inside to inside NAT?

Unanswered Question
Apr 8th, 2008
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I have a pretty standard NAT setup for a company with a small Cisco 871 WAN router:

int E0, IP=xxx.xx.xx.xx, ip nat outside

int Vlan1, IP= ip nat inside

one port forwarding rule:

ip nat inside source static tcp 110 xxx.xx.xx.xx 110 extendable

People have laptops set up with an email application that has the xxx.xx.xx.xx public IP hard-coded in it. It works fine outside "on the Internet", but when they bring their laptops into work, it doesn't work. Now, obviously, one solution is to change the hard-coding of the app to go to the Vlan1 IP of instead the outside public IP of xxx.xx.xx.xx

But is there a way to do this with "ip nat" statements?

I tried an "ip nat outside static xxx.xx.xx.xx" but that didn't work.

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Jason Fraioli Tue, 04/08/2008 - 11:23
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sounds like the more logical approach would be to use split DNS to control that. From the outside the address of = E0 (outside IP), but inside, the = your IP address.

Obviously this would require inside and outside DNS setup to accomplish this.

thomasdzubin Tue, 04/08/2008 - 11:32
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Yes, using DNS was considered, but (since I'm the network guy) I don't control the DNS servers and I'd rather see if a simple NAT statement can fix what I need.


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