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New Member

2651 Programming Questions


I have Cisco 2651 router running 12.1(3r)T2 IOS.

I have a special requirement that needs some special programming in my router.

The scenerio is this:

On FastEther0/0 is a switch to which my DNS server is connected xx.xx.xx.1. The IP assigned to Fastether0/0 is xx.xx.xx.3

On Fastether0/1 I have 2 IP assigned, each is its own class C subnet.

Currently I have an SMC gatway attached through a switch to Fastether0/1.

The WAN IP of the gateway belongs to yy.yy.yy.yy subnet.

The LAN IP of the gateway belongs to zz.zz.zz.zz subnet. Both of these subnets are configured on Fastether0/1.

I need to be able to remove the SMC gateway from the picture entirely, which is technically no problem.

The problem that I face is this:

My clients are currently configured with the LAN IP of the gateway as their DNS server. Many of my clients are no technically literate and it would be a struggle to get them reprogrammed.

I understand that through the router I can direct the IP that they are currently using as their DNS to my true DNS server which as stated is connected through Fastether0/0.

I have tried the ip nat inside, outside sequence along with ip nat inside source static etc, with no luck.

That sequence further caused problems for my client when trying to check their email for example, as that server is on the Fastether0/0 network.

I was reading about the DNS spoofing but my my version of the IOS does not support the ip dns command series.

I am desperate to get this problem resolved.

Please advise.


Re: 2651 Programming Questions

you may need the IP Plus IOS to get the dns commands you're looking for.

see this link for the IOS feature navigator: (you can find what IOS versions support DNS for your platform)

New Member

Re: 2651 Programming Questions

Without a service contract, how could I get an updated version of the IOS, such as 12.3 or 12.4?



Re: 2651 Programming Questions

Even most service contracts require you to buy upgrades between ios releases.

Any authorized cisco vendor can sell you IOS. If you search you will even find it on many of the online vendors that sell cisco. Just make sure they are authorized. If you buy it from a third party (like ebay) cisco will not honor the license and you may have issues putting the router on a service contract.

New Member

Re: 2651 Programming Questions

why you don t keep the SMC gateway, and in the config of that gateway you make the DNS server as the real DNS.

you don t need to connect the SMC directly to 0/1 you can use a hub if u need to attach other device to 0/1

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