NAT Explained | Overload, Dynamic & Static

[@yohaneranga8827]

I do not normally comment on videos , but as most of the viewers may agree with me , you deserve more subscribers. Your explanations are by far one of the best ,even better than what they call industry experts. Keeping it simple and one explains one thing at a time makes it pretty stress free to watch and understand. Keep it up and I'm looking forward to see more advance networking concepts simplified.

[@Certbros]

Thanks Yohan. Appreciate the comment. Glad it helped you out.

[@avengefulgamer3188]

This is a really great video. Im working on getting my CCNA and this really helped me understand how NAT works after school. thank you for the solid and slow paced information to let it sink in.

[@Certbros]

Good to hear this video helped you out. Thanks for the comment!

[@andywarrier489]

I am basically a dumb person, but mate, you make me feel intelligent and that is priceless for me. Thanks a ton and cheers!

[@Dragon-Slay3r]

The pinky second finger yesterday was fake thats why they deploy bey cap cover for bullshit 😭 aslong as people make money who cares

[@guidowitt-dorring124]

This is the first video I've seen that properly explains NAT. Most others are too superficial and skip some details that are crucial to understand for the system to logically make sense.

[@rikvanbrugge]

By a guy with no IT background at all: already on my sixth video today. Very clear text, good voices, excellent animations. Thanks a lot!

[@Certbros]

Thank you Rik! Really great to hear your enjoying the the content.

[@bootygoblinthaseaman3233]

my textbook overexplains tf out of everything so thanks for this bud

[@mehdiroudeau8809]

the best explanation I have ever had

[@Dragon-Slay3r]

In this stupid game the only real fake Jesus is me 😂 If anyone needs an attorney let me know I can find them counters with KZbin in court 😭😂

[@schrodinger6991]

I am watching this because my class was cancelled because our school is closed because of the virus, therefor our teacher can't explan the content so he sent as the video.

[@Certbros]

Thanks! It's really great to hear these videos are helping people during this time!

[@mujtabaarfat717]

because its closed becaused u want to study u watched it because u want to learn.

[@FoX84tac022]

Nothing like being supplied free content for a class your paying for... lol

[@schrodinger6991]

@@FoX84tac022 I am not paying for it education in Austria is free

[@FoX84tac022]

@@schrodinger6991 Well fuck me xD

[@Itsweet5533]

0:26 start -- thanks for the video!

[@TimonLevy]

Dude, this guy's voice is so calm I almost fell asleep watching this.

[@danteeep]

you explained better than any video on youtube ive checked so far.. thx

[@Certbros]

Thanks!

[@PHTM04]

I got a computing exam coming up, this video explained it flawlessly compared to the notes. Appreciate it bro! also subscribed :))

[@tiramisu2717]

This is a solid explanation of different types of NATs. It has helped me solidify my understanding! Thanks.

[@Certbros]

Thanks Ray!

[@Jarrah_Kilgour]

Nice video, but I have a hole in my understanding.... if the router swaps the private address for a public address as shown, how does that solve the issue of there not being enough public addresses? surely some other router somewhere is using the same public address in it's "pool".

[@nileshgujar4310]

You made it so easy to understand, as I read some articles and find myself scratching my head again n again ... Thank you

[@Certbros]

You're welcome Nilesh! Happy to help 👍

[@kabandajamir9844]

The world's best teacher

[@infinitelooping]

This video is a marvelous explanation of NAT, one of the bests I have ever seen. Well done

[@Aman2111]

Thats the skill, How beautifully he explained NAT.

[@itaybarok9405]

Thanks. I understood the concept of NAT strongly now and why it is important. Also, I know types of NAT like PAT NAT and static NAT and dynamic NAT. Great and useful video. Keep up with these good staff.

[@JP-ws4sv]

mate your videos are really good. your animation and voice really help simplify the essays ive read in CCNA books. thanks !

[@Certbros]

Thanks Jit! Happy it helped

[@shajondas9313]

Thank you!!! Your videos are below 10 minutes and in this short time you gave the concrete concept and so much information indeed . Thank you again.....

[@Certbros]

Thanks for the comment! I try and keep these videos as short and simple as possible so it's good to hear its working.

