Sometimes I see the term anycast, has something to do with this. Is it the equivalent to broadcast?
@@devarsdk You need to learn about ARP protocol. I think that will solve your problem
"Intended for you as a device, but not as an application" - Perfect way to explain the way the router works when you make a request to external network 👌
It is a dry topic, but somehow even with your thick accent and minimalist presentation style, your charisma makes this video a joy to watch. Seriously.
I have watched many youtube videos on the OSI layers, and this is my favorite one. This really gave me a good understanding of the OSI layers in a real world scenario. Explained simply and gets the points across. Just great!
Thank you for the explanation Hussein!
I was first exposed to the OSI layer through work when dealing with CAN networks in industrial vehicles (EE background), and have never found a resource that would help me create a solid mental model until now. This is it. The example is great, and it explains OSI's layers and main concepts really well.
At last i laughed when the web server got the GET request😉😉😉........Awesome explanation
I don't think I've ever heard any explanation of any topic to be this much interesting and fun ever! Thanks a lot! I wish I could learn every other subject from you...
First ever I came across the concept of OSI was in 3rd year bachelors and it's been 4 years since. Today is the first time I can say that I understand the whole damn thing and what each layer does. You are a legend Hussein.😁
Hey Hussein!
You really rocks!! It's amazing how clearly your explanations are about complex stuff!
Congrats!
Your humour lines in between your awesome teachings are really nice and engaging.
Thanks for a refresher and keep it up!
Your Channel is a gem. I landed on this channel searching about the difference between proxy vs reverse proxy, ended up watching at least 10 videos as of now. Though I am a frontend engineer, still I feel everyone should have this basic networking knowledge.
❤️ thank you Deepak! Welcome to the channel
the best explanation about how packet sniffing and interception works. thanks for this!
Omggg where was Nasser in 2015 when I was pursuing my undergrad?! Computer Networks made me cry as a subject just because I could not digest the huge amount of information bombarded at us during the coursework. This info along with the diagrams, is gold 💯. Really helped me understand the OSI model - something I thought would never be possible (coz I tend to get lazy when things stop making sense or when I'm unable to visualize what is happening)!!! Thank you Nasser 💯❤
Very useful, entertaining description of the OSI Model. Now I understand more about why it’s important to encrypt data in transit.
"I was in university 10 .... Ohh no maybe 20 years ago ... Damn I'm old" 😂😂😂
But you make awesome tutorials ... Keep it up !
Apoorv pandey 😂 Thanks 🙏 glad you enjoying the content
😂😂😂😂
Summary of:
OSI (Open Systems Interconnect) model, from a software Engineer's view (Please correct me if I'm wrong):
Layer 1 Physical
This is the physical layer, in which 1 and 0 data bytes can be sent as electric signals, wifi, or light via "the wire"
Layer 2 Data Link
These are the separation of the data bytes into frames.
Notably, the frames will identify the source and destination MAC addresses of the devices' network card.
Since electrical signals travel in all directions in a network, the data frames reach all devices in the network.
Once the data frame is able to identify that the device is not the intended destination, the frames drop.
In an unsecured network, this is where a malicious application can choose to not drop the frames, and steal the data.
Layer 3 Network
Once layer 2 is done, it generalizes the frames from MAC addresses to IP addresses.
Layer 4 Transport
This tranport layer further generalizes the network layer IP address into source and destination ports.
Layer 5 Session
Since there may be several TCP connections to one server at a time, with identical packet information from layers 1 through 4, we need a way to distinguish the session by ID to tag it.
Layer 6 Presentation
This is where the resource might be secured/encrypted with HTTPS/TLS by scrambling the HTTP request string.
I didn't know HTTPS encrypted anything. I thought it was only a way to identify the true identity of a website.
Also, encryption might be accomplished via VPN.
At this step, if the data is encrypted, the model decrypts the information to reach step 7.
It might be possible that a malicious attack to steal data can be avoided by encrypting.
"This is where you can get screwed if you are on public wifi...people can sniff your data."
Layer 7 Application
This is where a client device makes a request to a server device, such as a GET request.
This request contains a whole bunch of information, such as headers, cookies, content-type headers, etc, which is summarized into a string, so the string can participate with the rest of the OSI models as byte data.
Andres! Amazing summary thanks for taking the time to compile this. It would be nice to separate the summary based on the sender vs the receiver . Thanks for being a fan of this channel :)
Damn. Nice one. 👍Anyway you could summarize quantum mechanics too?
@@praiseokonta8879 😂
@@praiseokonta8879
Lol 😂
Read this after watching. Great summary to recap everything 👏👏👏👍
My god!! I’ve been trying to understand OSI from so long but theory sucks!! Glad that i just found your video! First time i got entire thing cleared ! Great work
You are just great . the way you explain and keeping things as simple as possible make your tutorials so interesting .
Best OSI explanation ever!
Sir, you make evrything seems as simple as the waterflow , thank you so much for all of your efforts
I am binge watching the backend engineering playlists. Awesome content. Keep up the good work! :)
Enjoy!
Literally after going through the video I felt like I have achieved a lot today already. Thanks you.
thank you so much, you amazingly simplified a complex topic that I did not fully understand when I was in university ❤️❤️❤️
I have used Wireshark before, and the way you introduce it in the video makes me try to correlate every technology that I am using as a developer.
A huuuuuuuuge plus from me. This is a best explanation of network communication I have ever seen in my engineer career.
Hey Nasser, This is the best explanation I have seen for OSI model. Thanks for the great video.
Congratulations!!
