Cisco IP NAT Outside vs Inside

NAT Playlist: • NAT
blog.ine.com/20...
www.astorinonet...
www.cisco.com/...
www.cisco.com/...
IP nat inside source (Normal NAT for Internet)
o Translates the source of the IP packets when traveling from inside to outside
o Translates the destination of the IP packets when traveling from outside to inside
IP nat outside source (Useful for overlapping subnets)
o Translates the source of the IP packets when traveling from outside to inside
o Translates the destination of the IP packets when traveling inside to outside

[@DerpyNetworking]

2:16 I meant to say inside to outside then outside to inside. I fix myself later on. Sorry. XD

[@thenbali]

Beautiful. WOW!

[@jitenderyadav7923]

Thanks a lot. It cleared all of my NAT confusion

[@nishan_nb]

Thanks for the great explanation. Keep up the good work!

[@dmitry3876]

Awesome explanation, thanks

[@richardcespedes3208]

Thank you for taking the time to do the video. But something's are not clear or confusing.

[@christosnicolaides4816]

I am doing a revision for CCNP... That's my video for NAT! Thanks!!!!

[@pastelek3]

more sloppy drawing with that marker, it only helps

[@wuyipiano]

Thank you so much.................

[@azatkhan4714]

Well done. Thanks

[@Mandalorx10]

Good job champ :)

[@qiaopuyun2139]

lady, you confuse yourself. :)-

[@joepoor5327]

thnk u

[@BlackBlueColor]

Thank you so much for this lap, it give me alot more understanding about inside and outside. I have tested on Cisco Packet tracer it work properly nice. but I have a stupid question haha, about the following routes this work properly ip route 8.0.0.50 255.255.255.255 1.1.1.2 ip route 10.0.0.50 255.255.255.255 2.2.2.2 ----------------------------------------------------------- but why this doesn't, why router cant make routes by this way ip route 9.0.0.50 255.255.255.255 1.1.1.2 ip route 10.0.0.51 255.255.255.255 2.2.2.2

[@DerpyNetworking]

I think you missed a key point. Don’t forget about routing and its order. Inside>Outside Route happens first then translation Outside>Inside Translation happens first then route As the packet arrives at R2 from R1, route happens first. Since the destination is 8.0.0.50, it looks at the routing table. In your second example, you are missing the 8.0.0.50 route. Thus the router drops the packet. A similar problem happens the other way. As the packet arrives at R2 from R3, translation happens first. The destination changes from 9.0.0.50 to 10.0.0.50. Route happens next. In your second example, you are missing the 10.0.0.50 route.

[@BlackBlueColor]

@@DerpyNetworking Excellent, I've never noticed about the order between route and translation. thanks :D

[@esakkiify]

@@DerpyNetworking wow explained awesome

[@Mark12434]

@@DerpyNetworking I know this is a two year comment but is the reason why its inside > outside then outside > inside because translation happen from one end packets exits the source the host and passes through the configured NAT device In your case the router so when it gets its receiving packet it has to translate from the other end back from public IP to private IP? so basically packet exits source to destination, gets translated to Public IP and then reaches destination returning packet gets sent to public IP, for ACK for an example gets translated to Private IP, then gets sent back to the host who initially sent the packet. so one end would you configure network address translation to function from one end and the outside for the other side in terms of packet migration.

[@theycxllmerichi6721]

@@Mark12434 I know im 7 months late but your explanation gave me right now the "aaaaaaaaa, now i get it moment" that i needed! Thank you very much!!!!!

[@sankets392]

i am messed up

[@DerpyNetworking]

How can I help?

[@sankets392]

@@DerpyNetworkingfor source A, Destination B....why actually destination nat of B at A is required while its coming in...as destination B public ip will any how announced in whole network of A where the destination nat B will b done

[@sankets392]

anyways i have seen ur blog for configuration....its really helpful....thank u boss

[@esakkiify]

I need clarification about 8.0.0.50 which need to configure on r3

[@esakkiify]

I don't need to configure the IP on R3 is right

[@DerpyNetworking]

@@esakkiify yes, you do not configure those IPs on any interface.

[@esakkiify]

I had tested outside Nat but it will not work R2 router having dummy ip route not having actual up route . and R3 having actual ip route not having dummy ip route. I tried ping and trace actual ip from R2 but will not ping . Kindly clarify because we have plan implement in production.

[@esakkiify]

I will not able to ping from actual source to actual destination but I can able to ping from actual destination to actual source. Why?

[@DerpyNetworking]

@@esakkiify There was a little bit more to getting this finished up. I just didn't have time to dive in a little deeper. Here is one of the articles I linked. I was going to do more research on this part. "It is important to note when you are trying to establish connectivity between two overlapping networks by running dynamic NAT on a single Cisco router, you must use DNS to create an outside local to outside global translation. If you do not use DNS, connectivity can be established with static NAT, but it is more difficult to manage."