[@zangreiner1048]

6 years since this video was published and i can confirm that it is still a great video

[@jimyork8196]

You took a somewhat mystifying concept and made it very easy to understand! Thanks!

[@Certbros]

Thanks Jim!

[@Brooksiebaby1113]

Thank you for the explanations on the different types of NAT. The second edition of Information Security: The Complete Reference by Mark Rhodes-Ousley does not explain the concepts thoroughly enough for me. The sections of PAT,dynamic NAT, and static NAT were a little too brief. Your video broke it down just enough for me and the added visuals will help me to remember the particulars.

[@Certbros]

Happy to hear it helped and thank you for commenting. Good luck with your studies!

[@ransfordaddai6992]

Great video., NAT simplified. i recommend this video to anyone struggling to understand this concept. Kindly do more of this video. the graphics, explanation and top notch

[@azran1180]

you are still replying, great and good video helped me for my assignments :)

[@Certbros]

I try to reply to all comments if I can. Glad you liked the video and good luck with the rest of your assignments.

[@EcripArts]

Glad I stumbled upon this channel. I'm setting up render servers at my office to connect to over VPN from home, with a pfSense server, but I had very limited understanding of why I had to do some things and how these things worked. So it's good to get some more background, I already understand alot more. Great work!

[@Certbros]

Glad to hear the videos have helped you out! It's always great to get these comments. Nice intros by the way!

[@EcripArts]

Thanks, I appreciate it! Most of it is rather outdated actually! And keep up the good work, I like the visual part of the explanation. People have told me about alot of network related stuff but this makes it much more clear to me.

[@ausmanx1161]

@@EcripArts what’s your job tittle now

[@EcripArts]

@@ausmanx1161 Due to illness, unfortunately nothing anymore. I used this for building a render farm for my 3D work.

[@lnrkothapalli4106]

After 2 or 3 days I got exact information what I am looking for thank u so much

[@Certbros]

Great to hear it! Thanks for watching.

[@lenbrake4982]

Thank you for a carefully explained short clarification!

[@karolisnorvilas9340]

the best material for networking!!

[@Certbros]

Thank you! Glad you like it.

[@BLOEDLINK]

Again, Best explained video's on the net!

[@Certbros]

Thanks Niels

[@8686joedog]

Awesome tutorial. What about “open” nat. I remember years ago my xbox would struggle with multiplayer connections because it said my nat was not set to “open”.

[@atharvabet1637]

Truly amazing! Just got what I was looking for. Please keep uploading such wonderful, crisp and informative videos in the upcoming time :))

[@Certbros]

Thank you Atharva. More to come!

[@speensaba]

keep it up, good explaination.

[@Certbros]

Thanks!

[@simray7602]

You deserve more subscriber , good animation make concept simple ,hope for more content coming

[@Certbros]

Really appreciate the support Wind Luo! A lot more content planned in the very near future.

[@mr.rd2m]

Thanks for the video. but what happens if two different internal private IP's use the same port? how does the NAT decide which packet goes where?

[@germankoster4910]

For what I understood, the port will be changed as it says in the video, if a port is already being used, it will take the next available one.

[@ramchandrapatil2215]

You explain with very clear and with example. Thanks.

[@Certbros]

Glad you liked it 👍

[@ramchandrapatil2215]

If possible can you please make videos for CCNP. It will really helpful to us and we don't need to anywhere for this.

[@geofftefl]

Excellent explanation, nicely illustrated. I'd like to know more about NAT when multiple routers are involved. Does it matter where NAT resides? That is, should it be on the internet facing router, or can it be on a router behind the internet connecting router? Perhaps that would mean the internet facing router can't provide NAT to other devices it serves, such as an IPTV box? I hope you can clarify for me. Thanks again for your quality videos, I'll study them for more insights.

[@Certbros]

Thanks Geoff! Generally speaking you would use NAT on the internet facing router to convert your private IPs to public IPs. You can use NAT internally if needed. Really it just depends on the situation.

[@geofftefl]

CertBros thanks for your response. Does having NAT enabled for both (outward and inward facing) routers introduce issues? The LAN IP for each, in my case, is separate (192.168.100.1 and 90.1), with the internet facing router acting as gateway to the internal router. Grateful for any guidance.

