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Newbie: Cisco 851w and nat


I am a network administrator and recently decided to upgrade my existing network infrastucture at my small office by purchasing a

Cisco 851w router.

I have 14 computers that need internet connection sharing and an Ubuntu 6.06 box running e-mail services, web and dns hosting for

my domain (master zone, running bind9).

Using SDM express I configured the network in 15 minutes, and also NAT for the Linux server. Everything is fine, except one

thing: when I access my domain (let`s say from my local network I don`t get my webpage or a response from the mail

server, but instead my SDM express login window. From an outside network I can access my mail and web page using

and Internally I get a response from the router.

This is how I configured the network with SDM express: as my routers ip address and network address, dhcp enabled, router`s name is router and domain "". At the

dhcp section I typed my ISP`s dns server. The linux box has the ip and runs bind9 for the "" as the master

server. I added the following NAT with SDM: 53 tcp and udp from WAN ip ( to, 22 tcp, 25 tcp, 80 tcp,

etc. WAN IP is the ip from my ISP (

Can I fix this using SDM, and how? It`s not an option to type as incoming mail server instead of I don`t know how to use CLI, I bought this router just to be able to run away from my old 486 iptables machine. :D

Thanks for you time!

New Member

Re: Newbie: Cisco 851w and nat

After searching the internet, I found this forum with the exact problem that I encounter: Could not find a proper fix for this. :(


Re: Newbie: Cisco 851w and nat

You are absolutly right in that you are not the only one with this problem.

Check this post and the link provided by Sundar out.;jsessionid=968333ACF23358AC6443CE3DC4C19CD9.SJ3B?page=netprof&forum=Network%20Infrastructure&topic=WAN%2C%20Routing%20and%20Switching&CommCmd=MB%3Fcmd%3Ddisplay_location%26location%3D.1ddccf83

And hopefully you will find a working solution.

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