MicroNugget: What is Network Address Translation?

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In this video, Keith Barker covers NAT, why it's necessary, and its relationship to PAT. Obviously a local network can assign addresses however it wants to, but somehow traffic headed for the Internet has to get a global address. Naturally, NAT's how it happens.
Speaking generally, an IP address isn't really anything more than a street name and a house number - useful if you're in the same area, but useless if you don't know what city, state or country the street is in. When you're on a local network, that's usually no problem - but private addresses don't work on the Internet. That's where Network Address Translation comes in.
When a host makes a request that's headed for the Internet, a router substitutes the private address for its own global address, and then when the fulfilled request comes back, the router remembers which host originated the request and untranslates the global address back to private. NAT and PAT are vital for routing and help keep the number of global addresses to a minimum.
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[@KeithBarker]

Hello Adam. Yes, you are absolutely correct! They often use a flavor of NAT called PAT (port address translation) that allows all the IP addresses on the inside be translated to the single IP address that is being used by the router itself. Cheers, Keith

[@joselevicanasenjo2171]

Keith, I just came across your channel. I just loved it. It has been very informative, the best!. THe Wireshark demostration is very helpful, and clarified many doubts I had. I dont know if there is another channel that explains networking as well as you do. I am starting to follow you!! Thanks for posting

[@KeithBarker]

Glad you like the videos. Thank you for the feedback! Keith

[@alittax]

Hello. Thanks for the videos! I've got one question about NAT: if the internet sends back all packets with the same IP, then how does the router (that does the NATing) tell the difference between each packet? How does the router know that packet A from the internet is destined to host A, and not host B, if the internet can't code any information that can tell the difference between packets A and B? Thanks.

[@niiodaie]

You are the best Keith....you keep it easy and simple, great JOB man!!! You + Jeremy rock the Networking World

[@KeithBarker]

Hi Manoj- Thanks for the feedback! I appreciate it. Keith

[@Santosh2730]

A simple and very informative video for beginners. Thanks a lot.

[@sbentjies]

Thanks for making it simple to understand!

[@18steps]

informative and easily understandable

[@cbtnuggets]

He's also working on several full length series for us, currently he's working on one for Network+

[@muhammadlateef7193]

Keith thanks for sharing very useful information. Can you please do a short nugget on NAT-T

[@Dinodialoo]

you and Jeremy are the best of the best , well done

[@KeithBarker]

Thanks Ankit! Keith

[@vigilantezack]

New sub, looking forward to all Net+ stuff. Thanks a bunch!

[@johnconnor9787]

Thank you for your awesome tutorials :) Could you please help with one question related to NAT configuration. Should we also configure our OUTSIDE port on a router as a default route (0.0.0.0 0.0.0.0 next_hop_ip)? Otherwise how the router will know that it should use NAT for a certain request of the user

[@ankitdoshi90]

Awesome Explanation while covering almost everything... Thank You Sir Don't stop with such tutorials in future :P It helps a lot :)

[@VS-ws4ls]

Helps alot! Im graduating tomorow and NAT is one of the question, I knew NOTHING about it, but now I know how it works pretty well! thanks

[@cbtnuggets]

Vojta Sleichert You're welcome. And congratulations on your graduation!

[@VS-ws4ls]

I guess I wrote it wrongly, Im not english talking guy :D I will have the exam tomorow... :D so idk if I will make it yet, but thanks :)

[@cbtnuggets]

Vojta Sleichert Oh well in that case, best of luck on your exam! :)

[@VS-ws4ls]

thanks alot ! :) will let you know how I ended up, if I will not forget :D

[@VS-ws4ls]

I DID IT!!!!!!!! YAAAAY but I did not get NAT question, but thanks anyway :D

[@Yatana108]

very good and simple explanation

[@1Midnight187]

thanks a lot for the informative video :)

[@cbtnuggets]

Daniel McRowley You are welcome! Don't forget to submit a MicroNugget request if you have one in the link above.

[@TauterHobo007]

Thanks a lot of good information but I do have a question..... when playing games online why does the NAT change to strict for some people?

[@TheVerengena]

real good one Keith

[@aquaticsplashes]

you're a good teacher

[@lupineye]

Yes! usually home wireless router has PAT and RIP as long as I know.

[@adityasingh4126]

Can we restrict the bandwidth from the private side of the NAT before forwarding it to public IP

[@Voodookillers]

this info.... is so basic it makes to much sense , THANK YOU! xD

[@khalidmorada550]

the best presentation! i like it..very useful. thank you

[@DavidJercinovic]

i understand the host on the inside is the inside local, but after that I have a hard time piecing together which is the inside global, outside local and outside global ... i understand the outside host must be google.com, the 8.8.8.8 address, but is that the outside global or outside local ? and if i type "what is my IP address" into google.com what address is that? inside global?

[@sudarshanpawar4596]

Thumbs up keith!

[@blackhathackerz]

nice video..you really helped me...thanks a lot

[@katarimanojrevs]

awesome exlanation..tanxxx

[@LovingDatMinecraft]

Saints row 4 is telling me I cant connect to games online because of my NAT how do i change that?

[@poligon333]

Thank you thank you thank you.

[@edinjusupovic8442]

Thank you alot.

[@AdamMT1618]

Thank you. so basically all home routers are NAT?

[@SakarSubedi]

How to port forward if case of NATing ??

[@hungvu-xc3uf]

so are there any problems with NAT?

[@thenextbigthing7268]

Also is this all still standard now? Except for the ip class though as we mostly use class c now right? My private ip is the 192 one.

[@cbtnuggets]

For the IP addresses, you are allowed to use a class A, B, or C within a private network. The default for home routers are going to be a class C address range.

[@Lardzor]

At 2:38 you say the router just swaps out the source address. So what happens if two people on the private network communicate to google at the same time. Both outgoing packets from the router would have a return address AND PORT that are identical. How would the router know which computer to send the return packets to? Doesn't the router have to give each outgoing packet unique port addresses, so it can distinguish the returning packets? If so, your comment at 2:38 is misleading.

[@haydo8373]

Good questions, I found this - whatismyipaddress.com/nat see paragraph four

[@maycoltreminio9914]

Very helpful. Thank ou

[@77jaykb]

Missed the point, why NAT in the first place. Coz we dont have enough ipv4 addresses

[@sourabhjaiswal1530]

Hello CBT Team, Can you please share the types cyber/ malware attack (hostile or intrusive software, including computer viruses, worms, trojan horses, ransom ware, spyware, adware, shareware, and diff malicious programs.) video on your channel. I need your help on this topics. Regards, Saurav J

[@NirajanParajuli]

nice video ..

[@thenextbigthing7268]

So how does getting hacked/ddosed or something work? Do they need the private one or global one?

[@cbtnuggets]

Hi! Thank you for your question. Getting hacked is having your systems be compromised. This can be achieved in many different ways, but it will mean either someone can gain access to your system or network. It doesn't even have to be full access, they may have a tool to send information. A DDoS is when hundreds/thousands of machines are compromised with some sort of malware to direct traffic to a specific location, which can overwhelm the one location. Let us know if you have any other questions!

[@FFxO]

wow sooo goood!

[@KeithBarker]

Hello- 2 or more inside clients, sharing the same (single) global address, is PAT. In answer to your question, yes. Keith

[@garyb2652]

the short verison