[@Certbros]

Yes double NAT is possible but if I understand the situation right then it's not needed. You just need NAT to covert the private IP to public. The internal router will be able to route the traffic between the connected internal (.100 / .90) subnets.

[@geofftefl]

Thanks once again, your interest and response is much appreciated. FYI, I experimented with disabling NAT on the internal router and communications basically stopped, so I enabled it again and for now will leave well enough alone. My next challenge is to get access from the internet through the primary router to the internal router that connects a Windows Server 2008 R2 instance. I'm fiddling with port forwarding and Windows Firewall to get through but it's stretching my knowledge. If you have any videos or can make one on this subject that would be great. Thanks again and regards.

[@Certbros]

Ah OK. This will most likely be because the internet router cannot route the traffic back to the internal routers LAN. A static route could resolve this but if you are happy with the double NAT then leave it like that. You will need to port forward from the internet router to the internal router, then from the internal router to the server. You may also need a DDNS record if you public IP is dynamic.

[@ok_gn]

Legend. Great teaching style. Thanks for the video.

[@samuelnwadike9042]

i really appreciate your teaching skills, simple and effective direct to the point. i will really love more of your videos you got a new fan. if you have stuffs on CCNA recent stuff or even exam dumps please just send me the link thanks

[@kychemclass5850]

Great video! Thank you!. When you said data can be even be send to the tab? Do you mean the router sends it to the tab? And if so how? - by attaching supplementary data like a "port extension" stored in the NAT? which the browser attached initially? Could anyone explain?

[@umunnahgentle6440]

This is the first time i have been able to understand this NAT lecture. Thanks a lot. Please do you have a video on IS-IS and BGP configurations

[@dencam]

Thanks for the solid and precise explanation.

[@Certbros]

Very welcome!

[@mattwilson717]

As a new IT student I have no fucking clue what I just watched, but I’m sure I’ll come back to it

[@Certbros]

Sure this might be a bit much to start with. Come back when you ready.

[@mikenerlyeustache]

What if I have multiple computers in private need to access to internet, as I have only one public IP from my ISP, how would be the NAT table? Thanks for your great explanation!

[@hassenbouchhiwa9827]

A question please: 3:55 the source port have to be above 49152 doesnt it ? to be dynamically assigned port number thanks

[@MrHuzzy93]

Great explanation! Keep the good work up. Highly appreciated!

[@Certbros]

+Hussein Jasin FIRST COMMENT! Thanks!

[@blemint3682]

I got an exam about this tomorrow and I'm so thankful for your good explanation. :)

[@Certbros]

How did the exam go?

[@Soosss]

@@Certbros he got a 0

[@PILIF1983]

4:43 I think there is a small mistake that port 8897 from the table is not the same with source port bellow (8879)

[@Certbros]

Good spot! You passed the test! Not really, its a typo. Thanks man.

[@ToothpasteJuiceBox]

A pool is basically a really wide and flat bucket :D Great video

[@Certbros]

Yes it is! It's a deep and narrow pool! haha.

[@nitin_manju]

In case of PAT, how does the router identify if two of my devices have the same kind of app (same port) running. 192.168.1.1:80 and 192.168.1.2:80

[@josephmulvey856]

because it has two different private IP addresses

[@AbinJoseph1996]

@@josephmulvey856 What he meant was, when an external device makes a request to an app hosted in the local network using the public IP of router how would the NAT knows which local address should it send the request to.

[@Certbros]

You would use static NAT for this. You would need to use different ports or different public ip addresses.

[@apollosolutions9961]

The Nat table will use the IP address of the source

[@wexwexexort]

Best explanation I've seen so far.

[@Certbros]

Thanks Mert

[@dothchabani8565]

Hi ! Thank you ! I finally understood how NAT works :D Just one thing, Dynamic NAT is a many to many mapping addresses not a one to one, that's according to ICND1 documentation ^^' Keep going ! :D

[@lesleybw]

I realised he confused NAT and Dynamic too there!! Great video nonetheless, it really helped clear this out for me!

[@lesleybw]

Static*

[@shakilalig]

As usual.. Certbros rocks!!!!

[@Certbros]

Thanks!!

