Inside Local, Inside Global, Outside Local, Outside Global -- NAT on Cisco IOS Routers

Cisco likes to use these terms to describe NAT: Inside Local, Inside Global, Outside Local, Outside Global. This video illustrates what each of these terms mean by defining the individual words within each term: Inside vs Outside, and Local vs Global.
This is a free lesson from my course on Network Address Translation on Udemy. The course runs $30 normally, to get it for $12.99, use this link:
www.udemy.com/...
If this link's coupon is expired, check this page for the most up to date discounted referral links:
www.practicaln...
(or pracnet.net/classes for short)
====
The full course has two modules:
The first module will teach you Everything there is to know about Network Address Translation: Why it exists, How it it works, What happens to packets as they get translated. This module will explain every type of translation: Static NAT, Static PAT, Dynamic PAT, and Dynamic NAT. You'll learn about each of these in a way that is completely vendor agnostic -- the concepts you learn here will apply to any vendor and any platform. You'll then learn how these four types of translations are used in Policy NAT and Twice NAT.
The second module will teach you how to Configure and Verify each type of address translation discussed in Module 1. If you configure or troubleshoot NAT on a Cisco Router, this is the module for you! We'll methodically take you through the the syntax for each type of NAT and show you various show commands that let you validate NAT's operation.
The lab topology will show and prove every NAT concept from Module 1, as we show you a packet capture before it arrives on the NAT router, and after it leaves the NAT router -- showing you exactly what is changed and in what situations.
This course is the last resource you will ever have to study to become a subject matter expert (SME) on NAT on a Cisco Router.

[@sinade1]

The instructor knows how to simplify difficult technologies. The uncommon quality among Cisco instructors. If you can understand these terminologies, NAT becomes easy. Well done!

[@PracticalNetworking]

Hi Sinade, thank you for the kind words =) I'm so glad you enjoyed this content!

[@darkconviction26]

This is the absolute best explanation I have ever seen for this, thank you so much!!

[@PracticalNetworking]

Glad it was helpful!

[@rogerward6242]

Finally, a clear explanation! Thank you!!

[@PracticalNetworking]

Glad you enjoyed it, Roger. You might also enjoy the rest of the videos in the NAT series: kzbin.info/aero/PLIFyRwBY_4bQ7tJvbLA9A0v8Fq9l-H923

[@catalyticcentaur5835]

I came back here for these definitions after quite some time... Good, that it's still here. Thank you, Ed, for providing your very good presentations.

[@anilrs8]

Nice and simply explained. Thanks for the video :)

[@usernotfound1044]

I have a final in Cisco 4 in like... 51 minutes. I found your channel reviewing for the exam and I really like your channel. Thank you so much for the effort you put into this. It's really helped me a lot.

[@PracticalNetworking]

Glad it's helped... but don't leave us in suspense, how did the final go? =)

[@eduardovilchis1107]

Very clear, nice and concise explanation of a complex topic. Thank you so much for uploading this video : )

[@Recken1]

I haven't come across NAT yet in my studies, but I'm sure I'm going to be grateful for this informative video. Great Job.

[@UnknownSend3r]

Best explanation of NAT.

[@PracticalNetworking]

Thank you, Aris =)

[@cspell]

Well presented, came back for a refresher and I remember it being trickier to understand when I first got my CCNA,

[@PracticalNetworking]

Thanks, Chris. =). I too wish it was explained like this when I first learned it.

[@christianvega03]

The best explanation that I've ever been seen.

[@PracticalNetworking]

Thank you, Christian. Glad you liked it =)

[@jerikho04]

Thank you for the short, clear and perfectly understandable video, sir.

[@PracticalNetworking]

You're welcome!

[@thearcher1740]

Oh God. Thank you. I was tearing my hair out reading obtuse RFC's and wondering why outside local/outside global are the same values (in which case why tf are they diff terms). But obviously I was unaware of more complex configs such as twiceNAT or NAT-ing destination IP

[@PracticalNetworking]

You're very welcome. I'm happy that this video helped it all click. =)

[@sahmad2084]

best explanation I have ever seen for this, thank you so much!! Free Palastine from america and Isreal

[@jeffsims5683]

This is a refresher for me and this explanation gave a clearer understanding than I had before. Thanks!

[@PracticalNetworking]

Awesome. Glad to hear it =)

[@TheSony7up]

Best explanation on outside local and globals.

[@PracticalNetworking]

Thanks, Rohit =)

[@user-ts9jq8pm1h]

Exactly what i was looking for, thanks.

[@ttitrends]

The topic is very difficult. But you explained in a very easy way and made me understand very well.

[@xN3Kr0]

Great video. It helped me, thank you!

[@PracticalNetworking]

You're welcome =)

[@Sijyro]

Thanks again for your videos, thses are really well made !

[@MeiinUK]

Now, this is useful. Kind of like lan, wan, etc.

[@PracticalNetworking]

Glad you enjoyed it, May =)

[@Marco-ls6ou]

Well Done! Keep up the good work! Thanks a lot!

[@PracticalNetworking]

You're welcome =). Thanks for the kind words.

[@nullsemicolon]

Great Video!

[@PracticalNetworking]

Thanks!

