[TriLUG] Off Topic: Need Cisco Router Config Help

[Tarus Balog]

On Apr 3, 2008, at 7:32 PM, Chris Bullock wrote:
> First thing I would do is without the help of the host file try to  
> ping
> private.opennms.com and see what you get.  Then perform a dig or  
> nslookup
> to see exactly what DNS server gave you that IP.

It's definitely not a DNS issue. It's a NAT issue.

Let's assume the external address is 10.1.1.1 and the internal LAN is  
172.20.1.0/24.

If www.example.com points to 10.1.1.1, the router will NAT port 80 to  
172.20.1.10.

 From outside the LAN, http://www.example.com works fine.

 From inside the LAN, http://www.example.com connects to the router's  
HTTP server (http://10.1.1.1), thus NAT is not working from the LAN.

The *workaround* is to set, on the LAN, www.example.com to point to  
172.20.1.10.

Now, when the router was a Linksys, www.example.com worked in all  
places. I was wondering if there was something in the way Cisco does  
NAT to make that work as well.

-T

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Tarus Balog, OpenNMS Maintainer             Main:   +1 919 533 0160
The OpenNMS Group, Inc.                     Fax:    +1 503 961 7746
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