[@vinnyseeram6418]

Great video! Would it be correct to say that the key difference between PAT and static NAT is the router building the NAT table vs manual configuration of the NAT table?

[@svalenzuelamusic]

Where would the use of ports from the “dynamic and private ports” range be implemented? I’ve read that when a computer makes a request to the internet (example: web request) it will make choose a source port from the aforementioned range to map to the application/service making the request (example: web browser). Wouldn’t the INSIDE address (source port) use one of these port numbers?

[@Certbros]

Not sure if I understand the question but one example of dynamic NAT would be to change the subnet to another private subnet. This can be useful if you have two networks with overlapping subnets.

[@pavelkarvutev8051]

Wow, finally I understand what NAT meant Big thanks, so good!

[@Certbros]

Happy to help! Thanks.

[@nikhilchoubey5479]

It is really short & simple explanation to understand it easily. Especially the slides representations helps a lot to understand. Thank you!!😊

[@Certbros]

Thanks Nikhil. Happy it helped you out.

[@TheAMOS45]

Amazing explanation . I got it on the first go

[@Certbros]

Thanks! Glad it helped you out.

[@jasonkittle326]

Mine has a lot going on. Thank you!

[@user-pg9te8ug1j]

Thank you so much. Fantastic explanation!! 10/10

[@pantelisvasileiadis2858]

thank you very much dude! very simply and well explained!

[@Certbros]

Thanks Pantelis! Appreciate it 😁

[@zi0]

Very well done lads.

[@Certbros]

Thanks Zi0!

[@jeshbargota7745]

Cheers mate, simple but very effective !

[@Certbros]

Thanks for the support!

[@DonMalik99]

excellent quick NAT explained, love it. Thanks

[@Certbros]

Thanks Don!

[@olafgunther9401]

what happens if two computers are requesting data from the same source and on the same port? does the data then get multicasted to both?

[@jing-weiho3900]

Very good video indeed, just one question, in the PAT section, your inside local IP 192.168.0.1:8897 should be mapped to 11.22.33.44:8897 in the NAT table. but the first switch at 4:16 shows it altered to 11.22.33.44:8879, and at 4:42 your table shows the correct mapping again. Was this, you especially try to explain if 8897 port was taken by other services the router would automative choose another port to replace it? if yes, I`m curious about how NAT deals with it , does NAT table in PAT mode also provides some alias mapping? Thanks for your answer!

[@Certbros]

That is a very good spot! This is a typo! Thanks.

[@jing-weiho3900]

Thank you for your respond! although I`m still curious about PAT's port selection logic :)

[@Certbros]

NAT will choose another port number and use the table to map the translation. The table will keep track of which internal IP+port was mapped to which external IP+port.

[@jing-weiho3900]

Thanks for reply. Very helpful!! love to see your videos

[@Certbros]

Thanks man!

[@TeX____]

very good and fast explanation of how NAT works. :)

[@Certbros]

Thanks TeX!

[@Scruibyxmontages]

Nice, feel like a genius now, really appreciated

[@Certbros]

Haha! You are a genius now!

[@atzeero]

Thank you very much for your lecture.

[@Certbros]

You're welcome! Thanks Omar

[@arsalalam5998]

great video. looks simple but all the required content in place.

[@jaelski1217]

I love you guys for this.

[@Certbros]

Love you too man! 👊

[@ranjitdhiwar8545]

Nice Explanation . Thank you so much !

[@Certbros]

Thanks!

[@TabInvader]

Fantastic explanation!!

[@vipulkrishna19]

pretty good explaination

[@Certbros]

Thanks!

[@justcode7326]

I've a doubt here, you explained only with one machine sending request and corresponding row is created,but what if multiple computers sending request,there would be same public ip mapped with it, then how will router know where to send package in local network?

[@Certbros]

Great question. This is possible using the source port number.

[@itsAnaMC]

Just wanted to say thanks for these very helpful videos! :)

[@Certbros]

You're welcome! Thanks for the comment.

[@ronaldocorrea8007]

Simple is better, perfect !

[@Certbros]

Thanks Ronaldo

[@ecvsio]

good vibeo but there was a smol mistake at 4:40 where it says 11.22.33.44:8879 instead of 11.22.33.44:8897

[@Certbros]

Typo! Good spot! Thanks.