[@joshuameaders8053]

Hands down best explanation

[@jkforristal]

Clear and.concise. Well done!

[@PracticalNetworking]

Thank you, Jim =)

[@SandeepKumar-gf2kj]

By reading Documents, was not making me understand these terms, but you explanation was quite clean :) keep it up

[@PracticalNetworking]

Thanks, will do!

[@mrvgarg]

Thanks! finally get it.

[@PracticalNetworking]

Congrats! =)

[@divinecorpus7277]

As expected - just wowwwww🔥🔥🔥

[@PracticalNetworking]

Thank you, Devine =)

[@Zen-lz1hc]

Really cool video It helped me alot to understand this confusing terms .. Many Thanks :)

[@PracticalNetworking]

You're welcome, Zen =)

[@pasanchethiya338]

Superb!!!

[@catalyticcentaur5835]

Yup. I think, this can't be explained better. wd, Sir!

[@PracticalNetworking]

Thank you =)

[@18mellow]

This series is really good, can you make DNS deep dive series like SSL, TCP/IP series? There is no series on youtube which talks about DNS at packet level.

[@messaoudi1997]

Thanks a lot man!

[@PracticalNetworking]

You're welcome, Anis =).

[@pte-entertainment]

THANK YOU

[@PracticalNetworking]

You're welcome =)

[@wolfram77]

5:03 Is a twice NAT used for VPN, to connect 2 private networks? (I still have a lot to learn)

[@PracticalNetworking]

Yup! That is a perfectly valid use case for Twice NAT =). I wrote about that here: www.practicalnetworking.net/stand-alone/vpn-overlapping-networks/ I wrote more about Twice NAT here: www.practicalnetworking.net/series/nat/policy-nat-twice-nat/

[@md.ifthahossainsagar5679]

Thank you very much

[@siddarthnaik7316]

Nicely explained👍🏻

[@hahaeggplanet12]

great!

[@johnharveynuyda2914]

very good video

[@PracticalNetworking]

Thanks

[@Flqmmable]

Thanks! Really helped alot!

[@talalakbarlaghari]

Bang - nailed it!

[@johnwinslow4541]

Great Video

[@aljabri272]

Thanks 🌹

[@OROZCO2323]

This is so good

[@sandromactallica296]

👍🏻

[@rnjnmhta.catomato]

#imp for it

[@admin_e]

👍👍👍

[@PracticalNetworking]

👍

[@FarsiSongs_IR_AF_TJK]

Great

[@alittax]

What if you have another host in the same network as A, and that host (let's call it C) uses the same port as A (3333) and sends a packet to the same destination IP+port combination? When host B responds, how does the NAT device know which packet belongs to A and C? Won't all information be the same? Or the source port on C cannot be the same as on A, because if C happens to select the same one at random as A, the NAT device sends it back to C and requests a new port address? I assume at least that the NAT device uses the ports in order to keep track of which packets belong to which hosts, but please correct me if I'm wrong.

[@PracticalNetworking]

Ahh, you're describing exactly the situation that forces a Dynamic PAT to change the source port on behalf of the host (Host C, in this case). I unpack it in more details in this article: www.practicalnetworking.net/series/nat/dynamic-pat/ Or, if you prefer video form, I also unpack it in this (free) NAT course: classes.pracnet.net/courses/network-address-translation

[@alittax]

@@PracticalNetworking Thank you very much, I'll check out both! :)

[@lucas93177]

Nice explanation! So the outside local address will always be the same as the outside global address ? In that case what is the point of having 2 types instead of one ?

[@PracticalNetworking]

Most of the time, yes, but not *all* of the time. There are instances where the Router is translating the Outside host address. You would see this in cases Twice NAT: www.practicalnetworking.net/series/nat/policy-nat-twice-nat/#twice-nat

[@lucas93177]

Thanks yes indeed and I just found out that they are also different when using ip nat outside for translating the source from a host outside to an inside host !

[@ahemednor5201]

🙏🙏🌹🌹

[@PracticalNetworking]

[@rajuraghavan4158]

Shouldn't the Outside local be different ?

[@gauravtrivedi80]

Great explanation, thanks!, i would like to buy the course on Udemy, can you please provide the discount code ?

[@PracticalNetworking]

Glad you enjoy it =) I have all the NAT courses on Udemy available for $10 on my classes site: classes.pracnet.net/ Let me know if you have any issues joining =)

[@gauravtrivedi80]

@@PracticalNetworking Much appreciated your response!, Thanks, but i was hoping to keep all my course at one place and i use app and desktop back and forth for studying, would appreciated if you can get me code that i can use on Udemy, i also saw TLS deep dive course, will review that one too, Regards: G

[@PracticalNetworking]

@@gauravtrivedi80 No worries. I understand. I've updated the codes for Udemy on my site: www.practicalnetworking.net/classes/ The Udemy coupon codes won't let me create a long-term coupon for less than $16.99. I know Udemy runs sales which drops courses to $10~ occasionally. When they do that, they take 1/2 the course fee. =/. Where as the instructor created coupon all the funds go to the instructor. The TLS course is only available on my own teaching platform. That course has been six months in the making and isn't something I could be comfortable with Udemy selling at $10 =/.