Your content has reached India. Now, sit back and watch your channel grow.
The "Yayy" at 4:58 had me weak 😂😂. Love your content man.. you give direction to aspiring backend engineers. Please make more 💯
i just addicted to this channel.
Thank you for this great explanation. After 8years finally I understood this model.
thank you sir.. you just explained something in a great and easy way that i couldn't understand though out my computer networks class. Now i am less scared of the subject
Lakshaya Sood really happy I could help! Best of luck on your study 📖 cheers!
Beautifully Explained, Thank you Sir
Thank you for making this so simple to understand!
I have been listening to your videos for days. I can finally understand this stuff. Thank you so much!
❤️❤️❤️
Very easy to understand and helpful. Thank you!
This is explained really well and it is abstraction done right for beginners. Good job and thank you!
Thanks! Glad you enjoyed the video cheers!
Finally i managed to understood OSI. Thanks Nasser.
Thank you so much for doing this, I have watched a lot of your video :3
Great! Thanks for your comments very happy I could help. Let me know what other software engineering content you would like me to make 😊
You are just insane buddy....amazing.....thank you millions
Dude, this is GOLD.
I wish i could understood the Beauty of OSI model a year before. Really awesome video ...
I am soo glad i found your channel right before my Amazon interview ♥
literally the best explanation fr
This video gave me a great understanding of the OSI and is a fundamental part of my progress in IT! Great work!!
Thanks Hussein! These videos are brilliant. I wish I had discovered them earlier.
No worries! glad they are helpful!
Finally found the perfect video after searching for long. Thanks!
Thanks a lot Hussein for sharing this. This is really amazing and the way you have explained is so awesome.
Such a good video overview of the topic. Great illustrations and presentation
Excellent explanation even compared to the university course. Thanks so much and all the best Hussein.
wonderful animations Nasser, Kudos.. thanks a bundle.
Feynman technique at its best
Dear Hussein, awesome video. I learned a lot and loved and laughed with every bit of your explanation!
" OSI is Open Systems Interconnect, I don't expect you to remember it"
Me: "meh I think I will"
*midway through the video*
"what's OSI again"
I relate too much to this 😂😂
Great explanation! Thank you!
I am Definitley going to use this approach to explain the concept to people
@Hussein absolutely nice explanation. The thing about bits converting to light is an eye opener. Just makes it so clear to connect the dots now.
Thanks buddy!
Thanks so much for this video tutorial.
Thanks for another good explanation bro, as a web developer your videos help me lot because they are basic and very understandable.
Eren Sertkaya thanks Eren, happy I can help and we all have room to always learn more! Its an infinite field
Best explanation of OSI I've ever seen (and I've seen lots of them)
it really is cool to finally understand what's happening. thanks a ton!
Gosh, brilliant deliver of dry OSI theory. Thanks!
This was hugely helpful for me to get into cybersecurity.
very very very underrated video, The best explanation I have ever seen on youtube sir.Thank you for making these kinds of videos 🙏🙏🙏🙏🙏🙏
This video is great. Clear explanations. Thanks for making it 👍👍
Excellent explanation. Really appreciate your effort!
Thank you for explaining so well. Thank you for your efforts
Thank you i wish i found your channel much eariler...
Thanks ! Your here now and thats what matter. enjoy the content ! And tell me what should I make next .
wonderful video Nasser!!!
Thank you sir. Really enjoyed this journey of data. ❤
Thanks Shovon! Its impressive right? Seeing how data flow
Thank you man for this. I wish you know how long i have been stuck in the osi plateau. It just clicked
I really enjoyed watching this, brilliant explanation. Thanks❤
This was awesome man. Thanks a bunch
A gem in tech world. Gracias brother.
Hussain, you are the BEST !!
Am glad you did this video.
Thanks a lot, really.
Thanks for this beautiful video!!
So now I can explain to non-techie people why you shouldn't connect to a public wifi network!!
Great video 💯
Well done sir. Thank you👍.
The best video ever made to explain OSI
Thank you Aniket!
ohh god i am so happy i found ur vidoes and so excited to watch all ur videos......i swear i am gonna binge watch ur videos.....and thanks a lot to you for making such amazing videos........sending lots of love to you.......thanks man
Sending love ❤️ back
Excellent stuff Hussein!!
Thank You Very much.
Excellent job man, you are the master, Keep it up man ...
Thanks..this is the best channel
Thumbs up ! Great Video ! Thanks a lot ! And its definitely not boring at all.
Perfectly explained
I like this explanation! So interesting and clear
thank you so much, I do enjoy your videos, I do appreciate the time and efforts you make.
Glad you do thanks Majed!
very well simplified
Great style!
This is really helpful. Thanks
Amazing explanation
Really a great understanding i have got today😇
Excellent much appreciated
Excellent, Thanks
Very well explained if it comes to particular layers, what happens in every layer, however the last part of video seems to be a bit too oversimplified for me. I think you should exemplify how data travels from one device to another with more 'tricky' network topology. Also I think you should distinct network devices such as switch, router and firewall, because in fact standard SOHO (small-office-home--office) 'router' consist of those 3 devices combined into one box.
Of course then the video wouldn't last 25 minutes, this is knowledge that need some time to be explained :)
Anyway, I love your content, your channel is really good place for backend engineers.
Greets from Poland!
no I am not yawning, its interesting how you are giving related knowledge also with the topic information. keep it up this way, i like it thank you for this informativve vedio.
You are amazing. Thank you brother. I appreciate you. Please keep making more
Thanks Eric!