[@mashabadigojane9261]

Thanks for the explanantion, extremely useful

[@sz3066]

great video👍🏻 but i have a question. Lets say if i have 2 devices in private network, and they use the same public network, is there a conflict? or it is usual?

[@Certbros]

Depending on the type of NAT being used, both devices will use the same Public IP address. NAT will keep track of this and separate the traffic.

[@sz3066]

@@Certbros thank you 😁

[@Throdne]

Loved the video! Do you think you can explain masquerade? Also, can you make a video just like this explaining firewall rules and how they work. E.g. like what’s the difference between related established invalid and new etc. I️ own a edge router, and I’m slowly trying to teach myself how to write firewall rules. Also, QoS would be awesome as well!!! Thank you, Throdne

[@Certbros]

Thanks Throdne! Masquerading is pretty much the Linux word for Overload/PAT in this video. I'm assuming your firewall is based on Linux so you likely have a SNAT (changes the source address) and DNAT (changes the destination address) option as well. Definitely going to do some security videos in the future!

[@jahidhossain5884]

i am from bangladesh ...it is very usefull for us...

[@sahilsanghvi929]

How would a public IP addres be translated into the private one. like how does the router know which device it should send it to if the public ip address is the same?

[@jagdishsingh5877]

smoothly DONE !!!

[@Certbros]

Thanks!!

[@L84AD88]

Very nice vid made it easy to understand

[@frederikandersen245]

3:56 "Now the port number is very imPORTent here", I see what you did there mister

[@karanb2067]

So in PAT, if we have multiple devices, how will the incoming traffic which device to direct to. I understand there is a table to keep track of all the devices but since there's only one public ip address, which the source passed, now how does the router know which private address to access and send the traffic to?

[@Certbros]

When the computer sends traffic it chooses a source port. When that traffic comes back, that source port will be the destination. Using that port number, the router knows where to send the traffic.

[@ChrisS-bq4pj]

So actually, these 3 modes differ in the way of what public ip they use: dynamic can use a different range of IP adresses, overload can change the port and static always have everything the same? Is this true?

[@tanvirhaider617]

thank you sir, you saved me a lot of time.

[@Certbros]

You're welcome!

[@trishasrivastava4824]

I have a question (off topic) if we put in URL bar HTTPS://123.52.67.32:8080 we are giving two ports 443 for https and additional 8080. what does that mean. I hope you look at this 😊

[@Certbros]

In this case, I believe you are using port 8080 rather than both ports.

[@Gisbert-12843]

Btw awesome explaining! Got an awesome voice!

[@DevonLv]

How does NAT work when devices between two LANs using the same private IP address range? For example, say there are two devices on a network with 192.168.0.2 and 192.168.0.3 addresses trying to communicate over the internet to another network with devices using the same addresses. If the PC with the 192.168.0.2 address in one network was sending a packet to the 192.168.0.3 address in the other network, how would the router know not to just send that packet to the other device within the same network?

[@Certbros]

Good question! When you send the packet, you would send it to the public address (NAT address) not the private address. PC 192.168.0.2 wouldn't send a packet to 192.168.0.3, it would use 192.168.0.3 public address instead.

[@IronHelpsUsPlay]

Nice voice, great explanation - you've earned your subscribe!

[@Certbros]

Thanks! Appreciate the support 👌

[@vaishalivg]

Excellent explanations 🔥🔥🔥

[@Gisbert-12843]

So since all of my networks devices share the same IP, the router only differs them by the used port? I feel like I'm missing something here.. my roommate and I certainly use different public IPs though we are on the same network..

[@Black-xy4pj]

Great video man! Thanks much

[@Kriisiity]

Could you make more videos which cover the CCNA topics ?

[@Certbros]

On the way. Stay tuned.

[@omemester6985]

If the router generates a new public ip address from the device that wants to connect to the internet, then why is the public ip address on my phone and computer the same?

[@Certbros]

The router generates a private IP address, not a public one. The reason your computer and your phone have the same public address is because your router is translating them. I hope this answers the question.

[@fit_with_a_techie]

Hi, could you please upload videos about router interfaces?

[@Certbros]

Do you mean the like the difference between different interface types?