Network Address Translation - Computerphile

IPv4 ran out of space, so how are we still all looking at the internet? - NAT has the answer! - Richard Mortier explains how the IP address space was expanded upon.

This video was filmed and edited by Sean Riley.

[mirageh]

Sooo, this 10 minute discussion of NAT made way more sense then the 1 week discussion of the same topic in my networks course at my university. I'm not sure how I feel about that

[stevenschiro]

To put it a little simpler, imagine your house with 10 devices on the internet (laptops, desktops, game consoles, etc). Those don't have their own external IP address (the one on the internet). You only have 1 for your modem/router, and your router then forwards a packet to each device based on the port # and internal IP address.

This is why you need to set up port forwarding if you've ever played an online game, so that when a packet hits your router on a certain port, it knows which computer to send it to

[mina]

If you want a computer inside your network to accept connections, it must be configured in NAT. This is called “port forwarding” and it instructs NAT that if it gets a connection to (say) port 80, it should direct it to (say) 10.0.0.1:80 in the private network. If there is no such configuration, incoming connections will be dropped. If incoming packet is part of already established connection, NAT just looks at destination port and maintains a state mapping it to ip:port in local network.

[gooeychocolatechipcookie]

what he explained was overloading, or PAT(port address translation). But it was still a very nice explanation of PAT. just clarifying.

[KarlBeeThree]

Finally, a rational, clear explanation of how NAT works and how it's implemented. Thanks !!

[Aemilindore]

University of Notingham is awesome. you guys have conversant professors! I also love Nottingham for the fact that Robbin lived there!! Regards from Sri Lanka.

[footballhighlightsbynyakwa]

You guys are my heroes, me who has no computer science background but I am learning how to develop softwares by myself. These videos are extremely helpful. God bless you all

[rlamacraft]

Im starting a degree in Computer Science in a couple of weeks and these videos are getting me really excited for my course - brilliant videos, every single one :)

[IzzyIkigai]

There are now also ISPs that use IPv4 NAT instead of upgrading to IPv6, so it could happen that your "external" address of your router is in fact an IP address in a private range. This can severely impact some software, for example games or remote desktop solutions. A colleague of mine had the problem with Teamviewer on one of the German cable networks.

[DoctorCobweb]

thankyou for uploading more of this guy. he explains things so clearly (as do all the others). going to rewatch them all soon. keep up the awesomeness.

[modus_ponens]

I would appreciate subtitles. He's talking quite quietly and quickly about complex things.

[CppExpedition]

👏👏thx i have that question for so long time, noone had explained me before that the translation not just translate the IP local to global, but also it translate THE PORT number!

[LittlePeng]

My opinion on what MUST appear on this channel is what actually is an algorithm. We had lesson about sorting algorithms, but not on algorithms in general.

[PlayStationKing]

nice, keep up the good work computerphile

[tretronthedragon]

i had a lot of trouble with my XBOX because my NAT type was closed. and port forwarding didn't work. after i seen this video i suddenly solft it :o thank you!

[locust]

UDP doesn't need any special trickery to be address translated. The PAT process isn't looking for sessions, it's looking at source and destination port pairs. Since UDP packets still have a source and destination port, they're translated without issue. Incoming port forwarding is the same.

[h.oliabak]

What tools did you use for creating this animation? Amazing!

[CaitlinJoRamsey]

Brady, it would be helpful to have a video focused on NAT or IPv6, or port-forwarding. I've been trying to solve a networking problem: connecting from a remote unix machine (a laptop--meaning I could be anywhere) to a database engine (SQL server) residing on my home network. I've learned more about networking than I ever wanted to know--just in tinkering to get to my database! But now I'm intrigued...

[RemixPicture]

A lot of counties are already using IPv6, though the US has a lot more IPv4 adresses than the rest of us so they keep using it. There's still some things to work out with IPv6 and there's still a lot of companies running old hardware that doesn't have IPv6 enabled which messes things up.

Going from IPv4 to IPv6 is a big step and you pretty much need everyone to be able to take it at the same time.

[ksng]

As a person who had very little computer science knowledge, I found this harder to understand than quantum physics, and I love it.