Cisco 800 Router NAT Loopback

Unanswered Question
Oct 30th, 2009

G'day Experts,

I have a private network: 192.168.1/24

I have a single public static IP address from my ADSL ISP.

I have a server which hosts a DNS with a private address in my private network.

I have created a NAT 1:1 to my private server to my public IP.

The requests from the internet work fine, my DNS resolve to my public IP address fine.


Requests from my private network 192.168.1/24 point to my public IP address which my router does not loop back through to my server.

I know a lot of routers/gateways support this feature, I just can't get it to work on my 800 series

Any assistance apreciated.



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thotsaphon Fri, 10/30/2009 - 10:51


It won't work in this case when private network tries to connect the IP of the DNS that is your public IP address on your router. The router won't do a static nat back to the Because the requesting packets are not coming from the outside interface(Internet interface). In case of ASA firewall, it has a dns doctoring to solve this problem. I have never seen any feature on the cisco IOS to do this. What about setting the dns with the private IP address for internal users? (grin)



Arthur_Mino Fri, 10/30/2009 - 17:17

G'day Toshi,

I have this config file from a Cisco 800 series which was doing it, I just can' tell how. I have a couple of these Routers at clients places setup by their ISP's that do it.

I refuse to think you can't do it with IOS, so many home brand router/gateways support this feature.

Any assistance very much appreciated.




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